retitle 655468 valgrind doesn't support the AVX instruction set.
severity 655468 wishlist
thanks
On Wed, Jan 11, 2012 at 02:29:25PM +0100, Ondra Lengal wrote:
> Package: valgrind
> Version: 1:3.7.0-1
> Severity: important
>
> Hi,
>
> I have a problem while debugging a GCC-compiled program on my Intel Core
> i7-2600 (Sandy Bridge) with valgrind. Although the program runs and GDB
> does not object as well, when run in valgrind it terminates with the
> "unhandled instruction bytes" message (see the attached report), so
> valgrind (and callgrind, ...) is currently unusable for me. My
> unqualified guess is that there is a problem is with the use of SSE4.2
> instructions.
>
> Do you have any advice how to remove this error?
It's nothing to do with sse4.2.
> vex amd64->IR: unhandled instruction bytes: 0xC5 0xFA 0x10 0x5 0x7E 0x70 0xE
> 0x0
Doing this:
$ cat ~/a.c
int main(void)
{
asm(".byte 0xC5, 0xFA, 0x10, 0x5, 0x7E, 0x70, 0xE, 0x0");
return 0;
}
$ make a
Shows in gdb:
Dump of assembler code for function main:
0x00000000004004d4 <+0>: push %rbp
0x00000000004004d5 <+1>: mov %rsp,%rbp
0x00000000004004d8 <+4>: vmovss 0xe707e(%rip),%xmm0 # 0x4e755e
0x00000000004004e0 <+12>: mov $0x0,%eax
0x00000000004004e5 <+17>: pop %rbp
0x00000000004004e6 <+18>: retq
vmovss is AVX and valgrind doesn't support avx instructions.
Solution: do not generate AVX insns (see gcc doc for that). It's likely that
you're either passing -mavx to your GCC or are optimizing for an AVX
enabled CPU. Just don't, it's not supported and documented.
--
·O· Pierre Habouzit
··O madco...@debian.org
OOO http://www.madism.org
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