[clang] [clang] Lower _BitInt(129+) to a different type in LLVM IR (PR #91364)

[John McCall via cfe-commits]

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@@ -2044,6 +2048,12 @@ llvm::Value *CodeGenFunction::EmitFromMemory(llvm::Value *Value, QualType Ty) {
     return emitBoolVecConversion(V, ValNumElems, "extractvec");
   }
 
+  if (hasBooleanRepresentation(Ty) || Ty->isBitIntType()) {
+    llvm::Type *ResTy = ConvertType(Ty);
+    bool Signed = Ty->isSignedIntegerOrEnumerationType();
+    return Builder.CreateIntCast(Value, ResTy, Signed, "loadedv");
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rjmccall wrote:

This is always a `trunc`, right?  Or do we need use `CreateIntCast` because it might be a trivial truncation?

https://github.com/llvm/llvm-project/pull/91364