llvm / llvm/llvm-project

[VFABI][X86] -fveclib may select calls not supported by -march

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#162,239 2 comments 0 reactions 0 assignees View on GitHub
backend:X86 vectorizers
Dominant language
LLVM
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Description

https://godbolt.org/z/E1a7Y8PEK

Even if AVX2 is unavailable, LLVM will generate a call to _ZGVd(AVX2).

Contributor guide

Open the contributing guide

Research direction

Start with the Godbolt reproduction linked in the issue and inspect how -fveclib selects vector-function calls when -march lacks AVX2. Reproduce the unsupported _ZGVd(AVX2) call, then trace the compiler's vector ABI selection; done means unsupported calls are no longer generated.

Written by the indexing model from the issue text.

Assessment

Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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