[clang] [llvm] CodeGen: Replace TargetOptions::ThreadModel with module flag (PR #223157)

[Nick Desaulniers via cfe-commits]

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@@ -333,7 +335,48 @@ bool AtomicExpandImpl::tryInsertFencesForAtomic(AtomicInst *AtomicI,
   return false;
 }
 
+/// In a single-threaded environment, atomic operations can be lowered to their
+/// non-atomic equivalents: fences are removed, and atomic loads, stores, RMW,
+/// and cmpxchg become plain memory operations.
+bool AtomicExpandImpl::lowerToNonAtomic(Instruction *I) {
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nickdesaulniers wrote:

LowerAtomic as in the `createLowerAtomicPass` call removed from llvm/lib/Target/ARM/ARMTargetMachine.cpp below? Are you planning to delete that pass?

https://github.com/llvm/llvm-project/pull/223157