[llvm] [X86] Prefer `lock or` over mfence (PR #106555)

[Simon Pilgrim via llvm-commits]

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@@ -1,6 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc < %s -mtriple=i386-unknown-unknown -mattr=+sse2 | FileCheck %s --check-prefix=X32
 ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=-sse2 | FileCheck %s --check-prefix=X64
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=-sse2,+avoid-mfence | FileCheck %s --check-prefix=X64-MFENCE
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RKSimon wrote:

X64-MFENCE -> X64-NO-MFENCE ?

https://github.com/llvm/llvm-project/pull/106555