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Diffstat (limited to 'gcc/unroll.c')
| -rw-r--r-- | gcc/unroll.c | 3840 |
1 files changed, 0 insertions, 3840 deletions
diff --git a/gcc/unroll.c b/gcc/unroll.c deleted file mode 100644 index cef4c6ecca3..00000000000 --- a/gcc/unroll.c +++ /dev/null @@ -1,3840 +0,0 @@ -/* Try to unroll loops, and split induction variables. - Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001, - 2002, 2003, 2004 - Free Software Foundation, Inc. - Contributed by James E. Wilson, Cygnus Support/UC Berkeley. - -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. */ - -/* Try to unroll a loop, and split induction variables. - - Loops for which the number of iterations can be calculated exactly are - handled specially. If the number of iterations times the insn_count is - less than MAX_UNROLLED_INSNS, then the loop is unrolled completely. - Otherwise, we try to unroll the loop a number of times modulo the number - of iterations, so that only one exit test will be needed. It is unrolled - a number of times approximately equal to MAX_UNROLLED_INSNS divided by - the insn count. - - Otherwise, if the number of iterations can be calculated exactly at - run time, and the loop is always entered at the top, then we try to - precondition the loop. That is, at run time, calculate how many times - the loop will execute, and then execute the loop body a few times so - that the remaining iterations will be some multiple of 4 (or 2 if the - loop is large). Then fall through to a loop unrolled 4 (or 2) times, - with only one exit test needed at the end of the loop. - - Otherwise, if the number of iterations can not be calculated exactly, - not even at run time, then we still unroll the loop a number of times - approximately equal to MAX_UNROLLED_INSNS divided by the insn count, - but there must be an exit test after each copy of the loop body. - - For each induction variable, which is dead outside the loop (replaceable) - or for which we can easily calculate the final value, if we can easily - calculate its value at each place where it is set as a function of the - current loop unroll count and the variable's value at loop entry, then - the induction variable is split into `N' different variables, one for - each copy of the loop body. One variable is live across the backward - branch, and the others are all calculated as a function of this variable. - This helps eliminate data dependencies, and leads to further opportunities - for cse. */ - -/* Possible improvements follow: */ - -/* ??? Add an extra pass somewhere to determine whether unrolling will - give any benefit. E.g. after generating all unrolled insns, compute the - cost of all insns and compare against cost of insns in rolled loop. - - - On traditional architectures, unrolling a non-constant bound loop - is a win if there is a giv whose only use is in memory addresses, the - memory addresses can be split, and hence giv increments can be - eliminated. - - It is also a win if the loop is executed many times, and preconditioning - can be performed for the loop. - Add code to check for these and similar cases. */ - -/* ??? Improve control of which loops get unrolled. Could use profiling - info to only unroll the most commonly executed loops. Perhaps have - a user specifiable option to control the amount of code expansion, - or the percent of loops to consider for unrolling. Etc. */ - -/* ??? Look at the register copies inside the loop to see if they form a - simple permutation. If so, iterate the permutation until it gets back to - the start state. This is how many times we should unroll the loop, for - best results, because then all register copies can be eliminated. - For example, the lisp nreverse function should be unrolled 3 times - while (this) - { - next = this->cdr; - this->cdr = prev; - prev = this; - this = next; - } - - ??? The number of times to unroll the loop may also be based on data - references in the loop. For example, if we have a loop that references - x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */ - -/* ??? Add some simple linear equation solving capability so that we can - determine the number of loop iterations for more complex loops. - For example, consider this loop from gdb - #define SWAP_TARGET_AND_HOST(buffer,len) - { - char tmp; - char *p = (char *) buffer; - char *q = ((char *) buffer) + len - 1; - int iterations = (len + 1) >> 1; - int i; - for (p; p < q; p++, q--;) - { - tmp = *q; - *q = *p; - *p = tmp; - } - } - Note that: - start value = p = &buffer + current_iteration - end value = q = &buffer + len - 1 - current_iteration - Given the loop exit test of "p < q", then there must be "q - p" iterations, - set equal to zero and solve for number of iterations: - q - p = len - 1 - 2*current_iteration = 0 - current_iteration = (len - 1) / 2 - Hence, there are (len - 1) / 2 (rounded up to the nearest integer) - iterations of this loop. */ - -/* ??? Currently, no labels are marked as loop invariant when doing loop - unrolling. This is because an insn inside the loop, that loads the address - of a label inside the loop into a register, could be moved outside the loop - by the invariant code motion pass if labels were invariant. If the loop - is subsequently unrolled, the code will be wrong because each unrolled - body of the loop will use the same address, whereas each actually needs a - different address. A case where this happens is when a loop containing - a switch statement is unrolled. - - It would be better to let labels be considered invariant. When we - unroll loops here, check to see if any insns using a label local to the - loop were moved before the loop. If so, then correct the problem, by - moving the insn back into the loop, or perhaps replicate the insn before - the loop, one copy for each time the loop is unrolled. */ - -#include "config.h" -#include "system.h" -#include "coretypes.h" -#include "tm.h" -#include "rtl.h" -#include "tm_p.h" -#include "insn-config.h" -#include "integrate.h" -#include "regs.h" -#include "recog.h" -#include "flags.h" -#include "function.h" -#include "expr.h" -#include "loop.h" -#include "toplev.h" -#include "hard-reg-set.h" -#include "basic-block.h" -#include "predict.h" -#include "params.h" -#include "cfgloop.h" - -/* The prime factors looked for when trying to unroll a loop by some - number which is modulo the total number of iterations. Just checking - for these 4 prime factors will find at least one factor for 75% of - all numbers theoretically. Practically speaking, this will succeed - almost all of the time since loops are generally a multiple of 2 - and/or 5. */ - -#define NUM_FACTORS 4 - -static struct _factor { const int factor; int count; } -factors[NUM_FACTORS] = { {2, 0}, {3, 0}, {5, 0}, {7, 0}}; - -/* Describes the different types of loop unrolling performed. */ - -enum unroll_types -{ - UNROLL_COMPLETELY, - UNROLL_MODULO, - UNROLL_NAIVE -}; - -/* Indexed by register number, if nonzero, then it contains a pointer - to a struct induction for a DEST_REG giv which has been combined with - one of more address givs. This is needed because whenever such a DEST_REG - giv is modified, we must modify the value of all split address givs - that were combined with this DEST_REG giv. */ - -static struct induction **addr_combined_regs; - -/* Indexed by register number, if this is a splittable induction variable, - then this will hold the current value of the register, which depends on the - iteration number. */ - -static rtx *splittable_regs; - -/* Indexed by register number, if this is a splittable induction variable, - then this will hold the number of instructions in the loop that modify - the induction variable. Used to ensure that only the last insn modifying - a split iv will update the original iv of the dest. */ - -static int *splittable_regs_updates; - -/* Forward declarations. */ - -static rtx simplify_cmp_and_jump_insns (enum rtx_code, enum machine_mode, - rtx, rtx, rtx); -static void init_reg_map (struct inline_remap *, int); -static rtx calculate_giv_inc (rtx, rtx, unsigned int); -static rtx initial_reg_note_copy (rtx, struct inline_remap *); -static void final_reg_note_copy (rtx *, struct inline_remap *); -static void copy_loop_body (struct loop *, rtx, rtx, - struct inline_remap *, rtx, int, - enum unroll_types, rtx, rtx, rtx, rtx); -static int find_splittable_regs (const struct loop *, enum unroll_types, - int); -static int find_splittable_givs (const struct loop *, struct iv_class *, - enum unroll_types, rtx, int); -static int reg_dead_after_loop (const struct loop *, rtx); -static rtx fold_rtx_mult_add (rtx, rtx, rtx, enum machine_mode); -static rtx remap_split_bivs (struct loop *, rtx); -static rtx find_common_reg_term (rtx, rtx); -static rtx loop_find_equiv_value (const struct loop *, rtx); - -/* Try to unroll one loop and split induction variables in the loop. - - The loop is described by the arguments LOOP and INSN_COUNT. - STRENGTH_REDUCTION_P indicates whether information generated in the - strength reduction pass is available. - - This function is intended to be called from within `strength_reduce' - in loop.c. */ - -void -unroll_loop (struct loop *loop, int insn_count, int strength_reduce_p) -{ - struct loop_info *loop_info = LOOP_INFO (loop); - struct loop_ivs *ivs = LOOP_IVS (loop); - int i, j; - unsigned int r; - unsigned HOST_WIDE_INT temp; - int unroll_number = 1; - rtx copy_start, copy_end; - rtx insn, sequence, pattern, tem; - int max_labelno, max_insnno; - rtx insert_before; - struct inline_remap *map; - char *local_label = NULL; - char *local_regno; - unsigned int max_local_regnum; - unsigned int maxregnum; - rtx exit_label = 0; - rtx start_label; - struct iv_class *bl; - int splitting_not_safe = 0; - enum unroll_types unroll_type = UNROLL_NAIVE; - int loop_preconditioned = 0; - rtx safety_label; - /* This points to the last real insn in the loop, which should be either - a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional - jumps). */ - rtx last_loop_insn; - rtx loop_start = loop->start; - rtx loop_end = loop->end; - - /* Don't bother unrolling huge loops. Since the minimum factor is - two, loops greater than one half of MAX_UNROLLED_INSNS will never - be unrolled. */ - if (insn_count > MAX_UNROLLED_INSNS / 2) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n"); - return; - } - - /* Determine type of unroll to perform. Depends on the number of iterations - and the size of the loop. */ - - /* If there is no strength reduce info, then set - loop_info->n_iterations to zero. This can happen if - strength_reduce can't find any bivs in the loop. A value of zero - indicates that the number of iterations could not be calculated. */ - - if (! strength_reduce_p) - loop_info->n_iterations = 0; - - if (loop_dump_stream && loop_info->n_iterations > 0) - fprintf (loop_dump_stream, "Loop unrolling: " HOST_WIDE_INT_PRINT_DEC - " iterations.\n", loop_info->n_iterations); - - /* Find and save a pointer to the last nonnote insn in the loop. */ - - last_loop_insn = prev_nonnote_insn (loop_end); - - /* Calculate how many times to unroll the loop. Indicate whether or - not the loop is being completely unrolled. */ - - if (loop_info->n_iterations == 1) - { - /* Handle the case where the loop begins with an unconditional - jump to the loop condition. Make sure to delete the jump - insn, otherwise the loop body will never execute. */ - - /* If the last instruction is not a BARRIER or a JUMP_INSN, then - don't do anything. */ - - if (BARRIER_P (last_loop_insn)) - { - /* Delete the jump insn. This will delete the barrier also. */ - last_loop_insn = PREV_INSN (last_loop_insn); - } - } - - if (loop_info->n_iterations > 0 - /* Avoid overflow in the next expression. */ - && loop_info->n_iterations < (unsigned) MAX_UNROLLED_INSNS - && loop_info->n_iterations * insn_count < (unsigned) MAX_UNROLLED_INSNS) - { - unroll_number = loop_info->n_iterations; - unroll_type = UNROLL_COMPLETELY; - } - else if (loop_info->n_iterations > 0) - { - /* Try to factor the number of iterations. Don't bother with the - general case, only using 2, 3, 5, and 7 will get 75% of all - numbers theoretically, and almost all in practice. */ - - for (i = 0; i < NUM_FACTORS; i++) - factors[i].count = 0; - - temp = loop_info->n_iterations; - for (i = NUM_FACTORS - 1; i >= 0; i--) - while (temp % factors[i].factor == 0) - { - factors[i].count++; - temp = temp / factors[i].factor; - } - - /* Start with the larger factors first so that we generally - get lots of unrolling. */ - - unroll_number = 1; - temp = insn_count; - for (i = 3; i >= 0; i--) - while (factors[i].count--) - { - if (temp * factors[i].factor < (unsigned) MAX_UNROLLED_INSNS) - { - unroll_number *= factors[i].factor; - temp *= factors[i].factor; - } - else - break; - } - - /* If we couldn't find any factors, then unroll as in the normal - case. */ - if (unroll_number == 1) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, "Loop unrolling: No factors found.\n"); - } - else - unroll_type = UNROLL_MODULO; - } - - /* Default case, calculate number of times to unroll loop based on its - size. */ - if (unroll_type == UNROLL_NAIVE) - { - if (8 * insn_count < MAX_UNROLLED_INSNS) - unroll_number = 8; - else if (4 * insn_count < MAX_UNROLLED_INSNS) - unroll_number = 4; - else - unroll_number = 2; - } - - /* Now we know how many times to unroll the loop. */ - - if (loop_dump_stream) - fprintf (loop_dump_stream, "Unrolling loop %d times.\n", unroll_number); - - if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO) - { - /* Loops of these types can start with jump down to the exit condition - in rare circumstances. - - Consider a pair of nested loops where the inner loop is part - of the exit code for the outer loop. - - In this case jump.c will not duplicate the exit test for the outer - loop, so it will start with a jump to the exit code. - - Then consider if the inner loop turns out to iterate once and - only once. We will end up deleting the jumps associated with - the inner loop. However, the loop notes are not removed from - the instruction stream. - - And finally assume that we can compute the number of iterations - for the outer loop. - - In this case unroll may want to unroll the outer loop even though - it starts with a jump to the outer loop's exit code. - - We could try to optimize this case, but it hardly seems worth it. - Just return without unrolling the loop in such cases. */ - - insn = loop_start; - while (!LABEL_P (insn) && !JUMP_P (insn)) - insn = NEXT_INSN (insn); - if (JUMP_P (insn)) - return; - } - - if (unroll_type == UNROLL_COMPLETELY) - { - /* Completely unrolling the loop: Delete the compare and branch at - the end (the last two instructions). This delete must done at the - very end of loop unrolling, to avoid problems with calls to - back_branch_in_range_p, which is called by find_splittable_regs. - All increments of splittable bivs/givs are changed to load constant - instructions. */ - - copy_start = loop_start; - - /* Set insert_before to the instruction immediately after the JUMP_INSN - (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of - the loop will be correctly handled by copy_loop_body. */ - insert_before = NEXT_INSN (last_loop_insn); - - /* Set copy_end to the insn before the jump at the end of the loop. */ - if (BARRIER_P (last_loop_insn)) - copy_end = PREV_INSN (PREV_INSN (last_loop_insn)); - else if (JUMP_P (last_loop_insn)) - { - copy_end = PREV_INSN (last_loop_insn); -#ifdef HAVE_cc0 - /* The instruction immediately before the JUMP_INSN may be a compare - instruction which we do not want to copy. */ - if (sets_cc0_p (PREV_INSN (copy_end))) - copy_end = PREV_INSN (copy_end); -#endif - } - else - { - /* We currently can't unroll a loop if it doesn't end with a - JUMP_INSN. There would need to be a mechanism that recognizes - this case, and then inserts a jump after each loop body, which - jumps to after the last loop body. */ - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Unrolling failure: loop does not end with a JUMP_INSN.