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* [gcc r14-1939] tree-optimization/110298 - CFG cleanup and stale nb_iterations
@ 2023-06-19 11:02 Richard Biener
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From: Richard Biener @ 2023-06-19 11:02 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:916add3bf6e46467e4391e358b11ecfbc4daa275
commit r14-1939-g916add3bf6e46467e4391e358b11ecfbc4daa275
Author: Richard Biener <rguenther@suse.de>
Date: Mon Jun 19 09:52:45 2023 +0200
tree-optimization/110298 - CFG cleanup and stale nb_iterations
When unrolling we eventually kill nb_iterations info since it may
refer to removed SSA names. But we do this only after cleaning
up the CFG which in turn can end up accessing it. Fixed by
swapping the two.
PR tree-optimization/110298
* tree-ssa-loop-ivcanon.cc (tree_unroll_loops_completely):
Clear number of iterations info before cleaning up the CFG.
* gcc.dg/torture/pr110298.c: New testcase.
Diff:
---
gcc/testsuite/gcc.dg/torture/pr110298.c | 20 ++++++++++++++++++++
gcc/tree-ssa-loop-ivcanon.cc | 7 ++++---
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/torture/pr110298.c b/gcc/testsuite/gcc.dg/torture/pr110298.c
new file mode 100644
index 00000000000..139f5c77d89
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr110298.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+
+int a, b, c, d, e;
+int f() {
+ c = 0;
+ for (; c >= 0; c--) {
+ d = 0;
+ for (; d <= 0; d++) {
+ e = 0;
+ for (; d + c + e >= 0; e--)
+ ;
+ a = 1;
+ b = 0;
+ for (; a; ++b)
+ a *= 2;
+ for (; b + d >= 0;)
+ return 0;
+ }
+ }
+}
diff --git a/gcc/tree-ssa-loop-ivcanon.cc b/gcc/tree-ssa-loop-ivcanon.cc
index 6a962a9f503..491b57ec0f1 100644
--- a/gcc/tree-ssa-loop-ivcanon.cc
+++ b/gcc/tree-ssa-loop-ivcanon.cc
@@ -1520,15 +1520,16 @@ tree_unroll_loops_completely (bool may_increase_size, bool unroll_outer)
}
BITMAP_FREE (fathers);
+ /* Clean up the information about numbers of iterations, since
+ complete unrolling might have invalidated it. */
+ scev_reset ();
+
/* This will take care of removing completely unrolled loops
from the loop structures so we can continue unrolling now
innermost loops. */
if (cleanup_tree_cfg ())
update_ssa (TODO_update_ssa_only_virtuals);
- /* Clean up the information about numbers of iterations, since
- complete unrolling might have invalidated it. */
- scev_reset ();
if (flag_checking && loops_state_satisfies_p (LOOP_CLOSED_SSA))
verify_loop_closed_ssa (true);
}
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