[clang] [CIR] Add support for constructor aliases (PR #145792)

[Andy Kaylor via cfe-commits]

================
@@ -888,6 +888,69 @@ void CIRGenModule::updateCompletedType(const TagDecl *td) {
   genTypes.updateCompletedType(td);
 }
 
+void CIRGenModule::addReplacement(StringRef name, mlir::Operation *op) {
+  replacements[name] = op;
+}
+
+void CIRGenModule::replacePointerTypeArgs(cir::FuncOp oldF, cir::FuncOp newF) {
+  std::optional<mlir::SymbolTable::UseRange> optionalUseRange =
+      oldF.getSymbolUses(theModule);
+  if (!optionalUseRange)
+    return;
+
+  for (const mlir::SymbolTable::SymbolUse &u : *optionalUseRange) {
+    // CallTryOp only shows up after FlattenCFG.
+    auto call = mlir::dyn_cast<cir::CallOp>(u.getUser());
+    if (!call)
+      continue;
+
+    mlir::OperandRange argOps = call.getArgs();
+    mlir::ArrayRef<mlir::Type> funcArgTypes =
+        newF.getFunctionType().getInputs();
+    // In the case of variadic functions, the call may have more arguments that
+    // the function type, so we can't use llvm::enumerate here.
----------------
andykaylor wrote:

In the full implementation from the incubator, the index is needed to replace the call arg with a bitcast if one is needed. However, I've convinced myself that we never hit the bitcast case, so I guess as long as this is just a check of that assumption, I can use llvm::zip.

https://github.com/llvm/llvm-project/pull/145792