\n"); - return; - } - } - else if (unroll_type == UNROLL_MODULO) - { - /* Partially unrolling the loop: The compare and branch at the end - (the last two instructions) must remain. Don't copy the compare - and branch instructions at the end of the loop. Insert the unrolled - code immediately before the compare/branch at the end so that the - code will fall through to them as before. */ - - copy_start = loop_start; - - /* Set insert_before to the jump insn at the end of the loop. - Set copy_end to before the jump insn at the end of the loop. */ - if (BARRIER_P (last_loop_insn)) - { - insert_before = PREV_INSN (last_loop_insn); - copy_end = PREV_INSN (insert_before); - } - else if (JUMP_P (last_loop_insn)) - { - insert_before = last_loop_insn; -#ifdef HAVE_cc0 - /* The instruction immediately before the JUMP_INSN may be a compare - instruction which we do not want to copy or delete. */ - if (sets_cc0_p (PREV_INSN (insert_before))) - insert_before = PREV_INSN (insert_before); -#endif - copy_end = PREV_INSN (insert_before); - } - else - { - /* We currently can't unroll a loop if it doesn't end with a - JUMP_INSN. There would need to be a mechanism that recognizes - this case, and then inserts a jump after each loop body, which - jumps to after the last loop body. */ - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Unrolling failure: loop does not end with a JUMP_INSN.\n"); - return; - } - } - else - { - /* Normal case: Must copy the compare and branch instructions at the - end of the loop. */ - - if (BARRIER_P (last_loop_insn)) - { - /* Loop ends with an unconditional jump and a barrier. - Handle this like above, don't copy jump and barrier. - This is not strictly necessary, but doing so prevents generating - unconditional jumps to an immediately following label. - - This will be corrected below if the target of this jump is - not the start_label. */ - - insert_before = PREV_INSN (last_loop_insn); - copy_end = PREV_INSN (insert_before); - } - else if (JUMP_P (last_loop_insn)) - { - /* Set insert_before to immediately after the JUMP_INSN, so that - NOTEs at the end of the loop will be correctly handled by - copy_loop_body. */ - insert_before = NEXT_INSN (last_loop_insn); - copy_end = last_loop_insn; - } - else - { - /* We currently can't unroll a loop if it doesn't end with a - JUMP_INSN. There would need to be a mechanism that recognizes - this case, and then inserts a jump after each loop body, which - jumps to after the last loop body. */ - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Unrolling failure: loop does not end with a JUMP_INSN.\n"); - return; - } - - /* If copying exit test branches because they can not be eliminated, - then must convert the fall through case of the branch to a jump past - the end of the loop. Create a label to emit after the loop and save - it for later use. Do not use the label after the loop, if any, since - it might be used by insns outside the loop, or there might be insns - added before it later by final_[bg]iv_value which must be after - the real exit label. */ - exit_label = gen_label_rtx (); - - insn = loop_start; - while (!LABEL_P (insn) && !JUMP_P (insn)) - insn = NEXT_INSN (insn); - - if (JUMP_P (insn)) - { - /* The loop starts with a jump down to the exit condition test. - Start copying the loop after the barrier following this - jump insn. */ - copy_start = NEXT_INSN (insn); - - /* Splitting induction variables doesn't work when the loop is - entered via a jump to the bottom, because then we end up doing - a comparison against a new register for a split variable, but - we did not execute the set insn for the new register because - it was skipped over. */ - splitting_not_safe = 1; - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Splitting not safe, because loop not entered at top.\n"); - } - else - copy_start = loop_start; - } - - /* This should always be the first label in the loop. */ - start_label = NEXT_INSN (copy_start); - /* There may be a line number note and/or a loop continue note here. */ - while (NOTE_P (start_label)) - start_label = NEXT_INSN (start_label); - if (!LABEL_P (start_label)) - { - /* This can happen as a result of jump threading. If the first insns in - the loop test the same condition as the loop's backward jump, or the - opposite condition, then the backward jump will be modified to point - to elsewhere, and the loop's start label is deleted. - - This case currently can not be handled by the loop unrolling code. */ - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Unrolling failure: unknown insns between BEG note and loop label.\n"); - return; - } - if (LABEL_NAME (start_label)) - { - /* The jump optimization pass must have combined the original start label - with a named label for a goto. We can't unroll this case because - jumps which go to the named label must be handled differently than - jumps to the loop start, and it is impossible to differentiate them - in this case. */ - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Unrolling failure: loop start label is gone\n"); - return; - } - - if (unroll_type == UNROLL_NAIVE - && BARRIER_P (last_loop_insn) - && JUMP_P (PREV_INSN (last_loop_insn)) - && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn))) - { - /* In this case, we must copy the jump and barrier, because they will - not be converted to jumps to an immediately following label. */ - - insert_before = NEXT_INSN (last_loop_insn); - copy_end = last_loop_insn; - } - - if (unroll_type == UNROLL_NAIVE - && JUMP_P (last_loop_insn) - && start_label != JUMP_LABEL (last_loop_insn)) - { - /* ??? The loop ends with a conditional branch that does not branch back - to the loop start label. In this case, we must emit an unconditional - branch to the loop exit after emitting the final branch. - copy_loop_body does not have support for this currently, so we - give up. It doesn't seem worthwhile to unroll anyways since - unrolling would increase the number of branch instructions - executed. */ - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Unrolling failure: final conditional branch not to loop start\n"); - return; - } - - /* Allocate a translation table for the labels and insn numbers. - They will be filled in as we copy the insns in the loop. */ - - max_labelno = max_label_num (); - max_insnno = get_max_uid (); - - /* Various paths through the unroll code may reach the "egress" label - without initializing fields within the map structure. - - To be safe, we use xcalloc to zero the memory. */ - map = xcalloc (1, sizeof (struct inline_remap)); - - /* Allocate the label map. */ - - if (max_labelno > 0) - { - map->label_map = xcalloc (max_labelno, sizeof (rtx)); - local_label = xcalloc (max_labelno, sizeof (char)); - } - - /* Search the loop and mark all local labels, i.e. the ones which have to - be distinct labels when copied. For all labels which might be - non-local, set their label_map entries to point to themselves. - If they happen to be local their label_map entries will be overwritten - before the loop body is copied. The label_map entries for local labels - will be set to a different value each time the loop body is copied. */ - - for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn)) - { - rtx note; - - if (LABEL_P (insn)) - local_label[CODE_LABEL_NUMBER (insn)] = 1; - else if (JUMP_P (insn)) - { - if (JUMP_LABEL (insn)) - set_label_in_map (map, - CODE_LABEL_NUMBER (JUMP_LABEL (insn)), - JUMP_LABEL (insn)); - else if (GET_CODE (PATTERN (insn)) == ADDR_VEC - || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) - { - rtx pat = PATTERN (insn); - int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC; - int len = XVECLEN (pat, diff_vec_p); - rtx label; - - for (i = 0; i < len; i++) - { - label = XEXP (XVECEXP (pat, diff_vec_p, i), 0); - set_label_in_map (map, CODE_LABEL_NUMBER (label), label); - } - } - } - if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX))) - set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)), - XEXP (note, 0)); - } - - /* Allocate space for the insn map. */ - - map->insn_map = xmalloc (max_insnno * sizeof (rtx)); - - /* The register and constant maps depend on the number of registers - present, so the final maps can't be created until after - find_splittable_regs is called. However, they are needed for - preconditioning, so we create temporary maps when preconditioning - is performed. */ - - /* The preconditioning code may allocate two new pseudo registers. */ - maxregnum = max_reg_num (); - - /* local_regno is only valid for regnos < max_local_regnum. */ - max_local_regnum = maxregnum; - - /* Allocate and zero out the splittable_regs and addr_combined_regs - arrays. These must be zeroed here because they will be used if - loop preconditioning is performed, and must be zero for that case. - - It is safe to do this here, since the extra registers created by the - preconditioning code and find_splittable_regs will never be used - to access the splittable_regs[] and addr_combined_regs[] arrays. */ - - splittable_regs = xcalloc (maxregnum, sizeof (rtx)); - splittable_regs_updates = xcalloc (maxregnum, sizeof (int)); - addr_combined_regs = xcalloc (maxregnum, sizeof (struct induction *)); - local_regno = xcalloc (maxregnum, sizeof (char)); - - /* Mark all local registers, i.e. the ones which are referenced only - inside the loop. */ - if (INSN_UID (copy_end) < max_uid_for_loop) - { - int copy_start_luid = INSN_LUID (copy_start); - int copy_end_luid = INSN_LUID (copy_end); - - /* If a register is used in the jump insn, we must not duplicate it - since it will also be used outside the loop. */ - if (JUMP_P (copy_end)) - copy_end_luid--; - - /* If we have a target that uses cc0, then we also must not duplicate - the insn that sets cc0 before the jump insn, if one is present. */ -#ifdef HAVE_cc0 - if (JUMP_P (copy_end) - && sets_cc0_p (PREV_INSN (copy_end))) - copy_end_luid--; -#endif - - /* If copy_start points to the NOTE that starts the loop, then we must - use the next luid, because invariant pseudo-regs moved out of the loop - have their lifetimes modified to start here, but they are not safe - to duplicate. */ - if (copy_start == loop_start) - copy_start_luid++; - - /* If a pseudo's lifetime is entirely contained within this loop, then we - can use a different pseudo in each unrolled copy of the loop. This - results in better code. */ - /* We must limit the generic test to max_reg_before_loop, because only - these pseudo registers have valid regno_first_uid info. */ - for (r = FIRST_PSEUDO_REGISTER; r < max_reg_before_loop; ++r) - if (REGNO_FIRST_UID (r) > 0 && REGNO_FIRST_UID (r) < max_uid_for_loop - && REGNO_FIRST_LUID (r) >= copy_start_luid - && REGNO_LAST_UID (r) > 0 && REGNO_LAST_UID (r) < max_uid_for_loop - && REGNO_LAST_LUID (r) <= copy_end_luid) - { - /* However, we must also check for loop-carried dependencies. - If the value the pseudo has at the end of iteration X is - used by iteration X+1, then we can not use a different pseudo - for each unrolled copy of the loop. */ - /* A pseudo is safe if regno_first_uid is a set, and this - set dominates all instructions from regno_first_uid to - regno_last_uid. */ - /* ??? This check is simplistic. We would get better code if - this check was more sophisticated. */ - if (set_dominates_use (r, REGNO_FIRST_UID (r), REGNO_LAST_UID (r), - copy_start, copy_end)) - local_regno[r] = 1; - - if (loop_dump_stream) - { - if (local_regno[r]) - fprintf (loop_dump_stream, "Marked reg %d as local\n", r); - else - fprintf (loop_dump_stream, "Did not mark reg %d as local\n", - r); - } - } - } - - /* If this loop requires exit tests when unrolled, check to see if we - can precondition the loop so as to make the exit tests unnecessary. - Just like variable splitting, this is not safe if the loop is entered - via a jump to the bottom. Also, can not do this if no strength - reduce info, because precondition_loop_p uses this info. */ - - /* Must copy the loop body for preconditioning before the following - find_splittable_regs call since that will emit insns which need to - be after the preconditioned loop copies, but immediately before the - unrolled loop copies. */ - - /* Also, it is not safe to split induction variables for the preconditioned - copies of the loop body. If we split induction variables, then the code - assumes that each induction variable can be represented as a function - of its initial value and the loop iteration number. This is not true - in this case, because the last preconditioned copy of the loop body - could be any iteration from the first up to the `unroll_number-1'th, - depending on the initial value of the iteration variable. Therefore - we can not split induction variables here, because we can not calculate - their value. Hence, this code must occur before find_splittable_regs - is called. */ - - if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p) - { - rtx initial_value, final_value, increment; - enum machine_mode mode; - - if (precondition_loop_p (loop, - &initial_value, &final_value, &increment, - &mode)) - { - rtx diff, insn; - rtx *labels; - int abs_inc, neg_inc; - enum rtx_code cc = loop_info->comparison_code; - int less_p = (cc == LE || cc == LEU || cc == LT || cc == LTU); - int unsigned_p = (cc == LEU || cc == GEU || cc == LTU || cc == GTU); - - map->reg_map = xmalloc (maxregnum * sizeof (rtx)); - - VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum, - "unroll_loop_precondition"); - global_const_equiv_varray = map->const_equiv_varray; - - init_reg_map (map, maxregnum); - - /* Limit loop unrolling to 4, since this will make 7 copies of - the loop body. */ - if (unroll_number > 4) - unroll_number = 4; - - /* Save the absolute value of the increment, and also whether or - not it is negative. */ - neg_inc = 0; - abs_inc = INTVAL (increment); - if (abs_inc < 0) - { - abs_inc = -abs_inc; - neg_inc = 1; - } - - start_sequence (); - - /* We must copy the final and initial values here to avoid - improperly shared rtl. */ - final_value = copy_rtx (final_value); - initial_value = copy_rtx (initial_value); - - /* Final value may have form of (PLUS val1 const1_rtx). We need - to convert it into general operand, so compute the real value. */ - - final_value = force_operand (final_value, NULL_RTX); - if (!nonmemory_operand (final_value, VOIDmode)) - final_value = force_reg (mode, final_value); - - /* Calculate the difference between the final and initial values. - Final value may be a (plus (reg x) (const_int 1)) rtx. - - We have to deal with for (i = 0; --i < 6;) type loops. - For such loops the real final value is the first time the - loop variable overflows, so the diff we calculate is the - distance from the overflow value. This is 0 or ~0 for - unsigned loops depending on the direction, or INT_MAX, - INT_MAX+1 for signed loops. We really do not need the - exact value, since we are only interested in the diff - modulo the increment, and the increment is a power of 2, - so we can pretend that the overflow value is 0/~0. */ - - if (cc == NE || less_p != neg_inc) - diff = simplify_gen_binary (MINUS, mode, final_value, - initial_value); - else - diff = simplify_gen_unary (neg_inc ? NOT : NEG, mode, - initial_value, mode); - diff = force_operand (diff, NULL_RTX); - - /* Now calculate (diff % (unroll * abs (increment))) by using an - and instruction. */ - diff = simplify_gen_binary (AND, mode, diff, - GEN_INT (unroll_number*abs_inc - 1)); - diff = force_operand (diff, NULL_RTX); - - /* Now emit a sequence of branches to jump to the proper precond - loop entry point. */ - - labels = xmalloc (sizeof (rtx) * unroll_number); - for (i = 0; i < unroll_number; i++) - labels[i] = gen_label_rtx (); - - /* Check for the case where the initial value is greater than or - equal to the final value. In that case, we want to execute - exactly one loop iteration. The code below will fail for this - case. This check does not apply if the loop has a NE - comparison at the end. */ - - if (cc != NE) - { - rtx incremented_initval; - enum rtx_code cmp_code; - - incremented_initval - = simplify_gen_binary (PLUS, mode, initial_value, increment); - incremented_initval - = force_operand (incremented_initval, NULL_RTX); - - cmp_code = (less_p - ? (unsigned_p ? GEU : GE) - : (unsigned_p ? LEU : LE)); - - insn = simplify_cmp_and_jump_insns (cmp_code, mode, - incremented_initval, - final_value, labels[1]); - if (insn) - predict_insn_def (insn, PRED_LOOP_CONDITION, TAKEN); - } - - /* Assuming the unroll_number is 4, and the increment is 2, then - for a negative increment: for a positive increment: - diff = 0,1 precond 0 diff = 0,7 precond 0 - diff = 2,3 precond 3 diff = 1,2 precond 1 - diff = 4,5 precond 2 diff = 3,4 precond 2 - diff = 6,7 precond 1 diff = 5,6 precond 3 */ - - /* We only need to emit (unroll_number - 1) branches here, the - last case just falls through to the following code. */ - - /* ??? This would give better code if we emitted a tree of branches - instead of the current linear list of branches. */ - - for (i = 0; i < unroll_number - 1; i++) - { - int cmp_const; - enum rtx_code cmp_code; - - /* For negative increments, must invert the constant compared - against, except when comparing against zero. */ - if (i == 0) - { - cmp_const = 0; - cmp_code = EQ; - } - else if (neg_inc) - { - cmp_const = unroll_number - i; - cmp_code = GE; - } - else - { - cmp_const = i; - cmp_code = LE; - } - - insn = simplify_cmp_and_jump_insns (cmp_code, mode, diff, - GEN_INT (abs_inc*cmp_const), - labels[i]); - if (insn) - predict_insn (insn, PRED_LOOP_PRECONDITIONING, - REG_BR_PROB_BASE / (unroll_number - i)); - } - - /* If the increment is greater than one, then we need another branch, - to handle other cases equivalent to 0. */ - - /* ??? This should be merged into the code above somehow to help - simplify the code here, and reduce the number of branches emitted. - For the negative increment case, the branch here could easily - be merged with the `0' case branch above. For the positive - increment case, it is not clear how this can be simplified. */ - - if (abs_inc != 1) - { - int cmp_const; - enum rtx_code cmp_code; - - if (neg_inc) - { - cmp_const = abs_inc - 1; - cmp_code = LE; - } - else - { - cmp_const = abs_inc * (unroll_number - 1) + 1; - cmp_code = GE; - } - - simplify_cmp_and_jump_insns (cmp_code, mode, diff, - GEN_INT (cmp_const), labels[0]); - } - - sequence = get_insns (); - end_sequence (); - loop_insn_hoist (loop, sequence); - - /* Only the last copy of the loop body here needs the exit - test, so set copy_end to exclude the compare/branch here, - and then reset it inside the loop when get to the last - copy. */ - - if (BARRIER_P (last_loop_insn)) - copy_end = PREV_INSN (PREV_INSN (last_loop_insn)); - else if (JUMP_P (last_loop_insn)) - { - copy_end = PREV_INSN (last_loop_insn); -#ifdef HAVE_cc0 - /* The immediately preceding insn may be a compare which - we do not want to copy. */ - if (sets_cc0_p (PREV_INSN (copy_end))) - copy_end = PREV_INSN (copy_end); -#endif - } - else - abort (); - - for (i = 1; i < unroll_number; i++) - { - emit_label_after (labels[unroll_number - i], - PREV_INSN (loop_start)); - - memset (map->insn_map, 0, max_insnno * sizeof (rtx)); - memset (&VARRAY_CONST_EQUIV (map->const_equiv_varray, 0), - 0, (VARRAY_SIZE (map->const_equiv_varray) - * sizeof (struct const_equiv_data))); - map->const_age = 0; - - for (j = 0; j < max_labelno; j++) - if (local_label[j]) - set_label_in_map (map, j, gen_label_rtx ()); - - for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++) - if (local_regno[r]) - { - map->reg_map[r] - = gen_reg_rtx (GET_MODE (regno_reg_rtx[r])); - record_base_value (REGNO (map->reg_map[r]), - regno_reg_rtx[r], 0); - } - /* The last copy needs the compare/branch insns at the end, - so reset copy_end here if the loop ends with a conditional - branch. */ - - if (i == unroll_number - 1) - { - if (BARRIER_P (last_loop_insn)) - copy_end = PREV_INSN (PREV_INSN (last_loop_insn)); - else - copy_end = last_loop_insn; - } - - /* None of the copies are the `last_iteration', so just - pass zero for that parameter. */ - copy_loop_body (loop, copy_start, copy_end, map, exit_label, 0, - unroll_type, start_label, loop_end, - loop_start, copy_end); - } - emit_label_after (labels[0], PREV_INSN (loop_start)); - - if (BARRIER_P (last_loop_insn)) - { - insert_before = PREV_INSN (last_loop_insn); - copy_end = PREV_INSN (insert_before); - } - else - { - insert_before = last_loop_insn; -#ifdef HAVE_cc0 - /* The instruction immediately before the JUMP_INSN may - be a compare instruction which we do not want to copy - or delete. */ - if (sets_cc0_p (PREV_INSN (insert_before))) - insert_before = PREV_INSN (insert_before); -#endif - copy_end = PREV_INSN (insert_before); - } - - /* Set unroll type to MODULO now. */ - unroll_type = UNROLL_MODULO; - loop_preconditioned = 1; - - /* Clean up. */ - free (labels); - } - } - - /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll - the loop unless all loops are being unrolled. */ - if (unroll_type == UNROLL_NAIVE && ! flag_old_unroll_all_loops) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Unrolling failure: Naive unrolling not being done.\n"); - goto egress; - } - - /* At this point, we are guaranteed to unroll the loop. */ - - /* Keep track of the unroll factor for the loop. */ - loop_info->unroll_number = unroll_number; - - /* And whether the loop has been preconditioned. */ - loop_info->preconditioned = loop_preconditioned; - - /* Remember whether it was preconditioned for the second loop pass. */ - NOTE_PRECONDITIONED (loop->end) = loop_preconditioned; - - /* For each biv and giv, determine whether it can be safely split into - a different variable for each unrolled copy of the loop body. - We precalculate and save this info here, since computing it is - expensive. - - Do this before deleting any instructions from the loop, so that - back_branch_in_range_p will work correctly. */ - - if (splitting_not_safe) - temp = 0; - else - temp = find_splittable_regs (loop, unroll_type, unroll_number); - - /* find_splittable_regs may have created some new registers, so must - reallocate the reg_map with the new larger size, and must realloc - the constant maps also. */ - - maxregnum = max_reg_num (); - map->reg_map = xmalloc (maxregnum * sizeof (rtx)); - - init_reg_map (map, maxregnum); - - if (map->const_equiv_varray == 0) - VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, - maxregnum + temp * unroll_number * 2, - "unroll_loop"); - global_const_equiv_varray = map->const_equiv_varray; - - /* Search the list of bivs and givs to find ones which need to be remapped - when split, and set their reg_map entry appropriately. */ - - for (bl = ivs->list; bl; bl = bl->next) - { - if (REGNO (bl->biv->src_reg) != bl->regno) - map->reg_map[bl->regno] = bl->biv->src_reg; -#if 0 - /* Currently, non-reduced/final-value givs are never split. */ - for (v = bl->giv; v; v = v->next_iv) - if (REGNO (v->src_reg) != bl->regno) - map->reg_map[REGNO (v->dest_reg)] = v->src_reg; -#endif - } - - /* Use our current register alignment and pointer flags. */ - map->regno_pointer_align = cfun->emit->regno_pointer_align; - map->x_regno_reg_rtx = cfun->emit->x_regno_reg_rtx; - - /* If the loop is being partially unrolled, and the iteration variables - are being split, and are being renamed for the split, then must fix up - the compare/jump instruction at the end of the loop to refer to the new - registers. This compare isn't copied, so the registers used in it - will never be replaced if it isn't done here. */ - - if (unroll_type == UNROLL_MODULO) - { - insn = NEXT_INSN (copy_end); - if (NONJUMP_INSN_P (insn) || JUMP_P (insn)) - PATTERN (insn) = remap_split_bivs (loop, PATTERN (insn)); - } - - /* For unroll_number times, make a copy of each instruction - between copy_start and copy_end, and insert these new instructions - before the end of the loop. */ - - for (i = 0; i < unroll_number; i++) - { - memset (map->insn_map, 0, max_insnno * sizeof (rtx)); - memset (&VARRAY_CONST_EQUIV (map->const_equiv_varray, 0), 0, - VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data)); - map->const_age = 0; - - for (j = 0; j < max_labelno; j++) - if (local_label[j]) - set_label_in_map (map, j, gen_label_rtx ()); - - for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++) - if (local_regno[r]) - { - map->reg_map[r] = gen_reg_rtx (GET_MODE (regno_reg_rtx[r])); - record_base_value (REGNO (map->reg_map[r]), - regno_reg_rtx[r], 0); - } - - /* If loop starts with a branch to the test, then fix it so that - it points to the test of the first unrolled copy of the loop. */ - if (i == 0 && loop_start != copy_start) - { - insn = PREV_INSN (copy_start); - pattern = PATTERN (insn); - - tem = get_label_from_map (map, - CODE_LABEL_NUMBER - (XEXP (SET_SRC (pattern), 0))); - SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem); - - /* Set the jump label so that it can be used by later loop unrolling - passes. */ - JUMP_LABEL (insn) = tem; - LABEL_NUSES (tem)++; - } - - copy_loop_body (loop, copy_start, copy_end, map, exit_label, - i == unroll_number - 1, unroll_type, start_label, - loop_end, insert_before, insert_before); - } - - /* Before deleting any insns, emit a CODE_LABEL immediately after the last - insn to be deleted. This prevents any runaway delete_insn call from - more insns that it should, as it always stops at a CODE_LABEL. */ - - /* Delete the compare and branch at the end of the loop if completely - unrolling the loop. Deleting the backward branch at the end also - deletes the code label at the start of the loop. This is done at - the very end to avoid problems with back_branch_in_range_p. */ - - if (unroll_type == UNROLL_COMPLETELY) - safety_label = emit_label_after (gen_label_rtx (), last_loop_insn); - else - safety_label = emit_label_after (gen_label_rtx (), copy_end); - - /* Delete all of the original loop instructions. Don't delete the - LOOP_BEG note, or the first code label in the loop. */ - - insn = NEXT_INSN (copy_start); - while (insn != safety_label) - { - /* ??? Don't delete named code labels. They will be deleted when the - jump that references them is deleted. Otherwise, we end up deleting - them twice, which causes them to completely disappear instead of turn - into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in - dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files - to handle deleted labels instead. Or perhaps fix DECL_RTL of the - associated LABEL_DECL to point to one of the new label instances. */ - /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */ - if (insn != start_label - && ! (LABEL_P (insn) && LABEL_NAME (insn)) - && ! (NOTE_P (insn) - && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL)) - insn = delete_related_insns (insn); - else - insn = NEXT_INSN (insn); - } - - /* Can now delete the 'safety' label emitted to protect us from runaway - delete_related_insns calls. */ - if (INSN_DELETED_P (safety_label)) - abort (); - delete_related_insns (safety_label); - - /* If exit_label exists, emit it after the loop. Doing the emit here - forces it to have a higher INSN_UID than any insn in the unrolled loop. - This is needed so that mostly_true_jump in reorg.c will treat jumps - to this loop end label correctly, i.e. predict that they are usually - not taken. */ - if (exit_label) - emit_label_after (exit_label, loop_end); - - egress: - if (unroll_type == UNROLL_COMPLETELY) - { - /* Remove the loop notes since this is no longer a loop. */ - if (loop_start) - delete_related_insns (loop_start); - if (loop_end) - delete_related_insns (loop_end); - } - - if (map->const_equiv_varray) - VARRAY_FREE (map->const_equiv_varray); - if (map->label_map) - { - free (map->label_map); - free (local_label); - } - free (map->insn_map); - free (splittable_regs); - free (splittable_regs_updates); - free (addr_combined_regs); - free (local_regno); - if (map->reg_map) - free (map->reg_map); - free (map); -} - -/* A helper function for unroll_loop. Emit a compare and branch to - satisfy (CMP OP1 OP2), but pass this through the simplifier first. - If the branch turned out to be conditional, return it, otherwise - return NULL. */ - -static rtx -simplify_cmp_and_jump_insns (enum rtx_code code, enum machine_mode mode, - rtx op0, rtx op1, rtx label) -{ - rtx t, insn; - - t = simplify_const_relational_operation (code, mode, op0, op1); - if (!t) - { - enum rtx_code scode = signed_condition (code); - emit_cmp_and_jump_insns (op0, op1, scode, NULL_RTX, mode, - code != scode, label); - insn = get_last_insn (); - - JUMP_LABEL (insn) = label; - LABEL_NUSES (label) += 1; - - return insn; - } - else if (t == const_true_rtx) - { - insn = emit_jump_insn (gen_jump (label)); - emit_barrier (); - JUMP_LABEL (insn) = label; - LABEL_NUSES (label) += 1; - } - - return NULL_RTX; -} - -/* Return true if the loop can be safely, and profitably, preconditioned - so that the unrolled copies of the loop body don't need exit tests. - - This only works if final_value, initial_value and increment can be - determined, and if increment is a constant power of 2. - If increment is not a power of 2, then the preconditioning modulo - operation would require a real modulo instead of a boolean AND, and this - is not considered `profitable'. */ - -/* ??? If the loop is known to be executed very many times, or the machine - has a very cheap divide instruction, then preconditioning is a win even - when the increment is not a power of 2. Use RTX_COST to compute - whether divide is cheap. - ??? A divide by constant doesn't actually need a divide, look at - expand_divmod. The reduced cost of this optimized modulo is not - reflected in RTX_COST. */ - -int -precondition_loop_p (const struct loop *loop, rtx *initial_value, - rtx *final_value, rtx *increment, - enum machine_mode *mode) -{ - rtx loop_start = loop->start; - struct loop_info *loop_info = LOOP_INFO (loop); - - if (loop_info->n_iterations > 0) - { - if (INTVAL (loop_info->increment) > 0) - { - *initial_value = const0_rtx; - *increment = const1_rtx; - *final_value = GEN_INT (loop_info->n_iterations); - } - else - { - *initial_value = GEN_INT (loop_info->n_iterations); - *increment = constm1_rtx; - *final_value = const0_rtx; - } - *mode = word_mode; - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Success, number of iterations known, " - HOST_WIDE_INT_PRINT_DEC ".