[clang] [CIR] Upstream basic alloca and load support (PR #128792)

[Andy Kaylor via cfe-commits]

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@@ -75,3 +110,34 @@ mlir::Value CIRGenFunction::emitScalarExpr(const Expr *e) {
 
   return ScalarExprEmitter(*this, builder).Visit(const_cast<Expr *>(e));
 }
+
+// Emit code for an explicit or implicit cast.  Implicit
+// casts have to handle a more broad range of conversions than explicit
+// casts, as they handle things like function to ptr-to-function decay
+// etc.
+mlir::Value ScalarExprEmitter::VisitCastExpr(CastExpr *ce) {
+  Expr *e = ce->getSubExpr();
+  QualType destTy = ce->getType();
+  CastKind kind = ce->getCastKind();
+
+  // Since almost all cast kinds apply to scalars, this switch doesn't have a
+  // default case, so the compiler will warn on a missing case. The cases are
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andykaylor wrote:

Oops. I kept the comment from the original code, which doesn't have a default.

https://github.com/llvm/llvm-project/pull/128792