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Diffstat (limited to 'gcc/tree-ssa-loop-ivopts.c')
| -rw-r--r-- | gcc/tree-ssa-loop-ivopts.c | 5077 |
1 files changed, 5077 insertions, 0 deletions
diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c new file mode 100644 index 00000000000..df567564dd7 --- /dev/null +++ b/gcc/tree-ssa-loop-ivopts.c @@ -0,0 +1,5077 @@ +/* Induction variable optimizations. + Copyright (C) 2003 Free Software Foundation, Inc. + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it +under the terms of the GNU General Public License as published by the +Free Software Foundation; either version 2, or (at your option) any +later version. + +GCC is distributed in the hope that it will be useful, but WITHOUT +ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING. If not, write to the Free +Software Foundation, 59 Temple Place - Suite 330, Boston, MA +02111-1307, USA. */ + +/* This pass tries to find the optimal set of induction variables for the loop. + It optimizes just the basic linear induction variables (although adding + support for other types should not be too hard). It includes the + optimizations commonly known as strength reduction, induction variable + coalescing and induction variable elimination. It does it in the + following steps: + + 1) The interesting uses of induction variables are found. This includes + + -- uses of induction variables in non-linear expressions + -- adresses of arrays + -- comparisons of induction variables + + 2) Candidates for the induction variables are found. This includes + + -- old induction variables + -- the variables defined by expressions derived from the "interesting + uses" above + + 3) The optimal (w.r. to a cost function) set of variables is chosen. The + cost function assigns a cost to sets of induction variables and consists + of three parts: + + -- The use costs. Each of the interesting uses choses the best induction + variable in the set and adds its cost to the sum. The cost reflects + the time spent on modifying the induction variables value to be usable + for the given purpose (adding base and offset for arrays, etc.). + -- The variable costs. Each of the variables has a cost assigned that + reflects the costs assoctiated with incrementing the value of the + variable. The original variables are somewhat preferred. + -- The set cost. Depending on the size of the set, extra cost may be + added to reflect register pressure. + + All the costs are defined in a machine-specific way, using the target + hooks and machine descriptions to determine them. + + 4) The trees are transformed to use the new variables, the dead code is + removed. + + All of this is done loop by loop. Doing it globally is theoretically + possible, it might give a better performance and it might enable us + to decide costs more precisely, but getting all the interactions right + would be complicated. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "tree.h" +#include "rtl.h" +#include "tm_p.h" +#include "hard-reg-set.h" +#include "basic-block.h" +#include "output.h" +#include "diagnostic.h" +#include "tree-flow.h" +#include "tree-dump.h" +#include "timevar.h" +#include "cfgloop.h" +#include "varray.h" +#include "expr.h" +#include "tree-pass.h" +#include "ggc.h" +#include "insn-config.h" +#include "recog.h" +#include "hashtab.h" +#include "tree-fold-const.h" +#include "tree-chrec.h" +#include "tree-scalar-evolution.h" + +/* The infinite cost. */ +#define INFTY 10000000 + +/* The expected number of loop iterations. TODO -- use profiling instead of + this. */ +#define AVG_LOOP_NITER(LOOP) 5 + +/* Just to shorten the ugly names. */ +#define EXEC_BINARY nondestructive_fold_binary_to_constant +#define EXEC_UNARY nondestructive_fold_unary_to_constant + +/* Representation of the induction variable. */ +struct iv +{ + tree base; /* Initial value of the iv. */ + tree step; /* Step of the iv (constant only). */ + tree ssa_name; /* The ssa name with the value. */ + bool biv_p; /* Is it a biv? */ + bool have_use_for; /* Do we already have a use for it? */ + unsigned use_id; /* The identificator in the use if it is the case. */ +}; + +/* Per-ssa version information (induction variable descriptions, etc.). */ +struct version_info +{ + tree name; /* The ssa name. */ + struct iv *iv; /* Induction variable description. */ + bool has_nonlin_use; /* For a loop-level invariant, whether it is used in + an expression that is not an induction variable. */ + unsigned inv_id; /* Id of an invariant. */ + bool preserve_biv; /* For the original biv, whether to preserve it. */ +}; + +/* Description of number of iterations of a loop. */ +struct tree_niter_desc +{ + tree assumptions; /* Assumptions for the number of iterations be valid. */ + tree may_be_zero; /* Condition under that the loop exits in the first + iteration. */ + tree niter; /* Number of iterations. */ +}; + +/* Information attached to loop. */ +struct loop_data +{ + unsigned n_exits; /* Number of exit edges. */ + edge single_exit; /* The exit edge in case there is exactly one and + its source dominates the loops latch. */ + struct tree_niter_desc niter; + /* Number of iterations. */ + + unsigned regs_used; /* Number of registers used. */ +}; + +/* Types of uses. */ +enum use_type +{ + USE_NONLINEAR_EXPR, /* Use in a nonlinear expression. */ + USE_OUTER, /* The induction variable is used outside the loop. */ + USE_ADDRESS, /* Use in an address. */ + USE_COMPARE /* Use is a compare. */ +}; + +/* The candidate - cost pair. */ +struct cost_pair +{ + struct iv_cand *cand; /* The candidate. */ + unsigned cost; /* The cost. */ + bitmap depends_on; /* The list of invariants that have to be + preserved. */ +}; + +/* Use. */ +struct iv_use +{ + unsigned id; /* The id of the use. */ + enum use_type type; /* Type of the use. */ + struct iv *iv; /* The induction variable it is based on. */ + tree stmt; /* Statement in that it occurs. */ + tree *op_p; /* The place where it occurs. */ + bitmap related_cands; /* The set of "related" iv candidates. */ + + unsigned n_map_members; /* Number of candidates in the cost_map list. */ + struct cost_pair *cost_map; + /* The costs wrto the iv candidates. */ + + struct iv_cand *selected; + /* The selected candidate. */ +}; + +/* The position where the iv is computed. */ +enum iv_position +{ + IP_NORMAL, /* At the end, just before the exit condition. */ + IP_END, /* At the end of the latch block. */ + IP_ORIGINAL /* The original biv. */ +}; + +/* The induction variable candidate. */ +struct iv_cand +{ + unsigned id; /* The number of the candidate. */ + bool important; /* Whether this is an "important" candidate, i.e. such + that it should be considered by all uses. */ + enum iv_position pos; /* Where it is computed. */ + tree incremented_at; /* For original biv, the statement where it is + incremented. */ + tree var_before; /* The variable used for it before incrementation. */ + tree var_after; /* The variable used for it after incrementation. */ + struct iv *iv; /* The value of the candidate. NULL for + "pseudocandidate" used to indicate the possibility + to replace the final value of an iv by direct + computation of the value. */ + unsigned cost; /* Cost of the candidate. */ +}; + +/* The data used by the induction variable optimizations. */ + +struct ivopts_data +{ + /* The currently optimized loop. */ + struct loop *current_loop; + + /* The size of version_info array allocated. */ + unsigned version_info_size; + + /* The array of information for the ssa names. */ + struct version_info *version_info; + + /* The bitmap of indices in version_info whose value was changed. */ + bitmap relevant; + + /* The maximum invariant id. */ + unsigned max_inv_id; + + /* The uses of induction variables. */ + varray_type iv_uses; + + /* The candidates. */ + varray_type iv_candidates; + + /* Whether to consider just related and important candidates when replacing a + use. */ + bool consider_all_candidates; +}; + +/* Bound on number of candidates below that all candidates are considered. */ + +#define CONSIDER_ALL_CANDIDATES_BOUND 15 + +/* The properties of the target. */ + +static unsigned avail_regs; /* Number of available registers. */ +static unsigned res_regs; /* Number of reserved registers. */ +static unsigned small_cost; /* The cost for register when there is a free one. */ +static unsigned pres_cost; /* The cost for register when there are not too many + free ones. */ +static unsigned spill_cost; /* The cost for register when we need to spill. */ + +/* The list of trees for that the decl_rtl field must be reset is stored + here. */ + +static varray_type decl_rtl_to_reset; + +#define SWAP(X, Y) do { void *tmp = (X); (X) = (Y); (Y) = tmp; } while (0) + +static tree force_gimple_operand (tree, tree *, bool); + +/* Number of uses recorded in DATA. */ + +static inline unsigned +n_iv_uses (struct ivopts_data *data) +{ + return VARRAY_ACTIVE_SIZE (data->iv_uses); +} + +/* Ith use recorded in DATA. */ + +static inline struct iv_use * +iv_use (struct ivopts_data *data, unsigned i) +{ + return VARRAY_GENERIC_PTR_NOGC (data->iv_uses, i); +} + +/* Number of candidates recorded in DATA. */ + +static inline unsigned +n_iv_cands (struct ivopts_data *data) +{ + return VARRAY_ACTIVE_SIZE (data->iv_candidates); +} + +/* Ith candidate recorded in DATA. */ + +static inline struct iv_cand * +iv_cand (struct ivopts_data *data, unsigned i) +{ + return VARRAY_GENERIC_PTR_NOGC (data->iv_candidates, i); +} + +/* The data for LOOP. */ + +static inline struct loop_data * +loop_data (struct loop *loop) +{ + return loop->aux; +} + +/* Dumps information about the induction variable IV to FILE. */ + +extern void dump_iv (FILE *, struct iv *); +void +dump_iv (FILE *file, struct iv *iv) +{ + fprintf (file, "ssa name "); + print_generic_expr (file, iv->ssa_name, TDF_SLIM); + fprintf (file, "\n"); + + if (iv->step) + { + fprintf (file, " base "); + print_generic_expr (file, iv->base, TDF_SLIM); + fprintf (file, "\n"); + + fprintf (file, " step "); + print_generic_expr (file, iv->step, TDF_SLIM); + fprintf (file, "\n"); + } + else + { + fprintf (file, " invariant "); + print_generic_expr (file, iv->base, TDF_SLIM); + fprintf (file, "\n"); + } + + if (iv->biv_p) + fprintf (file, " is a biv\n"); +} + +/* Dumps information about the USE to FILE. */ + +extern void dump_use (FILE *, struct iv_use *); +void +dump_use (FILE *file, struct iv_use *use) +{ + struct iv *iv = use->iv; + + fprintf (file, "use %d\n", use->id); + + switch (use->type) + { + case USE_NONLINEAR_EXPR: + fprintf (file, " generic\n"); + break; + + case USE_OUTER: + fprintf (file, " outside\n"); + break; + + case USE_ADDRESS: + fprintf (file, " address\n"); + break; + + case USE_COMPARE: + fprintf (file, " compare\n"); + break; + + default: + abort (); + } + + fprintf (file, " in statement "); + print_generic_expr (file, use->stmt, TDF_SLIM); + fprintf (file, "\n"); + + fprintf (file, " at position "); + print_generic_expr (file, *use->op_p, TDF_SLIM); + fprintf (file, "\n"); + + if (iv->step) + { + fprintf (file, " base "); + print_generic_expr (file, iv->base, TDF_SLIM); + fprintf (file, "\n"); + + fprintf (file, " step "); + print_generic_expr (file, iv->step, TDF_SLIM); + fprintf (file, "\n"); + } + else + { + fprintf (file, " invariant "); + print_generic_expr (file, iv->base, TDF_SLIM); + fprintf (file, "\n"); + } + + fprintf (file, " related candidates "); + dump_bitmap (file, use->related_cands); +} + +/* Dumps information about the uses to FILE. */ + +extern void dump_uses (FILE *, struct ivopts_data *); +void +dump_uses (FILE *file, struct ivopts_data *data) +{ + unsigned i; + struct iv_use *use; + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + + dump_use (file, use); + fprintf (file, "\n"); + } +} + +/* Dumps information about induction variable candidate CAND to FILE. */ + +extern void dump_cand (FILE *, struct iv_cand *); +void +dump_cand (FILE *file, struct iv_cand *cand) +{ + struct iv *iv = cand->iv; + + fprintf (file, "candidate %d%s\n", + cand->id, cand->important ? " (important)" : ""); + + if (!iv) + { + fprintf (file, " final value replacement\n"); + return; + } + + switch (cand->pos) + { + case IP_NORMAL: + fprintf (file, " incremented before exit test\n"); + break; + + case IP_END: + fprintf (file, " incremented at end\n"); + break; + + case IP_ORIGINAL: + fprintf (file, " original biv\n"); + break; + } + + if (iv->step) + { + fprintf (file, " base "); + print_generic_expr (file, iv->base, TDF_SLIM); + fprintf (file, "\n"); + + fprintf (file, " step "); + print_generic_expr (file, iv->step, TDF_SLIM); + fprintf (file, "\n"); + } + else + { + fprintf (file, " invariant "); + print_generic_expr (file, iv->base, TDF_SLIM); + fprintf (file, "\n"); + } +} + +/* Returns the info for ssa version VER. */ + +static inline struct version_info * +ver_info (struct ivopts_data *data, unsigned ver) +{ + return data->version_info + ver; +} + +/* Returns the info for ssa name NAME. */ + +static inline struct version_info * +name_info (struct ivopts_data *data, tree name) +{ + return ver_info (data, SSA_NAME_VERSION (name)); +} + +/* Checks whether ARG is either NULL_TREE or constant zero. */ + +static bool +zero_p (tree arg) +{ + if (!arg) + return true; + + return integer_zerop (arg); +} + +/* Checks that X is integer constant that fits in unsigned HOST_WIDE_INT. + Similar to host_integerp (x, 1), but does not fail if the value is + negative. */ + +static bool +cst_and_fits_in_hwi (tree x) +{ + if (TREE_CODE (x) != INTEGER_CST) + return false; + + return (TREE_INT_CST_HIGH (x) == 0 + || TREE_INT_CST_HIGH (x) == -1); +} + +/* Return value of a constant X. */ + +static HOST_WIDE_INT +int_cst_value (tree x) +{ + unsigned bits = TYPE_PRECISION (TREE_TYPE (x)); + unsigned HOST_WIDE_INT val = TREE_INT_CST_LOW (x); + bool negative = ((val >> (bits - 1)) & 1) != 0; + + if (negative) + val |= (~(unsigned HOST_WIDE_INT) 0) << (bits - 1) << 1; + else + val &= ~((~(unsigned HOST_WIDE_INT) 0) << (bits - 1) << 1); + + return val; +} + +/* Builds integer constant of type TYPE and value VAL. */ + +static tree +build_int_cst (tree type, unsigned HOST_WIDE_INT val) +{ + unsigned bits = TYPE_PRECISION (type); + bool signed_p = !TREE_UNSIGNED (type); + bool negative = ((val >> (bits - 1)) & 1) != 0; + tree ival; + + if (signed_p && negative) + { + val = val | (~(unsigned HOST_WIDE_INT) 0 << (bits - 1) << 1); + ival = build_int_2 (val, -1); + } + else + { + val = val & ~(~(unsigned HOST_WIDE_INT) 0 << (bits - 1) << 1); + ival = build_int_2 (val, 0); + } + + return convert (type, ival); +} + +/* Checks whether there exists number X such that X * B = A, counting modulo + 2^BITS. */ + +static bool +divide (unsigned bits, unsigned HOST_WIDE_INT a, unsigned HOST_WIDE_INT b, + HOST_WIDE_INT *x) +{ + unsigned HOST_WIDE_INT mask = ~(~(unsigned HOST_WIDE_INT) 0 << (bits - 1) << 1); + unsigned HOST_WIDE_INT inv, ex, val; + unsigned i; + + a &= mask; + b &= mask; + + /* First divide the whole equation by 2 as long as possible. */ + while (!(a & 1) && !(b & 1)) + { + a >>= 1; + b >>= 1; + bits--; + mask >>= 1; + } + + if (!