[clang] [CIR] Realign CIR-to-LLVM IR lowering code with incubator (PR #129293)

[Andy Kaylor via cfe-commits]

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@@ -218,12 +221,31 @@ mlir::LogicalResult CIRToLLVMGlobalOpLowering::matchAndRewrite(
   SmallVector<mlir::NamedAttribute> attributes;
 
   if (init.has_value()) {
-    GlobalInitAttrRewriter initRewriter(llvmType, rewriter);
-    init = initRewriter.rewriteInitAttr(init.value());
-    // If initRewriter returned a null attribute, init will have a value but
-    // the value will be null. If that happens, initRewriter didn't handle the
-    // attribute type. It probably needs to be added to GlobalInitAttrRewriter.
-    if (!init.value()) {
+    if (mlir::isa<cir::FPAttr, cir::IntAttr>(init.value())) {
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andykaylor wrote:

The incubator only has three types that get handled here, but it does look a bit cleaner with these being handled separately. There is a possibility that the `if` above could get out of sync with the types handled in `GlobalInitAttrRewriter` but that would trigger the error below, so we'd catch it in development.

https://github.com/llvm/llvm-project/pull/129293