/* Try to unroll loops, and split induction variables.
- Copyright (C) 1992, 93, 94, 95, 97, 98, 1999 Free Software Foundation, Inc.
+ Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000
+ Free Software Foundation, Inc.
Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
This file is part of GNU CC.
#define NUM_FACTORS 4
-struct _factor { int factor, count; } factors[NUM_FACTORS]
- = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
+struct _factor { int factor, 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 };
+enum unroll_types
+{
+ UNROLL_COMPLETELY,
+ UNROLL_MODULO,
+ UNROLL_NAIVE
+};
#include "config.h"
#include "system.h"
#include "expr.h"
#include "loop.h"
#include "toplev.h"
+#include "hard-reg-set.h"
+#include "basic-block.h"
/* This controls which loops are unrolled, and by how much we unroll
them. */
static rtx *splittable_regs;
/* Indexed by register number, if this is a splittable induction variable,
- this indicates if it was made from a derived giv. */
-static char *derived_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. */
/* Forward declarations. */
-static void init_reg_map PROTO((struct inline_remap *, int));
-static rtx calculate_giv_inc PROTO((rtx, rtx, int));
-static rtx initial_reg_note_copy PROTO((rtx, struct inline_remap *));
-static void final_reg_note_copy PROTO((rtx, struct inline_remap *));
-static void copy_loop_body PROTO((rtx, rtx, struct inline_remap *, rtx, int,
- enum unroll_types, rtx, rtx, rtx, rtx));
-static void iteration_info PROTO((rtx, rtx *, rtx *, rtx, rtx));
-static int find_splittable_regs PROTO((enum unroll_types, rtx, rtx, rtx, int,
- unsigned HOST_WIDE_INT));
-static int find_splittable_givs PROTO((struct iv_class *, enum unroll_types,
- rtx, rtx, rtx, int));
-static int reg_dead_after_loop PROTO((rtx, rtx, rtx));
-static rtx fold_rtx_mult_add PROTO((rtx, rtx, rtx, enum machine_mode));
-static int verify_addresses PROTO((struct induction *, rtx, int));
-static rtx remap_split_bivs PROTO((rtx));
-static rtx find_common_reg_term PROTO((rtx, rtx));
-static rtx subtract_reg_term PROTO((rtx, rtx));
-static rtx loop_find_equiv_value PROTO((rtx, rtx));
+static void init_reg_map PARAMS ((struct inline_remap *, int));
+static rtx calculate_giv_inc PARAMS ((rtx, rtx, unsigned int));
+static rtx initial_reg_note_copy PARAMS ((rtx, struct inline_remap *));
+static void final_reg_note_copy PARAMS ((rtx, struct inline_remap *));
+static void copy_loop_body PARAMS ((struct loop *, rtx, rtx,
+ struct inline_remap *, rtx, int,
+ enum unroll_types, rtx, rtx, rtx, rtx));
+static int find_splittable_regs PARAMS ((const struct loop *,
+ enum unroll_types, rtx, int));
+static int find_splittable_givs PARAMS ((const struct loop *,
+ struct iv_class *, enum unroll_types,
+ rtx, int));
+static int reg_dead_after_loop PARAMS ((const struct loop *, rtx));
+static rtx fold_rtx_mult_add PARAMS ((rtx, rtx, rtx, enum machine_mode));
+static int verify_addresses PARAMS ((struct induction *, rtx, int));
+static rtx remap_split_bivs PARAMS ((struct loop *, rtx));
+static rtx find_common_reg_term PARAMS ((rtx, rtx));
+static rtx subtract_reg_term PARAMS ((rtx, rtx));
+static rtx loop_find_equiv_value PARAMS ((const struct loop *, rtx));
+static rtx ujump_to_loop_cont PARAMS ((rtx, rtx));
/* Try to unroll one loop and split induction variables in the loop.
- The loop is described by the arguments LOOP_END, INSN_COUNT, and
- LOOP_START. END_INSERT_BEFORE indicates where insns should be added
- which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
- indicates whether information generated in the strength reduction pass
- is available.
+ The loop is described by the arguments LOOP and INSN_COUNT.
+ END_INSERT_BEFORE indicates where insns should be added which need
+ to be executed when the loop falls through. 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 (loop_end, insn_count, loop_start, end_insert_before,
- loop_info, strength_reduce_p)
- rtx loop_end;
+unroll_loop (loop, insn_count, end_insert_before, strength_reduce_p)
+ struct loop *loop;
int insn_count;
- rtx loop_start;
rtx end_insert_before;
- struct loop_info *loop_info;
int strength_reduce_p;
{
- int i, j, temp;
+ 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;
struct inline_remap *map;
char *local_label = NULL;
char *local_regno;
- int max_local_regnum;
- int maxregnum;
+ 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;
+ 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
block_begins++;
else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
block_ends++;
+ if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
+ || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
+ {
+ /* Note, would be nice to add code to unroll EH
+ regions, but until that time, we punt (don't
+ unroll). For the proper way of doing it, see
+ expand_inline_function. */
+
+ if (loop_dump_stream)
+ fprintf (loop_dump_stream,
+ "Unrolling failure: cannot unroll EH regions.\n");
+ return;
+ }
}
}
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. */
+
+ rtx ujump = ujump_to_loop_cont (loop->start, loop->cont);
+ if (ujump)
+ delete_insn (ujump);
+
/* If number of iterations is exactly 1, then eliminate the compare and
branch at the end of the loop since they will never be taken.
