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

[Eli Friedman via cfe-commits]

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@@ -5348,18 +5348,8 @@ Value *ScalarExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
     return llvm::UndefValue::get(ArgTy);
   }
 
-  // FIXME Volatility.
-  llvm::Value *Val = Builder.CreateLoad(ArgPtr);
-
-  // If EmitVAArg promoted the type, we must truncate it.
-  if (ArgTy != Val->getType()) {
-    if (ArgTy->isPointerTy() && !Val->getType()->isPointerTy())
-      Val = Builder.CreateIntToPtr(Val, ArgTy);
-    else
-      Val = Builder.CreateTrunc(Val, ArgTy);
-  }
-
-  return Val;
+  return CGF.EmitLoadOfScalar(ArgPtr, Ty.isVolatileQualified(), Ty,
+                              VE->getExprLoc());
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efriedma-quic wrote:

> That seems like it'd be wrong on big-endian targets if the variadic argument was promoted.

I don't think we actually depend on this behavior anymore; we either adjust the pointer to point to the correct bytes, or store the value in a temporary.

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