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[Bug tree-optimization/36038] New: miscompiled loop in perlbmk for -Os
- From: "janis at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 24 Apr 2008 17:52:51 -0000
- Subject: [Bug tree-optimization/36038] New: miscompiled loop in perlbmk for -Os
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
Test 253.perlbmk from SPEC CPU2000 gets wrong answers with current trunk on
powerpc64-unknown-linux-gnu when compiled with "-m64 -Os" due to wrong code
generated for this loop:
while (--count)
*dst-- = *src--;
where dst and src are of type "struct sv **". I'll attach a simplified
testcase
in which dst and src are of type "long long *".
The failure begins with this patch:
http://gcc.gnu.org/viewcvs?view=rev&rev=133102
r133102 | rguenth | 2008-03-11 09:36:51 +0000 (Tue, 11 Mar 2008)
--
Summary: miscompiled loop in perlbmk for -Os
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: janis at gcc dot gnu dot org
GCC target triplet: powerpc64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36038