[clang] [Clang] Fix incorrect type for `__mfp8` in `extractelement` codegen (PR #192977)

[Momchil Velikov via cfe-commits]

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@@ -2213,7 +2213,14 @@ Value *ScalarExprEmitter::VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
   if (CGF.SanOpts.has(SanitizerKind::ArrayBounds))
     CGF.EmitBoundsCheck(E, E->getBase(), Idx, IdxTy, /*Accessed*/true);
 
-  return Builder.CreateExtractElement(Base, Idx, "vecext");
+  Value *Ret = Builder.CreateExtractElement(Base, Idx, "vecext");
+
+  // Even being a scalar the `__mfp8` type corresponds to `<1 x i8>` in LLVM IR.
+  // Cast the extracted element to the vector type to keep it consistent in
+  // Clang.
+  if (E->getType()->isMFloat8Type())
+    Ret = Builder.CreateBitCast(Ret, ConvertType(E->getType()), "mfp8ext");
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momchil-velikov wrote:

Seem `insertelement` is the most sensible op to emit and it will either be left intact by `instcombine` or changed to a `shufflevector` if the index is a constant.

https://github.com/llvm/llvm-project/pull/192977