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unroll-1.c: New testcase.

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* gcc.dg/tree-prof/unroll-1.c: New testcase.

	* loop-unroll.c (decide_unroll_constant_iterations): Don't
	perform unrolling for loops with low iterations bounds or estimates.

From-SVN: r192638
This commit is contained in:
Jan Hubicka 2012-10-20 17:51:16 +02:00 • committed by Jan Hubicka
parent bcd8d322db
commit e598c332d8
4 changed files with 42 additions and 2 deletions
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5
gcc/ChangeLog
View file

@ -1,3 +1,8 @@
2012-10-20 Jan Hubicka <jh@suse.cz>
* loop-unroll.c (decide_unroll_constant_iterations): Don't
perform unrolling for loops with low iterations bounds or estimates.
2012-10-20 Jan Hubicka <jh@suse.cz>
* loop-iv.c (iv_number_of_iterations): Record the upper bound

11
gcc/loop-unroll.c
View file

@ -519,6 +519,7 @@ decide_unroll_constant_iterations (struct loop *loop, int flags)
{
unsigned nunroll, nunroll_by_av, best_copies, best_unroll = 0, n_copies, i;
struct niter_desc *desc;
double_int iterations;
if (!(flags & UAP_UNROLL))
{
@ -561,8 +562,14 @@ decide_unroll_constant_iterations (struct loop *loop, int flags)
return;
}
/* Check whether the loop rolls enough to consider. */
if (desc->niter < 2 * nunroll)
/* Check whether the loop rolls enough to consider.
Consult also loop bounds and profile; in the case the loop has more
than one exit it may well loop less than determined maximal number
of iterations. */
if (desc->niter < 2 * nunroll
|| ((estimated_loop_iterations (loop, &iterations)
|| max_loop_iterations (loop, &iterations))
&& iterations.ult (double_int::from_shwi (2 * nunroll))))
{
if (dump_file)
fprintf (dump_file, ";; Not unrolling loop, doesn't roll\n");

4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2012-10-20 Jan Hubicka <jh@suse.cz>
* gcc.dg/tree-prof/unroll-1.c: New testcase.
2012-10-19 Janus Weil <janus@gcc.gnu.org>
PR fortran/54224

24
gcc/testsuite/gcc.dg/tree-prof/unroll-1.c Normal file
View file

@ -0,0 +1,24 @@
/* { dg-options "-O3 -fdump-rtl-loop2_unroll -funroll-loops -fno-peel-loops" } */
void abort ();
int a[1000];
int
__attribute__ ((noinline))
t()
{
int i;
for (i=0;i<1000;i++)
if (!a[i])
return 1;
abort ();
}
main()
{
int i;
for (i=0;i<1000;i++)
t();
return 0;
}
/* { dg-final-use { scan-rtl-dump "Considering unrolling loop with constant number of iterations" "loop2_unroll" } } */
/* { dg-final-use { cleanup-rtl-dump "Not unrolling loop, doesn't roll" } } */
/* { dg-options "-O3 -fdump-rtl-loop2_unroll -funroll-loops -fno-peel-loops" } */