[llvm] [SPIRV] Audit `select` Result in SPIRVInstructionSelector (PR #115193)

[Greg Roth via llvm-commits]

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@@ -1229,17 +1244,26 @@ bool SPIRVInstructionSelector::selectAtomicCmpXchg(Register ResVReg,
     const MachineMemOperand *MemOp = *I.memoperands_begin();
     unsigned Scope = static_cast<uint32_t>(getMemScope(
         GR.CurMF->getFunction().getContext(), MemOp->getSyncScopeID()));
-    ScopeReg = buildI32Constant(Scope, I);
+    auto ScopeConstant = buildI32Constant(Scope, I);
+    ScopeReg = ScopeConstant.first;
+    Result &= ScopeConstant.second;
 
     unsigned ScSem = static_cast<uint32_t>(
         getMemSemanticsForStorageClass(GR.getPointerStorageClass(Ptr)));
     AtomicOrdering AO = MemOp->getSuccessOrdering();
     unsigned MemSemEq = static_cast<uint32_t>(getMemSemantics(AO)) | ScSem;
-    MemSemEqReg = buildI32Constant(MemSemEq, I);
+    auto MemSemEqConstant = buildI32Constant(MemSemEq, I);
+    MemSemEqReg = MemSemEqConstant.first;
+    Result &= MemSemEqConstant.second;
     AtomicOrdering FO = MemOp->getFailureOrdering();
     unsigned MemSemNeq = static_cast<uint32_t>(getMemSemantics(FO)) | ScSem;
-    MemSemNeqReg =
-        MemSemEq == MemSemNeq ? MemSemEqReg : buildI32Constant(MemSemNeq, I);
+    if (MemSemEq == MemSemNeq)
+      MemSemNeqReg = MemSemEqReg;
+    else {
+      auto MemSemNeqConstant = buildI32Constant(MemSemEq, I);
+      MemSemNeqReg = MemSemNeqConstant.first;
+      Result &= MemSemNeqConstant.second;
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pow2clk wrote:

I'm not going to insist on it, but just FYI, you could have made `buildI32Constant` return `Register()` in the failing case, which could be identified by checking `Register.isValid()` rather than returning an additional bool. It might have made this a little more elegant, but I'm not sure about that and it's entirely a non-functional change, so I'll happily defer to the implementer here.

https://github.com/llvm/llvm-project/pull/115193