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* [gcc r12-7651] ifcvt: Punt if not onlyjump_p for find_if_case_{1, 2} [PR104814]
@ 2022-03-15 8:14 Jakub Jelinek
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From: Jakub Jelinek @ 2022-03-15 8:14 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:a2645cd8fb33b36d737b310e26f4c47401305c7b
commit r12-7651-ga2645cd8fb33b36d737b310e26f4c47401305c7b
Author: Jakub Jelinek <jakub@redhat.com>
Date: Tue Mar 15 09:12:03 2022 +0100
ifcvt: Punt if not onlyjump_p for find_if_case_{1,2} [PR104814]
find_if_case_{1,2} implicitly assumes conditional jumps and rewrites them,
so if they have extra side-effects or are say asm goto, things don't work
well, either the side-effects are lost or we could ICE.
In particular, the testcase below on s390x has there a doloop instruction
that decrements a register in addition to testing it for non-zero and
conditionally jumping based on that.
The following patch fixes that by punting for !onlyjump_p case, i.e.
if there are side-effects in the jump instruction or it isn't a plain PC
setter.
Also, it assumes BB_END (test_bb) will be always non-NULL, because basic
blocks with 2 non-abnormal successor edges should always have some instruction
at the end that determines which edge to take.
2022-03-15 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/104814
* ifcvt.cc (find_if_case_1, find_if_case_2): Punt if test_bb doesn't
end with onlyjump_p. Assume BB_END (test_bb) is always non-NULL.
* gcc.c-torture/execute/pr104814.c: New test.
Diff:
---
gcc/ifcvt.cc | 14 ++++++++----
gcc/testsuite/gcc.c-torture/execute/pr104814.c | 30 ++++++++++++++++++++++++++
2 files changed, 40 insertions(+), 4 deletions(-)
diff --git a/gcc/ifcvt.cc b/gcc/ifcvt.cc
index 6305621e460..22960a67f89 100644
--- a/gcc/ifcvt.cc
+++ b/gcc/ifcvt.cc
@@ -5251,14 +5251,17 @@ find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
if ((BB_END (then_bb)
&& JUMP_P (BB_END (then_bb))
&& CROSSING_JUMP_P (BB_END (then_bb)))
- || (BB_END (test_bb)
- && JUMP_P (BB_END (test_bb))
+ || (JUMP_P (BB_END (test_bb))
&& CROSSING_JUMP_P (BB_END (test_bb)))
|| (BB_END (else_bb)
&& JUMP_P (BB_END (else_bb))
&& CROSSING_JUMP_P (BB_END (else_bb))))
return FALSE;
+ /* Verify test_bb ends in a conditional jump with no other side-effects. */
+ if (!onlyjump_p (BB_END (test_bb)))
+ return FALSE;
+
/* THEN has one successor. */
if (!single_succ_p (then_bb))
return FALSE;
@@ -5372,14 +5375,17 @@ find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
if ((BB_END (then_bb)
&& JUMP_P (BB_END (then_bb))
&& CROSSING_JUMP_P (BB_END (then_bb)))
- || (BB_END (test_bb)
- && JUMP_P (BB_END (test_bb))
+ || (JUMP_P (BB_END (test_bb))
&& CROSSING_JUMP_P (BB_END (test_bb)))
|| (BB_END (else_bb)
&& JUMP_P (BB_END (else_bb))
&& CROSSING_JUMP_P (BB_END (else_bb))))
return FALSE;
+ /* Verify test_bb ends in a conditional jump with no other side-effects. */
+ if (!onlyjump_p (BB_END (test_bb)))
+ return FALSE;
+
/* ELSE has one successor. */
if (!single_succ_p (else_bb))
return FALSE;
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr104814.c b/gcc/testsuite/gcc.c-torture/execute/pr104814.c
new file mode 100644
index 00000000000..7d4f8ab4b8c
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr104814.c
@@ -0,0 +1,30 @@
+/* PR rtl-optimization/104814 */
+
+short a = 0;
+static long b = 0;
+int c = 7;
+char d = 0;
+short *e = &a;
+long f = 0;
+
+unsigned long
+foo (unsigned long h, long j)
+{
+ return j == 0 ? h : h / j;
+}
+
+int
+main ()
+{
+ long k = f;
+ for (; c; --c)
+ {
+ for (int i = 0; i < 7; ++i)
+ ;
+ long m = foo (f, --b);
+ d = ((char) m | *e) <= 43165;
+ }
+ if (b != -7)
+ __builtin_abort ();
+ return 0;
+}
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