Your message dated Thu, 01 Apr 2010 02:06:58 +0200
with message-id <4bb3e3a2.40...@debian.org>
and subject line Re: Bug#576111: gcc-4.4 miscompiles __builtin_expect in -O0
has caused the Debian Bug report #576111,
regarding gcc-4.4 miscompiles __builtin_expect in -O0
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
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--
576111: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=576111
Debian Bug Tracking System
Contact ow...@bugs.debian.org with problems
--- Begin Message ---
Package: gcc-4.4
Version: 4.4.3-4
Severity: grave
Since gcc-4.4 version 4.4.3-4 (and yes -5 is still affected), gcc miscompiles
__builtin_expect when no optimization is set (at least).
Test case:
int foo(int t) {
if (__builtin_expect(t & 0x100, 0))
return 0;
return 1;
}
Bad assembly:
gcc -O0 -S -o /dev/stdout a.c
.file "a.c"
.text
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
movq %rsp, %rbp
.cfi_offset 6, -16
.cfi_def_cfa_register 6
movl %edi, -4(%rbp)
movl -4(%rbp), %eax
cltq
andl $256, %eax
movzbl %al, %eax <---------------------
testq %rax, %rax
je .L2
movl $0, %eax
jmp .L3
.L2:
movl $1, %eax
.L3:
leave
ret
.cfi_endproc
.LFE0:
.size foo, .-foo
.ident "GCC: (Debian 4.4.3-5) 4.4.3"
.section .note.GNU-stack,"",@progbits
The buggy line is marked with the arrow.
gcc-4.4 version 4.4.3-3 is correct and doesn't perform the buggy movzbl.
--- End Message ---
--- Begin Message ---
Version: 4.4.3-6
I realize that this version is not yet in unstable (uploaded, but ftp-master
problems). You may want to recheck with the current version in Ubuntu lucid for now.
--- End Message ---
