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Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations.
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From: |
Richard Henderson |
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Subject: |
Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations. |
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Date: |
Thu, 26 May 2011 06:56:56 -0700 |
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User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc15 Thunderbird/3.1.10 |
On 05/26/2011 05:36 AM, Kirill Batuzov wrote:
>> x = (int32_t)x >> (int32_t)y;
>>
> This expression has an implementation-defined behavior accroding to
> C99 6.5.7 so we decided to emulate signed shifts by hand.
Technically, yes. In practice, no. GCC, ICC, LLVM, MSVC all know
what the user wants here and will implement it "properly".
r~
- [Qemu-devel] [PATCH 0/6] Implement constant folding and copy propagation in TCG, Kirill Batuzov, 2011/05/20
- [Qemu-devel] [PATCH 1/6] Add TCG optimizations stub, Kirill Batuzov, 2011/05/20
- [Qemu-devel] [PATCH 6/6] Do constant folding for unary operations., Kirill Batuzov, 2011/05/20
- [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Kirill Batuzov, 2011/05/20
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Richard Henderson, 2011/05/20
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Kirill Batuzov, 2011/05/26
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations.,
Richard Henderson <=
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Blue Swirl, 2011/05/26
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Richard Henderson, 2011/05/26
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Blue Swirl, 2011/05/26
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Richard Henderson, 2011/05/26
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Jamie Lokier, 2011/05/27
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Blue Swirl, 2011/05/27
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Richard Henderson, 2011/05/27
- Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations., Paolo Bonzini, 2011/05/27
[Qemu-devel] [PATCH 2/6] Add copy and constant propagation., Kirill Batuzov, 2011/05/20