(b & 1)) + { + /* If b is still even, a is odd and there is no such x. */ + return false; + } + + /* Find the inverse of b. We compute it as + b^(2^(bits - 1) - 1) (mod 2^bits). */ + inv = 1; + ex = b; + for (i = 0; i < bits - 1; i++) + { + inv = (inv * ex) & mask; + ex = (ex * ex) & mask; + } + + val = (a * inv) & mask; + + if (((val * b) & mask) != a) + abort (); + + if ((val >> (bits - 1)) & 1) + val |= ~mask; + + *x = val; + + return true; +} + +/* Calls CBCK for each index in ADDR_P. It passes the pointer to the index, + the base if it is an array and DATA to the callback. If the callback returns + false, the whole search stops and false is returned. */ + +bool +for_each_index (tree *addr_p, bool (*cbck) (tree, tree *, void *), void *data) +{ + tree *nxt; + + for (; ; addr_p = nxt) + { + switch (TREE_CODE (*addr_p)) + { + case SSA_NAME: + return cbck (NULL, addr_p, data); + + case INDIRECT_REF: + nxt = &TREE_OPERAND (*addr_p, 0); + return cbck (NULL, nxt, data); + + case BIT_FIELD_REF: + case COMPONENT_REF: + nxt = &TREE_OPERAND (*addr_p, 0); + break; + + case ARRAY_REF: + nxt = &TREE_OPERAND (*addr_p, 0); + if (!cbck (*nxt, &TREE_OPERAND (*addr_p, 1), data)) + return false; + break; + + case VAR_DECL: + case PARM_DECL: + case STRING_CST: + case RESULT_DECL: + return true; + + default: + abort (); + } + } +} + +/* Forces IDX to be either constant or ssa name. Callback for + for_each_index. */ + +struct idx_fs_data +{ + tree stmts; +}; + +static bool +idx_force_simple (tree base ATTRIBUTE_UNUSED, tree *idx, void *data) +{ + struct idx_fs_data *d = data; + tree stmts; + + *idx = force_gimple_operand (*idx, &stmts, true); + + if (stmts) + { + tree_stmt_iterator tsi = tsi_start (d->stmts); + tsi_link_before (&tsi, stmts, TSI_SAME_STMT); + } + + return true; +} + +/* Updates TREE_ADDRESSABLE flag for the base variable of EXPR. */ + +static void +update_addressable_flag (tree expr) +{ + if (TREE_CODE (expr) != ADDR_EXPR) + abort (); + + expr = TREE_OPERAND (expr, 0); + while (TREE_CODE (expr) == ARRAY_REF + || TREE_CODE (expr) == COMPONENT_REF + || TREE_CODE (expr) == REALPART_EXPR + || TREE_CODE (expr) == IMAGPART_EXPR) + expr = TREE_OPERAND (expr, 0); + if (TREE_CODE (expr) != VAR_DECL + && TREE_CODE (expr) != PARM_DECL) + return; + + TREE_ADDRESSABLE (expr) = 1; +} + +/* Expands EXPR to list of gimple statements STMTS, forcing it to become + a gimple operand that is returned. If SIMPLE is true, force the operand + to be either ssa_name or integer constant. */ + +static tree +force_gimple_operand (tree expr, tree *stmts, bool simple) +{ + enum tree_code code = TREE_CODE (expr); + char class = TREE_CODE_CLASS (code); + tree op0, op1, stmts0, stmts1, stmt, rhs, name; + tree_stmt_iterator tsi; + struct idx_fs_data d; + tree atmp; + + if (is_gimple_val (expr) + && (!simple + || TREE_CODE (expr) == SSA_NAME + || TREE_CODE (expr) == INTEGER_CST)) + { + if (code == ADDR_EXPR) + update_addressable_flag (expr); + + *stmts = NULL_TREE; + return expr; + } + + if (code == ADDR_EXPR) + { + op0 = TREE_OPERAND (expr, 0); + if (TREE_CODE (op0) == INDIRECT_REF) + return force_gimple_operand (TREE_OPERAND (op0, 0), stmts, simple); + } + + atmp = create_tmp_var (TREE_TYPE (expr), "fgotmp"); + add_referenced_tmp_var (atmp); + + switch (class) + { + case '1': + case '2': + op0 = force_gimple_operand (TREE_OPERAND (expr, 0), &stmts0, false); + if (class == '2') + { + op1 = force_gimple_operand (TREE_OPERAND (expr, 1), &stmts1, false); + rhs = build (code, TREE_TYPE (expr), op0, op1); + } + else + { + rhs = build1 (code, TREE_TYPE (expr), op0); + stmts1 = NULL_TREE; + } + + stmt = build (MODIFY_EXPR, void_type_node, atmp, rhs); + name = make_ssa_name (atmp, stmt); + TREE_OPERAND (stmt, 0) = name; + + if (stmts0) + { + *stmts = stmts0; + if (stmts1) + { + tsi = tsi_last (*stmts); + tsi_link_after (&tsi, stmts1, TSI_CONTINUE_LINKING); + } + } + else if (stmts1) + *stmts = stmts1; + else + *stmts = alloc_stmt_list (); + + tsi = tsi_last (*stmts); + tsi_link_after (&tsi, stmt, TSI_CONTINUE_LINKING); + return name; + + default: + break; + } + + /* Some specially handled codes: */ + switch (TREE_CODE (expr)) + { + case ADDR_EXPR: + stmt = build (MODIFY_EXPR, void_type_node, atmp, expr); + name = make_ssa_name (atmp, stmt); + TREE_OPERAND (stmt, 0) = name; + + *stmts = alloc_stmt_list (); + tsi = tsi_last (*stmts); + tsi_link_after (&tsi, stmt, TSI_CONTINUE_LINKING); + + d.stmts = *stmts; + for_each_index (&TREE_OPERAND (expr, 0), idx_force_simple, &d); + + update_addressable_flag (TREE_OPERAND (stmt, 1)); + + return name; + + case INTEGER_CST: + if (!TREE_OVERFLOW (expr)) + abort (); + + stmt = build (MODIFY_EXPR, void_type_node, atmp, expr); + name = make_ssa_name (atmp, stmt); + TREE_OPERAND (stmt, 0) = name; + + *stmts = alloc_stmt_list (); + tsi = tsi_last (*stmts); + tsi_link_after (&tsi, stmt, TSI_CONTINUE_LINKING); + return name; + + default: + abort (); + } +} + +/* If TYPE is an array type, corresponding pointer type is returned, + otherwise the TYPE is returned unchanged. */ + +static tree +array2ptr (tree type) +{ + if (TREE_CODE (type) != ARRAY_TYPE) + return type; + + return build_pointer_type (TREE_TYPE (type)); +} + +/* Sets single_exit field for loops. */ + +static void +find_exit_edges (void) +{ + basic_block bb; + edge e; + struct loop *src, *dest;; + + FOR_EACH_BB (bb) + { + for (e = bb->succ; e; e = e->succ_next) + { + src = e->src->loop_father; + dest = find_common_loop (src, e->dest->loop_father); + + for (; src != dest; src = src->outer) + { + loop_data (src)->n_exits++; + if (loop_data (src)->n_exits > 1) + { + loop_data (src)->single_exit = NULL; + continue; + } + + if (!dominated_by_p (CDI_DOMINATORS, src->latch, e->src)) + continue; + + loop_data (src)->single_exit = e; + } + } + } +} + +/* Returns the basic block in that statements should be emitted for IP_END + position in LOOP. */ + +static basic_block +ip_end_pos (struct loop *loop) +{ + return loop->latch; +} + +/* Returns the basic block in that statements should be emitted for IP_NORMAL + position in LOOP. */ + +static basic_block +ip_normal_pos (struct loop *loop) +{ + tree last; + basic_block bb; + edge exit; + + if (loop->latch->pred->pred_next) + return NULL; + + bb = loop->latch->pred->src; + last = last_stmt (bb); + if (TREE_CODE (last) != COND_EXPR) + return NULL; + + exit = bb->succ; + if (exit->dest == loop->latch) + exit = exit->succ_next; + + if (flow_bb_inside_loop_p (loop, exit->dest)) + return NULL; + + return bb; +} + +/* Returs true if STMT is after the place where the IP_NORMAL ivs will be + emitted in LOOP. */ + +static bool +stmt_after_ip_normal_pos (struct loop *loop, tree stmt) +{ + basic_block bb = ip_normal_pos (loop), sbb = bb_for_stmt (stmt); + + if (!bb) + abort (); + + if (sbb == loop->latch) + return true; + + if (sbb != bb) + return false; + + return stmt == last_stmt (bb); +} + +/* Returns true if STMT if after the place where the original induction + variable CAND is incremented. */ + +static bool +stmt_after_ip_original_pos (struct iv_cand *cand, tree stmt) +{ + basic_block cand_bb = bb_for_stmt (cand->incremented_at); + basic_block stmt_bb = bb_for_stmt (stmt); + block_stmt_iterator bsi; + + if (!dominated_by_p (CDI_DOMINATORS, stmt_bb, cand_bb)) + return false; + + if (stmt_bb != cand_bb) + return true; + + /* Scan the block from the end, since the original ivs are usually + incremented at the end of the loop body. */ + for (bsi = bsi_last (stmt_bb); ; bsi_prev (&bsi)) + { + if (bsi_stmt (bsi) == cand->incremented_at) + return false; + if (bsi_stmt (bsi) == stmt) + return true; + } +} + +/* Returns true if STMT if after the place where the induction variable + CAND is incremented in LOOP. */ + +static bool +stmt_after_increment (struct loop *loop, struct iv_cand *cand, tree stmt) +{ + switch (cand->pos) + { + case IP_END: + return false; + + case IP_NORMAL: + return stmt_after_ip_normal_pos (loop, stmt); + + case IP_ORIGINAL: + return stmt_after_ip_original_pos (cand, stmt); + + default: + abort (); + } +} + +/* Initializes data structures used by the iv optimization pass, stored + in DATA. LOOPS is the loop tree. */ + +static void +tree_ssa_iv_optimize_init (struct loops *loops, struct ivopts_data *data) +{ + unsigned i; + + data->version_info_size = 2 * highest_ssa_version; + data->version_info = xcalloc (data->version_info_size, + sizeof (struct version_info)); + data->relevant = BITMAP_XMALLOC (); + data->max_inv_id = 0; + + for (i = 1; i < loops->num; i++) + if (loops->parray[i]) + loops->parray[i]->aux = xcalloc (1, sizeof (struct loop_data)); + + find_exit_edges (); + + VARRAY_GENERIC_PTR_NOGC_INIT (data->iv_uses, 20, "iv_uses"); + VARRAY_GENERIC_PTR_NOGC_INIT (data->iv_candidates, 20, "iv_candidates"); + VARRAY_GENERIC_PTR_NOGC_INIT (decl_rtl_to_reset, 20, "decl_rtl_to_reset"); + + scev_initialize (loops); +} + +/* Allocates an induction variable with given initial value BASE and step STEP + for loop LOOP. */ + +static struct iv * +alloc_iv (tree base, tree step) +{ + struct iv *iv = xcalloc (1, sizeof (struct iv)); + + if (step && integer_zerop (step)) + step = NULL_TREE; + + iv->base = base; + iv->step = step; + iv->biv_p = false; + iv->have_use_for = false; + iv->use_id = 0; + iv->ssa_name = NULL_TREE; + + return iv; +} + +/* Sets STEP and BASE for induction variable IV. */ + +static void +set_iv (struct ivopts_data *data, tree iv, tree base, tree step) +{ + struct version_info *info = name_info (data, iv); + + if (info->iv) + abort (); + + bitmap_set_bit (data->relevant, SSA_NAME_VERSION (iv)); + info->iv = alloc_iv (base, step); + info->iv->ssa_name = iv; +} + +/* Finds induction variable declaration for VAR. */ + +static struct iv * +get_iv (struct ivopts_data *data, tree var) +{ + basic_block bb; + + if (!name_info (data, var)->iv) + { + bb = bb_for_stmt (SSA_NAME_DEF_STMT (var)); + + if (!bb + || !flow_bb_inside_loop_p (data->current_loop, bb)) + set_iv (data, var, var, NULL_TREE); + } + + return name_info (data, var)->iv; +} + +/* Determines the step of a biv defined in PHI. */ + +static tree +determine_biv_step (tree phi) +{ + struct loop *loop = bb_for_stmt (phi)->loop_father; + tree name = PHI_RESULT (phi), ev, step; + tree type = TREE_TYPE (name); + + if (!is_gimple_reg (name)) + return NULL_TREE; + + /* Just work for integers and pointers. */ + if (TREE_CODE (type) != INTEGER_TYPE + && TREE_CODE (type) != POINTER_TYPE) + return NULL_TREE; + + ev = analyze_scalar_evolution (loop, name); + if (TREE_CODE (ev) == INTEGER_CST + || TREE_CODE (ev) == SSA_NAME) + return convert (type, integer_zero_node); + + if (TREE_CODE (ev) != POLYNOMIAL_CHREC) + return NULL_TREE; + + step = CHREC_RIGHT (ev); + + if (TREE_CODE (step) != INTEGER_CST) + return NULL_TREE; + + return step; +} + +/* Retunrs false if INDEX is a ssa name that occurs in an + abnormal phi node. Callback for for_each_index. */ + +static bool +idx_contains_abnormal_ssa_name_p (tree base ATTRIBUTE_UNUSED, tree *index, + void *data ATTRIBUTE_UNUSED) +{ + if (TREE_CODE (*index) != SSA_NAME) + return true; + + return SSA_NAME_OCCURS_IN_ABNORMAL_PHI (*index) == 0; +} + +/* Returns true if EXPR contains a ssa name that occurs in an + abnormal phi node. */ + +static bool +contains_abnormal_ssa_name_p (tree expr) +{ + enum tree_code code = TREE_CODE (expr); + char class = TREE_CODE_CLASS (code); + + if (code == SSA_NAME) + return SSA_NAME_OCCURS_IN_ABNORMAL_PHI (expr) != 0; + + if (code == INTEGER_CST + || is_gimple_min_invariant (expr)) + return false; + + if (code == ADDR_EXPR) + return !for_each_index (&TREE_OPERAND (expr, 1), + idx_contains_abnormal_ssa_name_p, + NULL); + + switch (class) + { + case '2': + if (contains_abnormal_ssa_name_p (TREE_OPERAND (expr, 1))) + return true; + + /* Fallthru. */ + case '1': + if (contains_abnormal_ssa_name_p (TREE_OPERAND (expr, 0))) + return true; + + break; + + default: + abort (); + } + + return false; +} + +/* Finds basic ivs. */ + +static bool +find_bivs (struct ivopts_data *data) +{ + tree phi, step, type, base; + bool found = false; + struct loop *loop = data->current_loop; + + for (phi = phi_nodes (loop->header); phi; phi = TREE_CHAIN (phi)) + { + if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi))) + continue; + + step = determine_biv_step (phi); + + if (!step) + continue; + if (cst_and_fits_in_hwi (step) + && int_cst_value (step) == 0) + continue; + + base = phi_element_for_edge (phi, loop_preheader_edge (loop))->def; + if (contains_abnormal_ssa_name_p (base)) + continue; + + type = TREE_TYPE (PHI_RESULT (phi)); + base = convert (type, base); + step = convert (type, step); + + set_iv (data, PHI_RESULT (phi), base, step); + found = true; + } + + return found; +} + +/* Marks basic ivs. */ + +static void +mark_bivs (struct ivopts_data *data) +{ + tree phi, var; + struct iv *iv, *incr_iv; + struct loop *loop = data->current_loop; + basic_block incr_bb; + + for (phi = phi_nodes (loop->header); phi; phi = TREE_CHAIN (phi)) + { + iv = get_iv (data, PHI_RESULT (phi)); + if (!iv) + continue; + + var = phi_element_for_edge (phi, loop_latch_edge (loop))->def; + incr_iv = get_iv (data, var); + if (!incr_iv) + continue; + + /* If the increment is in the subloop, ignore it. */ + incr_bb = bb_for_stmt (SSA_NAME_DEF_STMT (var)); + if (incr_bb->loop_father != data->current_loop + || (incr_bb->flags & BB_IRREDUCIBLE_LOOP)) + continue; + + iv->biv_p = true; + incr_iv->biv_p = true; + } +} + +/* Finds definition of VAR and fills in BASE and STEP accordingly. */ + +static bool +get_var_def (struct ivopts_data *data, tree var, tree *base, tree *step) +{ + struct iv *iv; + + if (is_gimple_min_invariant (var)) + { + *base = var; + *step = NULL_TREE; + return true; + } + + if (TREE_CODE (var) != SSA_NAME) + return false; + + iv = get_iv (data, var); + if (!iv) + return false; + + *base = iv->base; + *step = iv->step; + + return true; +} + +/* Checks whether STMT defines a linear induction variable and stores its + parameters to BASE and STEP. */ + +static bool +find_givs_in_stmt_scev (struct ivopts_data *data, tree stmt, + tree *base, tree *step) +{ + tree lhs, type, ev; + struct loop *loop = data->current_loop; + basic_block bb = bb_for_stmt (stmt); + + *base = NULL_TREE; + *step = NULL_TREE; + + if (TREE_CODE (stmt) != MODIFY_EXPR) + return false; + + lhs = TREE_OPERAND (stmt, 0); + if (TREE_CODE (lhs) != SSA_NAME) + return false; + + type = TREE_TYPE (lhs); + if (TREE_CODE (type) != INTEGER_TYPE + && TREE_CODE (type) != POINTER_TYPE) + return false; + + ev = analyze_scalar_evolution_in_loop (loop, bb->loop_father, lhs); + if (tree_does_not_contain_chrecs (ev) + && !chrec_contains_symbols (ev)) + { + *base = ev; + return true; + } + + if (TREE_CODE (ev) != POLYNOMIAL_CHREC + || CHREC_VARIABLE (ev) != (unsigned) loop->num) + return false; + + *step = CHREC_RIGHT (ev); + if (TREE_CODE (*step) != INTEGER_CST) + return false; + *base = CHREC_LEFT (ev); + if (tree_contains_chrecs (*base) + || chrec_contains_symbols (*base)) + return false; + + if (contains_abnormal_ssa_name_p (*base)) + return false; + + return true; +} + +/* Finds general ivs in statement STMT. */ + +static void +find_givs_in_stmt (struct ivopts_data *data, tree stmt) +{ + tree base, step; + + if (!find_givs_in_stmt_scev (data, stmt, &base, &step)) + return; + + set_iv (data, TREE_OPERAND (stmt, 0), base, step); +} + +/* Finds general ivs in basic block BB. */ + +static void +find_givs_in_bb (struct ivopts_data *data, basic_block bb) +{ + block_stmt_iterator bsi; + + for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) + find_givs_in_stmt (data, bsi_stmt (bsi)); +} + +/* Finds general ivs. */ + +static void +find_givs (struct ivopts_data *data) +{ + struct loop *loop = data->current_loop; + basic_block *body = get_loop_body_in_dom_order (loop); + unsigned i; + + for (i = 0; i < loop->num_nodes; i++) + find_givs_in_bb (data, body[i]); + free (body); +} + +/* Computes