\n", - loop_info->n_iterations); - return 1; - } - - if (loop_info->iteration_var == 0) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Could not find iteration variable.\n"); - return 0; - } - else if (loop_info->initial_value == 0) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Could not find initial value.\n"); - return 0; - } - else if (loop_info->increment == 0) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Could not find increment value.\n"); - return 0; - } - else if (GET_CODE (loop_info->increment) != CONST_INT) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Increment not a constant.\n"); - return 0; - } - else if ((exact_log2 (INTVAL (loop_info->increment)) < 0) - && (exact_log2 (-INTVAL (loop_info->increment)) < 0)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Increment not a constant power of 2.\n"); - return 0; - } - - /* Unsigned_compare and compare_dir can be ignored here, since they do - not matter for preconditioning. */ - - if (loop_info->final_value == 0) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: EQ comparison loop.\n"); - return 0; - } - - /* Must ensure that final_value is invariant, so call - loop_invariant_p to check. Before doing so, must check regno - against max_reg_before_loop to make sure that the register is in - the range covered by loop_invariant_p. If it isn't, then it is - most likely a biv/giv which by definition are not invariant. */ - if ((REG_P (loop_info->final_value) - && REGNO (loop_info->final_value) >= max_reg_before_loop) - || (GET_CODE (loop_info->final_value) == PLUS - && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop) - || ! loop_invariant_p (loop, loop_info->final_value)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Final value not invariant.\n"); - return 0; - } - - /* Fail for floating point values, since the caller of this function - does not have code to deal with them. */ - if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT - || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Floating point final or initial value.\n"); - return 0; - } - - /* Fail if loop_info->iteration_var is not live before loop_start, - since we need to test its value in the preconditioning code. */ - - if (REGNO_FIRST_LUID (REGNO (loop_info->iteration_var)) - > INSN_LUID (loop_start)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Preconditioning: Iteration var not live before loop start.\n"); - return 0; - } - - /* Note that loop_iterations biases the initial value for GIV iterators - such as "while (i-- > 0)" so that we can calculate the number of - iterations just like for BIV iterators. - - Also note that the absolute values of initial_value and - final_value are unimportant as only their difference is used for - calculating the number of loop iterations. */ - *initial_value = loop_info->initial_value; - *increment = loop_info->increment; - *final_value = loop_info->final_value; - - /* Decide what mode to do these calculations in. Choose the larger - of final_value's mode and initial_value's mode, or a full-word if - both are constants. */ - *mode = GET_MODE (*final_value); - if (*mode == VOIDmode) - { - *mode = GET_MODE (*initial_value); - if (*mode == VOIDmode) - *mode = word_mode; - } - else if (*mode != GET_MODE (*initial_value) - && (GET_MODE_SIZE (*mode) - < GET_MODE_SIZE (GET_MODE (*initial_value)))) - *mode = GET_MODE (*initial_value); - - /* Success! */ - if (loop_dump_stream) - fprintf (loop_dump_stream, "Preconditioning: Successful.\n"); - return 1; -} - -/* All pseudo-registers must be mapped to themselves. Two hard registers - must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_ - REGNUM, to avoid function-inlining specific conversions of these - registers. All other hard regs can not be mapped because they may be - used with different - modes. */ - -static void -init_reg_map (struct inline_remap *map, int maxregnum) -{ - int i; - - for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--) - map->reg_map[i] = regno_reg_rtx[i]; - /* Just clear the rest of the entries. */ - for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--) - map->reg_map[i] = 0; - - map->reg_map[VIRTUAL_STACK_VARS_REGNUM] - = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM]; - map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM] - = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM]; -} - -/* Strength-reduction will often emit code for optimized biv/givs which - calculates their value in a temporary register, and then copies the result - to the iv. This procedure reconstructs the pattern computing the iv; - verifying that all operands are of the proper form. - - PATTERN must be the result of single_set. - The return value is the amount that the giv is incremented by. */ - -static rtx -calculate_giv_inc (rtx pattern, rtx src_insn, unsigned int regno) -{ - rtx increment; - rtx increment_total = 0; - int tries = 0; - - retry: - /* Verify that we have an increment insn here. First check for a plus - as the set source. */ - if (GET_CODE (SET_SRC (pattern)) != PLUS) - { - /* SR sometimes computes the new giv value in a temp, then copies it - to the new_reg. */ - src_insn = PREV_INSN (src_insn); - pattern = single_set (src_insn); - if (GET_CODE (SET_SRC (pattern)) != PLUS) - abort (); - - /* The last insn emitted is not needed, so delete it to avoid confusing - the second cse pass. This insn sets the giv unnecessarily. */ - delete_related_insns (get_last_insn ()); - } - - /* Verify that we have a constant as the second operand of the plus. */ - increment = XEXP (SET_SRC (pattern), 1); - if (GET_CODE (increment) != CONST_INT) - { - /* SR sometimes puts the constant in a register, especially if it is - too big to be an add immed operand. */ - increment = find_last_value (increment, &src_insn, NULL_RTX, 0); - - /* SR may have used LO_SUM to compute the constant if it is too large - for a load immed operand. In this case, the constant is in operand - one of the LO_SUM rtx. */ - if (GET_CODE (increment) == LO_SUM) - increment = XEXP (increment, 1); - - /* Some ports store large constants in memory and add a REG_EQUAL - note to the store insn. */ - else if (MEM_P (increment)) - { - rtx note = find_reg_note (src_insn, REG_EQUAL, 0); - if (note) - increment = XEXP (note, 0); - } - - else if (GET_CODE (increment) == IOR - || GET_CODE (increment) == PLUS - || GET_CODE (increment) == ASHIFT - || GET_CODE (increment) == LSHIFTRT) - { - /* The rs6000 port loads some constants with IOR. - The alpha port loads some constants with ASHIFT and PLUS. - The sparc64 port loads some constants with LSHIFTRT. */ - rtx second_part = XEXP (increment, 1); - enum rtx_code code = GET_CODE (increment); - - increment = find_last_value (XEXP (increment, 0), - &src_insn, NULL_RTX, 0); - /* Don't need the last insn anymore. */ - delete_related_insns (get_last_insn ()); - - if (GET_CODE (second_part) != CONST_INT - || GET_CODE (increment) != CONST_INT) - abort (); - - if (code == IOR) - increment = GEN_INT (INTVAL (increment) | INTVAL (second_part)); - else if (code == PLUS) - increment = GEN_INT (INTVAL (increment) + INTVAL (second_part)); - else if (code == ASHIFT) - increment = GEN_INT (INTVAL (increment) << INTVAL (second_part)); - else - increment = GEN_INT ((unsigned HOST_WIDE_INT) INTVAL (increment) >> INTVAL (second_part)); - } - - if (GET_CODE (increment) != CONST_INT) - abort (); - - /* The insn loading the constant into a register is no longer needed, - so delete it. */ - delete_related_insns (get_last_insn ()); - } - - if (increment_total) - increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment)); - else - increment_total = increment; - - /* Check that the source register is the same as the register we expected - to see as the source. If not, something is seriously wrong. */ - if (!REG_P (XEXP (SET_SRC (pattern), 0)) - || REGNO (XEXP (SET_SRC (pattern), 0)) != regno) - { - /* Some machines (e.g. the romp), may emit two add instructions for - certain constants, so lets try looking for another add immediately - before this one if we have only seen one add insn so far. */ - - if (tries == 0) - { - tries++; - - src_insn = PREV_INSN (src_insn); - pattern = single_set (src_insn); - - delete_related_insns (get_last_insn ()); - - goto retry; - } - - abort (); - } - - return increment_total; -} - -/* Copy REG_NOTES, except for insn references, because not all insn_map - entries are valid yet. We do need to copy registers now though, because - the reg_map entries can change during copying. */ - -static rtx -initial_reg_note_copy (rtx notes, struct inline_remap *map) -{ - rtx copy; - - if (notes == 0) - return 0; - - copy = rtx_alloc (GET_CODE (notes)); - PUT_REG_NOTE_KIND (copy, REG_NOTE_KIND (notes)); - - if (GET_CODE (notes) == EXPR_LIST) - XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map, 0); - else if (GET_CODE (notes) == INSN_LIST) - /* Don't substitute for these yet. */ - XEXP (copy, 0) = copy_rtx (XEXP (notes, 0)); - else - abort (); - - XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map); - - return copy; -} - -/* Fixup insn references in copied REG_NOTES. */ - -static void -final_reg_note_copy (rtx *notesp, struct inline_remap *map) -{ - while (*notesp) - { - rtx note = *notesp; - - if (GET_CODE (note) == INSN_LIST) - { - rtx insn = map->insn_map[INSN_UID (XEXP (note, 0))]; - - /* If we failed to remap the note, something is awry. - Allow REG_LABEL as it may reference label outside - the unrolled loop. */ - if (!insn) - { - if (REG_NOTE_KIND (note) != REG_LABEL) - abort (); - } - else - XEXP (note, 0) = insn; - } - - notesp = &XEXP (note, 1); - } -} - -/* Copy each instruction in the loop, substituting from map as appropriate. - This is very similar to a loop in expand_inline_function. */ - -static void -copy_loop_body (struct loop *loop, rtx copy_start, rtx copy_end, - struct inline_remap *map, rtx exit_label, - int last_iteration, enum unroll_types unroll_type, - rtx start_label, rtx loop_end, rtx insert_before, - rtx copy_notes_from) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - rtx insn, pattern; - rtx set, tem, copy = NULL_RTX; - int dest_reg_was_split, i; -#ifdef HAVE_cc0 - rtx cc0_insn = 0; -#endif - rtx final_label = 0; - rtx giv_inc, giv_dest_reg, giv_src_reg; - - /* If this isn't the last iteration, then map any references to the - start_label to final_label. Final label will then be emitted immediately - after the end of this loop body if it was ever used. - - If this is the last iteration, then map references to the start_label - to itself. */ - if (! last_iteration) - { - final_label = gen_label_rtx (); - set_label_in_map (map, CODE_LABEL_NUMBER (start_label), final_label); - } - else - set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label); - - start_sequence (); - - insn = copy_start; - do - { - insn = NEXT_INSN (insn); - - map->orig_asm_operands_vector = 0; - - switch (GET_CODE (insn)) - { - case INSN: - pattern = PATTERN (insn); - copy = 0; - giv_inc = 0; - - /* Check to see if this is a giv that has been combined with - some split address givs. (Combined in the sense that - `combine_givs' in loop.c has put two givs in the same register.) - In this case, we must search all givs based on the same biv to - find the address givs. Then split the address givs. - Do this before splitting the giv, since that may map the - SET_DEST to a new register. */ - - if ((set = single_set (insn)) - && REG_P (SET_DEST (set)) - && addr_combined_regs[REGNO (SET_DEST (set))]) - { - struct iv_class *bl; - struct induction *v, *tv; - unsigned int regno = REGNO (SET_DEST (set)); - - v = addr_combined_regs[REGNO (SET_DEST (set))]; - bl = REG_IV_CLASS (ivs, REGNO (v->src_reg)); - - /* Although the giv_inc amount is not needed here, we must call - calculate_giv_inc here since it might try to delete the - last insn emitted. If we wait until later to call it, - we might accidentally delete insns generated immediately - below by emit_unrolled_add. */ - - giv_inc = calculate_giv_inc (set, insn, regno); - - /* Now find all address giv's that were combined with this - giv 'v'. */ - for (tv = bl->giv; tv; tv = tv->next_iv) - if (tv->giv_type == DEST_ADDR && tv->same == v) - { - int this_giv_inc; - - /* If this DEST_ADDR giv was not split, then ignore it. */ - if (*tv->location != tv->dest_reg) - continue; - - /* Scale this_giv_inc if the multiplicative factors of - the two givs are different. */ - this_giv_inc = INTVAL (giv_inc); - if (tv->mult_val != v->mult_val) - this_giv_inc = (this_giv_inc / INTVAL (v->mult_val) - * INTVAL (tv->mult_val)); - - tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc); - *tv->location = tv->dest_reg; - - if (last_iteration && unroll_type != UNROLL_COMPLETELY) - { - /* Must emit an insn to increment the split address - giv. Add in the const_adjust field in case there - was a constant eliminated from the address. */ - rtx value, dest_reg; - - /* tv->dest_reg will be either a bare register, - or else a register plus a constant. */ - if (REG_P (tv->dest_reg)) - dest_reg = tv->dest_reg; - else - dest_reg = XEXP (tv->dest_reg, 0); - - /* Check for shared address givs, and avoid - incrementing the shared pseudo reg more than - once. */ - if (! tv->same_insn && ! tv->shared) - { - /* tv->dest_reg may actually be a (PLUS (REG) - (CONST)) here, so we must call plus_constant - to add the const_adjust amount before calling - emit_unrolled_add below. */ - value = plus_constant (tv->dest_reg, - tv->const_adjust); - - if (GET_CODE (value) == PLUS) - { - /* The constant could be too large for an add - immediate, so can't directly emit an insn - here. */ - emit_unrolled_add (dest_reg, XEXP (value, 0), - XEXP (value, 1)); - } - } - - /* Reset the giv to be just the register again, in case - it is used after the set we have just emitted. - We must subtract the const_adjust factor added in - above. */ - tv->dest_reg = plus_constant (dest_reg, - -tv->const_adjust); - *tv->location = tv->dest_reg; - } - } - } - - /* If this is a setting of a splittable variable, then determine - how to split the variable, create a new set based on this split, - and set up the reg_map so that later uses of the variable will - use the new split variable. */ - - dest_reg_was_split = 0; - - if ((set = single_set (insn)) - && REG_P (SET_DEST (set)) - && splittable_regs[REGNO (SET_DEST (set))]) - { - unsigned int regno = REGNO (SET_DEST (set)); - unsigned int src_regno; - - dest_reg_was_split = 1; - - giv_dest_reg = SET_DEST (set); - giv_src_reg = giv_dest_reg; - /* Compute the increment value for the giv, if it wasn't - already computed above. */ - if (giv_inc == 0) - giv_inc = calculate_giv_inc (set, insn, regno); - - src_regno = REGNO (giv_src_reg); - - if (unroll_type == UNROLL_COMPLETELY) - { - /* Completely unrolling the loop. Set the induction - variable to a known constant value. */ - - /* The value in splittable_regs may be an invariant - value, so we must use plus_constant here. */ - splittable_regs[regno] - = plus_constant (splittable_regs[src_regno], - INTVAL (giv_inc)); - - if (GET_CODE (splittable_regs[regno]) == PLUS) - { - giv_src_reg = XEXP (splittable_regs[regno], 0); - giv_inc = XEXP (splittable_regs[regno], 1); - } - else - { - /* The splittable_regs value must be a REG or a - CONST_INT, so put the entire value in the giv_src_reg - variable. */ - giv_src_reg = splittable_regs[regno]; - giv_inc = const0_rtx; - } - } - else - { - /* Partially unrolling loop. Create a new pseudo - register for the iteration variable, and set it to - be a constant plus the original register. Except - on the last iteration, when the result has to - go back into the original iteration var register. */ - - /* Handle bivs which must be mapped to a new register - when split. This happens for bivs which need their - final value set before loop entry. The new register - for the biv was stored in the biv's first struct - induction entry by find_splittable_regs. */ - - if (regno < ivs->n_regs - && REG_IV_TYPE (ivs, regno) == BASIC_INDUCT) - { - giv_src_reg = REG_IV_CLASS (ivs, regno)->biv->src_reg; - giv_dest_reg = giv_src_reg; - } - -#if 0 - /* If non-reduced/final-value givs were split, then - this would have to remap those givs also. See - find_splittable_regs. */ -#endif - - splittable_regs[regno] - = simplify_gen_binary (PLUS, GET_MODE (giv_src_reg), - giv_inc, - splittable_regs[src_regno]); - giv_inc = splittable_regs[regno]; - - /* Now split the induction variable by changing the dest - of this insn to a new register, and setting its - reg_map entry to point to this new register. - - If this is the last iteration, and this is the last insn - that will update the iv, then reuse the original dest, - to ensure that the iv will have the proper value when - the loop exits or repeats. - - Using splittable_regs_updates here like this is safe, - because it can only be greater than one if all - instructions modifying the iv are always executed in - order. */ - - if (! last_iteration - || (splittable_regs_updates[regno]-- != 1)) - { - tem = gen_reg_rtx (GET_MODE (giv_src_reg)); - giv_dest_reg = tem; - map->reg_map[regno] = tem; - record_base_value (REGNO (tem), - giv_inc == const0_rtx - ? giv_src_reg - : gen_rtx_PLUS (GET_MODE (giv_src_reg), - giv_src_reg, giv_inc), - 1); - } - else - map->reg_map[regno] = giv_src_reg; - } - - /* The constant being added could be too large for an add - immediate, so can't directly emit an insn here. */ - emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc); - copy = get_last_insn (); - pattern = PATTERN (copy); - } - else - { - pattern = copy_rtx_and_substitute (pattern, map, 0); - copy = emit_insn (pattern); - } - REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map); - INSN_LOCATOR (copy) = INSN_LOCATOR (insn); - - /* If there is a REG_EQUAL note present whose value - is not loop invariant, then delete it, since it - may cause problems with later optimization passes. */ - if ((tem = find_reg_note (copy, REG_EQUAL, NULL_RTX)) - && !loop_invariant_p (loop, XEXP (tem, 0))) - remove_note (copy, tem); - -#ifdef HAVE_cc0 - /* If this insn is setting CC0, it may need to look at - the insn that uses CC0 to see what type of insn it is. - In that case, the call to recog via validate_change will - fail. So don't substitute constants here. Instead, - do it when we emit the following insn. - - For example, see the pyr.md file. That machine has signed and - unsigned compares. The compare patterns must check the - following branch insn to see which what kind of compare to - emit. - - If the previous insn set CC0, substitute constants on it as - well. */ - if (sets_cc0_p (PATTERN (copy)) != 0) - cc0_insn = copy; - else - { - if (cc0_insn) - try_constants (cc0_insn, map); - cc0_insn = 0; - try_constants (copy, map); - } -#else - try_constants (copy, map); -#endif - - /* Make split induction variable constants `permanent' since we - know there are no backward branches across iteration variable - settings which would invalidate this. */ - if (dest_reg_was_split) - { - int regno = REGNO (SET_DEST (set)); - - if ((size_t) regno < VARRAY_SIZE (map->const_equiv_varray) - && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age - == map->const_age)) - VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1; - } - break; - - case JUMP_INSN: - pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0); - copy = emit_jump_insn (pattern); - REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map); - INSN_LOCATOR (copy) = INSN_LOCATOR (insn); - - if (JUMP_LABEL (insn)) - { - JUMP_LABEL (copy) = get_label_from_map (map, - CODE_LABEL_NUMBER - (JUMP_LABEL (insn))); - LABEL_NUSES (JUMP_LABEL (copy))++; - } - if (JUMP_LABEL (insn) == start_label && insn == copy_end - && ! last_iteration) - { - - /* This is a branch to the beginning of the loop; this is the - last insn being copied; and this is not the last iteration. - In this case, we want to change the original fall through - case to be a branch past the end of the loop, and the - original jump label case to fall_through. */ - - if (!invert_jump (copy, exit_label, 0)) - { - rtx jmp; - rtx lab = gen_label_rtx (); - /* Can't do it by reversing the jump (probably because we - couldn't reverse the conditions), so emit a new - jump_insn after COPY, and redirect the jump around - that. */ - jmp = emit_jump_insn_after (gen_jump (exit_label), copy); - JUMP_LABEL (jmp) = exit_label; - LABEL_NUSES (exit_label)++; - jmp = emit_barrier_after (jmp); - emit_label_after (lab, jmp); - LABEL_NUSES (lab) = 0; - if (!redirect_jump (copy, lab, 0)) - abort (); - } - } - -#ifdef HAVE_cc0 - if (cc0_insn) - try_constants (cc0_insn, map); - cc0_insn = 0; -#endif - try_constants (copy, map); - - /* Set the jump label of COPY correctly to avoid problems with - later passes of unroll_loop, if INSN had jump label set. */ - if (JUMP_LABEL (insn)) - { - rtx label = 0; - - /* Can't use the label_map for every insn, since this may be - the backward branch, and hence the label was not mapped. */ - if ((set = single_set (copy))) - { - tem = SET_SRC (set); - if (GET_CODE (tem) == LABEL_REF) - label = XEXP (tem, 0); - else if (GET_CODE (tem) == IF_THEN_ELSE) - { - if (XEXP (tem, 1) != pc_rtx) - label = XEXP (XEXP (tem, 1), 0); - else - label = XEXP (XEXP (tem, 2), 0); - } - } - - if (label && LABEL_P (label)) - JUMP_LABEL (copy) = label; - else - { - /* An unrecognizable jump insn, probably the entry jump - for a switch statement. This label must have been mapped, - so just use the label_map to get the new jump label. */ - JUMP_LABEL (copy) - = get_label_from_map (map, - CODE_LABEL_NUMBER (JUMP_LABEL (insn))); - } - - /* If this is a non-local jump, then must increase the label - use count so that the label will not be deleted when the - original jump is deleted. */ - LABEL_NUSES (JUMP_LABEL (copy))++; - } - else if (GET_CODE (PATTERN (copy)) == ADDR_VEC - || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC) - { - rtx pat = PATTERN (copy); - int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC; - int len = XVECLEN (pat, diff_vec_p); - int i; - - for (i = 0; i < len; i++) - LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++; - } - - /* If this used to be a conditional jump insn but whose branch - direction is now known, we must do something special. */ - if (any_condjump_p (insn) && onlyjump_p (insn) && map->last_pc_value) - { -#ifdef HAVE_cc0 - /* If the previous insn set cc0 for us, delete it. */ - if (only_sets_cc0_p (PREV_INSN (copy))) - delete_related_insns (PREV_INSN (copy)); -#endif - - /* If this is now a no-op, delete it. */ - if (map->last_pc_value == pc_rtx) - { - delete_insn (copy); - copy = 0; - } - else - /* Otherwise, this is unconditional jump so we must put a - BARRIER after it. We could do some dead code elimination - here, but jump.c will do it just as well. */ - emit_barrier (); - } - break; - - case CALL_INSN: - pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0); - copy = emit_call_insn (pattern); - REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map); - INSN_LOCATOR (copy) = INSN_LOCATOR (insn); - SIBLING_CALL_P (copy) = SIBLING_CALL_P (insn); - CONST_OR_PURE_CALL_P (copy) = CONST_OR_PURE_CALL_P (insn); - - /* Because the USAGE information potentially contains objects other - than hard registers, we need to copy it. */ - CALL_INSN_FUNCTION_USAGE (copy) - = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn), - map, 0); - -#ifdef HAVE_cc0 - if (cc0_insn) - try_constants (cc0_insn, map); - cc0_insn = 0; -#endif - try_constants (copy, map); - - /* Be lazy and assume CALL_INSNs clobber all hard registers. */ - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0; - break; - - case CODE_LABEL: - /* If this is the loop start label, then we don't need to emit a - copy of this label since no one will use it. */ - - if (insn != start_label) - { - copy = emit_label (get_label_from_map (map, - CODE_LABEL_NUMBER (insn))); - map->const_age++; - } - break; - - case BARRIER: - copy = emit_barrier (); - break; - - case NOTE: - /* BASIC_BLOCK notes exist to stabilize basic block structures with - the associated rtl. We do not want to share the structure in - this new block. */ - - if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED - && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED_LABEL - && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK) - copy = emit_note_copy (insn); - else - copy = 0; - break; - - default: - abort (); - } - - map->insn_map[INSN_UID (insn)] = copy; - } - while (insn != copy_end); - - /* Now finish coping the REG_NOTES. */ - insn = copy_start; - do - { - insn = NEXT_INSN (insn); - if (INSN_P (insn) - && map->insn_map[INSN_UID (insn)]) - final_reg_note_copy (®_NOTES (map->insn_map[INSN_UID (insn)]), map); - } - while (insn != copy_end); - - /* There may be notes between copy_notes_from and loop_end. Emit a copy of - each of these notes here, since there may be some important ones, such as - NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last - iteration, because the original notes won't be deleted. - - We can't use insert_before here, because when from preconditioning, - insert_before points before the loop. We can't use copy_end, because - there may be insns already inserted after it (which we don't want to - copy) when not from preconditioning code. */ - - if (! last_iteration) - { - for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn)) - { - if (NOTE_P (insn) - && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED - && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK) - emit_note_copy (insn); - } - } - - if (final_label && LABEL_NUSES (final_label) > 0) - emit_label (final_label); - - tem = get_insns (); - end_sequence (); - loop_insn_emit_before (loop, 0, insert_before, tem); -} - -/* Emit an insn, using the expand_binop to ensure that a valid insn is - emitted. This will correctly handle the case where the increment value - won't fit in the immediate field of a PLUS insns. */ - -void -emit_unrolled_add (rtx dest_reg, rtx src_reg, rtx increment) -{ - rtx result; - - result = expand_simple_binop (GET_MODE (dest_reg), PLUS, src_reg, increment, - dest_reg, 0, OPTAB_LIB_WIDEN); - - if (dest_reg != result) - emit_move_insn (dest_reg, result); -} - -/* Searches the insns between INSN and LOOP->END. Returns 1 if there - is a backward branch in that range that branches to somewhere between - LOOP->START and INSN. Returns 0 otherwise. */ - -/* ??? This is quadratic algorithm. Could be rewritten to be linear. - In practice, this is not a problem, because this function is seldom called, - and uses a negligible amount of CPU time on average. */ - -int -back_branch_in_range_p (const struct loop *loop, rtx insn) -{ - rtx p, q, target_insn; - rtx loop_start = loop->start; - rtx loop_end = loop->end; - rtx orig_loop_end = loop->end; - - /* Stop before we get to the backward branch at the end of the loop. */ - loop_end = prev_nonnote_insn (loop_end); - if (BARRIER_P (loop_end)) - loop_end = PREV_INSN (loop_end); - - /* Check in case insn has been deleted, search forward for first non - deleted insn following it. */ - while (INSN_DELETED_P (insn)) - insn = NEXT_INSN (insn); - - /* Check for the case where insn is the last insn in the loop. Deal - with the case where INSN was a deleted loop test insn, in which case - it will now be the NOTE_LOOP_END. */ - if (insn == loop_end || insn == orig_loop_end) - return 0; - - for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p)) - { - if (JUMP_P (p)) - { - target_insn = JUMP_LABEL (p); - - /* Search from loop_start to insn, to see if one of them is - the target_insn. We can't use INSN_LUID comparisons here, - since insn may not have an LUID entry. */ - for (q = loop_start; q != insn; q = NEXT_INSN (q)) - if (q == target_insn) - return 1; - } - } - - return 0; -} - -/* Try to generate the simplest rtx for the expression - (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial - value of giv's. */ - -static rtx -fold_rtx_mult_add (rtx mult1, rtx mult2, rtx add1, enum machine_mode mode) -{ - rtx temp, mult_res; - rtx result; - - /* The modes must all be the same. This should always be true. For now, - check to make sure. */ - if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode) - || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode) - || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode)) - abort (); - - /* Ensure that if at least one of mult1/mult2 are constant, then mult2 - will be a constant. */ - if (GET_CODE (mult1) == CONST_INT) - { - temp = mult2; - mult2 = mult1; - mult1 = temp; - } - - mult_res = simplify_binary_operation (MULT, mode, mult1, mult2); - if (! mult_res) - mult_res = gen_rtx_MULT (mode, mult1, mult2); - - /* Again, put the constant second. */ - if (GET_CODE (add1) == CONST_INT) - { - temp = add1; - add1 = mult_res; - mult_res = temp; - } - - result = simplify_binary_operation (PLUS, mode, add1, mult_res); - if (! result) - result = gen_rtx_PLUS (mode, add1, mult_res); - - return result; -} - -/* Searches the list of induction struct's for the biv BL, to try to calculate - the total increment value for one iteration of the loop as a constant. - - Returns the increment value as an rtx, simplified as much as possible, - if it can be calculated. Otherwise, returns 0. */ - -rtx -biv_total_increment (const struct iv_class *bl) -{ - struct induction *v; - rtx result; - - /* For increment, must check every instruction that sets it. Each - instruction