[clang] [CIR] Implement 'simple' atomic inc/dec. (PR #222730)

[Andy Kaylor via cfe-commits]

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@@ -628,10 +628,88 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
     mlir::Value value;
     mlir::Value input;
 
-    if (type->getAs<AtomicType>()) {
+    if (const AtomicType *atomicTy = type->getAs<AtomicType>()) {
+      QualType valType = atomicTy->getValueType();
+      mlir::Location loc = cgf.getLoc(e->getSourceRange());
+      bool isInc = e->isIncrementOp();
+      bool isPre = e->isPrefix();
+
+      // Bools are always set-to-true, as decrement isn't legal on bools.
+      if (valType->isBooleanType()) {
+        assert(isInc);
+        // Atomic operations require an integer type; reinterpret the bool
+        // pointer as a pointer to its underlying storage integer type.
+        cir::IntType intTy = builder.getUInt8Ty();
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andykaylor wrote:

Classic codegen seems to be using `EmitToMemory` to get this type. I know we defer any conversion to memory for boolean types, but is there some other mechanism we should be using (or introducing) to get this from a central source of truth? Will we need to get the memory type for atomic bools in other places?

https://github.com/llvm/llvm-project/pull/222730