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Re: Length-Changing Prefixes problem with the x86 Backend
- From: Agner Fog <agner at agner dot org>
- To: Uros Bizjak <ubizjak at gmail dot com>, nadav256 at gmail dot com, gcc at gcc dot gnu dot org
- Date: Fri, 25 Jul 2008 15:11:25 +0200
- Subject: Re: Length-Changing Prefixes problem with the x86 Backend
On Thu, 26 Jun 2008 Uros wrote:
>Please also add a runtime test that can be used to analyze the problem.
I am a temporary guest on the gcc mailing list and I haven't seen your
mail before. In case your problem hasn't been solved yet, I can inform
you that I have a disassembler which puts comments into the disassembly
file in case of length-changing prefixes and other sub-optimal or
illegal instruction codes. Just compile with -c to get an object file
and run it on the disassembler:
objconv -fasm yourfile.o yourfile.asm
It supports all x86 instruction sets up to SSE4.2 and SSE5 (but not AVX
and FMA yet). It may be useful for testing other compiler features as
well, such as support for new instruction sets.
Get it from www.agner.org/optimize/objconv.zip
This is a cross-platform multi-purpose tool. The assembly output is in
MASM format, not AT&T. Use .intel_syntax noprefix in case you want to
assemble the disassembly on GAS.