Then return, since no other action is needed here. */
delete_insn (prev);
#endif
}
+
+ /* Remove the loop notes since this is no longer a loop. */
+ if (loop->vtop)
+ delete_insn (loop->vtop);
+ if (loop->cont)
+ delete_insn (loop->cont);
+ if (loop_start)
+ delete_insn (loop_start);
+ if (loop_end)
+ delete_insn (loop_end);
+
return;
}
else if (loop_info->n_iterations > 0
+ /* Avoid overflow in the next expression. */
+ && loop_info->n_iterations < MAX_UNROLLED_INSNS
&& loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
{
unroll_number = loop_info->n_iterations;
if (unroll_number == 1)
{
if (loop_dump_stream)
- fprintf (loop_dump_stream,
- "Loop unrolling: No factors found.\n");
+ 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_number == 1)
+ if (unroll_type == UNROLL_NAIVE)
{
if (8 * insn_count < MAX_UNROLLED_INSNS)
unroll_number = 8;
unroll_number = 4;
else
unroll_number = 2;
-
- unroll_type = UNROLL_NAIVE;
}
/* 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);
-
+ fprintf (loop_dump_stream, "Unrolling loop %d times.\n", unroll_number);
if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
{
max_labelno = max_label_num ();
max_insnno = get_max_uid ();
- map = (struct inline_remap *) alloca (sizeof (struct inline_remap));
+ /* Various paths through the unroll code may reach the "egress" label
+ without initializing fields within the map structure.
- map->integrating = 0;
- map->const_equiv_varray = 0;
+ To be safe, we use xcalloc to zero the memory. */
+ map = (struct inline_remap *) xcalloc (1, sizeof (struct inline_remap));
/* Allocate the label map. */
if (max_labelno > 0)
{
- map->label_map = (rtx *) alloca (max_labelno * sizeof (rtx));
+ map->label_map = (rtx *) xmalloc (max_labelno * sizeof (rtx));
- local_label = (char *) alloca (max_labelno);
- bzero (local_label, max_labelno);
+ local_label = (char *) xcalloc (max_labelno, sizeof (char));
}
- else
- map->label_map = 0;
/* 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
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);
+ set_label_in_map (map, CODE_LABEL_NUMBER (label), label);
}
}
}
/* Allocate space for the insn map. */
- map->insn_map = (rtx *) alloca (max_insnno * sizeof (rtx));
+ map->insn_map = (rtx *) xmalloc (max_insnno * sizeof (rtx));
/* Set this to zero, to indicate that we are doing loop unrolling,
not function inlining. */
preconditioning code and find_splittable_regs will never be used
to access the splittable_regs[] and addr_combined_regs[] arrays. */
- splittable_regs = (rtx *) alloca (maxregnum * sizeof (rtx));
- bzero ((char *) splittable_regs, maxregnum * sizeof (rtx));
- derived_regs = (char *) alloca (maxregnum);
- bzero (derived_regs, maxregnum);
- splittable_regs_updates = (int *) alloca (maxregnum * sizeof (int));
- bzero ((char *) splittable_regs_updates, maxregnum * sizeof (int));
+ splittable_regs = (rtx *) xcalloc (maxregnum, sizeof (rtx));
+ splittable_regs_updates = (int *) xcalloc (maxregnum, sizeof (int));
addr_combined_regs
- = (struct induction **) alloca (maxregnum * sizeof (struct induction *));
- bzero ((char *) addr_combined_regs, maxregnum * sizeof (struct induction *));
- local_regno = (char *) alloca (maxregnum);
- bzero (local_regno, maxregnum);
+ = (struct induction **) xcalloc (maxregnum, sizeof (struct induction *));
+ local_regno = (char *) xcalloc (maxregnum, sizeof (char));
/* Mark all local registers, i.e. the ones which are referenced only
inside the loop. */
/* 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 (GET_CODE (copy_end) == JUMP_INSN && sets_cc0_p (PREV_INSN (copy_end)))
+ if (GET_CODE (copy_end) == JUMP_INSN
+ && sets_cc0_p (PREV_INSN (copy_end)))
copy_end_luid--;
#endif
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 (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
- if (REGNO_FIRST_UID (j) > 0 && REGNO_FIRST_UID (j) <= max_uid_for_loop
- && uid_luid[REGNO_FIRST_UID (j)] >= copy_start_luid
- && REGNO_LAST_UID (j) > 0 && REGNO_LAST_UID (j) <= max_uid_for_loop
- && uid_luid[REGNO_LAST_UID (j)] <= copy_end_luid)
+ 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
regno_last_uid. */
/* ??? This check is simplistic. We would get better code if
this check was more sophisticated. */
- if (set_dominates_use (j, REGNO_FIRST_UID (j), REGNO_LAST_UID (j),
+ if (set_dominates_use (r, REGNO_FIRST_UID (r), REGNO_LAST_UID (r),
copy_start, copy_end))
- local_regno[j] = 1;
+ local_regno[r] = 1;
if (loop_dump_stream)
{
- if (local_regno[j])
- fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
+ 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",
- j);
+ r);
}
}
- /* Givs that have been created from multiple biv increments always have
- local registers. */
- for (j = first_increment_giv; j <= last_increment_giv; j++)
- {
- local_regno[j] = 1;
- if (loop_dump_stream)
- fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
- }
}
/* If this loop requires exit tests when unrolled, check to see if we
rtx initial_value, final_value, increment;
enum machine_mode mode;
- if (precondition_loop_p (loop_start, loop_info,
+ if (precondition_loop_p (loop,
&initial_value, &final_value, &increment,
&mode))
{
- register rtx diff ;
+ register rtx diff;
rtx *labels;
int abs_inc, neg_inc;
- map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
+ map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
- "unroll_loop");
+ "unroll_loop_precondition");
global_const_equiv_varray = map->const_equiv_varray;
init_reg_map (map, maxregnum);
abs_inc = INTVAL (increment);
if (abs_inc < 0)
{
- abs_inc = - abs_inc;
+ abs_inc = -abs_inc;
neg_inc = 1;
}
/* Now emit a sequence of branches to jump to the proper precond
loop entry point. */
- labels = (rtx *) alloca (sizeof (rtx) * unroll_number);
+ labels = (rtx *) xmalloc (sizeof (rtx) * unroll_number);
