/* 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); }