[PATCH] D73208: [objc_direct] fix codegen for mismatched Decl/Impl return types

[Pierre Habouzit via Phabricator via cfe-commits]

MadCoder updated this revision to Diff 241599.
MadCoder added a comment.

@dexonsmith here, I still hook the same method but do it in a more LLVM-approved way ;)

It works with minimap perf impect because the only case we call GenerateDirectMethod with an Implementation is if we're about to codegen the body, so the case when you build against a header without seing the @implementation will not be affected perf-wise.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73208/new/

https://reviews.llvm.org/D73208

Files:
  clang/lib/CodeGen/CGObjCMac.cpp
  clang/test/CodeGenObjC/direct-method-ret-mismatch.m


Index: clang/test/CodeGenObjC/direct-method-ret-mismatch.m
===================================================================
--- /dev/null
+++ clang/test/CodeGenObjC/direct-method-ret-mismatch.m
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -emit-llvm -fobjc-arc -triple x86_64-apple-darwin10 %s -o - | FileCheck %s
+
+__attribute__((objc_root_class))
+ at interface Root
+- (Root *)method __attribute__((objc_direct));
+ at end
+
+ at implementation Root
+// CHECK-LABEL: define internal i8* @"\01-[Root something]"(
+- (id)something {
+  // CHECK: %{{[^ ]*}} = call {{.*}} @"\01-[Root method]"
+  return [self method];
+}
+
+// CHECK-LABEL: define hidden i8* @"\01-[Root method]"(
+- (id)method {
+  return self;
+}
+ at end
Index: clang/lib/CodeGen/CGObjCMac.cpp
===================================================================
--- clang/lib/CodeGen/CGObjCMac.cpp
+++ clang/lib/CodeGen/CGObjCMac.cpp
@@ -4032,22 +4032,50 @@
 llvm::Function *
 CGObjCCommonMac::GenerateDirectMethod(const ObjCMethodDecl *OMD,
                                       const ObjCContainerDecl *CD) {
-  auto I = DirectMethodDefinitions.find(OMD->getCanonicalDecl());
-  if (I != DirectMethodDefinitions.end())
-    return I->second;
+  auto *COMD = OMD->getCanonicalDecl();
+  auto I = DirectMethodDefinitions.find(COMD);
+  llvm::Function *OldFn = nullptr, *Fn = nullptr;
 
-  SmallString<256> Name;
-  GetNameForMethod(OMD, CD, Name, /*ignoreCategoryNamespace*/true);
+  if (I != DirectMethodDefinitions.end()) {
+    // Objective-C allows for the declaration and implementation types
+    // to differ slightly.
+	//
+	// If we're being asked for the Function associated for a method
+	// implementation, a previous value might have been cached
+	// based on the type of the canonical declaration.
+	//
+	// If these do not match, then we'll replace this function with
+	// a new one that has the proper type below.
+    if (!OMD->getBody() || COMD->getReturnType() == OMD->getReturnType()) {
+      return I->second;
+    }
+    OldFn = I->second;
+  }
 
   CodeGenTypes &Types = CGM.getTypes();
   llvm::FunctionType *MethodTy =
     Types.GetFunctionType(Types.arrangeObjCMethodDeclaration(OMD));
-  llvm::Function *Method =
-      llvm::Function::Create(MethodTy, llvm::GlobalValue::ExternalLinkage,
-                             Name.str(), &CGM.getModule());
-  DirectMethodDefinitions.insert(std::make_pair(OMD->getCanonicalDecl(), Method));
 
-  return Method;
+  if (OldFn) {
+    Fn = llvm::Function::Create(MethodTy, llvm::GlobalValue::ExternalLinkage,
+                                "", &CGM.getModule());
+    Fn->takeName(OldFn);
+    OldFn->replaceAllUsesWith(
+        llvm::ConstantExpr::getBitCast(Fn, OldFn->getType()));
+    OldFn->eraseFromParent();
+
+	// Replace the cached function in the map.
+    I->second = Fn;
+  } else {
+    SmallString<256> Name;
+    GetNameForMethod(OMD, CD, Name, /*ignoreCategoryNamespace*/ true);
+
+    Fn = llvm::Function::Create(MethodTy, llvm::GlobalValue::ExternalLinkage,
+                                Name.str(), &CGM.getModule());
+    DirectMethodDefinitions.insert(std::make_pair(COMD, Fn));
+  }
+
+  return Fn;
 }
 
 void CGObjCCommonMac::GenerateDirectMethodPrologue(


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