for (i = 0; i < unroll_number; i++)
labels[i] = gen_label_rtx ();
{
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. */
+ /* 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
emit_label_after (labels[unroll_number - i],
PREV_INSN (loop_start));
- bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
- bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
- (VARRAY_SIZE (map->const_equiv_varray)
- * sizeof (struct const_equiv_data)));
+ memset ((char *) map->insn_map, 0, max_insnno * sizeof (rtx));
+ memset ((char *) &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 (j = FIRST_PSEUDO_REGISTER; j < max_local_regnum; j++)
- if (local_regno[j])
+ for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
+ if (local_regno[r])
{
- map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
- record_base_value (REGNO (map->reg_map[j]),
- regno_reg_rtx[j], 0);
+ 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
/* None of the copies are the `last_iteration', so just
pass zero for that parameter. */
- copy_loop_body (copy_start, copy_end, map, exit_label, 0,
+ copy_loop_body (loop, copy_start, copy_end, map, exit_label, 0,
unroll_type, start_label, loop_end,
loop_start, copy_end);
}
{
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. */
+ /* 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
/* Set unroll type to MODULO now. */
unroll_type = UNROLL_MODULO;
loop_preconditioned = 1;
+
+ /* Clean up. */
+ free (labels);
}
}
if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
{
if (loop_dump_stream)
- fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
+ fprintf (loop_dump_stream,
+ "Unrolling failure: Naive unrolling not being done.\n");
goto egress;
}
if (splitting_not_safe)
temp = 0;
else
- temp = find_splittable_regs (unroll_type, loop_start, loop_end,
- end_insert_before, unroll_number,
- loop_info->n_iterations);
+ temp = find_splittable_regs (loop, unroll_type,
+ end_insert_before, 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 = (rtx *) alloca (maxregnum * sizeof (rtx));
+ map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
init_reg_map (map, maxregnum);
/* 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 = loop_iv_list; bl; bl = bl->next)
+ 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;
}
/* Use our current register alignment and pointer flags. */
- map->regno_pointer_flag = current_function->emit->regno_pointer_flag;
- map->regno_pointer_align = current_function->emit->regno_pointer_align;
+ 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
{
insn = NEXT_INSN (copy_end);
if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
- PATTERN (insn) = remap_split_bivs (PATTERN (insn));
+ PATTERN (insn) = remap_split_bivs (loop, PATTERN (insn));
}
/* For unroll_number times, make a copy of each instruction
for (i = 0; i < unroll_number; i++)
{
- bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
- bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
- VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
+ memset ((char *) map->insn_map, 0, max_insnno * sizeof (rtx));
+ memset ((char *) &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 (j = FIRST_PSEUDO_REGISTER; j < max_local_regnum; j++)
- if (local_regno[j])
+ for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
+ if (local_regno[r])
{
- map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
- record_base_value (REGNO (map->reg_map[j]),
- regno_reg_rtx[j], 0);
+ 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
LABEL_NUSES (tem)++;
}
- copy_loop_body (copy_start, copy_end, map, exit_label,
+ 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);
}
emit_label_after (exit_label, loop_end);
egress:
- if (map && map->const_equiv_varray)
+ if (unroll_type == UNROLL_COMPLETELY)
+ {
+ /* Remove the loop notes since this is no longer a loop. */
+ if (loop->vtop)
+ delete_insn (loop->vtop);
+ if (loop->cont)
+ delete_insn (loop->cont);
+ if (loop_start)
+ delete_insn (loop_start);
+ if (loop_end)
+ delete_insn (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);
}
\f
/* Return true if the loop can be safely, and profitably, preconditioned
reflected in RTX_COST. */
int
-precondition_loop_p (loop_start, loop_info,
- initial_value, final_value, increment, mode)
- rtx loop_start;
- struct loop_info *loop_info;
+precondition_loop_p (loop, initial_value, final_value, increment, mode)
+ const struct loop *loop;
rtx *initial_value, *final_value, *increment;
enum machine_mode *mode;
{
+ rtx loop_start = loop->start;
+ struct loop_info *loop_info = LOOP_INFO (loop);
if (loop_info->n_iterations > 0)
{
return 0;
}
else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
- && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
+ && (exact_log2 (-INTVAL (loop_info->increment)) < 0))
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
return 0;
}
- /* Must ensure that final_value is invariant, so call 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 invariant_p.
- If it isn't, then it is most likely a biv/giv which by definition are
- not invariant. */
+ /* 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 ((GET_CODE (loop_info->final_value) == REG
&& 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)
- || ! invariant_p (loop_info->final_value))
+ || ! loop_invariant_p (loop, loop_info->final_value))
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
/* Fail if loop_info->iteration_var is not live before loop_start,
since we need to test its value in the preconditioning code. */
- if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
+ if (REGNO_FIRST_LUID (REGNO (loop_info->iteration_var))
> INSN_LUID (loop_start))
{
if (loop_dump_stream)
return 0;
}
- /* Note that iteration_info biases the initial value for GIV iterators
+ /* 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.