must be executed only once each time through the loop. - To verify this, we check that the insn is always executed, and that - there are no backward branches after the insn that branch to before it. - Also, the insn must have a mult_val of one (to make sure it really is - an increment). */ - - result = const0_rtx; - for (v = bl->biv; v; v = v->next_iv) - { - if (v->always_computable && v->mult_val == const1_rtx - && ! v->maybe_multiple - && SCALAR_INT_MODE_P (v->mode)) - { - /* If we have already counted it, skip it. */ - if (v->same) - continue; - - result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode); - } - else - return 0; - } - - return result; -} - -/* For each biv and giv, determine whether it can be safely split into - a different variable for each unrolled copy of the loop body. If it - is safe to split, then indicate that by saving some useful info - in the splittable_regs array. - - If the loop is being completely unrolled, then splittable_regs will hold - the current value of the induction variable while the loop is unrolled. - It must be set to the initial value of the induction variable here. - Otherwise, splittable_regs will hold the difference between the current - value of the induction variable and the value the induction variable had - at the top of the loop. It must be set to the value 0 here. - - Returns the total number of instructions that set registers that are - splittable. */ - -/* ?? If the loop is only unrolled twice, then most of the restrictions to - constant values are unnecessary, since we can easily calculate increment - values in this case even if nothing is constant. The increment value - should not involve a multiply however. */ - -/* ?? Even if the biv/giv increment values aren't constant, it may still - be beneficial to split the variable if the loop is only unrolled a few - times, since multiplies by small integers (1,2,3,4) are very cheap. */ - -static int -find_splittable_regs (const struct loop *loop, - enum unroll_types unroll_type, int unroll_number) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct iv_class *bl; - struct induction *v; - rtx increment, tem; - rtx biv_final_value; - int biv_splittable; - int result = 0; - - for (bl = ivs->list; bl; bl = bl->next) - { - /* Biv_total_increment must return a constant value, - otherwise we can not calculate the split values. */ - - increment = biv_total_increment (bl); - if (! increment || GET_CODE (increment) != CONST_INT) - continue; - - /* The loop must be unrolled completely, or else have a known number - of iterations and only one exit, or else the biv must be dead - outside the loop, or else the final value must be known. Otherwise, - it is unsafe to split the biv since it may not have the proper - value on loop exit. */ - - /* loop_number_exit_count is nonzero if the loop has an exit other than - a fall through at the end. */ - - biv_splittable = 1; - biv_final_value = 0; - if (unroll_type != UNROLL_COMPLETELY - && (loop->exit_count || unroll_type == UNROLL_NAIVE) - && (REGNO_LAST_LUID (bl->regno) >= INSN_LUID (loop->end) - || ! bl->init_insn - || INSN_UID (bl->init_insn) >= max_uid_for_loop - || (REGNO_FIRST_LUID (bl->regno) - < INSN_LUID (bl->init_insn)) - || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set))) - && ! (biv_final_value = final_biv_value (loop, bl))) - biv_splittable = 0; - - /* If any of the insns setting the BIV don't do so with a simple - PLUS, we don't know how to split it. */ - for (v = bl->biv; biv_splittable && v; v = v->next_iv) - if ((tem = single_set (v->insn)) == 0 - || !REG_P (SET_DEST (tem)) - || REGNO (SET_DEST (tem)) != bl->regno - || GET_CODE (SET_SRC (tem)) != PLUS) - biv_splittable = 0; - - /* If final value is nonzero, then must emit an instruction which sets - the value of the biv to the proper value. This is done after - handling all of the givs, since some of them may need to use the - biv's value in their initialization code. */ - - /* This biv is splittable. If completely unrolling the loop, save - the biv's initial value. Otherwise, save the constant zero. */ - - if (biv_splittable == 1) - { - if (unroll_type == UNROLL_COMPLETELY) - { - /* If the initial value of the biv is itself (i.e. it is too - complicated for strength_reduce to compute), or is a hard - register, or it isn't invariant, then we must create a new - pseudo reg to hold the initial value of the biv. */ - - if (REG_P (bl->initial_value) - && (REGNO (bl->initial_value) == bl->regno - || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER - || ! loop_invariant_p (loop, bl->initial_value))) - { - rtx tem = gen_reg_rtx (bl->biv->mode); - - record_base_value (REGNO (tem), bl->biv->add_val, 0); - loop_insn_hoist (loop, - gen_move_insn (tem, bl->biv->src_reg)); - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Biv %d initial value remapped to %d.\n", - bl->regno, REGNO (tem)); - - splittable_regs[bl->regno] = tem; - } - else - splittable_regs[bl->regno] = bl->initial_value; - } - else - splittable_regs[bl->regno] = const0_rtx; - - /* Save the number of instructions that modify the biv, so that - we can treat the last one specially. */ - - splittable_regs_updates[bl->regno] = bl->biv_count; - result += bl->biv_count; - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Biv %d safe to split.\n", bl->regno); - } - - /* Check every giv that depends on this biv to see whether it is - splittable also. Even if the biv isn't splittable, givs which - depend on it may be splittable if the biv is live outside the - loop, and the givs aren't. */ - - result += find_splittable_givs (loop, bl, unroll_type, increment, - unroll_number); - - /* If final value is nonzero, then must emit an instruction which sets - the value of the biv to the proper value. This is done after - handling all of the givs, since some of them may need to use the - biv's value in their initialization code. */ - if (biv_final_value) - { - /* If the loop has multiple exits, emit the insns before the - loop to ensure that it will always be executed no matter - how the loop exits. Otherwise emit the insn after the loop, - since this is slightly more efficient. */ - if (! loop->exit_count) - loop_insn_sink (loop, gen_move_insn (bl->biv->src_reg, - biv_final_value)); - else - { - /* Create a new register to hold the value of the biv, and then - set the biv to its final value before the loop start. The biv - is set to its final value before loop start to ensure that - this insn will always be executed, no matter how the loop - exits. */ - rtx tem = gen_reg_rtx (bl->biv->mode); - record_base_value (REGNO (tem), bl->biv->add_val, 0); - - loop_insn_hoist (loop, gen_move_insn (tem, bl->biv->src_reg)); - loop_insn_hoist (loop, gen_move_insn (bl->biv->src_reg, - biv_final_value)); - - if (loop_dump_stream) - fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n", - REGNO (bl->biv->src_reg), REGNO (tem)); - - /* Set up the mapping from the original biv register to the new - register. */ - bl->biv->src_reg = tem; - } - } - } - return result; -} - -/* For every giv based on the biv BL, check to determine whether it is - splittable. This is a subroutine to find_splittable_regs (). - - Return the number of instructions that set splittable registers. */ - -static int -find_splittable_givs (const struct loop *loop, struct iv_class *bl, - enum unroll_types unroll_type, rtx increment, - int unroll_number ATTRIBUTE_UNUSED) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct induction *v, *v2; - rtx final_value; - rtx tem; - int result = 0; - - /* Scan the list of givs, and set the same_insn field when there are - multiple identical givs in the same insn. */ - for (v = bl->giv; v; v = v->next_iv) - for (v2 = v->next_iv; v2; v2 = v2->next_iv) - if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg) - && ! v2->same_insn) - v2->same_insn = v; - - for (v = bl->giv; v; v = v->next_iv) - { - rtx giv_inc, value; - - /* Only split the giv if it has already been reduced, or if the loop is - being completely unrolled. */ - if (unroll_type != UNROLL_COMPLETELY && v->ignore) - continue; - - /* The giv can be split if the insn that sets the giv is executed once - and only once on every iteration of the loop. */ - /* An address giv can always be split. v->insn is just a use not a set, - and hence it does not matter whether it is always executed. All that - matters is that all the biv increments are always executed, and we - won't reach here if they aren't. */ - if (v->giv_type != DEST_ADDR - && (! v->always_computable - || back_branch_in_range_p (loop, v->insn))) - continue; - - /* The giv increment value must be a constant. */ - giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx, - v->mode); - if (! giv_inc || GET_CODE (giv_inc) != CONST_INT) - continue; - - /* The loop must be unrolled completely, or else have a known number of - iterations and only one exit, or else the giv must be dead outside - the loop, or else the final value of the giv must be known. - Otherwise, it is not safe to split the giv since it may not have the - proper value on loop exit. */ - - /* The used outside loop test will fail for DEST_ADDR givs. They are - never used outside the loop anyways, so it is always safe to split a - DEST_ADDR giv. */ - - final_value = 0; - if (unroll_type != UNROLL_COMPLETELY - && (loop->exit_count || unroll_type == UNROLL_NAIVE) - && v->giv_type != DEST_ADDR - /* The next part is true if the pseudo is used outside the loop. - We assume that this is true for any pseudo created after loop - starts, because we don't have a reg_n_info entry for them. */ - && (REGNO (v->dest_reg) >= max_reg_before_loop - || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn) - /* Check for the case where the pseudo is set by a shift/add - sequence, in which case the first insn setting the pseudo - is the first insn of the shift/add sequence. */ - && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX)) - || (REGNO_FIRST_UID (REGNO (v->dest_reg)) - != INSN_UID (XEXP (tem, 0))))) - /* Line above always fails if INSN was moved by loop opt. */ - || (REGNO_LAST_LUID (REGNO (v->dest_reg)) - >= INSN_LUID (loop->end))) - && ! (final_value = v->final_value)) - continue; - -#if 0 - /* Currently, non-reduced/final-value givs are never split. */ - /* Should emit insns after the loop if possible, as the biv final value - code below does. */ - - /* If the final value is nonzero, and the giv has not been reduced, - then must emit an instruction to set the final value. */ - if (final_value && !v->new_reg) - { - /* Create a new register to hold the value of the giv, and then set - the giv to its final value before the loop start. The giv is set - to its final value before loop start to ensure that this insn - will always be executed, no matter how we exit. */ - tem = gen_reg_rtx (v->mode); - loop_insn_hoist (loop, gen_move_insn (tem, v->dest_reg)); - loop_insn_hoist (loop, gen_move_insn (v->dest_reg, final_value)); - - if (loop_dump_stream) - fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n", - REGNO (v->dest_reg), REGNO (tem)); - - v->src_reg = tem; - } -#endif - - /* This giv is splittable. If completely unrolling the loop, save the - giv's initial value. Otherwise, save the constant zero for it. */ - - if (unroll_type == UNROLL_COMPLETELY) - { - /* It is not safe to use bl->initial_value here, because it may not - be invariant. It is safe to use the initial value stored in - the splittable_regs array if it is set. In rare cases, it won't - be set, so then we do exactly the same thing as - find_splittable_regs does to get a safe value. */ - rtx biv_initial_value; - - if (splittable_regs[bl->regno]) - biv_initial_value = splittable_regs[bl->regno]; - else if (!REG_P (bl->initial_value) - || (REGNO (bl->initial_value) != bl->regno - && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER)) - biv_initial_value = bl->initial_value; - else - { - rtx tem = gen_reg_rtx (bl->biv->mode); - - record_base_value (REGNO (tem), bl->biv->add_val, 0); - loop_insn_hoist (loop, gen_move_insn (tem, bl->biv->src_reg)); - biv_initial_value = tem; - } - biv_initial_value = extend_value_for_giv (v, biv_initial_value); - value = fold_rtx_mult_add (v->mult_val, biv_initial_value, - v->add_val, v->mode); - } - else - value = const0_rtx; - - if (v->new_reg) - { - /* If a giv was combined with another giv, then we can only split - this giv if the giv it was combined with was reduced. This - is because the value of v->new_reg is meaningless in this - case. */ - if (v->same && ! v->same->new_reg) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "giv combined with unreduced giv not split.\n"); - continue; - } - /* If the giv is an address destination, it could be something other - than a simple register, these have to be treated differently. */ - else if (v->giv_type == DEST_REG) - { - /* If value is not a constant, register, or register plus - constant, then compute its value into a register before - loop start. This prevents invalid rtx sharing, and should - generate better code. We can use bl->initial_value here - instead of splittable_regs[bl->regno] because this code - is going before the loop start. */ - if (unroll_type == UNROLL_COMPLETELY - && GET_CODE (value) != CONST_INT - && !REG_P (value) - && (GET_CODE (value) != PLUS - || !REG_P (XEXP (value, 0)) - || GET_CODE (XEXP (value, 1)) != CONST_INT)) - { - rtx tem = gen_reg_rtx (v->mode); - record_base_value (REGNO (tem), v->add_val, 0); - loop_iv_add_mult_hoist (loop, - extend_value_for_giv (v, bl->initial_value), - v->mult_val, v->add_val, tem); - value = tem; - } - - splittable_regs[reg_or_subregno (v->new_reg)] = value; - } - else - continue; - } - else - { -#if 0 - /* Currently, unreduced giv's can't be split. This is not too much - of a problem since unreduced giv's are not live across loop - iterations anyways. When unrolling a loop completely though, - it makes sense to reduce&split givs when possible, as this will - result in simpler instructions, and will not require that a reg - be live across loop iterations. */ - - splittable_regs[REGNO (v->dest_reg)] = value; - fprintf (stderr, "Giv %d at insn %d not reduced\n", - REGNO (v->dest_reg), INSN_UID (v->insn)); -#else - continue; -#endif - } - - /* Unreduced givs are only updated once by definition. Reduced givs - are updated as many times as their biv is. Mark it so if this is - a splittable register. Don't need to do anything for address givs - where this may not be a register. */ - - if (REG_P (v->new_reg)) - { - int count = 1; - if (! v->ignore) - count = REG_IV_CLASS (ivs, REGNO (v->src_reg))->biv_count; - - splittable_regs_updates[reg_or_subregno (v->new_reg)] = count; - } - - result++; - - if (loop_dump_stream) - { - int regnum; - - if (GET_CODE (v->dest_reg) == CONST_INT) - regnum = -1; - else if (!REG_P (v->dest_reg)) - regnum = REGNO (XEXP (v->dest_reg, 0)); - else - regnum = REGNO (v->dest_reg); - fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n", - regnum, INSN_UID (v->insn)); - } - } - - return result; -} - -/* Try to prove that the register is dead after the loop exits. Trace every - loop exit looking for an insn that will always be executed, which sets - the register to some value, and appears before the first use of the register - is found. If successful, then return 1, otherwise return 0. */ - -/* ?? Could be made more intelligent in the handling of jumps, so that - it can search past if statements and other similar structures. */ - -static int -reg_dead_after_loop (const struct loop *loop, rtx reg) -{ - rtx insn, label; - int jump_count = 0; - int label_count = 0; - - /* In addition to checking all exits of this loop, we must also check - all exits of inner nested loops that would exit this loop. We don't - have any way to identify those, so we just give up if there are any - such inner loop exits. */ - - for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label)) - label_count++; - - if (label_count != loop->exit_count) - return 0; - - /* HACK: Must also search the loop fall through exit, create a label_ref - here which points to the loop->end, and append the loop_number_exit_labels - list to it. */ - label = gen_rtx_LABEL_REF (VOIDmode, loop->end); - LABEL_NEXTREF (label) = loop->exit_labels; - - for (; label; label = LABEL_NEXTREF (label)) - { - /* Succeed if find an insn which sets the biv or if reach end of - function. Fail if find an insn that uses the biv, or if come to - a conditional jump. */ - - insn = NEXT_INSN (XEXP (label, 0)); - while (insn) - { - if (INSN_P (insn)) - { - rtx set, note; - - if (reg_referenced_p (reg, PATTERN (insn))) - return 0; - - note = find_reg_equal_equiv_note (insn); - if (note && reg_overlap_mentioned_p (reg, XEXP (note, 0))) - return 0; - - set = single_set (insn); - if (set && rtx_equal_p (SET_DEST (set), reg)) - break; - - if (JUMP_P (insn)) - { - if (GET_CODE (PATTERN (insn)) == RETURN) - break; - else if (!any_uncondjump_p (insn) - /* Prevent infinite loop following infinite loops. */ - || jump_count++ > 20) - return 0; - else - insn = JUMP_LABEL (insn); - } - } - - insn = NEXT_INSN (insn); - } - } - - /* Success, the register is dead on all loop exits. */ - return 1; -} - -/* Try to calculate the final value of the biv, the value it will have at - the end of the loop. If we can do it, return that value. */ - -rtx -final_biv_value (const struct loop *loop, struct iv_class *bl) -{ - unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations; - rtx increment, tem; - - /* ??? This only works for MODE_INT biv's. Reject all others for now. */ - - if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT) - return 0; - - /* The final value for reversed bivs must be calculated differently than - for ordinary bivs. In this case, there is already an insn after the - loop which sets this biv's final value (if necessary), and there are - no other loop exits, so we can return any value. */ - if (bl->reversed) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Final biv value for %d, reversed biv.\n", bl->regno); - - return const0_rtx; - } - - /* Try to calculate the final value as initial value + (number of iterations - * increment). For this to work, increment must be invariant, the only - exit from the loop must be the fall through at the bottom (otherwise - it may not have its final value when the loop exits), and the initial - value of the biv must be invariant. */ - - if (n_iterations != 0 - && ! loop->exit_count - && loop_invariant_p (loop, bl->initial_value)) - { - increment = biv_total_increment (bl); - - if (increment && loop_invariant_p (loop, increment)) - { - /* Can calculate the loop exit value, emit insns after loop - end to calculate this value into a temporary register in - case it is needed later. */ - - tem = gen_reg_rtx (bl->biv->mode); - record_base_value (REGNO (tem), bl->biv->add_val, 0); - loop_iv_add_mult_sink (loop, increment, GEN_INT (n_iterations), - bl->initial_value, tem); - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Final biv value for %d, calculated.\n", bl->regno); - - return tem; - } - } - - /* Check to see if the biv is dead at all loop exits. */ - if (reg_dead_after_loop (loop, bl->biv->src_reg)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Final biv value for %d, biv dead after loop exit.\n", - bl->regno); - - return const0_rtx; - } - - return 0; -} - -/* Try to calculate the final value of the giv, the value it will have at - the end of the loop. If we can do it, return that value. */ - -rtx -final_giv_value (const struct loop *loop, struct induction *v) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - struct iv_class *bl; - rtx insn; - rtx increment, tem; - rtx seq; - rtx loop_end = loop->end; - unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations; - - bl = REG_IV_CLASS (ivs, REGNO (v->src_reg)); - - /* The final value for givs which depend on reversed bivs must be calculated - differently than for ordinary givs. In this case, there is already an - insn after the loop which sets this giv's final value (if necessary), - and there are no other loop exits, so we can return any value. */ - if (bl->reversed) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Final giv value for %d, depends on reversed biv\n", - REGNO (v->dest_reg)); - return const0_rtx; - } - - /* Try to calculate the final value as a function of the biv it depends - upon. The only exit from the loop must be the fall through at the bottom - and the insn that sets the giv must be executed on every iteration - (otherwise the giv may not have its final value when the loop exits). */ - - /* ??? Can calculate the final giv value by subtracting off the - extra biv increments times the giv's mult_val. The loop must have - only one exit for this to work, but the loop iterations does not need - to be known. */ - - if (n_iterations != 0 - && ! loop->exit_count - && v->always_executed) - { - /* ?? It is tempting to use the biv's value here since these insns will - be put after the loop, and hence the biv will have its final value - then. However, this fails if the biv is subsequently eliminated. - Perhaps determine whether biv's are eliminable before trying to - determine whether giv's are replaceable so that we can use the - biv value here if it is not eliminable. */ - - /* We are emitting code after the end of the loop, so we must make - sure that bl->initial_value is still valid then. It will still - be valid if it is invariant. */ - - increment = biv_total_increment (bl); - - if (increment && loop_invariant_p (loop, increment) - && loop_invariant_p (loop, bl->initial_value)) - { - /* Can calculate the loop exit value of its biv as - (n_iterations * increment) + initial_value */ - - /* The loop exit value of the giv is then - (final_biv_value - extra increments) * mult_val + add_val. - The extra increments are any increments to the biv which - occur in the loop after the giv's value is calculated. - We must search from the insn that sets the giv to the end - of the loop to calculate this value. */ - - /* Put the final biv value in tem. */ - tem = gen_reg_rtx (v->mode); - record_base_value (REGNO (tem), bl->biv->add_val, 0); - loop_iv_add_mult_sink (loop, extend_value_for_giv (v, increment), - GEN_INT (n_iterations), - extend_value_for_giv (v, bl->initial_value), - tem); - - /* Subtract off extra increments as we find them. */ - for (insn = NEXT_INSN (v->insn); insn != loop_end; - insn = NEXT_INSN (insn)) - { - struct induction *biv; - - for (biv = bl->biv; biv; biv = biv->next_iv) - if (biv->insn == insn) - { - start_sequence (); - tem = expand_simple_binop (GET_MODE (tem), MINUS, tem, - biv->add_val, NULL_RTX, 0, - OPTAB_LIB_WIDEN); - seq = get_insns (); - end_sequence (); - loop_insn_sink (loop, seq); - } - } - - /* Now calculate the giv's final value. */ - loop_iv_add_mult_sink (loop, tem, v->mult_val, v->add_val, tem); - - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Final giv value for %d, calc from biv's value.\n", - REGNO (v->dest_reg)); - - return tem; - } - } - - /* Replaceable giv's should never reach here. */ - if (v->replaceable) - abort (); - - /* Check to see if the biv is dead at all loop exits. */ - if (reg_dead_after_loop (loop, v->dest_reg)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Final giv value for %d, giv dead after loop exit.\n", - REGNO (v->dest_reg)); - - return const0_rtx; - } - - return 0; -} - -/* Look back before LOOP->START for the insn that sets REG and return - the equivalent constant if there is a REG_EQUAL note otherwise just - the SET_SRC of REG. */ - -static rtx -loop_find_equiv_value (const struct loop *loop, rtx reg) -{ - rtx loop_start = loop->start; - rtx insn, set; - rtx ret; - - ret = reg; - for (insn = PREV_INSN (loop_start); insn; insn = PREV_INSN (insn)) - { - if (LABEL_P (insn)) - break; - - else if (INSN_P (insn) && reg_set_p (reg, insn)) - { - /* We found the last insn before the loop that sets the register. - If it sets the entire register, and has a REG_EQUAL note, - then use the value of the REG_EQUAL note. */ - if ((set = single_set (insn)) - && (SET_DEST (set) == reg)) - { - rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX); - - /* Only use the REG_EQUAL note if it is a constant. - Other things, divide in particular, will cause - problems later if we use them. */ - if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST - && CONSTANT_P (XEXP (note, 0))) - ret = XEXP (note, 0); - else - ret = SET_SRC (set); - - /* We cannot do this if it changes between the - assignment and loop start though. */ - if (modified_between_p (ret, insn, loop_start)) - ret = reg; - } - break; - } - } - return ret; -} - -/* Find and return register term common to both expressions OP0 and - OP1 or NULL_RTX if no such term exists. Each expression must be a - REG or a PLUS of a REG. */ - -static rtx -find_common_reg_term (rtx op0, rtx op1) -{ - if ((REG_P (op0) || GET_CODE (op0) == PLUS) - && (REG_P (op1) || GET_CODE (op1) == PLUS)) - { - rtx op00; - rtx op01; - rtx op10; - rtx op11; - - if (GET_CODE (op0) == PLUS) - op01 = XEXP (op0, 1), op00 = XEXP (op0, 0); - else - op01 = const0_rtx, op00 = op0; - - if (GET_CODE (op1) == PLUS) - op11 = XEXP (op1, 1), op10 = XEXP (op1, 0); - else - op11 = const0_rtx, op10 = op1; - - /* Find and return common register term if present. */ - if (REG_P (op00) && (op00 == op10 || op00 == op11)) - return op00; - else if (REG_P (op01) && (op01 == op10 || op01 == op11)) - return op01; - } - - /* No common register term found. */ - return NULL_RTX; -} - -/* Determine the loop iterator and calculate the number of loop - iterations. Returns the exact number of loop iterations if it can - be calculated, otherwise returns zero. */ - -unsigned HOST_WIDE_INT -loop_iterations (struct loop *loop) -{ - struct loop_info *loop_info = LOOP_INFO (loop); - struct loop_ivs *ivs = LOOP_IVS (loop); - rtx comparison, comparison_value; - rtx iteration_var, initial_value, increment, final_value; - enum rtx_code comparison_code; - HOST_WIDE_INT inc; - unsigned HOST_WIDE_INT abs_inc; - unsigned HOST_WIDE_INT abs_diff; - int off_by_one; - int increment_dir; - int unsigned_p, compare_dir, final_larger; - rtx last_loop_insn; - struct iv_class *bl; - - loop_info->n_iterations = 0; - loop_info->initial_value = 0; - loop_info->initial_equiv_value = 0; - loop_info->comparison_value = 0; - loop_info->final_value = 0; - loop_info->final_equiv_value = 0; - loop_info->increment = 0; - loop_info->iteration_var = 0; - loop_info->unroll_number = 1; - loop_info->iv = 0; - - /* We used to use prev_nonnote_insn here, but that fails because it might - accidentally get the branch for a contained loop if the branch for this - loop was deleted. We can only trust branches immediately before the - loop_end. */ - last_loop_insn = PREV_INSN (loop->end); - - /* ??? We should probably try harder to find the jump insn - at the end of the loop. The following code assumes that - the last loop insn is a jump to the top of the loop. */ - if (!JUMP_P (last_loop_insn)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: No final conditional branch found.\n"); - return 0; - } - - /* If there is a more than a single jump to the top of the loop - we cannot (easily) determine the iteration count. */ - if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Loop has multiple back edges.\n"); - return 0; - } - - /* Find the iteration variable. If the last insn is a conditional - branch, and the insn before tests a register value, make that the - iteration variable. */ - - comparison = get_condition_for_loop (loop, last_loop_insn); - if (comparison == 0) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: No final comparison found.\n"); - return 0; - } - - /* ??? Get_condition may switch position of induction variable and - invariant register when it canonicalizes the comparison. */ - - comparison_code = GET_CODE (comparison); - iteration_var = XEXP (comparison, 0); - comparison_value = XEXP (comparison, 1); - - if (!REG_P (iteration_var)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Comparison not against register.\n"); - return 0; - } - - /* The only new registers that are created before loop iterations - are givs made from biv increments or registers created by - load_mems. In the latter case, it is possible that try_copy_prop - will propagate a new pseudo into the old iteration register but - this will be marked by having the REG_USERVAR_P bit set. */ - - if ((unsigned) REGNO (iteration_var) >= ivs->n_regs - && ! REG_USERVAR_P (iteration_var)) - abort (); - - /* Determine the initial value of the iteration variable, and the amount - that it is incremented each loop. Use the tables constructed by - the strength reduction pass to calculate these values. */ - - /* Clear the result values, in case no answer can be found. */ - initial_value = 0; - increment = 0; - - /* The iteration variable can be either a giv or a biv. Check to see - which it is, and compute the variable's initial value, and increment - value if possible. */ - - /* If this is a new register, can't handle it since we don't have any - reg_iv_type entry for it. */ - if ((unsigned) REGNO (iteration_var) >= ivs->n_regs) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: No reg_iv_type entry for iteration var.\n"); - return 0; - } - - /* Reject iteration variables larger than the host wide int size, since they - could result in a number of iterations greater than the range of our - `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */ - else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var)) - > HOST_BITS_PER_WIDE_INT)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Iteration var rejected because mode too large.\n"); - return 0; - } - else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Iteration var not an integer.\n"); - return 0; - } - - /* Try swapping the comparison to identify a suitable iv. */ - if (REG_IV_TYPE (ivs, REGNO (iteration_var)) != BASIC_INDUCT - && REG_IV_TYPE (ivs, REGNO (iteration_var)) != GENERAL_INDUCT - && REG_P (comparison_value) - && REGNO (comparison_value) < ivs->n_regs) - { - rtx temp = comparison_value; - comparison_code = swap_condition (comparison_code); - comparison_value = iteration_var; - iteration_var = temp; - } - - if (REG_IV_TYPE (ivs, REGNO (iteration_var)) == BASIC_INDUCT) - { - if (REGNO (iteration_var) >= ivs->n_regs) - abort (); - - /* Grab initial value, only useful if it is a constant. */ - bl = REG_IV_CLASS (ivs, REGNO (iteration_var)); - initial_value = bl->initial_value; - if (!bl->biv->always_executed || bl->biv->maybe_multiple) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Basic induction var not set once in each iteration.