inverse of X modulo 2^s, where MASK = 2^s-1. */ + +static tree +inverse (tree x, tree mask) +{ + tree type = TREE_TYPE (x); + tree ctr = EXEC_BINARY (RSHIFT_EXPR, type, mask, integer_one_node); + tree rslt = convert (type, integer_one_node); + + while (integer_nonzerop (ctr)) + { + rslt = EXEC_BINARY (MULT_EXPR, type, rslt, x); + rslt = EXEC_BINARY (BIT_AND_EXPR, type, rslt, mask); + x = EXEC_BINARY (MULT_EXPR, type, x, x); + x = EXEC_BINARY (BIT_AND_EXPR, type, x, mask); + ctr = EXEC_BINARY (RSHIFT_EXPR, type, ctr, integer_one_node); + } + + return rslt; +} + +/* Determine the number of iterations according to condition (for staying + inside loop) BASE0 + STEP0 * i (CODE) BASE1 + STEP1 * i, computed in TYPE. + Store the results to NITER. */ + +static void +number_of_iterations_cond (tree type, tree base0, tree step0, + enum tree_code code, tree base1, tree step1, + struct tree_niter_desc *niter) +{ + tree step, delta, mmin, mmax; + tree may_xform, bound, s, d, tmp; + bool was_sharp = false; + tree assumption; + tree assumptions = boolean_true_node; + tree noloop_assumptions = boolean_false_node; + tree unsigned_step_type; + + /* The meaning of these assumptions is this: + if !assumptions + then the rest of information does not have to be valid + if noloop_assumptions then the loop does not have to roll + (but it is only conservative approximation, i.e. it only says that + if !noloop_assumptions, then the loop does not end before the computed + number of iterations) */ + + /* Make < comparison from > ones. */ + if (code == GE_EXPR + || code == GT_EXPR) + { + SWAP (base0, base1); + SWAP (step0, step1); + code = swap_tree_comparison (code); + } + + /* We can take care of the case of two induction variables chasing each other + if the test is NE. I have never seen a loop using it, but still it is + cool. */ + if (!zero_p (step0) && !zero_p (step1)) + { + if (code != NE_EXPR) + return; + + step0 = EXEC_BINARY (MINUS_EXPR, type, step0, step1); + step1 = NULL_TREE; + } + + /* If the result is a constant, the loop is weird. More precise handling + would be possible, but the situation is not common enough to waste time + on it. */ + if (zero_p (step0) && zero_p (step1)) + return; + + /* Ignore loops of while (i-- < 10) type. */ + if (code != NE_EXPR) + { + if (step0 && !tree_expr_nonnegative_p (step0)) + return; + + if (!zero_p (step1) && tree_expr_nonnegative_p (step1)) + return; + } + + /* For pointers these are NULL. We assume pointer arithmetics never + overflows. */ + mmin = TYPE_MIN_VALUE (type); + mmax = TYPE_MAX_VALUE (type); + + /* Some more condition normalization. We must record some assumptions + due to overflows. */ + + if (code == LT_EXPR) + { + /* We want to take care only of <=; this is easy, + as in cases the overflow would make the transformation unsafe the loop + does not roll. Seemingly it would make more sense to want to take + care of <, as NE is more simmilar to it, but the problem is that here + the transformation would be more difficult due to possibly infinite + loops. */ + if (zero_p (step0)) + { + if (mmax) + assumption = fold (build (EQ_EXPR, boolean_type_node, base0, mmax)); + else + assumption = boolean_true_node; + if (integer_nonzerop (assumption)) + goto zero_iter; + base0 = fold (build (PLUS_EXPR, type, base0, + convert (type, integer_one_node))); + } + else + { + if (mmin) + assumption = fold (build (EQ_EXPR, boolean_type_node, base1, mmin)); + else + assumption = boolean_true_node; + if (integer_nonzerop (assumption)) + goto zero_iter; + base1 = fold (build (MINUS_EXPR, type, base1, + convert (type, integer_one_node))); + } + noloop_assumptions = assumption; + code = LE_EXPR; + + /* It will be useful to be able to tell the difference once more in + <= -> != reduction. */ + was_sharp = true; + } + + /* Take care of trivially infinite loops. */ + if (code != NE_EXPR) + { + if (zero_p (step0) + && mmin + && operand_equal_p (base0, mmin, 0)) + return; + if (zero_p (step1) + && mmax + && operand_equal_p (base1, mmax, 0)) + return; + } + + /* If we can we want to take care of NE conditions instead of size + comparisons, as they are much more friendly (most importantly + this takes care of special handling of loops with step 1). We can + do it if we first check that upper bound is greater or equal to + lower bound, their difference is constant c modulo step and that + there is not an overflow. */ + if (code != NE_EXPR) + { + if (zero_p (step0)) + step = EXEC_UNARY (NEGATE_EXPR, type, step1); + else + step = step0; + delta = build (MINUS_EXPR, type, base1, base0); + delta = fold (build (FLOOR_MOD_EXPR, type, delta, step)); + may_xform = boolean_false_node; + + if (TREE_CODE (delta) == INTEGER_CST) + { + tmp = EXEC_BINARY (MINUS_EXPR, type, step, integer_zero_node); + if (was_sharp + && operand_equal_p (delta, tmp, 0)) + { + /* A special case. We have transformed condition of type + for (i = 0; i < 4; i += 4) + into + for (i = 0; i <= 3; i += 4) + obviously if the test for overflow during that transformation + passed, we cannot overflow here. Most importantly any + loop with sharp end condition and step 1 falls into this + cathegory, so handling this case specially is definitely + worth the troubles. */ + may_xform = boolean_true_node; + } + else if (zero_p (step0)) + { + if (!mmin) + may_xform = boolean_true_node; + else + { + bound = EXEC_BINARY (PLUS_EXPR, type, mmin, step); + bound = EXEC_BINARY (MINUS_EXPR, type, bound, delta); + may_xform = fold (build (LE_EXPR, boolean_type_node, + bound, base0)); + } + } + else + { + if (!mmax) + may_xform = boolean_true_node; + else + { + bound = EXEC_BINARY (MINUS_EXPR, type, mmax, step); + bound = EXEC_BINARY (PLUS_EXPR, type, bound, delta); + may_xform = fold (build (LE_EXPR, boolean_type_node, + base1, bound)); + } + } + } + + if (!integer_zerop (may_xform)) + { + /* We perform the transformation always provided that it is not + completely senseless. This is OK, as we would need this assumption + to determine the number of iterations anyway. */ + if (!integer_nonzerop (may_xform)) + assumptions = may_xform; + + if (zero_p (step0)) + { + base0 = build (PLUS_EXPR, type, base0, delta); + base0 = fold (build (MINUS_EXPR, type, base0, step)); + } + else + { + base1 = build (MINUS_EXPR, type, base1, delta); + base1 = fold (build (PLUS_EXPR, type, base1, step)); + } + + assumption = fold (build (GT_EXPR, boolean_type_node, base0, base1)); + noloop_assumptions = fold (build (TRUTH_OR_EXPR, boolean_type_node, + noloop_assumptions, assumption)); + code = NE_EXPR; + } + } + + /* Count the number of iterations. */ + if (code == NE_EXPR) + { + /* Everything we do here is just arithmetics modulo size of mode. This + makes us able to do more involved computations of number of iterations + than in other cases. First transform the condition into shape + s * i <> c, with s positive. */ + base1 = fold (build (MINUS_EXPR, type, base1, base0)); + base0 = NULL_TREE; + if (!zero_p (step1)) + step0 = EXEC_UNARY (NEGATE_EXPR, type, step1); + step1 = NULL_TREE; + if (!tree_expr_nonnegative_p (step0)) + { + step0 = EXEC_UNARY (NEGATE_EXPR, type, step0); + base1 = fold (build1 (NEGATE_EXPR, type, base1)); + } + + /* Let nsd (s, size of mode) = d. If d does not divide c, the loop + is infinite. Otherwise, the number of iterations is + (inverse(s/d) * (c/d)) mod (size of mode/d). */ + s = step0; + d = integer_one_node; + unsigned_step_type = make_unsigned_type (TYPE_PRECISION (type)); + bound = convert (unsigned_step_type, build_int_2 (~0, ~0)); + while (1) + { + tmp = EXEC_BINARY (BIT_AND_EXPR, type, s, integer_one_node); + if (integer_nonzerop (tmp)) + break; + + s = EXEC_BINARY (RSHIFT_EXPR, type, s, integer_one_node); + d = EXEC_BINARY (LSHIFT_EXPR, type, d, integer_one_node); + bound = EXEC_BINARY (RSHIFT_EXPR, type, bound, integer_one_node); + } + + tmp = fold (build (EXACT_DIV_EXPR, type, base1, d)); + tmp = fold (build (MULT_EXPR, type, tmp, inverse (s, bound))); + niter->niter = fold (build (BIT_AND_EXPR, type, tmp, bound)); + } + else + { + if (zero_p (step1)) + /* Condition in shape a + s * i <= b + We must know that b + s does not overflow and a <= b + s and then we + can compute number of iterations as (b + s - a) / s. (It might + seem that we in fact could be more clever about testing the b + s + overflow condition using some information about b - a mod s, + but it was already taken into account during LE -> NE transform). */ + { + if (mmax) + { + bound = EXEC_BINARY (MINUS_EXPR, type, mmax, step0); + assumption = fold (build (LE_EXPR, boolean_type_node, + base1, bound)); + assumptions = fold (build (TRUTH_AND_EXPR, boolean_type_node, + assumptions, assumption)); + } + step = step0; + tmp = fold (build (PLUS_EXPR, type, base1, step0)); + assumption = fold (build (GT_EXPR, boolean_type_node, base0, tmp)); + delta = fold (build (PLUS_EXPR, type, base1, step)); + delta = fold (build (MINUS_EXPR, type, delta, base0)); + } + else + { + /* Condition in shape a <= b - s * i + We must know that a - s does not overflow and a - s <= b and then + we can again compute number of iterations as (b - (a - s)) / s. */ + if (mmin) + { + bound = EXEC_BINARY (MINUS_EXPR, type, mmin, step1); + assumption = fold (build (LE_EXPR, boolean_type_node, + bound, base0)); + assumptions = fold (build (TRUTH_AND_EXPR, boolean_type_node, + assumptions, assumption)); + } + step = fold (build1 (NEGATE_EXPR, type, step1)); + tmp = fold (build (PLUS_EXPR, type, base0, step1)); + assumption = fold (build (GT_EXPR, boolean_type_node, tmp, base1)); + delta = fold (build (MINUS_EXPR, type, base0, step)); + delta = fold (build (MINUS_EXPR, type, base1, delta)); + } + noloop_assumptions = fold (build (TRUTH_OR_EXPR, boolean_type_node, + noloop_assumptions, assumption)); + delta = fold (build (FLOOR_DIV_EXPR, type, delta, step)); + niter->niter = delta; + } + + niter->assumptions = assumptions; + niter->may_be_zero = noloop_assumptions; + return; + +zero_iter: + niter->assumptions = boolean_true_node; + niter->may_be_zero = boolean_true_node; + niter->niter = convert (type, integer_zero_node); + return; +} + +/* Determine the number of iterations of the current loop. */ + +static void +determine_number_of_iterations (struct ivopts_data *data) +{ + tree stmt, cond, type; + tree op0, base0, step0; + tree op1, base1, step1; + enum tree_code code; + struct loop *loop = data->current_loop; + + if (!loop_data (loop)->single_exit) + return; + + stmt = last_stmt (loop_data (loop)->single_exit->src); + if (!stmt || TREE_CODE (stmt) != COND_EXPR) + return; + + /* We want the condition for staying inside loop. */ + cond = COND_EXPR_COND (stmt); + if (loop_data (loop)->single_exit->flags & EDGE_TRUE_VALUE) + cond = invert_truthvalue (cond); + + code = TREE_CODE (cond); + switch (code) + { + case GT_EXPR: + case GE_EXPR: + case NE_EXPR: + case LT_EXPR: + case LE_EXPR: + break; + + default: + return; + } + + op0 = TREE_OPERAND (cond, 0); + op1 = TREE_OPERAND (cond, 1); + type = TREE_TYPE (op0); + + if (TREE_CODE (type) != INTEGER_TYPE + && TREE_CODE (type) != POINTER_TYPE) + return; + + if (!get_var_def (data, op0, &base0, &step0)) + return; + if (!get_var_def (data, op1, &base1, &step1)) + return; + + number_of_iterations_cond (type, base0, step0, code, base1, step1, + &loop_data (loop)->niter); +} + +/* For each ssa name defined in LOOP determines whether it is an induction + variable and if so, its initial value and step. */ + +static bool +find_induction_variables (struct ivopts_data *data) +{ + unsigned i; + struct loop *loop = data->current_loop; + + if (!find_bivs (data)) + return false; + + find_givs (data); + mark_bivs (data); + determine_number_of_iterations (data); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + if (loop_data (loop)->niter.niter) + { + fprintf (dump_file, " number of iterations "); + print_generic_expr (dump_file, loop_data (loop)->niter.niter, + TDF_SLIM); + fprintf (dump_file, "\n"); + + fprintf (dump_file, " may be zero if "); + print_generic_expr (dump_file, loop_data (loop)->niter.may_be_zero, + TDF_SLIM); + fprintf (dump_file, "\n"); + + fprintf (dump_file, " bogus unless "); + print_generic_expr (dump_file, loop_data (loop)->niter.assumptions, + TDF_SLIM); + fprintf (dump_file, "\n"); + fprintf (dump_file, "\n"); + }; + + fprintf (dump_file, "Induction variables:\n\n"); + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, + { + if (ver_info (data, i)->iv) + dump_iv (dump_file, ver_info (data, i)->iv); + }); + } + + return true; +} + +/* Records a use of type USE_TYPE at *USE_P in STMT whose value is IV. */ + +static struct iv_use * +record_use (struct ivopts_data *data, tree *use_p, struct iv *iv, + tree stmt, enum use_type use_type) +{ + struct iv_use *use = xcalloc (1, sizeof (struct iv_use)); + + use->id = n_iv_uses (data); + use->type = use_type; + use->iv = iv; + use->stmt = stmt; + use->op_p = use_p; + use->related_cands = BITMAP_XMALLOC (); + + if (dump_file && (dump_flags & TDF_DETAILS)) + dump_use (dump_file, use); + + VARRAY_PUSH_GENERIC_PTR_NOGC (data->iv_uses, use); + + return use; +} + +/* Checks whether OP is a loop-level invariant and if so, records it. + NONLINEAR_USE is true if the invariant is used in a way we do not + handle specially. */ + +static void +record_invariant (struct ivopts_data *data, tree op, bool nonlinear_use) +{ + basic_block bb; + struct version_info *info; + + if (TREE_CODE (op) != SSA_NAME + || !is_gimple_reg (op)) + return; + + bb = bb_for_stmt (SSA_NAME_DEF_STMT (op)); + if (bb + && flow_bb_inside_loop_p (data->current_loop, bb)) + return; + + info = name_info (data, op); + info->name = op; + info->has_nonlin_use |= nonlinear_use; + if (!info->inv_id) + info->inv_id = ++data->max_inv_id; + bitmap_set_bit (data->relevant, SSA_NAME_VERSION (op)); +} + +/* Checks whether the use OP is interesting and if so, records it + as TYPE. */ + +static struct iv_use * +find_interesting_uses_outer_or_nonlin (struct ivopts_data *data, tree op, + enum use_type type) +{ + struct iv *iv; + struct iv *civ; + tree stmt, *op_p; + struct iv_use *use; + + if (TREE_CODE (op) != SSA_NAME) + return NULL; + + iv = get_iv (data, op); + if (!iv) + return NULL; + + if (iv->have_use_for) + { + use = iv_use (data, iv->use_id); + + if (use->type != USE_NONLINEAR_EXPR + && use->type != USE_OUTER) + abort (); + + if (type == USE_NONLINEAR_EXPR) + use->type = USE_NONLINEAR_EXPR; + return use; + } + + if (zero_p (iv->step)) + { + record_invariant (data, op, true); + return NULL; + } + iv->have_use_for = true; + + civ = xmalloc (sizeof (struct iv)); + *civ = *iv; + + stmt = SSA_NAME_DEF_STMT (op); + if (TREE_CODE (stmt) == PHI_NODE) + op_p = &PHI_RESULT (stmt); + else if (TREE_CODE (stmt) == MODIFY_EXPR) + op_p = &TREE_OPERAND (stmt, 0); + else + abort (); + + use = record_use (data, op_p, civ, stmt, type); + iv->use_id = use->id; + + return use; +} + +/* Checks whether the use OP is interesting and if so, records it. */ + +static struct iv_use * +find_interesting_uses_op (struct ivopts_data *data, tree op) +{ + return find_interesting_uses_outer_or_nonlin (data, op, USE_NONLINEAR_EXPR); +} + +/* Records a definition of induction variable OP that is used outside of the + loop. */ + +static struct iv_use * +find_interesting_uses_outer (struct ivopts_data *data, tree op) +{ + return find_interesting_uses_outer_or_nonlin (data, op, USE_OUTER); +} + +/* Checks whether the condition *COND_P in STMT is interesting + and if so, records it. */ + +static void +find_interesting_uses_cond (struct