< GET_MODE_SIZE (GET_MODE (*initial_value))))
*mode = GET_MODE (*initial_value);
- /* Success! */
+ /* 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
static rtx
calculate_giv_inc (pattern, src_insn, regno)
rtx pattern, src_insn;
- int regno;
+ unsigned int regno;
{
rtx increment;
rtx increment_total = 0;
PUT_MODE (copy, GET_MODE (notes));
if (GET_CODE (notes) == EXPR_LIST)
- XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map);
+ 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) = XEXP (notes, 0);
This is very similar to a loop in expand_inline_function. */
static void
-copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
+copy_loop_body (loop, copy_start, copy_end, map, exit_label, last_iteration,
unroll_type, start_label, loop_end, insert_before,
copy_notes_from)
+ struct loop *loop;
rtx copy_start, copy_end;
struct inline_remap *map;
rtx exit_label;
enum unroll_types unroll_type;
rtx start_label, loop_end, insert_before, copy_notes_from;
{
+ struct loop_ivs *ivs = LOOP_IVS (loop);
rtx insn, pattern;
- rtx set, tem, copy;
+ rtx set, tem, copy = NULL_RTX;
int dest_reg_was_split, i;
#ifdef HAVE_cc0
rtx cc0_insn = 0;
if (! last_iteration)
{
final_label = gen_label_rtx ();
- set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
- final_label);
+ 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);
{
struct iv_class *bl;
struct induction *v, *tv;
- int regno = REGNO (SET_DEST (set));
+ unsigned int regno = REGNO (SET_DEST (set));
v = addr_combined_regs[REGNO (SET_DEST (set))];
- bl = reg_biv_class[REGNO (v->src_reg)];
+ 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
we might accidentally delete insns generated immediately
below by emit_unrolled_add. */
- if (! derived_regs[regno])
- giv_inc = calculate_giv_inc (set, insn, regno);
+ giv_inc = calculate_giv_inc (set, insn, regno);
/* Now find all address giv's that were combined with this
giv 'v'. */
value = plus_constant (tv->dest_reg,
tv->const_adjust);
- /* 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));
+ 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
We must subtract the const_adjust factor added in
above. */
tv->dest_reg = plus_constant (dest_reg,
- - tv->const_adjust);
+ -tv->const_adjust);
*tv->location = tv->dest_reg;
}
}
&& GET_CODE (SET_DEST (set)) == REG
&& splittable_regs[REGNO (SET_DEST (set))])
{
- int regno = REGNO (SET_DEST (set));
- int src_regno;
+ unsigned int regno = REGNO (SET_DEST (set));
+ unsigned int src_regno;
dest_reg_was_split = 1;
giv_dest_reg = SET_DEST (set);
- if (derived_regs[regno])
- {
- /* ??? This relies on SET_SRC (SET) to be of
- the form (plus (reg) (const_int)), and thus
- forces recombine_givs to restrict the kind
- of giv derivations it does before unrolling. */
- giv_src_reg = XEXP (SET_SRC (set), 0);
- giv_inc = XEXP (SET_SRC (set), 1);
- }
- else
- {
- 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);
- }
+ 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)
for the biv was stored in the biv's first struct
induction entry by find_splittable_regs. */
- if (regno < max_reg_before_loop
- && REG_IV_TYPE (regno) == BASIC_INDUCT)
+ if (regno < ivs->n_regs
+ && REG_IV_TYPE (ivs, regno) == BASIC_INDUCT)
{
- giv_src_reg = reg_biv_class[regno]->biv->src_reg;
+ giv_src_reg = REG_IV_CLASS (ivs, regno)->biv->src_reg;
giv_dest_reg = giv_src_reg;
}
#endif
splittable_regs[regno]
- = GEN_INT (INTVAL (giv_inc)
- + INTVAL (splittable_regs[src_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
}
else
{
- pattern = copy_rtx_and_substitute (pattern, map);
+ pattern = copy_rtx_and_substitute (pattern, map, 0);
copy = emit_insn (pattern);
}
REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
/* 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
- && (GET_CODE (pattern) == SET || GET_CODE (pattern) == USE))
+ if (dest_reg_was_split)
{
- int regno = REGNO (SET_DEST (pattern));
+ 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
break;
case JUMP_INSN:
- pattern = copy_rtx_and_substitute (PATTERN (insn), map);
+ 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);
if (JUMP_LABEL (insn) == start_label && insn == copy_end
&& ! last_iteration)
{
+ /* Update JUMP_LABEL make invert_jump work correctly. */
+ JUMP_LABEL (copy) = get_label_from_map (map,
+ CODE_LABEL_NUMBER
+ (JUMP_LABEL (insn)));
+ LABEL_NUSES (JUMP_LABEL (copy))++;
+
/* 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_exp (pattern, copy))
- {
- if (! redirect_exp (&pattern,
- get_label_from_map (map,
- CODE_LABEL_NUMBER
- (JUMP_LABEL (insn))),
- exit_label, copy))
- abort ();
- }
- else
+ if (!invert_jump (copy, exit_label, 0))
{
rtx jmp;
rtx lab = gen_label_rtx ();
jmp = emit_barrier_after (jmp);
emit_label_after (lab, jmp);
LABEL_NUSES (lab) = 0;
- if (! redirect_exp (&pattern,
- get_label_from_map (map,
- CODE_LABEL_NUMBER
- (JUMP_LABEL (insn))),
- lab, copy))
+ if (!redirect_jump (copy, lab, 0))
abort ();
}
}
/* If this used to be a conditional jump insn but whose branch
direction is now known, we must do something special. */
- if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
+ 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. */
break;
case CALL_INSN:
- pattern = copy_rtx_and_substitute (PATTERN (insn), map);
+ 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);
/* 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);
+ = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn),
+ map, 0);
#ifdef HAVE_cc0
if (cc0_insn)
/* VTOP and CONT notes are valid only before the loop exit test.
If placed anywhere else, loop may generate bad code. */
/* BASIC_BLOCK notes exist to stabilize basic block structures with
- the associated rtl. We do not want to share the structure in
+ 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
&& ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
&& NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
emit_move_insn (dest_reg, result);
}
\f
-/* Searches the insns between INSN and LOOP_END. Returns 1 if there
+/* 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. */
+ 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 (insn, loop_start, loop_end)
+back_branch_in_range_p (loop, insn)
+ const struct loop *loop;
rtx insn;
- rtx loop_start, loop_end;
{
rtx p, q, target_insn;
- rtx orig_loop_end = loop_end;
+ 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 it can be calculated. Otherwise, returns 0. */
rtx
-biv_total_increment (bl, loop_start, loop_end)
+biv_total_increment (bl)
struct iv_class *bl;
- rtx loop_start, loop_end;
{
struct induction *v;
rtx result;
return result;
}
-/* 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.
