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authorrakdver <rakdver@138bc75d-0d04-0410-961f-82ee72b054a4>2004-10-07 06:20:34 +0000
committerrakdver <rakdver@138bc75d-0d04-0410-961f-82ee72b054a4>2004-10-07 06:20:34 +0000
commitcde5a3a06903346ad26d866abb2d57c0bd7fd077 (patch)
treeefc9e42c4cc8b306c06213b3eb2b7863c35140d8 /gcc/loop-doloop.c
parentafd309ebbf8eb2f1e258faaf54f55f0f06f0f7dd (diff)
downloadgcc-cde5a3a06903346ad26d866abb2d57c0bd7fd077.tar.gz
PR rtl-optimization/17791
* loop-doloop.c (doloop_modify): Take number of iterations as argument. (doloop_optimize): Extend or shorten the number of iterations when changing mode of counter register. * loop-iv.c (lowpart_subreg): Export. * rtl.h (lowpart_subreg): Declare. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@88668 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc/loop-doloop.c')
-rw-r--r--gcc/loop-doloop.c47
1 files changed, 38 insertions, 9 deletions
diff --git a/gcc/loop-doloop.c b/gcc/loop-doloop.c
index 1b5ca4dc6d2..1e56eb5cebe 100644
--- a/gcc/loop-doloop.c
+++ b/gcc/loop-doloop.c
@@ -257,20 +257,21 @@ add_test (rtx cond, basic_block bb, basic_block dest)
describes the loop, DESC describes the number of iterations of the
loop, and DOLOOP_INSN is the low-overhead looping insn to emit at the
end of the loop. CONDITION is the condition separated from the
- DOLOOP_SEQ. */
+ DOLOOP_SEQ. COUNT is the number of iterations of the LOOP. */
static void
doloop_modify (struct loop *loop, struct niter_desc *desc,
- rtx doloop_seq, rtx condition)
+ rtx doloop_seq, rtx condition, rtx count)
{
rtx counter_reg;
- rtx count, tmp, noloop = NULL_RTX;
+ rtx tmp, noloop = NULL_RTX;
rtx sequence;
rtx jump_insn;
rtx jump_label;
int nonneg = 0, irr;
bool increment_count;
basic_block loop_end = desc->out_edge->src;
+ enum machine_mode mode;
jump_insn = BB_END (loop_end);
@@ -291,8 +292,8 @@ doloop_modify (struct loop *loop, struct niter_desc *desc,
counter_reg = XEXP (condition, 0);
if (GET_CODE (counter_reg) == PLUS)
counter_reg = XEXP (counter_reg, 0);
+ mode = GET_MODE (counter_reg);
- count = copy_rtx (desc->niter_expr);
increment_count = false;
switch (GET_CODE (condition))
{
@@ -323,7 +324,7 @@ doloop_modify (struct loop *loop, struct niter_desc *desc,
Note that the maximum value loaded is iterations_max - 1. */
if (desc->niter_max
<= ((unsigned HOST_WIDEST_INT) 1
- << (GET_MODE_BITSIZE (GET_MODE (counter_reg)) - 1)))
+ << (GET_MODE_BITSIZE (mode) - 1)))
nonneg = 1;
break;
@@ -333,7 +334,7 @@ doloop_modify (struct loop *loop, struct niter_desc *desc,
}
if (increment_count)
- count = simplify_gen_binary (PLUS, desc->mode, count, const1_rtx);
+ count = simplify_gen_binary (PLUS, mode, count, const1_rtx);
/* Insert initialization of the count register into the loop header. */
start_sequence ();
@@ -438,12 +439,14 @@ doloop_optimize (struct loop *loop)
{
enum machine_mode mode;
rtx doloop_seq, doloop_pat, doloop_reg;
- rtx iterations;
+ rtx iterations, count;
rtx iterations_max;
rtx start_label;
rtx condition;
unsigned level, est_niter;
struct niter_desc *desc;
+ unsigned word_mode_size;
+ unsigned HOST_WIDE_INT word_mode_max;
if (dump_file)
fprintf (dump_file, "Doloop: Processing loop %d.\n", loop->num);
@@ -481,6 +484,7 @@ doloop_optimize (struct loop *loop)
return false;
}
+ count = copy_rtx (desc->niter_expr);
iterations = desc->const_iter ? desc->niter_expr : const0_rtx;
iterations_max = GEN_INT (desc->niter_max);
level = get_loop_level (loop) + 1;
@@ -492,8 +496,33 @@ doloop_optimize (struct loop *loop)
doloop_reg = gen_reg_rtx (mode);
doloop_seq = gen_doloop_end (doloop_reg, iterations, iterations_max,
GEN_INT (level), start_label);
- if (! doloop_seq && mode != word_mode)
+
+ word_mode_size = GET_MODE_BITSIZE (word_mode);
+ word_mode_max
+ = ((unsigned HOST_WIDE_INT) 1 << (word_mode_size - 1) << 1) - 1;
+ if (! doloop_seq
+ && mode != word_mode
+ /* Before trying mode different from the one in that # of iterations is
+ computed, we must be sure that the number of iterations fits into
+ the new mode. */
+ && (word_mode_size >= GET_MODE_BITSIZE (mode)
+ || desc->niter_max <= word_mode_max))
{
+ if (word_mode_size > GET_MODE_BITSIZE (mode))
+ {
+ count = simplify_gen_unary (ZERO_EXTEND, word_mode,
+ iterations, mode);
+ iterations = simplify_gen_unary (ZERO_EXTEND, word_mode,
+ iterations, mode);
+ iterations_max = simplify_gen_unary (ZERO_EXTEND, word_mode,
+ iterations_max, mode);
+ }
+ else
+ {
+ count = lowpart_subreg (word_mode, count, mode);
+ iterations = lowpart_subreg (word_mode, iterations, mode);
+ iterations_max = lowpart_subreg (word_mode, iterations_max, mode);
+ }
PUT_MODE (doloop_reg, word_mode);
doloop_seq = gen_doloop_end (doloop_reg, iterations, iterations_max,
GEN_INT (level), start_label);
@@ -528,7 +557,7 @@ doloop_optimize (struct loop *loop)
return false;
}
- doloop_modify (loop, desc, doloop_seq, condition);
+ doloop_modify (loop, desc, doloop_seq, condition, count);
return true;
}