ivopts_data *data, tree stmt, tree *cond_p) +{ + tree *op0_p; + tree *op1_p; + struct iv *iv0 = NULL, *iv1 = NULL, *civ; + struct iv const_iv; + tree zero = integer_zero_node; + + const_iv.step = NULL_TREE; + + if (integer_zerop (*cond_p) + || integer_nonzerop (*cond_p)) + return; + + if (TREE_CODE (*cond_p) == SSA_NAME) + { + op0_p = cond_p; + op1_p = &zero; + } + else + { + op0_p = &TREE_OPERAND (*cond_p, 0); + op1_p = &TREE_OPERAND (*cond_p, 1); + } + + if (TREE_CODE (*op0_p) == SSA_NAME) + iv0 = get_iv (data, *op0_p); + else + iv0 = &const_iv; + + if (TREE_CODE (*op1_p) == SSA_NAME) + iv1 = get_iv (data, *op1_p); + else + iv1 = &const_iv; + + if (/* When comparing with non-invariant value, we may not do any senseful + induction variable elimination. */ + (!iv0 || !iv1) + /* Eliminating condition based on two ivs would be nontrivial. + ??? TODO -- it is not really important to handle this case. */ + || (!zero_p (iv0->step) && !zero_p (iv1->step))) + { + find_interesting_uses_op (data, *op0_p); + find_interesting_uses_op (data, *op1_p); + return; + } + + if (zero_p (iv0->step) && zero_p (iv1->step)) + { + /* If both are invariants, this is a work for unswitching. */ + return; + } + + civ = xmalloc (sizeof (struct iv)); + *civ = zero_p (iv0->step) ? *iv1: *iv0; + record_use (data, cond_p, civ, stmt, USE_COMPARE); +} + +/* Cumulates the steps of indices into DATA and replaces their values with the + initial ones. Returns false when the value of the index cannot be determined. + Callback for for_each_index. */ + +static struct ivopts_data *ifs_ivopts_data; +static bool +idx_find_step (tree base, tree *idx, void *data) +{ + tree *step_p = data; + struct iv *iv; + tree step, type, iv_type; + + if (TREE_CODE (*idx) != SSA_NAME) + return true; + + iv = get_iv (ifs_ivopts_data, *idx); + if (!iv) + return false; + + *idx = iv->base; + + if (!iv->step) + return true; + + iv_type = TREE_TYPE (iv->base); + if (base) + { + type = array2ptr (TREE_TYPE (base)); + step = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (base))); + } + else + { + type = TREE_TYPE (*idx); + /* The step for pointer arithmetics already is 1 byte. */ + step = convert (type, integer_one_node); + } + + if (TYPE_PRECISION (iv_type) < TYPE_PRECISION (type)) + { + /* The index might wrap. */ + + /* TODO -- this is especially bad for targets where + sizeof (int) < sizeof (void *). We should at least: + + 1) Use the number of iterations of the current loop to prove + that the index cannot wrap. + 2) Record whether only a signed arithmetics is used during computation + of the index (behavior of overflows during signed arithmetics is + undefined, so we may assume that it does not happen). Problems: + * The optimizations may create overflowing signed arithmetics. + * And they may also remove the no-op casts used to make the + behavior of overflows defined. + 3) Use array bounds when known (if the memory is accessed at each + iteration, we know the index cannot come out of them). Better, + use this to estimate the number of iterations of the loop. + 4) If all indices are of the same type, we can also rewrite the + access as &base + (extend) (step * i), and optimize the step * i + part separately. */ + return false; + } + + step = EXEC_BINARY (MULT_EXPR, type, step, + convert (type, iv->step)); + + if (!*step_p) + *step_p = step; + else + *step_p = EXEC_BINARY (PLUS_EXPR, type, *step_p, step); + + return true; +} + +/* Records use in index IDX. Callback for for_each_index. Ivopts data + object is passed to it in DATA. */ + +static bool +idx_record_use (tree base ATTRIBUTE_UNUSED, tree *idx, + void *data) +{ + find_interesting_uses_op (data, *idx); + return true; +} + +/* Finds addresses in *OP_P inside STMT. */ + +static void +find_interesting_uses_address (struct ivopts_data *data, tree stmt, tree *op_p) +{ + tree base = unshare_expr (*op_p), step = NULL; + struct iv *civ; + + /* Ignore bitfields for now. Not really something terribly complicated + to handle. TODO. */ + if (TREE_CODE (base) == COMPONENT_REF + && DECL_NONADDRESSABLE_P (TREE_OPERAND (base, 1))) + goto fail; + + ifs_ivopts_data = data; + if (!for_each_index (&base, idx_find_step, &step) + || zero_p (step)) + goto fail; + + if (TREE_CODE (base) == INDIRECT_REF) + base = TREE_OPERAND (base, 0); + else + base = build1 (ADDR_EXPR, + build_pointer_type (TREE_TYPE (base)), + base); + + civ = alloc_iv (base, step); + record_use (data, op_p, civ, stmt, USE_ADDRESS); + return; + +fail: + for_each_index (op_p, idx_record_use, data); +} + +/* Finds and records invariants used in STMT. */ + +static void +find_invariants_stmt (struct ivopts_data *data, tree stmt) +{ + use_optype uses = NULL; + unsigned i, n; + tree op; + + if (TREE_CODE (stmt) == PHI_NODE) + n = PHI_NUM_ARGS (stmt); + else + { + get_stmt_operands (stmt); + uses = STMT_USE_OPS (stmt); + n = NUM_USES (uses); + } + + for (i = 0; i < n; i++) + { + if (TREE_CODE (stmt) == PHI_NODE) + op = PHI_ARG_DEF (stmt, i); + else + op = USE_OP (uses, i); + + record_invariant (data, op, false); + } +} + +/* Finds interesting uses of induction variables in the statement STMT. */ + +static void +find_interesting_uses_stmt (struct ivopts_data *data, tree stmt) +{ + struct iv *iv; + tree *op_p, lhs, rhs; + use_optype uses = NULL; + unsigned i, n; + + find_invariants_stmt (data, stmt); + + if (TREE_CODE (stmt) == COND_EXPR) + { + find_interesting_uses_cond (data, stmt, &COND_EXPR_COND (stmt)); + return; + } + + if (TREE_CODE (stmt) == MODIFY_EXPR) + { + lhs = TREE_OPERAND (stmt, 0); + rhs = TREE_OPERAND (stmt, 1); + + if (TREE_CODE (lhs) == SSA_NAME) + { + /* If the statement defines an induction variable, the uses are not + interesting by themselves. */ + + iv = get_iv (data, lhs); + + if (iv && !zero_p (iv->step)) + return; + } + + switch (TREE_CODE_CLASS (TREE_CODE (rhs))) + { + case '<': + find_interesting_uses_cond (data, stmt, &TREE_OPERAND (stmt, 1)); + return; + + case 'r': + find_interesting_uses_address (data, stmt, &TREE_OPERAND (stmt, 1)); + if (TREE_CODE_CLASS (TREE_CODE (lhs)) == 'r') + find_interesting_uses_address (data, stmt, &TREE_OPERAND (stmt, 0)); + return; + + default: ; + } + + if (TREE_CODE_CLASS (TREE_CODE (lhs)) == 'r') + { + find_interesting_uses_address (data, stmt, &TREE_OPERAND (stmt, 0)); + find_interesting_uses_op (data, rhs); + return; + } + } + + if (TREE_CODE (stmt) == PHI_NODE + && bb_for_stmt (stmt) == data->current_loop->header) + { + lhs = PHI_RESULT (stmt); + iv = get_iv (data, lhs); + + if (iv && !zero_p (iv->step)) + return; + } + + if (TREE_CODE (stmt) == PHI_NODE) + n = PHI_NUM_ARGS (stmt); + else + { + uses = STMT_USE_OPS (stmt); + n = NUM_USES (uses); + } + + for (i = 0; i < n; i++) + { + if (TREE_CODE (stmt) == PHI_NODE) + op_p = &PHI_ARG_DEF (stmt, i); + else + op_p = USE_OP_PTR (uses, i); + + if (TREE_CODE (*op_p) != SSA_NAME) + continue; + + iv = get_iv (data, *op_p); + if (!iv) + continue; + + find_interesting_uses_op (data, *op_p); + } +} + +/* Finds interesting uses of induction variables outside of loops + on loop exit edge EXIT. */ + +static void +find_interesting_uses_outside (struct ivopts_data *data, edge exit) +{ + tree phi, def; + + for (phi = phi_nodes (exit->dest); phi; phi = TREE_CHAIN (phi)) + { + def = phi_element_for_edge (phi, exit)->def; + find_interesting_uses_outer (data, def); + } +} + +/* Finds uses of the induction variables that are interesting. */ + +static void +find_interesting_uses (struct ivopts_data *data) +{ + basic_block bb; + block_stmt_iterator bsi; + tree phi; + basic_block *body = get_loop_body (data->current_loop); + unsigned i; + struct version_info *info; + edge e; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Uses:\n\n"); + + for (i = 0; i < data->current_loop->num_nodes; i++) + { + bb = body[i]; + + for (e = bb->succ; e; e = e->succ_next) + if (e->dest != EXIT_BLOCK_PTR + && !flow_bb_inside_loop_p (data->current_loop, e->dest)) + find_interesting_uses_outside (data, e); + + for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi)) + find_interesting_uses_stmt (data, phi); + for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) + find_interesting_uses_stmt (data, bsi_stmt (bsi)); + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "\n"); + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, + { + info = ver_info (data, i); + if (info->inv_id) + { + fprintf (dump_file, " "); + print_generic_expr (dump_file, info->name, TDF_SLIM); + fprintf (dump_file, " is invariant (%d)%s\n", + info->inv_id, info->has_nonlin_use ? "" : ", eliminable"); + } + }); + + fprintf (dump_file, "\n"); + } + + free (body); +} + +/* Adds a candidate BASE + STEP * i. Important field is set to IMPORTANT and + position to POS. If USE is not NULL, the candidate is set as related to + it. If both BASE and STEP are NULL, we add a pseudocandidate for the + replacement of the final value of the iv by a direct computation. */ + +static struct iv_cand * +add_candidate_1 (struct ivopts_data *data, + tree base, tree step, bool important, enum iv_position pos, + struct iv_use *use, tree incremented_at) +{ + unsigned i; + struct iv_cand *cand = NULL; + + for (i = 0; i < n_iv_cands (data); i++) + { + cand = iv_cand (data, i); + + if (cand->pos != pos) + continue; + + if (cand->incremented_at != incremented_at) + continue; + + if (!cand->iv) + { + if (!base && !step) + break; + + continue; + } + + if (!base && !step) + continue; + + if (!operand_equal_p (base, cand->iv->base, 0)) + continue; + + if (zero_p (cand->iv->step)) + { + if (zero_p (step)) + break; + } + else + { + if (step && operand_equal_p (step, cand->iv->step, 0)) + break; + } + } + + if (i == n_iv_cands (data)) + { + cand = xcalloc (1, sizeof (struct iv_cand)); + cand->id = i; + + if (!base && !step) + cand->iv = NULL; + else + cand->iv = alloc_iv (base, step); + + cand->pos = pos; + if (pos != IP_ORIGINAL && cand->iv) + { + cand->var_before = create_tmp_var_raw (TREE_TYPE (base), "ivtmp"); + cand->var_after = cand->var_before; + } + cand->important = important; + cand->incremented_at = incremented_at; + VARRAY_PUSH_GENERIC_PTR_NOGC (data->iv_candidates, cand); + + if (dump_file && (dump_flags & TDF_DETAILS)) + dump_cand (dump_file, cand); + } + + if (important && !cand->important) + { + cand->important = true; + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Candidate %d is important\n", cand->id); + } + + if (use) + { + bitmap_set_bit (use->related_cands, i); + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Candidate %d is related to use %d\n", + cand->id, use->id); + } + + return cand; +} + +/* Adds a candidate BASE + STEP * i. Important field is set to IMPORTANT and + position to POS. If USE is not NULL, the candidate is set as related to + it. The candidate computation is scheduled on all available positions. */ + +static void +add_candidate (struct ivopts_data *data, + tree base, tree step, bool important, struct iv_use *use) +{ + if (ip_normal_pos (data->current_loop)) + add_candidate_1 (data, base, step, important, IP_NORMAL, use, NULL_TREE); + if (ip_end_pos (data->current_loop)) + add_candidate_1 (data, base, step, important, IP_END, use, NULL_TREE); +} + +/* Adds standard iv candidates. */ + +static void +add_standard_iv_candidates (struct ivopts_data *data) +{ + /* Add 0 + 1 * iteration candidate. */ + add_candidate (data, + convert (integer_type_node, integer_zero_node), + convert (integer_type_node, integer_one_node), + true, NULL); + + /* The same for a long type. */ + add_candidate (data, + convert (long_integer_type_node, integer_zero_node), + convert (long_integer_type_node, integer_one_node), + true, NULL); +} + + +/* Adds candidates bases on the old induction variable IV. */ + +static void +add_old_iv_candidates (struct ivopts_data *data, struct iv *iv) +{ + tree phi, def; + struct iv_cand *cand; + + add_candidate (data, iv->base, iv->step, true, NULL); + + /* The same, but with initial value zero. */ + add_candidate (data, + convert (TREE_TYPE (iv->base), integer_zero_node), + iv->step, true, NULL); + + phi = SSA_NAME_DEF_STMT (iv->ssa_name); + if (TREE_CODE (phi) == PHI_NODE) + { + /* Additionally record the possibility of leaving the original iv + untouched. */ + def = phi_element_for_edge (phi, + loop_latch_edge (data->current_loop))->def; + cand = add_candidate_1 (data, + iv->base, iv->step, true, IP_ORIGINAL, NULL, + SSA_NAME_DEF_STMT (def)); + cand->var_before = iv->ssa_name; + cand->var_after = def; + } +} + +/* Adds candidates based on the old induction variables. */ + +static void +add_old_ivs_candidates (struct ivopts_data *data) +{ + unsigned i; + struct iv *iv; + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, + { + iv = ver_info (data, i)->iv; + if (iv && iv->biv_p && !zero_p (iv->step)) + add_old_iv_candidates (data, iv); + }); +} + +/* Adds candidates based on the value of the induction variable IV and USE. */ + +static void +add_iv_value_candidates (struct ivopts_data *data, + struct iv *iv, struct iv_use *use) +{ + add_candidate (data, iv->base, iv->step, false, use); + + /* The same, but with initial value zero. */ + add_candidate (data, + convert (array2ptr (TREE_TYPE (iv->base)), integer_zero_node), + iv->step, false, use); +} + +/* Adds candidates based on the address IV and USE. */ + +static void +add_address_candidates (struct ivopts_data *data, + struct iv *iv, struct iv_use *use) +{ + tree base, type; + + /* First, the trivial choices. */ + add_iv_value_candidates (data, iv, use); + + /* Second, try removing the COMPONENT_REFs. */ + if (TREE_CODE (iv->base) == ADDR_EXPR) + { + base = TREE_OPERAND (iv->base, 0); + type = TREE_TYPE (iv->base); + while (TREE_CODE (base) == COMPONENT_REF + || (TREE_CODE (base) == ARRAY_REF + && TREE_CODE (TREE_OPERAND (base, 1)) == INTEGER_CST)) + base = TREE_OPERAND (base, 0); + + if (base != TREE_OPERAND (iv->base, 0)) + { + if (TREE_CODE (base) == INDIRECT_REF) + base = TREE_OPERAND (base, 0); + else + base = build1 (ADDR_EXPR, type, base); + add_candidate (data, base, iv->step, false, use); + } + } +} + +/* Possibly adds pseudocandidate for replacing the final value of USE by + a direct computation. */ + +static void +add_iv_outer_candidates (struct ivopts_data *data, struct iv_use *use) +{ + struct tree_niter_desc *niter; + struct loop *loop = data->current_loop; + + /* We must know where we exit the loop and how many times does it roll. */ + if (!loop_data (loop)->single_exit) + return; + + niter = &loop_data (loop)->niter; + if (!niter->niter + || !operand_equal_p (niter->assumptions, boolean_true_node, 0) + || !operand_equal_p (niter->may_be_zero, boolean_false_node, 0)) + return; + + add_candidate_1 (data, NULL, NULL, false, IP_NORMAL, use, NULL_TREE); +} + +/* Adds candidates based on the uses. */ + +static void +add_derived_ivs_candidates (struct ivopts_data *data) +{ + unsigned i; + + for (i = 0; i < n_iv_uses (data); i++) + { + struct iv_use *use = iv_use (data, i); + + if (!use) + continue; + + switch (use->type) + { + case USE_NONLINEAR_EXPR: + case USE_COMPARE: + /* Just add the ivs based on the value of the iv used here. */ + add_iv_value_candidates (data, use->iv, use); + break; + + case USE_OUTER: + add_iv_value_candidates (data, use->iv, use); + + /* Additionally, add the pseudocandidate for the possibility to + replace the final value by a direct computation. */ + add_iv_outer_candidates (data, use); + break; + + case USE_ADDRESS: + add_address_candidates (data, use->iv, use); + break; + + default: + abort (); + } + } +} + +/* Finds the