-
- Initial_value and/or increment are set to zero if their values could not
- be calculated. */
-
-static void
-iteration_info (iteration_var, initial_value, increment, loop_start, loop_end)
- rtx iteration_var, *initial_value, *increment;
- rtx loop_start, loop_end;
-{
- struct iv_class *bl;
-#if 0
- struct induction *v;
-#endif
-
- /* 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) >= reg_iv_type->num_elements)
- {
- if (loop_dump_stream)
- fprintf (loop_dump_stream,
- "Loop unrolling: No reg_iv_type entry for iteration var.\n");
- return;
- }
-
- /* 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 unrolling: Iteration var rejected because mode too large.\n");
- return;
- }
- else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
- {
- if (loop_dump_stream)
- fprintf (loop_dump_stream,
- "Loop unrolling: Iteration var not an integer.\n");
- return;
- }
- else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
- {
- /* When reg_iv_type / reg_iv_info is resized for biv increments
- that are turned into givs, reg_biv_class is not resized.
- So check here that we don't make an out-of-bounds access. */
- if (REGNO (iteration_var) >= max_reg_before_loop)
- abort ();
-
- /* Grab initial value, only useful if it is a constant. */
- bl = reg_biv_class[REGNO (iteration_var)];
- *initial_value = bl->initial_value;
-
- *increment = biv_total_increment (bl, loop_start, loop_end);
- }
- else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
- {
- HOST_WIDE_INT offset = 0;
- struct induction *v = REG_IV_INFO (REGNO (iteration_var));
-
- if (REGNO (v->src_reg) >= max_reg_before_loop)
- abort ();
-
- bl = reg_biv_class[REGNO (v->src_reg)];
-
- /* Increment value is mult_val times the increment value of the biv. */
-
- *increment = biv_total_increment (bl, loop_start, loop_end);
- if (*increment)
- {
- struct induction *biv_inc;
-
- *increment
- = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx, v->mode);
- /* The caller assumes that one full increment has occured 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))
- offset -= INTVAL (biv_inc->add_val);
- }
- offset *= INTVAL (v->mult_val);
- }
- if (loop_dump_stream)
- fprintf (loop_dump_stream,
- "Loop unrolling: 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. */
- *initial_value
- = fold_rtx_mult_add (v->mult_val,
- plus_constant (bl->initial_value, offset),
- v->add_val, v->mode);
- }
- else
- {
- if (loop_dump_stream)
- fprintf (loop_dump_stream,
- "Loop unrolling: Not basic or general induction var.\n");
- return;
- }
-}
-
-
/* 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
times, since multiplies by small integers (1,2,3,4) are very cheap. */
static int
-find_splittable_regs (unroll_type, loop_start, loop_end, end_insert_before,
- unroll_number, n_iterations)
+find_splittable_regs (loop, unroll_type, end_insert_before, unroll_number)
+ const struct loop *loop;
enum unroll_types unroll_type;
- rtx loop_start, loop_end;
rtx end_insert_before;
int unroll_number;
- unsigned HOST_WIDE_INT n_iterations;
{
+ 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;
+ rtx loop_start = loop->start;
+ rtx loop_end = loop->end;
- for (bl = loop_iv_list; bl; bl = bl->next)
+ 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, loop_start, loop_end);
+ increment = biv_total_increment (bl);
if (! increment || GET_CODE (increment) != CONST_INT)
continue;
biv_splittable = 1;
biv_final_value = 0;
if (unroll_type != UNROLL_COMPLETELY
- && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
- || unroll_type == UNROLL_NAIVE)
- && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
+ && (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
- || (uid_luid[REGNO_FIRST_UID (bl->regno)]
+ || (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 (bl, loop_start, loop_end,
- n_iterations)))
+ && ! (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
if (GET_CODE (bl->initial_value) == REG
&& (REGNO (bl->initial_value) == bl->regno
|| REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
- || ! invariant_p (bl->initial_value)))
+ || ! loop_invariant_p (loop, bl->initial_value)))
{
rtx tem = gen_reg_rtx (bl->biv->mode);
loop_start);
if (loop_dump_stream)
- fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
+ fprintf (loop_dump_stream,
+ "Biv %d initial value remapped to %d.\n",
bl->regno, REGNO (tem));
splittable_regs[bl->regno] = tem;
depend on it may be splittable if the biv is live outside the
loop, and the givs aren't. */
- result += find_splittable_givs (bl, unroll_type, loop_start, loop_end,
- increment, unroll_number);
+ result += find_splittable_givs (loop, bl, unroll_type, increment,
+ unroll_number);
/* If final value is non-zero, then must emit an instruction which sets
the value of the biv to the proper value. This is done after
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_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
+ if (! loop->exit_count)
emit_insn_before (gen_move_insn (bl->biv->src_reg,
biv_final_value),
end_insert_before);
Return the number of instructions that set splittable registers. */
static int
-find_splittable_givs (bl, unroll_type, loop_start, loop_end, increment,
- unroll_number)
+find_splittable_givs (loop, bl, unroll_type, increment, unroll_number)
+ const struct loop *loop;
struct iv_class *bl;
enum unroll_types unroll_type;
- rtx loop_start, loop_end;
rtx increment;
int unroll_number;
{
+ struct loop_ivs *ivs = LOOP_IVS (loop);
struct induction *v, *v2;
rtx final_value;
rtx tem;
won't reach here if they aren't. */
if (v->giv_type != DEST_ADDR
&& (! v->always_computable
- || back_branch_in_range_p (v->insn, loop_start, loop_end)))
+ || back_branch_in_range_p (loop, v->insn)))
continue;
/* The giv increment value must be a constant. */
final_value = 0;
if (unroll_type != UNROLL_COMPLETELY
- && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
- || unroll_type == UNROLL_NAIVE)
+ && (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
|| (REGNO_FIRST_UID (REGNO (v->dest_reg))
!= INSN_UID (XEXP (tem, 0)))))
/* Line above always fails if INSN was moved by loop opt. */
- || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
- >= INSN_LUID (loop_end)))
- /* Givs made from biv increments are missed by the above test, so
- test explicitly for them. */
- && (REGNO (v->dest_reg) < first_increment_giv
- || REGNO (v->dest_reg) > last_increment_giv)
+ || (REGNO_LAST_LUID (REGNO (v->dest_reg))
+ >= INSN_LUID (loop->end)))
&& ! (final_value = v->final_value))
continue;
record_base_value (REGNO (tem), bl->biv->add_val, 0);
emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
- loop_start);
+ loop->start);
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);
}
rtx tem = gen_reg_rtx (v->mode);
record_base_value (REGNO (tem), v->add_val, 0);
emit_iv_add_mult (bl->initial_value, v->mult_val,
- v->add_val, tem, loop_start);
+ v->add_val, tem, loop->start);
value = tem;
}
splittable_regs[REGNO (v->new_reg)] = value;
- derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
}
else
{
rtx new_reg = v->new_reg;
record_base_value (REGNO (tem), v->add_val, 0);
- if (same && same->derived_from)
- {
- /* calculate_giv_inc doesn't work for derived givs.
