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From: | Richard Henderson |
Subject: | Re: [Qemu-devel] possible qemu miscompilation by latest gcc |
Date: | Thu, 21 Jan 2010 08:57:32 -0800 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Thunderbird/3.0 |
On 01/20/2010 10:15 PM, John Regehr wrote:
Hi folks- Just wanted to let you know that perhaps the function helper_neon_rshl_s8() is being miscompiled by the latest gcc. I'm using qemu 0.12.2 and gcc rev 156103, which is a pre-version of gcc 4.5. This is on an x86 machine running Ubuntu 9.10. At -O2 or higher this is the resulting object code: 00002060 <helper_neon_rshl_s8>: 2060: 31 c0 xor %eax,%eax 2062: c3 ret If this is not the intended result, then either the function has a latent bug or else the compiler is doing something bad.
Confirmed. The compiler is at fault. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42833 r~
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