candidates for the induction variables. */ + +static void +find_iv_candidates (struct ivopts_data *data) +{ + /* Add commonly used ivs. */ + add_standard_iv_candidates (data); + + /* Add old induction variables. */ + add_old_ivs_candidates (data); + + /* Add induction variables derived from uses. */ + add_derived_ivs_candidates (data); +} + +/* Allocates the data structure mapping the (use, candidate) pairs to costs. + If consider_all_candidates is true, we use a two-dimensional array, otherwise + we allocate a simple list to every use. */ + +static void +alloc_use_cost_map (struct ivopts_data *data) +{ + unsigned i, n_imp = 0, size, j; + + if (!data->consider_all_candidates) + { + for (i = 0; i < n_iv_cands (data); i++) + { + struct iv_cand *cand = iv_cand (data, i); + if (cand->important) + n_imp++; + } + } + + for (i = 0; i < n_iv_uses (data); i++) + { + struct iv_use *use = iv_use (data, i); + + if (data->consider_all_candidates) + { + size = n_iv_cands (data); + use->n_map_members = size; + } + else + { + size = n_imp; + EXECUTE_IF_SET_IN_BITMAP (use->related_cands, 0, j, size++); + use->n_map_members = 0; + } + + use->cost_map = xcalloc (size, sizeof (struct cost_pair)); + } +} + +/* Sets cost of (USE, CANDIDATE) pair to COST and record that it depends + on invariants DEPENDS_ON. */ + +static void +set_use_iv_cost (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand, unsigned cost, + bitmap depends_on) +{ + if (cost == INFTY + && depends_on) + { + BITMAP_XFREE (depends_on); + depends_on = NULL; + } + + if (data->consider_all_candidates) + { + use->cost_map[cand->id].cand = cand; + use->cost_map[cand->id].cost = cost; + use->cost_map[cand->id].depends_on = depends_on; + return; + } + + if (cost == INFTY) + return; + + use->cost_map[use->n_map_members].cand = cand; + use->cost_map[use->n_map_members].cost = cost; + use->cost_map[use->n_map_members].depends_on = depends_on; + use->n_map_members++; +} + +/* Gets cost of (USE, CANDIDATE) pair. Stores the bitmap of dependencies to + DEPENDS_ON. */ + +static unsigned +get_use_iv_cost (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand, bitmap *depends_on) +{ + unsigned i; + + if (!cand) + return INFTY; + + if (data->consider_all_candidates) + i = cand->id; + else + { + for (i = 0; i < use->n_map_members; i++) + if (use->cost_map[i].cand == cand) + break; + + if (i == use->n_map_members) + return INFTY; + } + + if (depends_on) + *depends_on = use->cost_map[i].depends_on; + return use->cost_map[i].cost; +} + +/* Returns estimate on cost of computing SEQ. */ + +static unsigned +seq_cost (rtx seq) +{ + unsigned cost = 0; + rtx set; + + for (; seq; seq = NEXT_INSN (seq)) + { + set = single_set (seq); + if (set) + cost += rtx_cost (set, SET); + else + cost++; + } + + return cost; +} + +/* Prepares decl_rtl for variables referred in *EXPR_P. Callback for + walk_tree. DATA contains the actual fake register number. */ + +static tree +prepare_decl_rtl (tree *expr_p, int *ws, void *data) +{ + tree obj = NULL_TREE; + rtx x = NULL_RTX; + int *regno = data; + + switch (TREE_CODE (*expr_p)) + { + case SSA_NAME: + *ws = 0; + obj = SSA_NAME_VAR (*expr_p); + if (!DECL_RTL_SET_P (obj)) + x = gen_raw_REG (DECL_MODE (obj), (*regno)++); + break; + + case VAR_DECL: + case PARM_DECL: + case RESULT_DECL: + *ws = 0; + obj = *expr_p; + + if (DECL_RTL_SET_P (obj)) + break; + + if (DECL_MODE (obj) == BLKmode) + { + if (TREE_STATIC (obj) + || DECL_EXTERNAL (obj)) + { + const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (obj)); + x = gen_rtx_SYMBOL_REF (Pmode, name); + } + else + x = gen_raw_REG (Pmode, (*regno)++); + + x = gen_rtx_MEM (DECL_MODE (obj), x); + } + else + x = gen_raw_REG (DECL_MODE (obj), (*regno)++); + + break; + + default: + break; + } + + if (x) + { + VARRAY_PUSH_GENERIC_PTR_NOGC (decl_rtl_to_reset, obj); + SET_DECL_RTL (obj, x); + } + + return NULL_TREE; +} + +/* Determines cost of the computation of EXPR. */ + +static unsigned +computation_cost (tree expr) +{ + rtx seq, rslt; + tree type = TREE_TYPE (expr); + unsigned cost; + int regno = 0; + + walk_tree (&expr, prepare_decl_rtl, ®no, NULL); + start_sequence (); + rslt = expand_expr (expr, NULL_RTX, TYPE_MODE (type), EXPAND_NORMAL); + seq = get_insns (); + end_sequence (); + + cost = seq_cost (seq); + if (GET_CODE (rslt) == MEM) + cost += address_cost (XEXP (rslt, 0), TYPE_MODE (type)); + + return cost; +} + +/* Returns variable containing the value of candidate CAND at statement AT. */ + +static tree +var_at_stmt (struct loop *loop, struct iv_cand *cand, tree stmt) +{ + if (stmt_after_increment (loop, cand, stmt)) + return cand->var_after; + else + return cand->var_before; +} + +/* Determines the expression by that USE is expressed from induction variable + CAND at statement AT in LOOP. */ + +static tree +get_computation_at (struct loop *loop, + struct iv_use *use, struct iv_cand *cand, tree at) +{ + tree ubase = use->iv->base, ustep = use->iv->step; + tree cbase = cand->iv->base, cstep = cand->iv->step; + tree utype = TREE_TYPE (ubase), ctype = TREE_TYPE (cbase); + tree expr, delta; + tree ratio; + unsigned HOST_WIDE_INT ustepi, cstepi; + HOST_WIDE_INT ratioi; + + expr = var_at_stmt (loop, cand, at); + + if (TYPE_PRECISION (utype) > TYPE_PRECISION (ctype)) + { + /* We do not have a precision to express the values of use. */ + return NULL_TREE; + } + + if (utype != ctype) + { + expr = convert (utype, expr); + cbase = convert (utype, cbase); + cstep = convert (utype, cstep); + } + + if (!cst_and_fits_in_hwi (cstep) + || !cst_and_fits_in_hwi (ustep)) + return NULL_TREE; + + ustepi = int_cst_value (ustep); + cstepi = int_cst_value (cstep); + + if (!divide (TYPE_PRECISION (utype), ustepi, cstepi, &ratioi)) + { + /* TODO maybe consider case when ustep divides cstep and the ratio is + a power of 2 (so that the division is fast to execute)? We would + need to be much more careful with overflows etc. then. */ + return NULL_TREE; + } + + /* We may need to shift the value if we are after the increment. */ + if (stmt_after_increment (loop, cand, at)) + cbase = fold (build (PLUS_EXPR, utype, cbase, cstep)); + + /* use = ubase + ratio * (var - cbase). If either cbase is a constant + or |ratio| == 1, it is better to handle this like + + ubase - ratio * cbase + ratio * var. */ + + if (ratioi == 1) + { + delta = fold (build (MINUS_EXPR, utype, ubase, cbase)); + expr = fold (build (PLUS_EXPR, utype, expr, delta)); + } + else if (ratioi == -1) + { + delta = fold (build (PLUS_EXPR, utype, ubase, cbase)); + expr = fold (build (MINUS_EXPR, utype, delta, expr)); + } + else if (TREE_CODE (cbase) == INTEGER_CST) + { + ratio = build_int_cst (utype, ratioi); + delta = fold (build (MULT_EXPR, utype, ratio, cbase)); + delta = fold (build (MINUS_EXPR, utype, ubase, delta)); + expr = fold (build (MULT_EXPR, utype, ratio, expr)); + expr = fold (build (PLUS_EXPR, utype, delta, expr)); + } + else + { + expr = fold (build (MINUS_EXPR, utype, expr, cbase)); + ratio = build_int_cst (utype, ratioi); + expr = fold (build (MULT_EXPR, utype, ratio, expr)); + expr = fold (build (PLUS_EXPR, utype, ubase, expr)); + } + + return expr; +} + +/* Determines the expression by that USE is expressed from induction variable + CAND in LOOP. */ + +static tree +get_computation (struct loop *loop, struct iv_use *use, struct iv_cand *cand) +{ + return get_computation_at (loop, use, cand, use->stmt); +} + +/* Strips constant offsets from EXPR and adds them to OFFSET. */ + +static void +strip_offset (tree *expr, unsigned HOST_WIDE_INT *offset) +{ + tree op0, op1; + enum tree_code code; + + while (1) + { + if (cst_and_fits_in_hwi (*expr)) + { + *offset += int_cst_value (*expr); + *expr = integer_zero_node; + return; + } + + code = TREE_CODE (*expr); + + if (code != PLUS_EXPR && code != MINUS_EXPR) + return; + + op0 = TREE_OPERAND (*expr, 0); + op1 = TREE_OPERAND (*expr, 1); + + if (cst_and_fits_in_hwi (op1)) + { + if (code == PLUS_EXPR) + *offset += int_cst_value (op1); + else + *offset -= int_cst_value (op1); + + *expr = op0; + continue; + } + + if (code != PLUS_EXPR) + return; + + if (!cst_and_fits_in_hwi (op0)) + return; + + *offset += int_cst_value (op0); + *expr = op1; + } +} + +/* Returns cost of addition in MODE. */ + +static unsigned +add_cost (enum machine_mode mode) +{ + static unsigned costs[NUM_MACHINE_MODES]; + rtx seq; + unsigned cost; + + if (costs[mode]) + return costs[mode]; + + start_sequence (); + force_operand (gen_rtx_fmt_ee (PLUS, mode, + gen_raw_REG (mode, FIRST_PSEUDO_REGISTER), + gen_raw_REG (mode, FIRST_PSEUDO_REGISTER + 1)), + NULL_RTX); + seq = get_insns (); + end_sequence (); + + cost = seq_cost (seq); + if (!cost) + cost = 1; + + costs[mode] = cost; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Addition in %s costs %d\n", + GET_MODE_NAME (mode), cost); + return cost; +} + +/* Entry in a hashtable of already known costs for multiplication. */ +struct mbc_entry +{ + HOST_WIDE_INT cst; /* The constant to multiply by. */ + enum machine_mode mode; /* In mode. */ + unsigned cost; /* The cost. */ +}; + +/* Counts hash value for the ENTRY. */ + +static hashval_t +mbc_entry_hash (const void *entry) +{ + const struct mbc_entry *e = entry; + + return 57 * (hashval_t) e->mode + (hashval_t) (e->cst % 877); +} + +/* Compares the hash table entries ENTRY1 and ENTRY2. */ + +static int +mbc_entry_eq (const void *entry1, const void *entry2) +{ + const struct mbc_entry *e1 = entry1; + const struct mbc_entry *e2 = entry2; + + return (e1->mode == e2->mode + && e1->cst == e2->cst); +} + +/* Returns cost of multiplication by constant CST in MODE. */ + +static unsigned +multiply_by_cost (HOST_WIDE_INT cst, enum machine_mode mode) +{ + static htab_t costs; + struct mbc_entry **cached, act; + rtx seq; + unsigned cost; + + if (!costs) + costs = htab_create (100, mbc_entry_hash, mbc_entry_eq, free); + + act.mode = mode; + act.cst = cst; + cached = (struct mbc_entry **) htab_find_slot (costs, &act, INSERT); + if (*cached) + return (*cached)->cost; + + *cached = xmalloc (sizeof (struct mbc_entry)); + (*cached)->mode = mode; + (*cached)->cst = cst; + + start_sequence (); + expand_mult (mode, gen_raw_REG (mode, FIRST_PSEUDO_REGISTER), GEN_INT (cst), + NULL_RTX, 0); + seq = get_insns (); + end_sequence (); + + cost = seq_cost (seq); + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Multiplication by %d in %s costs %d\n", + (int) cst, GET_MODE_NAME (mode), cost); + + (*cached)->cost = cost; + + return cost; +} + +/* Returns cost of address in shape symbol + var + OFFSET + RATIO * index. + If SYMBOL_PRESENT is false, symbol is omitted. If VAR_PRESENT is false, + variable is omitted. The created memory accesses MODE. + + TODO -- there must be some better way. This all is quite crude. */ + +static unsigned +get_address_cost (bool symbol_present, bool var_present, + unsigned HOST_WIDE_INT offset, HOST_WIDE_INT ratio) +{ +#define MAX_RATIO 128 + static sbitmap valid_mult; + static HOST_WIDE_INT rat, off; + static HOST_WIDE_INT min_offset, max_offset; + static unsigned costs[2][2][2][2]; + unsigned cost, acost; + rtx seq, addr, base; + bool offset_p, ratio_p; + rtx reg1; + HOST_WIDE_INT s_offset; + unsigned HOST_WIDE_INT mask; + unsigned bits; + + if (!valid_mult) + { + HOST_WIDE_INT i; + + reg1 = gen_raw_REG (Pmode, FIRST_PSEUDO_REGISTER); + + addr = gen_rtx_fmt_ee (PLUS, Pmode, reg1, NULL_RTX); + for (i = 1; i <= 1 << 20; i <<= 1) + { + XEXP (addr, 1) = GEN_INT (i); + if (!memory_address_p (Pmode, addr)) + break; + } + max_offset = i >> 1; + off = max_offset; + + for (i = 1; i <= 1 << 20; i <<= 1) + { + XEXP (addr, 1) = GEN_INT (-i); + if (!memory_address_p (Pmode, addr)) + break; + } + min_offset = -(i >> 1); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "get_address_cost:\n"); + fprintf (dump_file, " min offset %d\n", (int) min_offset); + fprintf (dump_file, " max offset %d\n", (int) max_offset); + } + + valid_mult = sbitmap_alloc (2 * MAX_RATIO + 1); + sbitmap_zero (valid_mult); + rat = 1; + addr = gen_rtx_fmt_ee (MULT, Pmode, reg1, NULL_RTX); + for (i = -MAX_RATIO; i <= MAX_RATIO; i++) + { + XEXP (addr, 1) = GEN_INT (i); + if (memory_address_p (Pmode, addr)) + { + SET_BIT (valid_mult, i + MAX_RATIO); + rat = i; + } + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " allowed multipliers:"); + for (i = -MAX_RATIO; i <= MAX_RATIO; i++) + if (TEST_BIT (valid_mult, i + MAX_RATIO)) + fprintf (dump_file, " %d", (int) i); + fprintf (dump_file, "\n"); + fprintf (dump_file, "\n"); + } + } + + bits = GET_MODE_BITSIZE (Pmode); + mask = ~(~(unsigned HOST_WIDE_INT) 0 << (bits - 1) << 1); + offset &= mask; + if ((offset >> (bits - 1) & 1)) + offset |= ~mask; + s_offset = offset; + + cost = 0; + offset_p = (min_offset <= s_offset && s_offset <= max_offset); + ratio_p = (ratio != 1 + && -MAX_RATIO <= ratio && ratio <= MAX_RATIO + && TEST_BIT (valid_mult, ratio + MAX_RATIO)); + + if (ratio != 1 && !ratio_p) + cost += multiply_by_cost (ratio, Pmode); + + if (s_offset && !offset_p && !symbol_present) + { + cost += add_cost (Pmode); + var_present = true; + } + + acost = costs[symbol_present][var_present][offset_p][ratio_p]; + if (!acost) + { + acost = 0; + + addr = gen_raw_REG (Pmode, FIRST_PSEUDO_REGISTER); + reg1 = gen_raw_REG (Pmode, FIRST_PSEUDO_REGISTER + 1); + if (ratio_p) + addr = gen_rtx_fmt_ee (MULT, Pmode, addr, GEN_INT (rat)); + + if (symbol_present) + { + base = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup ("")); + if (offset_p) + base = gen_rtx_fmt_e (CONST, Pmode, + gen_rtx_fmt_ee (PLUS, Pmode, + base, + GEN_INT (off))); + if (var_present) + base = gen_rtx_fmt_ee (PLUS, Pmode, reg1, base); + } + + else if (var_present) + { + base = reg1; + if (offset_p) + base = gen_rtx_fmt_ee (PLUS, Pmode, base, GEN_INT (off)); + } + else if (offset_p) + base = GEN_INT (off); + else + base = NULL_RTX; + + if (base) + addr = gen_rtx_fmt_ee (PLUS, Pmode, base, addr); + + start_sequence (); + addr = memory_address (Pmode, addr); + seq = get_insns (); + end_sequence (); + + acost = seq_cost (seq); + acost += address_cost (addr, Pmode); + + if (!acost) + acost = 1; + costs[symbol_present][var_present][offset_p][ratio_p] = acost; + } + + return cost + acost; +} + +/* Records invariants in *EXPR_P. Callback for walk_tree. DATA contains + the bitmap to that we should store it. */ + +static struct ivopts_data *fd_ivopts_data; +static tree +find_depends (tree *expr_p, int *ws ATTRIBUTE_UNUSED, void *data) +{ + bitmap *depends_on = data; + struct version_info *info; + + if (TREE_CODE (*expr_p) != SSA_NAME) + return NULL_TREE; + info = name_info (fd_ivopts_data, *expr_p); + + if (!info->inv_id || info->has_nonlin_use) + return NULL_TREE; + + if (!