- copy_loop_body works around the problem for the
- DEST_REG givs themselves, but it can't handle
- DEST_ADDR givs that have been combined with
- a derived DEST_REG giv.
- So Handle V as if the giv from which V->SAME has
- been derived has been combined with V.
- recombine_givs only derives givs from givs that
- are reduced the ordinary, so we need not worry
- about same->derived_from being in turn derived. */
-
- same = same->derived_from;
- new_reg = express_from (same, v);
- new_reg = replace_rtx (new_reg, same->dest_reg,
- same->new_reg);
- }
-
/* If the address giv has a constant in its new_reg value,
then this constant can be pulled out and put in value,
instead of being part of the initialization code. */
/* Save the negative of the eliminated const, so
that we can calculate the dest_reg's increment
value later. */
- v->const_adjust = - INTVAL (XEXP (new_reg, 1));
+ v->const_adjust = -INTVAL (XEXP (new_reg, 1));
new_reg = XEXP (new_reg, 0);
if (loop_dump_stream)
to calculate the value from scratch. */
emit_insn_before (gen_rtx_SET (VOIDmode, tem,
copy_rtx (v->new_reg)),
- loop_start);
- if (recog_memoized (PREV_INSN (loop_start)) < 0)
+ loop->start);
+ if (recog_memoized (PREV_INSN (loop->start)) < 0)
{
rtx sequence, ret;
value, because the loop may have been preconditioned.
We must calculate it from NEW_REG. Try using
force_operand instead of emit_iv_add_mult. */
- delete_insn (PREV_INSN (loop_start));
+ delete_insn (PREV_INSN (loop->start));
start_sequence ();
ret = force_operand (v->new_reg, tem);
emit_move_insn (tem, ret);
sequence = gen_sequence ();
end_sequence ();
- emit_insn_before (sequence, loop_start);
+ emit_insn_before (sequence, loop->start);
if (loop_dump_stream)
fprintf (loop_dump_stream,
INSN_UID (v->insn));
continue;
}
- if (v->same && v->same->derived_from)
- {
- /* Handle V as if the giv from which V->SAME has
- been derived has been combined with V. */
-
- v->same = v->same->derived_from;
- v->new_reg = express_from (v->same, v);
- v->new_reg = replace_rtx (v->new_reg, v->same->dest_reg,
- v->same->new_reg);
- }
-
}
/* Store the value of dest_reg into the insn. This sharing
Make sure that it's giv is marked as splittable here. */
splittable_regs[REGNO (v->new_reg)] = value;
- derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
/* Make it appear to depend upon itself, so that the
giv will be properly split in the main loop above. */
{
int count = 1;
if (! v->ignore)
- count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
-
- if (count > 1 && v->derived_from)
- /* In this case, there is one set where the giv insn was and one
- set each after each biv increment. (Most are likely dead.) */
- count++;
+ count = REG_IV_CLASS (ivs, REGNO (v->src_reg))->biv_count;
splittable_regs_updates[REGNO (v->new_reg)] = count;
}
it can search past if statements and other similar structures. */
static int
-reg_dead_after_loop (reg, loop_start, loop_end)
- rtx reg, loop_start, loop_end;
+reg_dead_after_loop (loop, reg)
+ const struct loop *loop;
+ rtx reg;
{
rtx insn, label;
enum rtx_code code;
int jump_count = 0;
int label_count = 0;
- int this_loop_num = uid_loop_num[INSN_UID (loop_start)];
/* 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_number_exit_labels[this_loop_num]; label;
- label = LABEL_NEXTREF (label))
+ for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label))
label_count++;
- if (label_count != loop_number_exit_count[this_loop_num])
+ 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
+ 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_number_exit_labels[this_loop_num];
+ label = gen_rtx_LABEL_REF (VOIDmode, loop->end);
+ LABEL_NEXTREF (label) = loop->exit_labels;
- for ( ; label; label = LABEL_NEXTREF (label))
+ 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
{
if (GET_CODE (PATTERN (insn)) == RETURN)
break;
- else if (! simplejump_p (insn)
+ else if (!any_uncondjump_p (insn)
/* Prevent infinite loop following infinite loops. */
|| jump_count++ > 20)
return 0;
the end of the loop. If we can do it, return that value. */
rtx
-final_biv_value (bl, loop_start, loop_end, n_iterations)
+final_biv_value (loop, bl)
+ const struct loop *loop;
struct iv_class *bl;
- rtx loop_start, loop_end;
- unsigned HOST_WIDE_INT n_iterations;
{
+ rtx loop_end = loop->end;
+ 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. */
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
+ 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)
value of the biv must be invariant. */
if (n_iterations != 0
- && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
- && invariant_p (bl->initial_value))
+ && ! loop->exit_count
+ && loop_invariant_p (loop, bl->initial_value))
{
- increment = biv_total_increment (bl, loop_start, loop_end);
+ increment = biv_total_increment (bl);
- if (increment && invariant_p (increment))
+ 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
}
/* Check to see if the biv is dead at all loop exits. */
- if (reg_dead_after_loop (bl->biv->src_reg, loop_start, loop_end))
+ if (reg_dead_after_loop (loop, bl->biv->src_reg))
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
the end of the loop. If we can do it, return that value. */
rtx
-final_giv_value (v, loop_start, loop_end, n_iterations)
+final_giv_value (loop, v)
