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* [gcc r12-7243] tree-optimization/104543 - fix unroll-and-jam precondition
@ 2022-02-15 12:22 Richard Biener
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From: Richard Biener @ 2022-02-15 12:22 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:d03a67dc69251dc86c0772a432380a6e9bcb8617
commit r12-7243-gd03a67dc69251dc86c0772a432380a6e9bcb8617
Author: Richard Biener <rguenther@suse.de>
Date: Tue Feb 15 12:27:14 2022 +0100
tree-optimization/104543 - fix unroll-and-jam precondition
We have to make sure that outer loop exits come after the inner
loop since we otherwise will put it into the fused loop body.
2022-02-15 Richard Biener <rguenther@suse.de>
PR tree-optimization/104543
* gimple-loop-jam.cc (unroll_jam_possible_p): Check outer loop exits
come after the inner loop.
* gcc.dg/torture/pr104543.c: New testcase.
Diff:
---
gcc/gimple-loop-jam.cc | 10 ++++++++--
gcc/testsuite/gcc.dg/torture/pr104543.c | 21 +++++++++++++++++++++
2 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/gcc/gimple-loop-jam.cc b/gcc/gimple-loop-jam.cc
index d9a77727665..e33dd9091df 100644
--- a/gcc/gimple-loop-jam.cc
+++ b/gcc/gimple-loop-jam.cc
@@ -198,7 +198,8 @@ unroll_jam_possible_p (class loop *outer, class loop *loop)
if (!empty_block_p (loop->latch))
return false;
- if (!single_exit (loop))
+ edge exit;
+ if (!(exit = single_exit (loop)))
return false;
/* We need a perfect nest. Quick check for adjacent inner loops. */
@@ -259,7 +260,12 @@ unroll_jam_possible_p (class loop *outer, class loop *loop)
n = get_loop_body_with_size (outer, bbs, n_basic_blocks_for_fn (cfun));
for (i = 0; i < n; i++)
- if (bbs[i]->loop_father == outer && bb_prevents_fusion_p (bbs[i]))
+ if (bbs[i]->loop_father == outer
+ && (bb_prevents_fusion_p (bbs[i])
+ /* Outer loop exits must come after the inner loop, otherwise
+ we'll put the outer loop exit into the fused inner loop. */
+ || (loop_exits_from_bb_p (outer, bbs[i])
+ && !dominated_by_p (CDI_DOMINATORS, bbs[i], exit->src))))
break;
free (bbs);
if (i != n)
diff --git a/gcc/testsuite/gcc.dg/torture/pr104543.c b/gcc/testsuite/gcc.dg/torture/pr104543.c
new file mode 100644
index 00000000000..48963514f77
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr104543.c
@@ -0,0 +1,21 @@
+/* { dg-do run } */
+/* { dg-additional-options "-floop-unroll-and-jam" } */
+
+int a[3], b, c;
+static int e()
+{
+ if (!c) {
+ for (b = 0; b < 3; b++)
+ for (c = 0; c < 3; c++)
+ a[c] ^= 1;
+ return -1;
+ }
+ return 0;
+}
+int main()
+{
+ e();
+ if (a[1] != 1)
+ __builtin_abort();
+ return 0;
+}
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