\n"); - return 0; - } - - increment = biv_total_increment (bl); - } - else if (REG_IV_TYPE (ivs, REGNO (iteration_var)) == GENERAL_INDUCT) - { - HOST_WIDE_INT offset = 0; - struct induction *v = REG_IV_INFO (ivs, REGNO (iteration_var)); - rtx biv_initial_value; - - if (REGNO (v->src_reg) >= ivs->n_regs) - abort (); - - if (!v->always_executed || v->maybe_multiple) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: General induction var not set once in each iteration.\n"); - return 0; - } - - bl = REG_IV_CLASS (ivs, REGNO (v->src_reg)); - - /* Increment value is mult_val times the increment value of the biv. */ - - increment = biv_total_increment (bl); - if (increment) - { - struct induction *biv_inc; - - increment = fold_rtx_mult_add (v->mult_val, - extend_value_for_giv (v, increment), - const0_rtx, v->mode); - /* The caller assumes that one full increment has occurred at the - first loop test. But that's not true when the biv is incremented - after the giv is set (which is the usual case), e.g.: - i = 6; do {;} while (i++ < 9) . - Therefore, we bias the initial value by subtracting the amount of - the increment that occurs between the giv set and the giv test. */ - for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv) - { - if (loop_insn_first_p (v->insn, biv_inc->insn)) - { - if (REG_P (biv_inc->add_val)) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Basic induction var add_val is REG %d.\n", - REGNO (biv_inc->add_val)); - return 0; - } - - /* If we have already counted it, skip it. */ - if (biv_inc->same) - continue; - - offset -= INTVAL (biv_inc->add_val); - } - } - } - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Giv iterator, initial value bias %ld.\n", - (long) offset); - - /* Initial value is mult_val times the biv's initial value plus - add_val. Only useful if it is a constant. */ - biv_initial_value = extend_value_for_giv (v, bl->initial_value); - initial_value - = fold_rtx_mult_add (v->mult_val, - plus_constant (biv_initial_value, offset), - v->add_val, v->mode); - } - else - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Not basic or general induction var.\n"); - return 0; - } - - if (initial_value == 0) - return 0; - - unsigned_p = 0; - off_by_one = 0; - switch (comparison_code) - { - case LEU: - unsigned_p = 1; - case LE: - compare_dir = 1; - off_by_one = 1; - break; - case GEU: - unsigned_p = 1; - case GE: - compare_dir = -1; - off_by_one = -1; - break; - case EQ: - /* Cannot determine loop iterations with this case. */ - compare_dir = 0; - break; - case LTU: - unsigned_p = 1; - case LT: - compare_dir = 1; - break; - case GTU: - unsigned_p = 1; - case GT: - compare_dir = -1; - break; - case NE: - compare_dir = 0; - break; - default: - abort (); - } - - /* If the comparison value is an invariant register, then try to find - its value from the insns before the start of the loop. */ - - final_value = comparison_value; - if (REG_P (comparison_value) - && loop_invariant_p (loop, comparison_value)) - { - final_value = loop_find_equiv_value (loop, comparison_value); - - /* If we don't get an invariant final value, we are better - off with the original register. */ - if (! loop_invariant_p (loop, final_value)) - final_value = comparison_value; - } - - /* Calculate the approximate final value of the induction variable - (on the last successful iteration). The exact final value - depends on the branch operator, and increment sign. It will be - wrong if the iteration variable is not incremented by one each - time through the loop and (comparison_value + off_by_one - - initial_value) % increment != 0. - ??? Note that the final_value may overflow and thus final_larger - will be bogus. A potentially infinite loop will be classified - as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */ - if (off_by_one) - final_value = plus_constant (final_value, off_by_one); - - /* Save the calculated values describing this loop's bounds, in case - precondition_loop_p will need them later. These values can not be - recalculated inside precondition_loop_p because strength reduction - optimizations may obscure the loop's structure. - - These values are only required by precondition_loop_p and insert_bct - whenever the number of iterations cannot be computed at compile time. - Only the difference between final_value and initial_value is - important. Note that final_value is only approximate. */ - loop_info->initial_value = initial_value; - loop_info->comparison_value = comparison_value; - loop_info->final_value = plus_constant (comparison_value, off_by_one); - loop_info->increment = increment; - loop_info->iteration_var = iteration_var; - loop_info->comparison_code = comparison_code; - loop_info->iv = bl; - - /* Try to determine the iteration count for loops such - as (for i = init; i < init + const; i++). When running the - loop optimization twice, the first pass often converts simple - loops into this form. */ - - if (REG_P (initial_value)) - { - rtx reg1; - rtx reg2; - rtx const2; - - reg1 = initial_value; - if (GET_CODE (final_value) == PLUS) - reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1); - else - reg2 = final_value, const2 = const0_rtx; - - /* Check for initial_value = reg1, final_value = reg2 + const2, - where reg1 != reg2. */ - if (REG_P (reg2) && reg2 != reg1) - { - rtx temp; - - /* Find what reg1 is equivalent to. Hopefully it will - either be reg2 or reg2 plus a constant. */ - temp = loop_find_equiv_value (loop, reg1); - - if (find_common_reg_term (temp, reg2)) - initial_value = temp; - else if (loop_invariant_p (loop, reg2)) - { - /* Find what reg2 is equivalent to. Hopefully it will - either be reg1 or reg1 plus a constant. Let's ignore - the latter case for now since it is not so common. */ - temp = loop_find_equiv_value (loop, reg2); - - if (temp == loop_info->iteration_var) - temp = initial_value; - if (temp == reg1) - final_value = (const2 == const0_rtx) - ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2); - } - } - } - - loop_info->initial_equiv_value = initial_value; - loop_info->final_equiv_value = final_value; - - /* For EQ comparison loops, we don't have a valid final value. - Check this now so that we won't leave an invalid value if we - return early for any other reason. */ - if (comparison_code == EQ) - loop_info->final_equiv_value = loop_info->final_value = 0; - - if (increment == 0) - { - if (loop_dump_stream) - fprintf (loop_dump_stream, - "Loop iterations: Increment value can't be calculated.\n"); - return 0; - } - - if (GET_CODE (increment) != CONST_INT) - { - /* If we have a REG, check to see if REG holds a constant value. */ - /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't - clear if it is worthwhile to try to handle such RTL. */ - if (REG_P (increment) || GET_CODE (increment) == SUBREG) - increment = loop_find_equiv_value (loop, increment); - - if (GET_CODE (increment) != CONST_INT) - { - if (loop_dump_stream) - { - fprintf (loop_dump_stream, - "Loop iterations: Increment value not constant "); - print_simple_rtl (loop_dump_stream, increment); - fprintf (loop_dump_stream, ".\n"); - } - return 0; - } - loop_info->increment = increment; - } - - if (GET_CODE (initial_value) != CONST_INT) - { - if (loop_dump_stream) - { - fprintf (loop_dump_stream, - "Loop iterations: Initial value not constant "); - print_simple_rtl (loop_dump_stream, initial_value); - fprintf (loop_dump_stream, ".\n"); - } - return 0; - } - else if (GET_CODE (final_value) != CONST_INT) - { - if (loop_dump_stream) - { - fprintf (loop_dump_stream, - "Loop iterations: Final value not constant "); - print_simple_rtl (loop_dump_stream, final_value); - fprintf (loop_dump_stream, ".\n"); - } - return 0; - } - else if (comparison_code == EQ) - { - rtx inc_once; - - if (loop_dump_stream) - fprintf (loop_dump_stream, "Loop iterations: EQ comparison loop.\n"); - - inc_once = gen_int_mode (INTVAL (initial_value) + INTVAL (increment), - GET_MODE (iteration_var)); - - if (inc_once == final_value) - { - /* The iterator value once through the loop is equal to the - comparison value. Either we have an infinite loop, or - we'll loop twice. */ - if (increment == const0_rtx) - return 0; - loop_info->n_iterations = 2; - } - else - loop_info->n_iterations = 1; - - if (GET_CODE (loop_info->initial_value) == CONST_INT) - loop_info->final_value - = gen_int_mode ((INTVAL (loop_info->initial_value) - + loop_info->n_iterations * INTVAL (increment)), - GET_MODE (iteration_var)); - else - loop_info->final_value - = plus_constant (loop_info->initial_value, - loop_info->n_iterations * INTVAL (increment)); - loop_info->final_equiv_value - = gen_int_mode ((INTVAL (initial_value) - + loop_info->n_iterations * INTVAL (increment)), - GET_MODE (iteration_var)); - return loop_info->n_iterations; - } - - /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */ - if (unsigned_p) - final_larger - = ((unsigned HOST_WIDE_INT) INTVAL (final_value) - > (unsigned HOST_WIDE_INT) INTVAL (initial_value)) - - ((unsigned HOST_WIDE_INT) INTVAL (final_value) - < (unsigned HOST_WIDE_INT) INTVAL (initial_value)); - else - final_larger = (INTVAL (final_value) > INTVAL (initial_value)) - - (INTVAL (final_value) < INTVAL (initial_value)); - - if (INTVAL (increment) > 0) - increment_dir = 1; - else if (INTVAL (increment) == 0) - increment_dir = 0; - else - increment_dir = -1; - - /* There are 27 different cases: compare_dir = -1, 0, 1; - final_larger = -1, 0, 1; increment_dir = -1, 0, 1. - There are 4 normal cases, 4 reverse cases (where the iteration variable - will overflow before the loop exits), 4 infinite loop cases, and 15 - immediate exit (0 or 1 iteration depending on loop type) cases. - Only try to optimize the normal cases. */ - - /* (compare_dir/final_larger/increment_dir) - Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1) - Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1) - Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0) - Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */ - - /* ?? If the meaning of reverse loops (where the iteration variable - will overflow before the loop exits) is undefined, then could - eliminate all of these special checks, and just always assume - the loops are normal/immediate/infinite. Note that this means - the sign of increment_dir does not have to be known. Also, - since it does not really hurt if immediate exit loops or infinite loops - are optimized, then that case could be ignored also, and hence all - loops can be optimized. - - According to ANSI Spec, the reverse loop case result is undefined, - because the action on overflow is undefined. - - See also the special test for NE loops below. */ - - if (final_larger == increment_dir && final_larger != 0 - && (final_larger == compare_dir || compare_dir == 0)) - /* Normal case. */ - ; - else - { - if (loop_dump_stream) - fprintf (loop_dump_stream, "Loop iterations: Not normal loop.\n"); - return 0; - } - - /* Calculate the number of iterations, final_value is only an approximation, - so correct for that. Note that abs_diff and n_iterations are - unsigned, because they can be as large as 2^n - 1. */ - - inc = INTVAL (increment); - if (inc > 0) - { - abs_diff = INTVAL (final_value) - INTVAL (initial_value); - abs_inc = inc; - } - else if (inc < 0) - { - abs_diff = INTVAL (initial_value) - INTVAL (final_value); - abs_inc = -inc; - } - else - abort (); - - /* Given that iteration_var is going to iterate over its own mode, - not HOST_WIDE_INT, disregard higher bits that might have come - into the picture due to sign extension of initial and final - values. */ - abs_diff &= ((unsigned HOST_WIDE_INT) 1 - << (GET_MODE_BITSIZE (GET_MODE (iteration_var)) - 1) - << 1) - 1; - - /* For NE tests, make sure that the iteration variable won't miss - the final value. If abs_diff mod abs_incr is not zero, then the - iteration variable will overflow before the loop exits, and we - can not calculate the number of iterations. */ - if (compare_dir == 0 && (abs_diff % abs_inc) != 0) - return 0; - - /* Note that the number of iterations could be calculated using - (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to - handle potential overflow of the summation. */ - loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0); - return loop_info->n_iterations; -} - -/* Replace uses of split bivs with their split pseudo register. This is - for original instructions which remain after loop unrolling without - copying. */ - -static rtx -remap_split_bivs (struct loop *loop, rtx x) -{ - struct loop_ivs *ivs = LOOP_IVS (loop); - enum rtx_code code; - int i; - const char *fmt; - - if (x == 0) - return x; - - code = GET_CODE (x); - switch (code) - { - case SCRATCH: - case PC: - case CC0: - case CONST_INT: - case CONST_DOUBLE: - case CONST: - case SYMBOL_REF: - case LABEL_REF: - return x; - - case REG: -#if 0 - /* If non-reduced/final-value givs were split, then this would also - have to remap those givs also. */ -#endif - if (REGNO (x) < ivs->n_regs - && REG_IV_TYPE (ivs, REGNO (x)) == BASIC_INDUCT) - return REG_IV_CLASS (ivs, REGNO (x))->biv->src_reg; - break; - - default: - break; - } - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - XEXP (x, i) = remap_split_bivs (loop, XEXP (x, i)); - else if (fmt[i] == 'E') - { - int j; - for (j = 0; j < XVECLEN (x, i); j++) - XVECEXP (x, i, j) = remap_split_bivs (loop, XVECEXP (x, i, j)); - } - } - return x; -} - -/* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g. - FIST_UID is always executed if LAST_UID is), then return 1. Otherwise - return 0. COPY_START is where we can start looking for the insns - FIRST_UID and LAST_UID. COPY_END is where we stop looking for these - insns. - - If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID - must dominate LAST_UID. - - If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID - may not dominate LAST_UID. - - If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID - must dominate LAST_UID. */ - -int -set_dominates_use (int regno, int first_uid, int last_uid, rtx copy_start, - rtx copy_end) -{ - int passed_jump = 0; - rtx p = NEXT_INSN (copy_start); - - while (INSN_UID (p) != first_uid) - { - if (JUMP_P (p)) - passed_jump = 1; - /* Could not find FIRST_UID. */ - if (p == copy_end) - return 0; - p = NEXT_INSN (p); - } - - /* Verify that FIRST_UID is an insn that entirely sets REGNO. */ - if (! INSN_P (p) || ! dead_or_set_regno_p (p, regno)) - return 0; - - /* FIRST_UID is always executed. */ - if (passed_jump == 0) - return 1; - - while (INSN_UID (p) != last_uid) - { - /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we - can not be sure that FIRST_UID dominates LAST_UID. */ - if (LABEL_P (p)) - return 0; - /* Could not find LAST_UID, but we reached the end of the loop, so - it must be safe. */ - else if (p == copy_end) - return 1; - p = NEXT_INSN (p); - } - - /* FIRST_UID is always executed if LAST_UID is executed. */ - return 1; -} - |