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tree-optimization/102893 - properly DCE empty loops inside infinite loops

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The following fixes the test for an exit edge I put in place for
the fix for PR45178 where I somehow misunderstood how the cyclic
list works.

2021-10-22  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/102893
	* tree-ssa-dce.c (find_obviously_necessary_stmts): Fix the
	test for an exit edge.

	* gcc.dg/tree-ssa/ssa-dce-9.c: New testcase.
This commit is contained in:
Richard Biener 2021-10-22 12:45:32 +02:00
parent 8a0faddadd
commit c2a9a98a36
2 changed files with 11 additions and 1 deletions
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10
gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-9.c Normal file
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@ -0,0 +1,10 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-cddce1" } */
int main()
{
while(1)
for(int i=0; i<9000000; i++){}
}
/* { dg-final { scan-tree-dump-not "if" "cddce1" } } */

2
gcc/tree-ssa-dce.c
View file

@ -436,7 +436,7 @@ find_obviously_necessary_stmts (bool aggressive)
for (auto loop : loops_list (cfun, 0))
/* For loops without an exit do not mark any condition. */
if (loop->exits->next && !finite_loop_p (loop))
if (loop->exits->next->e && !finite_loop_p (loop))
{
if (dump_file)
fprintf (dump_file, "cannot prove finiteness of loop %i\n",