[llvm] [X86] Fold atomic loads into compares (PR #221290)

[Simon Pilgrim via llvm-commits]

================
@@ -0,0 +1,212 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
----------------
RKSimon wrote:

Please can you add 32-bit test coverage as well:
```
; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s --check-prefixes=CHECK,X64
; RUN: llc < %s -mtriple=i686-unknown-linux-gnu | FileCheck %s --check-prefixes=CHECK,X86
```
(You might need to drop CHECK if there's no matches)

https://github.com/llvm/llvm-project/pull/221290