+ const struct loop *loop;
struct induction *v;
- rtx loop_start, loop_end;
- unsigned HOST_WIDE_INT n_iterations;
{
+ struct loop_ivs *ivs = LOOP_IVS (loop);
struct iv_class *bl;
rtx insn;
rtx increment, tem;
rtx insert_before, seq;
+ rtx loop_end = loop->end;
+ unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
- bl = reg_biv_class[REGNO (v->src_reg)];
+ 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
to be known. */
if (n_iterations != 0
- && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
+ && ! loop->exit_count)
{
/* ?? 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
sure that bl->initial_value is still valid then. It will still
be valid if it is invariant. */
- increment = biv_total_increment (bl, loop_start, loop_end);
+ increment = biv_total_increment (bl);
- if (increment && invariant_p (increment)
- && invariant_p (bl->initial_value))
+ 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 */
insert_before = NEXT_INSN (loop_end);
/* Put the final biv value in tem. */
- tem = gen_reg_rtx (bl->biv->mode);
+ tem = gen_reg_rtx (v->mode);
record_base_value (REGNO (tem), bl->biv->add_val, 0);
- emit_iv_add_mult (increment, GEN_INT (n_iterations),
- bl->initial_value, tem, insert_before);
+ emit_iv_add_mult (extend_value_for_giv (v, increment),
+ GEN_INT (n_iterations),
+ extend_value_for_giv (v, bl->initial_value),
+ tem, insert_before);
/* Subtract off extra increments as we find them. */
for (insn = NEXT_INSN (v->insn); insn != loop_end;
}
/* Now calculate the giv's final value. */
- emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
- insert_before);
+ emit_iv_add_mult (tem, v->mult_val, v->add_val, tem, insert_before);
if (loop_dump_stream)
fprintf (loop_dump_stream,
abort ();
/* Check to see if the biv is dead at all loop exits. */
- if (reg_dead_after_loop (v->dest_reg, loop_start, loop_end))
+ if (reg_dead_after_loop (loop, v->dest_reg))
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
return 0;
}
-
-/* Look back before LOOP_START for then insn that sets REG and return
+/* Look back before LOOP->START for then 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 (loop_start, reg)
- rtx loop_start;
+loop_find_equiv_value (loop, reg)
+ 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))
+ for (insn = PREV_INSN (loop_start); insn; insn = PREV_INSN (insn))
{
if (GET_CODE (insn) == CODE_LABEL)
break;
- else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
- && reg_set_p (reg, insn))
+ 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))
+ && (SET_DEST (set) == reg))
{
rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
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;
}
abort ();
}
-
/* 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. */
return NULL_RTX;
}
-/* Calculate the number of loop iterations. Returns the exact number of loop
- iterations if it can be calculated, otherwise returns zero. */
+/* 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 (loop_start, loop_end, loop_info)
- rtx loop_start, loop_end;
- struct loop_info *loop_info;
+loop_iterations (loop)
+ 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;
int unsigned_p, compare_dir, final_larger;
rtx last_loop_insn;
rtx reg_term;
+ struct iv_class *bl;
loop_info->n_iterations = 0;
loop_info->initial_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);
+ 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
branch, and the insn before tests a register value, make that the
iteration variable. */
- comparison = get_condition_for_loop (last_loop_insn);
+ comparison = get_condition_for_loop (loop, last_loop_insn);
if (comparison == 0)
{
if (loop_dump_stream)
return 0;
}
- /* The only new registers that care created before loop iterations are
- givs made from biv increments, so this should never occur. */
+ /* 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) >= reg_iv_type->num_elements)
+ if ((unsigned) REGNO (iteration_var) >= ivs->n_regs
+ && ! REG_USERVAR_P (iteration_var))
abort ();
- iteration_info (iteration_var, &initial_value, &increment,
- loop_start, loop_end);
+ /* 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;
+ }
+ else 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;
+
+ 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 ();
+
+ 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 occured 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))
+ offset -= INTVAL (biv_inc->add_val);
+ }
+ offset *= INTVAL (v->mult_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)
- /* iteration_info already printed a message. */
return 0;
unsigned_p = 0;
its value from the insns before the start of the loop. */
final_value = comparison_value;
- if (GET_CODE (comparison_value) == REG && invariant_p (comparison_value))
+ if (GET_CODE (comparison_value) == REG
+ && loop_invariant_p (loop, comparison_value))
{
- final_value = loop_find_equiv_value (loop_start, 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 (!invariant_p (final_value))
+ if (! loop_invariant_p (loop, final_value))
final_value = comparison_value;
}
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
/* Find what reg1 is equivalent to. Hopefully it will
either be reg2 or reg2 plus a constant. */
- temp = loop_find_equiv_value (loop_start, reg1);
