public inbox for gcc-cvs@sourceware.org
help / color / mirror / Atom feed
* [gcc r13-670] Fix OMP CAS expansion with separate condition
@ 2022-05-19 14:27 Richard Biener
0 siblings, 0 replies; only message in thread
From: Richard Biener @ 2022-05-19 14:27 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:060173dd73fcaf0767215f9d989ad064e2d5fe2a
commit r13-670-g060173dd73fcaf0767215f9d989ad064e2d5fe2a
Author: Richard Biener <rguenther@suse.de>
Date: Fri May 13 12:07:58 2022 +0200
Fix OMP CAS expansion with separate condition
When forcing the condition to be split out from COND_EXPRs I see
a runtime failure of libgomp.fortran/atomic-19.f90 which can be
reduced to
!$omp atomic update, compare, capture
if (x == 69_2 - r) x = 6_8
v = x
being miscompiled, the difference being
- _13 = .ATOMIC_COMPARE_EXCHANGE (_9, _10, _11, 4, 0, 0);
- _14 = IMAGPART_EXPR <_13>;
- _15 = REALPART_EXPR <_13>;
- _16 = _14 != 0 ? _11 : _15;
- _2 = (integer(kind=4)) _16;
- v_17 = _2;
+ _14 = .ATOMIC_COMPARE_EXCHANGE (_10, _11, _12, 4, 0, 0);
+ _15 = IMAGPART_EXPR <_14>;
+ _16 = REALPART_EXPR <_14>;
+ _2 = (logical(kind=1)) _15;
+ _3 = (integer(kind=4)) _16;
+ v_17 = _3;
where one can see a missing COND_EXPR. It seems to be a latent
issue to me given the code can be exercised, it just maybe misses
a 'need_new' testcase combined with 'cond_stmt'. Appearantly
the if (cond_stmt) code is just to avoid creating a temporary
(and possibly to preserve the condition compute if used elsewhere
since the original stmt is going to be deleted). The following
makes the failure go away for me in my patched tree and it
also survives libgomp and gomp testing in an unpatched tree.
2022-05-13 Richard Biener <rguenther@suse.de>
* omp-expand.cc (expand_omp_atomic_cas): Do not short-cut
computation of the new value.
Diff:
---
gcc/omp-expand.cc | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/gcc/omp-expand.cc b/gcc/omp-expand.cc
index ee708314793..9fcc67a3448 100644
--- a/gcc/omp-expand.cc
+++ b/gcc/omp-expand.cc
@@ -9092,16 +9092,17 @@ expand_omp_atomic_cas (basic_block load_bb, tree addr,
if (cond_stmt)
{
- g = gimple_build_assign (gimple_assign_lhs (cond_stmt),
- NOP_EXPR, im);
+ g = gimple_build_assign (cond, NOP_EXPR, im);
gimple_set_location (g, loc);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
}
- else if (need_new)
+
+ if (need_new)
{
g = gimple_build_assign (create_tmp_reg (itype), COND_EXPR,
- build2 (NE_EXPR, boolean_type_node,
- im, build_zero_cst (itype)),
+ cond_stmt
+ ? cond : build2 (NE_EXPR, boolean_type_node,
+ im, build_zero_cst (itype)),
d, re);
gimple_set_location (g, loc);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2022-05-19 14:27 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-19 14:27 [gcc r13-670] Fix OMP CAS expansion with separate condition Richard Biener
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).