Address review feedback, add alias parsing

Author: andykaylor

clang/lib/CIR/CodeGen/CIRGenModule.cpp

@@ -904,13 +904,9 @@ void CIRGenModule::replacePointerTypeArgs(cir::FuncOp oldF, cir::FuncOp newF) {
     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.
-    for (unsigned i = 0; i < funcArgTypes.size(); i++) {
-      if (argOps[i].getType() == funcArgTypes[i])
+    for (const auto [argOp, fnArgType] :
+         llvm::zip(call.getArgs(), newF.getFunctionType().getInputs())) {
+      if (argOp.getType() == fnArgType)
         continue;
 
       // The purpose of this entire function is to insert bitcasts in the case

clang/lib/CIR/Dialect/IR/CIRDialect.cpp

@@ -1403,11 +1403,27 @@ ParseResult cir::FuncOp::parse(OpAsmParser &parser, OperationState &state) {
   state.addAttribute(getFunctionTypeAttrName(state.name),
                      TypeAttr::get(fnType));
 
+  bool hasAlias = false;
+  mlir::StringAttr aliaseeNameAttr = getAliaseeAttrName(state.name);
+  if (parser.parseOptionalKeyword("alias").succeeded()) {
+    if (parser.parseLParen().failed())
+      return failure();
+    mlir::StringAttr aliaseeAttr;
+    if (parser.parseOptionalSymbolName(aliaseeAttr).failed())
+      return failure();
+    state.addAttribute(aliaseeNameAttr, FlatSymbolRefAttr::get(aliaseeAttr));
+    if (parser.parseRParen().failed())
+      return failure();
+    hasAlias = true;
+  }
+
   // Parse the optional function body.
   auto *body = state.addRegion();
   OptionalParseResult parseResult = parser.parseOptionalRegion(
       *body, arguments, /*enableNameShadowing=*/false);
   if (parseResult.has_value()) {
+    if (hasAlias)
+      return parser.emitError(loc, "function alias shall not have a body");
     if (failed(*parseResult))
       return failure();
     // Function body was parsed, make sure its not empty.

clang/test/CIR/IR/func.cir

@@ -32,6 +32,10 @@ cir.func @intfunc() -> !s32i {
 // CHECK:   cir.return %[[VAL]] : !s32i
 // CHECK: }
 
+// Should print/parse function aliases.
+cir.func @a_empty() alias(@empty)
+// CHECK: cir.func @a_empty() alias(@empty)
+
 // int scopes() {
 //  {
 //    {

clang/test/CIR/IR/invalid-func.cir

@@ -0,0 +1,11 @@
+// RUN: cir-opt %s -verify-diagnostics
+
+module {
+  cir.func @l0() {
+    cir.return
+  }
+
+  cir.func @l1() alias(@l0) { // expected-error {{function alias shall not have a body}}
+    cir.return
+  }
+}