https://bugs.llvm.org/show_bug.cgi?id=51371
Bug ID: 51371
Summary: X86 SSE4.1 instruction problem
Product: clang
Version: 7.0
Hardware: PC
OS: MacOS X
Status: NEW
Severity: enhancement
Priority: P
Component: C
Assignee: unassignedclangb...@nondot.org
Reporter: oucwangshi...@163.com
CC: blitzrak...@gmail.com, dgre...@apple.com,
erik.pilking...@gmail.com, llvm-bugs@lists.llvm.org,
richard-l...@metafoo.co.uk
Hi,
I was build SSE performance work on mac intel. But I found the performance of
my SSE4.1 version code using in xcode 12.4 is not as good as xcode 10.1, so I
checked the assembly of my code. The one _mm_mul_epi() instruction was
translated into three pmuludq, which is the SSE2 instruction, while this was
normal when compiling on xcode 10.1 and _mm_mul_epi() was translated into
pmuldq. So I checked the clang version, and I found this error occured when
clang version larger than 7.0.0.
The simple case can be found: https://godbolt.org/z/Tf7qeocvz
I probably think this is a clang compiler bug. And I hope to get some advice
on how to solve this issue.
Thanks.
Best,
Wade
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