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* [gcc r12-4627] tree-optimization/102893 - properly DCE empty loops inside infinite loops
@ 2021-10-22 11:43 Richard Biener
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From: Richard Biener @ 2021-10-22 11:43 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:c2a9a98a369528c8689ecb68db576f8e7dc2fa45
commit r12-4627-gc2a9a98a369528c8689ecb68db576f8e7dc2fa45
Author: Richard Biener <rguenther@suse.de>
Date: Fri Oct 22 12:45:32 2021 +0200
tree-optimization/102893 - properly DCE empty loops inside infinite loops
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.
Diff:
---
gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-9.c | 10 ++++++++++
gcc/tree-ssa-dce.c | 2 +-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-9.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-9.c
new file mode 100644
index 00000000000..e1ffa7f038d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dce-9.c
@@ -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" } } */
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index c4907af923c..372e0691ae6 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -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",
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