+ temp = loop_find_equiv_value (loop, reg1);
+
if (find_common_reg_term (temp, reg2))
initial_value = temp;
else
/* 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_start, reg2);
+ temp = loop_find_equiv_value (loop, reg2);
+
if (temp == loop_info->iteration_var)
temp = initial_value;
if (temp == reg1)
? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
}
}
- else if (loop_info->vtop && GET_CODE (reg2) == CONST_INT)
+ else if (loop->vtop && GET_CODE (reg2) == CONST_INT)
{
rtx temp;
- /* When running the loop optimizer twice, check_dbra_loop
- further obfuscates reversible loops of the form:
- for (i = init; i < init + const; i++). We often end up with
- final_value = 0, initial_value = temp, temp = temp2 - init,
- where temp2 = init + const. If the loop has a vtop we
- can replace initial_value with const. */
+ /* When running the loop optimizer twice, check_dbra_loop
+ further obfuscates reversible loops of the form:
+ for (i = init; i < init + const; i++). We often end up with
+ final_value = 0, initial_value = temp, temp = temp2 - init,
+ where temp2 = init + const. If the loop has a vtop we
+ can replace initial_value with const. */
+
+ temp = loop_find_equiv_value (loop, reg1);
- temp = loop_find_equiv_value (loop_start, reg1);
if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
{
- rtx temp2 = loop_find_equiv_value (loop_start, XEXP (temp, 0));
+ rtx temp2 = loop_find_equiv_value (loop, XEXP (temp, 0));
+
if (GET_CODE (temp2) == PLUS
&& XEXP (temp2, 0) == XEXP (temp, 1))
initial_value = XEXP (temp2, 1);
??? Without a vtop we could still perform the optimization if we check
the initial and final values carefully. */
- if (loop_info->vtop
+ if (loop->vtop
&& (reg_term = find_common_reg_term (initial_value, final_value)))
{
initial_value = subtract_reg_term (initial_value, reg_term);
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;
+ loop_info->final_equiv_value = loop_info->final_value = 0;
if (increment == 0)
{
/* ??? 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 (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
- increment = loop_find_equiv_value (loop_start, increment);
+ increment = loop_find_equiv_value (loop, increment);
if (GET_CODE (increment) != CONST_INT)
{
else if (comparison_code == EQ)
{
if (loop_dump_stream)
- fprintf (loop_dump_stream,
- "Loop iterations: EQ comparison loop.\n");
+ fprintf (loop_dump_stream, "Loop iterations: EQ comparison loop.\n");
return 0;
}
else if (GET_CODE (final_value) != CONST_INT)
else
{
if (loop_dump_stream)
- fprintf (loop_dump_stream,
- "Loop iterations: Not normal loop.\n");
+ fprintf (loop_dump_stream, "Loop iterations: Not normal loop.\n");
return 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 (x)
+remap_split_bivs (loop, x)
+ struct loop *loop;
rtx x;
{
+ struct loop_ivs *ivs = LOOP_IVS (loop);
register enum rtx_code code;
register int i;
register const char *fmt;
/* If non-reduced/final-value givs were split, then this would also
have to remap those givs also. */
#endif
- if (REGNO (x) < max_reg_before_loop
- && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
- return reg_biv_class[REGNO (x)]->biv->src_reg;
+ 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:
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
if (fmt[i] == 'e')
- XEXP (x, i) = remap_split_bivs (XEXP (x, i));
- if (fmt[i] == 'E')
+ XEXP (x, i) = remap_split_bivs (loop, XEXP (x, i));
+ else if (fmt[i] == 'E')
{
register int j;
for (j = 0; j < XVECLEN (x, i); j++)
- XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
+ XVECEXP (x, i, j) = remap_split_bivs (loop, XVECEXP (x, i, j));
}
}
return x;
while (INSN_UID (p) != first_uid)
{
if (GET_CODE (p) == JUMP_INSN)
- passed_jump= 1;
+ passed_jump = 1;
/* Could not find FIRST_UID. */
if (p == copy_end)
return 0;
}
/* Verify that FIRST_UID is an insn that entirely sets REGNO. */
- if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
- || ! dead_or_set_regno_p (p, regno))
+ if (! INSN_P (p) || ! dead_or_set_regno_p (p, regno))
return 0;
/* FIRST_UID is always executed. */
/* FIRST_UID is always executed if LAST_UID is executed. */
return 1;
}
+
+/* This routine is called when the number of iterations for the unrolled
+ loop is one. The goal is to identify a loop that begins with an
+ unconditional branch to the loop continuation note (or a label just after).
+ In this case, the unconditional branch that starts the loop needs to be
+ deleted so that we execute the single iteration. */
+
+static rtx
+ujump_to_loop_cont (loop_start, loop_cont)
+ rtx loop_start;
+ rtx loop_cont;
+{
+ rtx x, label, label_ref;
+
+ /* See if loop start, or the next insn is an unconditional jump. */
+ loop_start = next_nonnote_insn (loop_start);
+
+ x = pc_set (loop_start);
+ if (!x)
+ return NULL_RTX;
+
+ label_ref = SET_SRC (x);
+ if (!label_ref)
+ return NULL_RTX;
+
+ /* Examine insn after loop continuation note. Return if not a label. */
+ label = next_nonnote_insn (loop_cont);
+ if (label == 0 || GET_CODE (label) != CODE_LABEL)
+ return NULL_RTX;
+
+ /* Return the loop start if the branch label matches the code label. */
+ if (CODE_LABEL_NUMBER (label) == CODE_LABEL_NUMBER (XEXP (label_ref, 0)))
+ return loop_start;
+ else
+ return NULL_RTX;
+}
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