[llvm-dev] VMOVNTDQ in LLVM

Stephen Canon via llvm-dev llvm-dev at lists.llvm.org
Thu Sep 28 06:36:01 PDT 2017


This thread from last year has some additional detail regarding the hazards of aggressive MOVNT generation if you’re interested:

http://lists.llvm.org/pipermail/llvm-dev/2016-May/098980.html <http://lists.llvm.org/pipermail/llvm-dev/2016-May/098980.html>

– Steve

> On Sep 28, 2017, at 9:31 AM, Stephen Canon via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> What code did you write where you expected VMOVNTDQ to be generated?
> 
> The x86 MOVNT instructions are something of an attractive nuisance. There are cases where they are beneficial, but those cases are much less common and harder to characterize than you might expect. LLVM is deliberately conservative about using MOVNT (IIRC it’s currently only generated if you explicitly ask for it by using intrinsics).
> 
> – Steve
> 
>> On Sep 28, 2017, at 9:10 AM, hameeza ahmed via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>> 
>> Hello, i am using llvm 4.0 i am generating intel avx code. But in code i dont find VMOVNTDQ instruction. Why is that so? When does this instruction generated?
>> 
>> 
>> Please clarify.
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