*depends_on) + *depends_on = BITMAP_XMALLOC (); + bitmap_set_bit (*depends_on, info->inv_id); + + return NULL_TREE; +} + +/* Estimates cost of forcing EXPR into variable. DEPENDS_ON is a set of the + invariants the computation depends on. */ + +static unsigned +force_var_cost (struct ivopts_data *data, + tree expr, bitmap *depends_on) +{ + if (depends_on) + { + fd_ivopts_data = data; + walk_tree (&expr, find_depends, depends_on, NULL); + } + + if (TREE_INVARIANT (expr) + || SSA_VAR_P (expr)) + return 0; + + return spill_cost; +} + +/* Peels a single layer of ADDR. If DIFF is not NULL, do it only if the + offset is constant and add the offset to DIFF. */ + +static tree +peel_address (tree addr, unsigned HOST_WIDE_INT *diff) +{ + tree off, size; + HOST_WIDE_INT bit_offset; + + switch (TREE_CODE (addr)) + { + case SSA_NAME: + case INDIRECT_REF: + case BIT_FIELD_REF: + case VAR_DECL: + case PARM_DECL: + case RESULT_DECL: + case STRING_CST: + return NULL_TREE; + + case COMPONENT_REF: + off = DECL_FIELD_BIT_OFFSET (TREE_OPERAND (addr, 1)); + bit_offset = TREE_INT_CST_LOW (off); + + if (bit_offset % BITS_PER_UNIT) + abort (); + + if (diff) + *diff += bit_offset / BITS_PER_UNIT; + + return TREE_OPERAND (addr, 0); + + case ARRAY_REF: + off = TREE_OPERAND (addr, 1); + + if (diff) + { + if (!cst_and_fits_in_hwi (off)) + return NULL_TREE; + + size = TYPE_SIZE_UNIT (TREE_TYPE (addr)); + if (!cst_and_fits_in_hwi (size)) + return NULL_TREE; + + *diff += TREE_INT_CST_LOW (off) * TREE_INT_CST_LOW (size); + } + + return TREE_OPERAND (addr, 0); + + default: + abort (); + } +} + +/* Checks whether E1 and E2 have constant difference, and if they do, + store it in *DIFF. */ + +static bool +ptr_difference_const (tree e1, tree e2, unsigned HOST_WIDE_INT *diff) +{ + int d1 = 0, d2 = 0; + tree x; + unsigned HOST_WIDE_INT delta1 = 0, delta2 = 0; + + /* Find depths of E1 and E2. */ + for (x = e1; x; x = peel_address (x, NULL)) + d1++; + for (x = e2; x; x = peel_address (x, NULL)) + d2++; + + for (; e1 && d1 > d2; e1 = peel_address (e1, &delta1)) + d1--; + for (; e2 && d2 > d1; e2 = peel_address (e2, &delta2)) + d2--; + + while (e1 && e2 && !operand_equal_p (e1, e2, 0)) + { + e1 = peel_address (e1, &delta1); + e2 = peel_address (e2, &delta1); + } + + if (!e1 || !e2) + return false; + + *diff = delta1 - delta2; + return true; +} + +/* Estimates cost of expressing address ADDR as var + symbol + offset. The + value of offset is added to OFFSET, SYMBOL_PRESENT and VAR_PRESENT are set + to false if the corresponding part is missing. DEPENDS_ON is a set of the + invariants the computation depends on. */ + +static unsigned +split_address_cost (struct ivopts_data *data, + tree addr, bool *symbol_present, bool *var_present, + unsigned HOST_WIDE_INT *offset, bitmap *depends_on) +{ + tree core = addr; + + while (core + && TREE_CODE (core) != VAR_DECL) + core = peel_address (core, offset); + + if (!core) + { + *symbol_present = false; + *var_present = true; + fd_ivopts_data = data; + walk_tree (&addr, find_depends, depends_on, NULL); + return spill_cost; + } + + if (TREE_STATIC (core) + || DECL_EXTERNAL (core)) + { + *symbol_present = true; + *var_present = false; + return 0; + } + + *symbol_present = false; + *var_present = true; + return 0; +} + +/* Estimates cost of expressing difference of addresses E1 - E2 as + var + symbol + offset. The value of offset is added to OFFSET, + SYMBOL_PRESENT and VAR_PRESENT are set to false if the corresponding + part is missing. DEPENDS_ON is a set of the invariants the computation + depends on. */ + +static unsigned +ptr_difference_cost (struct ivopts_data *data, + tree e1, tree e2, bool *symbol_present, bool *var_present, + unsigned HOST_WIDE_INT *offset, bitmap *depends_on) +{ + unsigned HOST_WIDE_INT diff = 0; + unsigned cost; + + if (TREE_CODE (e1) != ADDR_EXPR) + abort (); + + if (TREE_CODE (e2) == ADDR_EXPR + && ptr_difference_const (TREE_OPERAND (e1, 0), + TREE_OPERAND (e2, 0), &diff)) + { + *offset += diff; + *symbol_present = false; + *var_present = false; + return 0; + } + + if (e2 == integer_zero_node) + return split_address_cost (data, TREE_OPERAND (e1, 0), + symbol_present, var_present, offset, depends_on); + + *symbol_present = false; + *var_present = true; + + cost = force_var_cost (data, e1, depends_on); + cost += force_var_cost (data, e2, depends_on); + cost += add_cost (Pmode); + + return cost; +} + +/* Estimates cost of expressing difference E1 - E2 as + var + symbol + offset. The value of offset is added to OFFSET, + SYMBOL_PRESENT and VAR_PRESENT are set to false if the corresponding + part is missing. DEPENDS_ON is a set of the invariants the computation + depends on. */ + +static unsigned +difference_cost (struct ivopts_data *data, + tree e1, tree e2, bool *symbol_present, bool *var_present, + unsigned HOST_WIDE_INT *offset, bitmap *depends_on) +{ + unsigned cost; + enum machine_mode mode = TYPE_MODE (TREE_TYPE (e1)); + + strip_offset (&e1, offset); + *offset = -*offset; + strip_offset (&e2, offset); + *offset = -*offset; + + if (TREE_CODE (e1) == ADDR_EXPR) + return ptr_difference_cost (data, e1, e2, symbol_present, var_present, offset, + depends_on); + *symbol_present = false; + + if (operand_equal_p (e1, e2, 0)) + { + *var_present = false; + return 0; + } + *var_present = true; + if (zero_p (e2)) + return force_var_cost (data, e1, depends_on); + + if (zero_p (e1)) + { + cost = force_var_cost (data, e2, depends_on); + cost += multiply_by_cost (-1, mode); + + return cost; + } + + cost = force_var_cost (data, e1, depends_on); + cost += force_var_cost (data, e2, depends_on); + cost += add_cost (mode); + + return cost; +} + +/* Determines the cost of the computation by that USE is expressed + from induction variable CAND. If ADDRESS_P is true, we just need + to create an address from it, otherwise we want to get it into + register. A set of invariants we depend on is stored in + DEPENDS_ON. AT is the statement at that the value is computed. */ + +static unsigned +get_computation_cost_at (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand, + bool address_p, bitmap *depends_on, tree at) +{ + tree ubase = use->iv->base, ustep = use->iv->step; + tree cbase, cstep; + tree utype = TREE_TYPE (ubase), ctype; + unsigned HOST_WIDE_INT ustepi, cstepi, offset = 0; + HOST_WIDE_INT ratio, aratio; + bool var_present, symbol_present; + unsigned cost = 0, n_sums; + + *depends_on = NULL; + + /* Only consider real candidates. */ + if (!cand->iv) + return INFTY; + + cbase = cand->iv->base; + cstep = cand->iv->step; + ctype = TREE_TYPE (cbase); + + if (TYPE_PRECISION (utype) > TYPE_PRECISION (ctype)) + { + /* We do not have a precision to express the values of use. */ + return INFTY; + } + + if (!cst_and_fits_in_hwi (ustep) + || !cst_and_fits_in_hwi (cstep)) + return INFTY; + + if (TREE_CODE (ubase) == INTEGER_CST + && !cst_and_fits_in_hwi (ubase)) + goto fallback; + + if (TREE_CODE (cbase) == INTEGER_CST + && !cst_and_fits_in_hwi (cbase)) + goto fallback; + + ustepi = int_cst_value (ustep); + cstepi = int_cst_value (cstep); + + if (TYPE_PRECISION (utype) != TYPE_PRECISION (ctype)) + { + /* TODO -- add direct handling of this case. */ + goto fallback; + } + + if (!divide (TYPE_PRECISION (utype), ustepi, cstepi, &ratio)) + return INFTY; + + /* use = ubase + ratio * (var - cbase). If either cbase is a constant + or ratio == 1, it is better to handle this like + + ubase - ratio * cbase + ratio * var + + (also holds in the case ratio == -1, TODO. */ + + if (TREE_CODE (cbase) == INTEGER_CST) + { + offset = - ratio * int_cst_value (cbase); + cost += difference_cost (data, + ubase, integer_zero_node, + &symbol_present, &var_present, &offset, + depends_on); + } + else if (ratio == 1) + { + cost += difference_cost (data, + ubase, cbase, + &symbol_present, &var_present, &offset, + depends_on); + } + else + { + cost += force_var_cost (data, cbase, depends_on); + cost += add_cost (TYPE_MODE (ctype)); + cost += difference_cost (data, + ubase, integer_zero_node, + &symbol_present, &var_present, &offset, + depends_on); + } + + /* If we are after the increment, the value of the candidate is higher by + one iteration. */ + if (stmt_after_increment (data->current_loop, cand, at)) + offset -= ratio * cstepi; + + /* Now the computation is in shape symbol + var1 + const + ratio * var2. + (symbol/var/const parts may be omitted). If we are looking for an address, + find the cost of addressing this. */ + if (address_p) + return get_address_cost (symbol_present, var_present, offset, ratio); + + /* Otherwise estimate the costs for computing the expression. */ + aratio = ratio > 0 ? ratio : -ratio; + if (!symbol_present && !var_present && !offset) + { + if (ratio != 1) + cost += multiply_by_cost (ratio, TYPE_MODE (ctype)); + + return cost; + } + + if (aratio != 1) + cost += multiply_by_cost (aratio, TYPE_MODE (ctype)); + + n_sums = 1; + if (var_present + /* Symbol + offset should be compile-time computable. */ + && (symbol_present || offset)) + n_sums++; + + return cost + n_sums * add_cost (TYPE_MODE (ctype)); + +fallback: + { + /* Just get the expression, expand it and measure the cost. */ + tree comp = get_computation_at (data->current_loop, use, cand, at); + + if (!comp) + return INFTY; + + if (address_p) + comp = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (comp)), comp); + + return computation_cost (comp); + } +} + +/* Determines the cost of the computation by that USE is expressed + from induction variable CAND. If ADDRESS_P is true, we just need + to create an address from it, otherwise we want to get it into + register. A set of invariants we depend on is stored in + DEPENDS_ON. */ + +static unsigned +get_computation_cost (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand, + bool address_p, bitmap *depends_on) +{ + return get_computation_cost_at (data, + use, cand, address_p, depends_on, use->stmt); +} + +/* Determines cost of basing replacement of USE on CAND in a generic + expression. */ + +static void +determine_use_iv_cost_generic (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + bitmap depends_on; + unsigned cost = get_computation_cost (data, use, cand, false, &depends_on); + + set_use_iv_cost (data, use, cand, cost, depends_on); +} + +/* Determines cost of basing replacement of USE on CAND in an address. */ + +static void +determine_use_iv_cost_address (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + bitmap depends_on; + unsigned cost = get_computation_cost (data, use, cand, true, &depends_on); + + set_use_iv_cost (data, use, cand, cost, depends_on); +} + +/* Computes value of induction variable IV in iteration NITER. */ + +static tree +iv_value (struct iv *iv, tree niter) +{ + tree val; + tree type = TREE_TYPE (iv->base); + + niter = convert (type, niter); + val = fold (build (MULT_EXPR, type, iv->step, niter)); + + return fold (build (PLUS_EXPR, type, iv->base, val)); +} + +/* Computes value of candidate CAND at position AT in iteration NITER. */ + +static tree +cand_value_at (struct loop *loop, struct iv_cand *cand, tree at, tree niter) +{ + tree type = TREE_TYPE (niter); + + if (stmt_after_increment (loop, cand, at)) + niter = fold (build (PLUS_EXPR, type, niter, + convert (type, integer_one_node))); + + return iv_value (cand->iv, niter); +} + +/* Check whether it is possible to express the condition in USE by comparison + of candidate CAND. If so, store the comparison code to COMPARE and the + value compared with to BOUND. */ + +static bool +may_eliminate_iv (struct loop *loop, + struct iv_use *use, struct iv_cand *cand, + enum tree_code *compare, tree *bound) +{ + edge exit; + struct tree_niter_desc *niter; + + /* For now just very primitive -- we work just for the single exit condition, + and are quite conservative about the possible overflows. TODO -- both of + these can be improved. */ + exit = loop_data (loop)->single_exit; + if (!exit) + return false; + if (use->stmt != last_stmt (exit->src)) + return false; + + niter = &loop_data (loop)->niter; + if (!niter->niter + || !operand_equal_p (niter->assumptions, boolean_true_node, 0) + || !operand_equal_p (niter->may_be_zero, boolean_false_node, 0)) + return false; + + /* FIXME -- we ignore the possible overflow here. For example + in case the loop iterates MAX_UNSIGNED_INT / 2 times and + the step of candidate is 4, this is wrong. */ + if (exit->flags & EDGE_TRUE_VALUE) + *compare = EQ_EXPR; + else + *compare = NE_EXPR; + + *bound = cand_value_at (loop, cand, use->stmt, niter->niter); + + return true; +} + +/* Determines cost of basing replacement of USE on CAND in a condition. */ + +static void +determine_use_iv_cost_condition (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + tree bound; + enum tree_code compare; + + /* Only consider real candidates. */ + if (!cand->iv) + { + set_use_iv_cost (data, use, cand, INFTY, NULL); + return; + } + + if (may_eliminate_iv (data->current_loop, use, cand, &compare, &bound)) + { + bitmap depends_on = NULL; + unsigned cost = force_var_cost (data, bound, &depends_on); + + set_use_iv_cost (data, use, cand, cost, depends_on); + return; + } + + /* The induction variable elimination failed; just express the original + giv. If it is compared with an invariant, note that we cannot get + rid of it. */ + if (TREE_CODE (*use->op_p) == SSA_NAME) + record_invariant (data, *use->op_p, true); + else + { + record_invariant (data, TREE_OPERAND (*use->op_p, 0), true); + record_invariant (data, TREE_OPERAND (*use->op_p, 1), true); + } + + determine_use_iv_cost_generic (data, use, cand); +} + +/* Checks whether it is possible to replace the final value of USE by + a direct computation. If so, the formula is stored to *VALUE. */ + +static bool +may_replace_final_value (struct loop *loop, struct iv_use *use, tree *value) +{ + edge exit; + struct tree_niter_desc *niter; + + exit = loop_data (loop)->single_exit; + if (!exit) + return false; + + if (!dominated_by_p (CDI_DOMINATORS, exit->src, + bb_for_stmt (use->stmt))) + abort (); + + niter = &loop_data (loop)->niter; + if (!niter->niter + || !operand_equal_p (niter->assumptions, boolean_true_node, 0) + || !operand_equal_p (niter->may_be_zero, boolean_false_node, 0)) + return false; + + *value = iv_value (use->iv, niter->niter); + + return true; +} + +/* Determines cost of replacing final value of USE using CAND. */ + +static void +determine_use_iv_cost_outer (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + bitmap depends_on; + unsigned cost; + edge exit; + tree value; + struct loop *loop = data->current_loop; + + if (!cand->iv) + { + if (!may_replace_final_value (loop, use, &value)) + { + set_use_iv_cost (data, use, cand, INFTY, NULL); + return; + } + + depends_on = NULL; + cost = force_var_cost (data, value, &depends_on); + + cost /= AVG_LOOP_NITER (loop); + + set_use_iv_cost (data, use, cand, cost, depends_on); + return; + } + + exit = loop_data (loop)->single_exit; + if (exit) + { + /* If there is just a single exit, we may use value of the candidate + after we take it to determine the value of use. */ + cost = get_computation_cost_at (data, use, cand, false, &depends_on, + last_stmt (exit->src)); + cost /= AVG_LOOP_NITER (loop); + } + else + { + /* Otherwise we just need to compute the iv. */ + cost = get_computation_cost (data, use, cand, false, &depends_on); + } + + set_use_iv_cost (data, use, cand, cost, depends_on); +} + +/* Determines cost of basing replacement of USE on CAND. */ + +static void +determine_use_iv_cost (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + switch (use->type) + { + case USE_NONLINEAR_EXPR: + determine_use_iv_cost_generic (data, use, cand); + break; + + case USE_OUTER: + determine_use_iv_cost_outer (data, use, cand); + break; + + case USE_ADDRESS: + determine_use_iv_cost_address (data, use, cand); + break; + + case USE_COMPARE: + determine_use_iv_cost_condition (data, use, cand); + break; + + default: + abort (); + } +} + +/* Determines costs of basing the use of the iv on an iv candidate. */ + +static void +determine_use_iv_costs (struct ivopts_data *data) +{ + unsigned i, j; + struct iv_use *use; + struct iv_cand *cand; + + data->consider_all_candidates = (n_iv_cands (data) + <= CONSIDER_ALL_CANDIDATES_BOUND); + + alloc_use_cost_map (data); + + if (!data->consider_all_candidates) + { + /* Add the important candidate entries. */ + for (j = 0; j < n_iv_cands (data); j++) + { + cand = iv_cand (data, j); + if (!cand->important) + continue; + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + determine_use_iv_cost (data, use, cand); + } + } + } + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + + if (data->consider_all_candidates) + { + for (j = 0; j < n_iv_cands (data); j++) + { + cand = iv_cand (data, j); + determine_use_iv_cost (data, use, cand); + } + } + else + { + EXECUTE_IF_SET_IN_BITMAP (use->related_cands, 0, j, + { + cand = iv_cand (data, j); + if (!cand->important) + determine_use_iv_cost (data, use, cand); + }); + } + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Use-candidate costs:\n"); + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + + fprintf (dump_file, "Use %d:\n", i); + fprintf (dump_file, " cand\tcost\tdepends on\n"); + for (j = 0; j < use->n_map_members; j++) + { + if (!use->cost_map[j].cand + || use->cost_map[j].cost == INFTY) + continue; + + fprintf (dump_file, " %d\t%d\t", + use->cost_map[j].cand->id, + use->cost_map[j].cost); + if (use->cost_map[j].depends_on) + bitmap_print (dump_file, + use->cost_map[j].depends_on, "",""); + fprintf (dump_file, "\n"); + } + + fprintf (dump_file, "\n"); + } + fprintf (dump_file, "\n"); + } +} + +/* Determines cost of the candidate CAND. */ + +static void +determine_iv_cost (struct ivopts_data *data, struct iv_cand *cand) +{ + unsigned cost_base, cost_step; + tree base, last; + basic_block bb; + + if (!cand->iv) + { + cand->cost = 0; + return; + } + + /* There are two costs associated with the candidate -- its incrementation + and its initialization. The second is almost negligible for any loop + that rolls enough, so we take it just very little into account. */ + + base = cand->iv->base; + cost_base = force_var_cost (data, base, NULL); + cost_step = add_cost (TYPE_MODE (TREE_TYPE (base))); + + cand->cost = cost_step + cost_base / AVG_LOOP_NITER (current_loop); + + /* Prefer the original iv unless we may gain something by replacing it. */ + if (cand->pos == IP_ORIGINAL) + cand->cost--; + + /* Prefer not to insert statements into latch unless there are some + already (so that we do not create unnecesary jumps). */ + if (cand->pos == IP_END) + { + bb = ip_end_pos (data->current_loop); + last = last_stmt (bb); + + if (!last + || TREE_CODE (last) == LABEL_EXPR) + cand->cost++; + } +} + +/* Determines costs of computation of the candidates. */ + +static void +determine_iv_costs (struct ivopts_data *data) +{ + unsigned i; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Candidate costs:\n"); + fprintf (dump_file, " cand\tcost\n"); + } + + for (i = 0; i < n_iv_cands (data); i++) + { + struct iv_cand *cand = iv_cand (data, i); + + determine_iv_cost (data, cand); + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, " %d\t%d\n", i, cand->cost); + } + +if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "\n"); +} + +/* Calculates cost for having SIZE new loop global variables. REGS_USED is the + number of global registers used in loop. N_USES is the number of relevant + variable uses. */ + +unsigned +global_cost_for_size (unsigned size, unsigned regs_used, unsigned n_uses) +{ + unsigned regs_needed = regs_used + size; + unsigned cost = 0; + + if (regs_needed + res_regs <= avail_regs) + cost += small_cost * size; + else if (regs_needed <= avail_regs) + cost += pres_cost * size; + else + { + cost += pres_cost * size; + cost += spill_cost * n_uses * (regs_needed - avail_regs) / regs_needed; + } + + return cost; +} + +/* Calculates cost for having SIZE induction variables. */ + +static unsigned +ivopts_global_cost_for_size (struct ivopts_data *data, unsigned size) +{ + return global_cost_for_size (size, + loop_data (data->current_loop)->regs_used, + n_iv_uses (data)); +} + +/* Initialize the constants for computing set costs. */ + +void +init_set_costs (void) +{ + rtx seq; + rtx reg1 = gen_raw_REG (SImode, FIRST_PSEUDO_REGISTER); + rtx reg2 = gen_raw_REG (SImode, FIRST_PSEUDO_REGISTER + 1); + rtx addr = gen_raw_REG (Pmode, FIRST_PSEUDO_REGISTER + 2); + rtx mem = validize_mem (gen_rtx_MEM (SImode, addr)); + unsigned i; + + for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) + if (TEST_HARD_REG_BIT (reg_class_contents[GENERAL_REGS], i) + && !fixed_regs[i]) + avail_regs++; + + res_regs = 3; + + /* These are really just heuristic values. */ + + start_sequence (); + emit_move_insn (reg1, reg2); + seq = get_insns (); + end_sequence (); + small_cost = seq_cost (seq); + pres_cost = 2 * small_cost; + + start_sequence (); + emit_move_insn (mem, reg1); + emit_move_insn (reg2, mem); + seq = get_insns (); + end_sequence (); + spill_cost = seq_cost (seq); +} + +/* For each size of the induction variable set determine the penalty. */ + +static void +determine_set_costs (struct ivopts_data *data) +{ + unsigned j, n; + tree phi, op; + struct loop *loop = data->current_loop; + + /* We use the following model (definitely improvable, especially the + cost function -- TODO): + + We estimate the number of registers available (using MD data), name it A. + + We estimate the number of registers used by the loop, name it U. This + number is obtained as the number of loop phi nodes (not counting virtual + registers and bivs) + the number of variables from outside of the loop. + + We set a reserve R (free regs that are used for temporary computations, + etc.). For now the reserve a constant 3. + + Let I be the number of induction variables. + + -- if U + I + R <= A, the cost is I * SMALL_COST (just not to encourage + make a lot of ivs without a reason). + -- if A - R < U + I <= A, the cost is I * PRES_COST + -- if U + I > A, the cost is I * PRES_COST and + number of uses * SPILL_COST * (U + I - A) / (U + I) is added. */ + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Global costs:\n"); + fprintf (dump_file, " avail_regs %d\n", avail_regs); + fprintf (dump_file, " small_cost %d\n", small_cost); + fprintf (dump_file, " pres_cost %d\n", pres_cost); + fprintf (dump_file, " spill_cost %d\n", spill_cost); + } + + n = 0; + for (phi = phi_nodes (loop->header); phi; phi = TREE_CHAIN (phi)) + { + op = PHI_RESULT (phi); + + if (!is_gimple_reg (op)) + continue; + + if (get_iv (data, op)) + continue; + + n++; + } + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, j, + { + struct version_info *info = ver_info (data, j); + + if (info->inv_id && info->has_nonlin_use) + n++; + }); + + loop_data (loop)->regs_used = n; + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, " regs_used %d\n", n); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " cost for size:\n"); + fprintf (dump_file, " ivs\tcost\n"); + for (j = 0; j <= 2 * avail_regs; j++) + fprintf (dump_file, " %d\t%d\n", j, + ivopts_global_cost_for_size (data, j)); + fprintf (dump_file, "\n"); + } +} + +/* Finds a best candidate for USE and stores it to CAND. The candidates are + taken from the set SOL and they may depend on invariants in the set INV. + The really used candidate and invariants are noted to USED_IVS and + USED_INV. */ + +static unsigned +find_best_candidate (struct ivopts_data *data, + struct iv_use *use, bitmap sol, bitmap inv, + bitmap used_ivs, bitmap used_inv, struct iv_cand **cand) +{ + unsigned c, d; + unsigned best_cost = INFTY, cost; + struct iv_cand *cnd = NULL, *acnd; + bitmap depends_on = NULL; + + EXECUTE_IF_SET_IN_BITMAP (sol, 0, c, + { + acnd = iv_cand (data, c); + cost = get_use_iv_cost (data, use, acnd, &depends_on); + + if (cost == INFTY) + goto next_cand; + if (cost > best_cost) + goto next_cand; + if (cost == best_cost) + { + /* Prefer the cheaper iv. */ + if (acnd->cost >= cnd->cost) + goto next_cand; + } + + if (depends_on) + { + EXECUTE_IF_AND_COMPL_IN_BITMAP (depends_on, inv, 0, d, + goto next_cand); + if (used_inv) + bitmap_a_or_b (used_inv, used_inv, depends_on); + } + + cnd = acnd; + best_cost = cost; +next_cand: ; + }); + + if (cnd && used_ivs) + bitmap_set_bit (used_ivs, cnd->id); + + if (cand) + *cand = cnd; + + return best_cost; +} + +/* Computes cost of set of ivs SOL + invariants INV. Removes unnecessary + induction variable candidates and invariants from the sets. */ + +static unsigned +set_cost (struct ivopts_data *data, bitmap sol, bitmap inv) +{ + unsigned i; + unsigned cost = 0, size = 0, acost; + struct iv_use *use; + struct iv_cand *cand; + bitmap used_ivs = BITMAP_XMALLOC (), used_inv = BITMAP_XMALLOC (); + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + acost = find_best_candidate (data, use, sol, inv, + used_ivs, used_inv, NULL); + if (acost == INFTY) + { + BITMAP_XFREE (used_ivs); + BITMAP_XFREE (used_inv); + return INFTY; + } + cost += acost; + } + + EXECUTE_IF_SET_IN_BITMAP (used_ivs, 0, i, + { + cand = iv_cand (data, i); + + /* Do not count the pseudocandidates. */ + if (cand->iv) + size++; + + cost += cand->cost; + }); + EXECUTE_IF_SET_IN_BITMAP (used_inv, 0, i, size++); + cost += ivopts_global_cost_for_size (data, size); + + bitmap_copy (sol, used_ivs); + bitmap_copy (inv, used_inv); + + BITMAP_XFREE (used_ivs); + BITMAP_XFREE (used_inv); + + return cost; +} + +/* Finds an initial set of IVS and invariants INV. We do this by simply + chosing the best candidate for each use. */ + +static unsigned +get_initial_solution (struct ivopts_data *data, bitmap ivs, bitmap inv) +{ + unsigned i; + + for (i = 0; i < n_iv_cands (data); i++) + bitmap_set_bit (ivs, i); + for (i = 1; i <= data->max_inv_id; i++) + if (!ver_info (data, i)->has_nonlin_use) + bitmap_set_bit (inv, i); + + return set_cost (data, ivs, inv); +} + +/* Tries to improve set of induction variables IVS and invariants INV to get + it better than COST. */ + +static bool +try_improve_iv_set (struct ivopts_data *data, + bitmap ivs, bitmap inv, unsigned *cost) +{ + unsigned i, acost; + bitmap new_ivs = BITMAP_XMALLOC (), new_inv = BITMAP_XMALLOC (); + bitmap best_new_ivs = NULL, best_new_inv = NULL; + + /* Try altering the set of induction variables by one. */ + for (i = 0; i < n_iv_cands (data); i++) + { + bitmap_copy (new_ivs, ivs); + bitmap_copy (new_inv, inv); + + if (bitmap_bit_p (ivs, i)) + bitmap_clear_bit (new_ivs, i); + else + bitmap_set_bit (new_ivs, i); + + acost = set_cost (data, new_ivs, new_inv); + if (acost >= *cost) + continue; + + if (!best_new_ivs) + { + best_new_ivs = BITMAP_XMALLOC (); + best_new_inv = BITMAP_XMALLOC (); + } + + *cost = acost; + bitmap_copy (best_new_ivs, new_ivs); + bitmap_copy (best_new_inv, new_inv); + } + + /* Ditto for invariants. */ + for (i = 1; i <= data->max_inv_id; i++) + { + if (ver_info (data, i)->has_nonlin_use) + continue; + + bitmap_copy (new_ivs, ivs); + bitmap_copy (new_inv, inv); + + if (bitmap_bit_p (inv, i)) + bitmap_clear_bit (new_inv, i); + else + bitmap_set_bit (new_inv, i); + + acost = set_cost (data, new_ivs, new_inv); + if (acost >= *cost) + continue; + + if (!best_new_ivs) + { + best_new_ivs = BITMAP_XMALLOC (); + best_new_inv = BITMAP_XMALLOC (); + } + + *cost = acost; + bitmap_copy (best_new_ivs, new_ivs); + bitmap_copy (best_new_inv, new_inv); + } + + BITMAP_XFREE (new_ivs); + BITMAP_XFREE (new_inv); + + if (!best_new_ivs) + return false; + + bitmap_copy (ivs, best_new_ivs); + bitmap_copy (inv, best_new_inv); + BITMAP_XFREE (best_new_ivs); + BITMAP_XFREE (best_new_inv); + return true; +} + +/* Attempts to find the optimal set of induction variables. We do simple + greedy heuristic -- we try to replace at most one candidate in the selected + solution and remove the unused ivs while this improves the cost. */ + +static bitmap +find_optimal_iv_set (struct ivopts_data *data) +{ + unsigned cost, i; + bitmap set = BITMAP_XMALLOC (); + bitmap inv = BITMAP_XMALLOC (); + struct iv_use *use; + + /* Set the upper bound. */ + cost = get_initial_solution (data, set, inv); + if (cost == INFTY) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Unable to substitute for ivs, failed.\n"); + BITMAP_XFREE (inv); + BITMAP_XFREE (set); + return NULL; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Initial set of candidates (cost %d): ", cost); + bitmap_print (dump_file, set, "", ""); + fprintf (dump_file, " invariants "); + bitmap_print (dump_file, inv, "", ""); + fprintf (dump_file, "\n"); + } + + while (try_improve_iv_set (data, set, inv, &cost)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Improved to (cost %d): ", cost); + bitmap_print (dump_file, set, "", ""); + fprintf (dump_file, " invariants "); + bitmap_print (dump_file, inv, "", ""); + fprintf (dump_file, "\n"); + } + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Final cost %d\n\n", cost); + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + find_best_candidate (data, use, set, inv, NULL, NULL, &use->selected); + } + + BITMAP_XFREE (inv); + + return set; +} + +/* Creates an induction variable with value BASE + STEP * iteration in LOOP. + It is expected that neither BASE nor STEP are shared with other expressions + (unless the sharing rules allow this). Use VAR as a base var_decl for it + (if NULL, a new temporary will be created). The increment will occur at + INCR_POS (after it if AFTER is true, before it otherwise). The ssa versions + of the variable before and after increment will be stored in VAR_BEFORE and + VAR_AFTER (unless they are NULL). */ + +void +create_iv (tree base, tree step, tree var, struct loop *loop, + block_stmt_iterator *incr_pos, bool after, + tree *var_before, tree *var_after) +{ + tree stmt, stmts, initial; + tree vb, va; + + if (!var) + { + var = create_tmp_var (TREE_TYPE (base), "ivtmp"); + add_referenced_tmp_var (var); + } + + vb = make_ssa_name (var, NULL_TREE); + if (var_before) + *var_before = vb; + va = make_ssa_name (var, NULL_TREE); + if (var_after) + *var_after = va; + + stmt = build (MODIFY_EXPR, void_type_node, va, + build (PLUS_EXPR, TREE_TYPE (base), + vb, step)); + SSA_NAME_DEF_STMT (va) = stmt; + if (after) + bsi_insert_after (incr_pos, stmt, BSI_NEW_STMT); + else + bsi_insert_before (incr_pos, stmt, BSI_NEW_STMT); + + initial = force_gimple_operand (base, &stmts, false); + if (stmts) + { + basic_block new_bb; + edge pe = loop_preheader_edge (loop); + + new_bb = bsi_insert_on_edge_immediate (pe, stmts); + if (new_bb) + add_bb_to_loop (new_bb, new_bb->pred->src->loop_father); + } + + stmt = create_phi_node (vb, loop->header); + SSA_NAME_DEF_STMT (vb) = stmt; + add_phi_arg (&stmt, initial, loop_preheader_edge (loop)); + add_phi_arg (&stmt, va, loop_latch_edge (loop)); +} + +/* Creates a new induction variable corresponding to CAND. */ + +static void +create_new_iv (struct ivopts_data *data, struct iv_cand *cand) +{ + block_stmt_iterator incr_pos; + tree base; + bool after = false; + + if (!cand->iv) + return; + + switch (cand->pos) + { + case IP_NORMAL: + incr_pos = bsi_last (ip_normal_pos (data->current_loop)); + break; + + case IP_END: + incr_pos = bsi_last (ip_end_pos (data->current_loop)); + after = true; + break; + + case IP_ORIGINAL: + /* Mark that the iv is preserved. */ + name_info (data, cand->var_before)->preserve_biv = true; + name_info (data, cand->var_after)->preserve_biv = true; + + /* Rewrite the increment so that it uses var_before directly. */ + find_interesting_uses_op (data, cand->var_after)->selected = cand; + + return; + } + + gimple_add_tmp_var (cand->var_before); + add_referenced_tmp_var (cand->var_before); + + base = unshare_expr (cand->iv->base); + + create_iv (base, cand->iv->step, cand->var_before, data->current_loop, + &incr_pos, after, &cand->var_before, &cand->var_after); +} + +/* Creates new induction variables described in SET. */ + +static void +create_new_ivs (struct ivopts_data *data, bitmap set) +{ + unsigned i; + struct iv_cand *cand; + + EXECUTE_IF_SET_IN_BITMAP (set, 0, i, + { + cand = iv_cand (data, i); + create_new_iv (data, cand); + }); +} + +/* Removes statement STMT (real or a phi node). If INCLUDING_DEFINED_NAME + is true, remove also the ssa name defined by the statement. */ + +static void +remove_statement (tree stmt, bool including_defined_name) +{ + if (TREE_CODE (stmt) == PHI_NODE) + { + if (!including_defined_name) + { + /* Prevent the ssa name defined by the statement from being removed. */ + PHI_RESULT (stmt) = NULL; + } + remove_phi_node (stmt, NULL_TREE, bb_for_stmt (stmt)); + } + else + { + block_stmt_iterator bsi = stmt_bsi (stmt); + + bsi_remove (&bsi); + } +} + +/* Rewrites USE (definition of iv used in a nonlinear expression) + using candidate CAND. */ + +static void +rewrite_use_nonlinear_expr (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + tree comp = unshare_expr (get_computation (data->current_loop, + use, cand)); + tree op, stmts, tgt, ass; + block_stmt_iterator bsi, pbsi; + + if (TREE_CODE (use->stmt) == PHI_NODE) + { + tgt = PHI_RESULT (use->stmt); + + /* If we should keep the biv, do not replace it. */ + if (name_info (data, tgt)->preserve_biv) + return; + + pbsi = bsi = bsi_start (bb_for_stmt (use->stmt)); + while (!bsi_end_p (pbsi) + && TREE_CODE (bsi_stmt (pbsi)) == LABEL_EXPR) + { + bsi = pbsi; + bsi_next (&pbsi); + } + } + else + { + tgt = TREE_OPERAND (use->stmt, 0); + bsi = stmt_bsi (use->stmt); + } + + op = force_gimple_operand (comp, &stmts, false); + + if (TREE_CODE (use->stmt) == PHI_NODE) + { + if (stmts) + bsi_insert_after (&bsi, stmts, BSI_CONTINUE_LINKING); + ass = build (MODIFY_EXPR, TREE_TYPE (tgt), tgt, op); + bsi_insert_after (&bsi, ass, BSI_NEW_STMT); + remove_statement (use->stmt, false); + SSA_NAME_DEF_STMT (tgt) = ass; + } + else + { + if (stmts) + bsi_insert_before (&bsi, stmts, BSI_SAME_STMT); + TREE_OPERAND (use->stmt, 1) = op; + } +} + +/* Rewrites USE (address that is an iv) using candidate CAND. */ + +static void +rewrite_use_address (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + tree comp = unshare_expr (get_computation (data->current_loop, + use, cand)); + block_stmt_iterator bsi = stmt_bsi (use->stmt); + tree stmts; + tree op = force_gimple_operand (comp, &stmts, false); + tree var, tmp_var, name; + + if (stmts) + bsi_insert_before (&bsi, stmts, BSI_SAME_STMT); + + if (TREE_CODE (op) == SSA_NAME) + { + /* We need to add a memory tag for the variable. But we do not want + to add it to the temporary used for the computations, since this leads + to problems in redundancy elimination when there are common parts + in two computations refering to the different arrays. So we rewrite + the base variable of the ssa name to a new temporary. */ + tmp_var = create_tmp_var (TREE_TYPE (op), "ruatmp"); + add_referenced_tmp_var (tmp_var); + SSA_NAME_VAR (op) = tmp_var; + + var = get_base_address (*use->op_p); + if (TREE_CODE (var) == INDIRECT_REF) + var = TREE_OPERAND (var, 0); + if (TREE_CODE (var) == SSA_NAME) + { + name = var; + var = SSA_NAME_VAR (var); + } + else + name = NULL_TREE; + if (var_ann (var)->type_mem_tag) + var = var_ann (var)->type_mem_tag; + var_ann (tmp_var)->type_mem_tag = var; + + if (name) + { + ssa_name_ann_t ann = ssa_name_ann (name), new_ann; + + if (ann && ann->name_mem_tag) + { + new_ann = get_ssa_name_ann (op); + new_ann->name_mem_tag = ann->name_mem_tag; + } + } + } + + *use->op_p = build1 (INDIRECT_REF, TREE_TYPE (*use->op_p), op); +} + +/* Rewrites USE (the condition such that one of the arguments is an iv) using + candidate CAND. */ + +static void +rewrite_use_compare (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + tree comp; + tree *op_p, cond, op, stmts, bound; + block_stmt_iterator bsi = stmt_bsi (use->stmt); + enum tree_code compare; + + if (may_eliminate_iv (data->current_loop, + use, cand, &compare, &bound)) + { + op = force_gimple_operand (unshare_expr (bound), &stmts, false); + + if (stmts) + bsi_insert_before (&bsi, stmts, BSI_SAME_STMT); + + *use->op_p = build (compare, boolean_type_node, + var_at_stmt (data->current_loop, + cand, use->stmt), op); + modify_stmt (use->stmt); + return; + } + + /* The induction variable elimination failed; just express the original + giv. */ + comp = unshare_expr (get_computation (data->current_loop, use, cand)); + + cond = *use->op_p; + op_p = &TREE_OPERAND (cond, 0); + if (TREE_CODE (*op_p) != SSA_NAME + || zero_p (get_iv (data, *op_p)->step)) + op_p = &TREE_OPERAND (cond, 1); + + op = force_gimple_operand (comp, &stmts, false); + if (stmts) + bsi_insert_before (&bsi, stmts, BSI_SAME_STMT); + + *op_p = op; +} + +/* Split loop exit edge EXIT. The things are a bit complicated by a need to + preserve the loop closed ssa form. */ + +static void +split_loop_exit_edge (edge exit) +{ + basic_block dest = exit->dest; + basic_block bb = loop_split_edge_with (exit, NULL); + tree phi, *def_p, new_phi, new_name; + + for (phi = phi_nodes (dest); phi; phi = TREE_CHAIN (phi)) + { + def_p = &phi_element_for_edge (phi, bb->succ)->def; + + new_name = duplicate_ssa_name (*def_p, NULL); + new_phi = create_phi_node (new_name, bb); + SSA_NAME_DEF_STMT (new_name) = new_phi; + add_phi_arg (&new_phi, *def_p, exit); + *def_p = new_name; + } +} + +/* Ensure that operand *OP_P may be used at the end of EXIT without + violating loop closed ssa form. */ + +static void +protect_loop_closed_ssa_form_use (edge exit, tree *op_p) +{ + basic_block def_bb; + struct loop *def_loop; + tree phi; + + if (TREE_CODE (*op_p) != SSA_NAME) + return; + + def_bb = bb_for_stmt (SSA_NAME_DEF_STMT (*op_p)); + if (!def_bb) + return; + + def_loop = def_bb->loop_father; + if (flow_bb_inside_loop_p (def_loop, exit->dest)) + return; + + /* Try finding a phi node that copies the value out of the loop. */ + for (phi = phi_nodes (exit->dest); phi; phi = TREE_CHAIN (phi)) + if (phi_element_for_edge (phi, exit)->def == *op_p) + break; + + if (!phi) + { + /* Create such a phi node. */ + tree new_name = duplicate_ssa_name (*op_p, NULL); + + phi = create_phi_node (new_name, exit->dest); + SSA_NAME_DEF_STMT (new_name) = phi; + add_phi_arg (&phi, *op_p, exit); + } + + *op_p = PHI_RESULT (phi); +} + +/* Ensure that operands of STMT may be used at the end of EXIT without + violating loop closed ssa form. */ + +static void +protect_loop_closed_ssa_form (edge exit, tree stmt) +{ + use_optype uses; + vuse_optype vuses; + vdef_optype vdefs; + unsigned i; + + get_stmt_operands (stmt); + + uses = STMT_USE_OPS (stmt); + for (i = 0; i < NUM_USES (uses); i++) + protect_loop_closed_ssa_form_use (exit, USE_OP_PTR (uses, i)); + + vuses = STMT_VUSE_OPS (stmt); + for (i = 0; i < NUM_VUSES (vuses); i++) + protect_loop_closed_ssa_form_use (exit, VUSE_OP_PTR (vuses, i)); + + vdefs = STMT_VDEF_OPS (stmt); + for (i = 0; i < NUM_VDEFS (vdefs); i++) + protect_loop_closed_ssa_form_use (exit, VDEF_OP_PTR (vdefs, i)); +} + +/* STMTS compute a value of a phi argument OP on EXIT of a loop. Arrange things + so that they are emitted on the correct place, and so that the loop closed + ssa form is preserved. */ + +void +compute_phi_arg_on_exit (edge exit, tree stmts, tree op) +{ + tree_stmt_iterator tsi; + block_stmt_iterator bsi; + tree phi, stmt, def, next; + + if (exit->dest->pred->pred_next) + split_loop_exit_edge (exit); + + if (TREE_CODE (stmts) == STATEMENT_LIST) + { + for (tsi = tsi_start (stmts); !tsi_end_p (tsi); tsi_next (&tsi)) + protect_loop_closed_ssa_form (exit, tsi_stmt (tsi)); + } + else + protect_loop_closed_ssa_form (exit, stmts); + + /* Ensure there is label in exit->dest, so that we can + insert after it. */ + tree_block_label (exit->dest); + bsi = bsi_after_labels (exit->dest); + bsi_insert_after (&bsi, stmts, BSI_CONTINUE_LINKING); + + if (!op) + return; + + for (phi = phi_nodes (exit->dest); phi; phi = next) + { + next = TREE_CHAIN (phi); + + if (phi_element_for_edge (phi, exit)->def == op) + { + def = PHI_RESULT (phi); + remove_statement (phi, false); + stmt = build (MODIFY_EXPR, TREE_TYPE (op), + def, op); + SSA_NAME_DEF_STMT (def) = stmt; + bsi_insert_after (&bsi, stmt, BSI_CONTINUE_LINKING); + } + } +} + +/* Rewrites the final value of USE (that is only needed outside of the loop) + using candidate CAND. */ + +static void +rewrite_use_outer (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + edge exit; + tree value, op, stmts, tgt = *use->op_p; + tree phi; + + exit = loop_data (data->current_loop)->single_exit; + + if (exit) + { + if (!cand->iv) + { + if (!may_replace_final_value (data->current_loop, use, &value)) + abort (); + } + else + value = get_computation_at (data->current_loop, + use, cand, last_stmt (exit->src)); + + op = force_gimple_operand (value, &stmts, true); + + /* If we will preserve the iv anyway and we would need to perform + some computation to replace the final value, do nothing. */ + if (stmts && name_info (data, tgt)->preserve_biv) + return; + + for (phi = phi_nodes (exit->dest); phi; phi = TREE_CHAIN (phi)) + { + tree *def_p = &phi_element_for_edge (phi, exit)->def; + + if (*def_p == tgt) + *def_p = op; + } + + if (stmts) + compute_phi_arg_on_exit (exit, stmts, op); + + /* Enable removal of the statement. We cannot remove it directly, + since we may still need the aliasing information attached to the + ssa name defined by it. */ + name_info (data, tgt)->iv->have_use_for = false; + return; + } + + /* If the variable is going to be preserved anyway, there is nothing to + do. */ + if (name_info (data, tgt)->preserve_biv) + return; + + /* Otherwise we just need to compute the iv. */ + rewrite_use_nonlinear_expr (data, use, cand); +} + +/* Rewrites USE using candidate CAND. */ + +static void +rewrite_use (struct ivopts_data *data, + struct iv_use *use, struct iv_cand *cand) +{ + switch (use->type) + { + case USE_NONLINEAR_EXPR: + rewrite_use_nonlinear_expr (data, use, cand); + break; + + case USE_OUTER: + rewrite_use_outer (data, use, cand); + break; + + case USE_ADDRESS: + rewrite_use_address (data, use, cand); + break; + + case USE_COMPARE: + rewrite_use_compare (data, use, cand); + break; + + default: + abort (); + } + modify_stmt (use->stmt); +} + +/* Rewrite the uses using the selected induction variables. */ + +static void +rewrite_uses (struct ivopts_data *data) +{ + unsigned i; + struct iv_cand *cand; + struct iv_use *use; + + for (i = 0; i < n_iv_uses (data); i++) + { + use = iv_use (data, i); + cand = use->selected; + if (!cand) + abort (); + + rewrite_use (data, use, cand); + } +} + +/* Removes the ivs that are not used after rewriting. */ + +static void +remove_unused_ivs (struct ivopts_data *data) +{ + unsigned j; + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, j, + { + struct version_info *info; + + info = ver_info (data, j); + if (info->iv + && !zero_p (info->iv->step) + && !info->inv_id + && !info->iv->have_use_for + && !info->preserve_biv) + remove_statement (SSA_NAME_DEF_STMT (info->iv->ssa_name), true); + }); +} + +/* Frees data allocated by the optimization of a single loop. */ + +static void +free_loop_data (struct ivopts_data *data) +{ + unsigned i, j; + + EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, + { + struct version_info *info; + + info = ver_info (data, i); + if (info->iv) + free (info->iv); + info->iv = NULL; + info->has_nonlin_use = false; + info->preserve_biv = false; + info->inv_id = 0; + }); + bitmap_clear (data->relevant); + + for (i = 0; i < n_iv_uses (data); i++) + { + struct iv_use *use = iv_use (data, i); + + free (use->iv); + BITMAP_XFREE (use->related_cands); + for (j = 0; j < use->n_map_members; j++) + if (use->cost_map[j].depends_on) + BITMAP_XFREE (use->cost_map[j].depends_on); + free (use->cost_map); + free (use); + } + VARRAY_POP_ALL (data->iv_uses); + + for (i = 0; i < n_iv_cands (data); i++) + { + struct iv_cand *cand = iv_cand (data, i); + + if (cand->iv) + free (cand->iv); + free (cand); + } + VARRAY_POP_ALL (data->iv_candidates); + + if (data->version_info_size < highest_ssa_version) + { + data->version_info_size = 2 * highest_ssa_version; + free (data->version_info); + data->version_info = xcalloc (data->version_info_size, + sizeof (struct version_info)); + } + + data->max_inv_id = 0; + + for (i = 0; i < VARRAY_ACTIVE_SIZE (decl_rtl_to_reset); i++) + { + tree obj = VARRAY_GENERIC_PTR_NOGC (decl_rtl_to_reset, i); + + SET_DECL_RTL (obj, NULL_RTX); + } + VARRAY_POP_ALL (decl_rtl_to_reset); +} + +/* Finalizes data structures used by the iv optimization pass. LOOPS is the + loop tree. */ + +static void +tree_ssa_iv_optimize_finalize (struct loops *loops, struct ivopts_data *data) +{ + unsigned i; + + for (i = 1; i < loops->num; i++) + if (loops->parray[i]) + { + free (loops->parray[i]->aux); + loops->parray[i]->aux = NULL; + } + + free_loop_data (data); + free (data->version_info); + BITMAP_XFREE (data->relevant); + + VARRAY_FREE (decl_rtl_to_reset); + VARRAY_FREE (data->iv_uses); + VARRAY_FREE (data->iv_candidates); + + scev_finalize (); +} + +/* Optimizes the LOOP. Returns true if anything changed. */ + +static bool +tree_ssa_iv_optimize_loop (struct ivopts_data *data, struct loop *loop) +{ + bool changed = false; + bitmap iv_set; + + data->current_loop = loop; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Processing loop %d\n", loop->num); + fprintf (dump_file, " %d exits\n", loop_data (loop)->n_exits); + if (loop_data (loop)->single_exit) + { + edge ex = loop_data (loop)->single_exit; + + fprintf (dump_file, " single exit %d -> %d, exit condition ", + ex->src->index, ex->dest->index); + print_generic_expr (dump_file, last_stmt (ex->src), TDF_SLIM); + fprintf (dump_file, "\n"); + } + fprintf (dump_file, "\n"); + } + + /* For each ssa name determines whether it behaves as an induction variable + in some loop. */ + if (!find_induction_variables (data)) + goto finish; + + /* Finds interesting uses (item 1). */ + find_interesting_uses (data); + + /* Finds candidates for the induction variables (item 2). */ + find_iv_candidates (data); + + /* Calculates the costs (item 3, part 1). */ + determine_use_iv_costs (data); + determine_iv_costs (data); + determine_set_costs (data); + + /* Find the optimal set of induction variables (item 3, part 2). */ + iv_set = find_optimal_iv_set (data); + if (!iv_set) + goto finish; + changed = true; + + /* Create the new induction variables (item 4, part 1). */ + create_new_ivs (data, iv_set); + + /* Rewrite the uses (item 4, part 2). */ + rewrite_uses (data); + + /* Remove the ivs that are unused after rewriting. */ + remove_unused_ivs (data); + + loop_commit_inserts (); + + BITMAP_XFREE (iv_set); +finish: + free_loop_data (data); + + return changed; +} + +/* Main entry point. Optimizes induction variables in LOOPS. */ + +void +tree_ssa_iv_optimize (struct loops *loops) +{ + struct loop *loop; + struct ivopts_data data; + + timevar_push (TV_TREE_LOOP_IVOPTS); + tree_ssa_iv_optimize_init (loops, &data); + + /* Optimize the loops starting with the innermost ones. */ + loop = loops->tree_root; + while (loop->inner) + loop = loop->inner; + +#ifdef ENABLE_CHECKING + verify_loop_closed_ssa (); +#endif + + /* Scan the loops, inner ones first. */ + while (loop != loops->tree_root) + { + if (tree_ssa_iv_optimize_loop (&data, loop)) + { +#ifdef ENABLE_CHECKING + verify_loop_closed_ssa (); +#endif + } + + if (loop->next) + { + loop = loop->next; + while (loop->inner) + loop = loop->inner; + } + else + loop = loop->outer; + } + + tree_ssa_iv_optimize_finalize (loops, &data); + + timevar_pop (TV_TREE_LOOP_IVOPTS); +} |