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[Bug target/52670] New: -mabi=ms generates bad code
- From: "dg at cowlark dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 22 Mar 2012 15:45:22 +0000
- Subject: [Bug target/52670] New: -mabi=ms generates bad code
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52670
Bug #: 52670
Summary: -mabi=ms generates bad code
Classification: Unclassified
Product: gcc
Version: 4.6.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: dg@cowlark.com
If I take this test case:
int z(int i) { return i; }
...and compile it with:
gcc-4.6 -Os -m32 -mabi=sysv -o test.s -c test.c -S -fomit-frame-pointer
...I get this (trimmed):
movl 4(%esp), %eax
ret
However, if I compile it with this:
gcc-4.6 -Os -m32 -mabi=ms -o test.s -c test.c -S -fomit-frame-pointer
...then I get this, which is wrong:
movl 36(%esp), %eax
ret
Compiling with a copy of the Mingw compiler or with Visual C produces (the
equivalent of) the 4 result. The -fomit-frame-pointer is there purely to reduce
the size of the output; the bug persists without it. This appears to affect all
stack accesses. It *seems* to only apply to ia32 code. amd64 code appears to be
fine, but my target environment is ia32 only so I haven't looked into amd64
much.
This was discussed on gcc-help here:
http://gcc.gnu.org/ml/gcc-help/2012-03/msg00281.html
This patch appears to fix the issue:
http://gcc.gnu.org/ml/gcc-patches/2011-03/txt00118.txt
(although the patch needs a bit of work to apply).