[CodeGenObjC] Use an invoke instead of a call when calling `objc_alloc` or `objc_allocWithZone`

[erik.pilkington]

Summary

objc_alloc and objc_allocWithZone may throw exceptions if the underlying method does. If we're in a @try block, then make sure we emit an invoke instead of a call.

Fixes rdar://47610407

Thanks for taking a look!
Erik

[erik.pilkington]

clang/test/CodeGenObjC/convert-messages-to-runtime-calls.m

43–44

er, these should be invokes too. Looks like this was just happening to work out because the SSA value was named %call in asserts mode. Updating the diff...

[erik.pilkington]

Fix a mistake in the tests.

[pete]

LGTM. Thanks for fixing this!

clang/lib/CodeGen/CGObjC.cpp

 
 /// Perform an operation having the signature
 ///   i8* (i8*)
 /// where a null input causes a no-op and returns null.
 static llvm::Value *emitObjCValueOperation(CodeGenFunction &CGF,
                                            llvm::Value *value,
                                            llvm::Type *returnType,
                                            llvm::Constant *&fn,
-                                           StringRef fnName) {
+                                           StringRef fnName,
+                                           bool MayThrow) {
   if (isa<llvm::ConstantPointerNull>(value))
     return value;
 
   if (!fn) {
     llvm::FunctionType *fnType =
       llvm::FunctionType::get(CGF.Int8PtrTy, CGF.Int8PtrTy, false);
     fn = CGF.CGM.CreateRuntimeFunction(fnType, fnName);
 
     // We have Native ARC, so set nonlazybind attribute for performance
     if (llvm::Function *f = dyn_cast<llvm::Function>(fn))
       if (fnName == "objc_retain")
         f->addFnAttr(llvm::Attribute::NonLazyBind);
   }
 
   // Cast the argument to 'id'.
   llvm::Type *origType = returnType ? returnType : value->getType();
   value = CGF.Builder.CreateBitCast(value, CGF.Int8PtrTy);
 
   // Call the function.
-  llvm::CallInst *call = CGF.EmitNounwindRuntimeCall(fn, value);
+  llvm::CallBase *Inst = nullptr;
+  if (MayThrow)
+    Inst = CGF.EmitCallOrInvoke(fn, value);
+  else
+    Inst = CGF.EmitNounwindRuntimeCall(fn, value);
 
   // Cast the result back to the original type.
-  return CGF.Builder.CreateBitCast(call, origType);
+  return CGF.Builder.CreateBitCast(Inst, origType);
 }
 
 /// Produce the code to do a retain.  Based on the type, calls one of:
 ///   call i8* \@objc_retain(i8* %value)
 ///   call i8* \@objc_retainBlock(i8* %value)
 llvm::Value *CodeGenFunction::EmitARCRetain(QualType type, llvm::Value *value) {
   if (type->isBlockPointerType())
     return EmitARCRetainBlock(value, /*mandatory*/ false);

 }
 
 /// Allocate the given objc object.
 ///   call i8* \@objc_alloc(i8* %value)
 llvm::Value *CodeGenFunction::EmitObjCAlloc(llvm::Value *value,
                                             llvm::Type *resultType) {
   return emitObjCValueOperation(*this, value, resultType,
                                 CGM.getObjCEntrypoints().objc_alloc,
-                                "objc_alloc");
+                                "objc_alloc", /*MayThrow=*/true);
 }
 
 /// Allocate the given objc object.
 ///   call i8* \@objc_allocWithZone(i8* %value)
 llvm::Value *CodeGenFunction::EmitObjCAllocWithZone(llvm::Value *value,
                                                     llvm::Type *resultType) {
   return emitObjCValueOperation(*this, value, resultType,
                                 CGM.getObjCEntrypoints().objc_allocWithZone,
-                                "objc_allocWithZone");
+                                "objc_allocWithZone", /*MayThrow=*/true);
 }
 
 /// Produce the code to do a primitive release.
 /// [tmp drain];
 void CodeGenFunction::EmitObjCMRRAutoreleasePoolPop(llvm::Value *Arg) {
   IdentifierInfo *II = &CGM.getContext().Idents.get("drain");
   Selector DrainSel = getContext().Selectors.getSelector(0, &II);
   CallArgList Args;

   llvm::Value *value = CGF.Builder.CreateLoad(addr);
   CGF.EmitARCIntrinsicUse(value);
 }
 
 /// Autorelease the given object.
 ///   call i8* \@objc_autorelease(i8* %value)
 llvm::Value *CodeGenFunction::EmitObjCAutorelease(llvm::Value *value,
                                                   llvm::Type *returnType) {
-  return emitObjCValueOperation(*this, value, returnType,
-                      CGM.getObjCEntrypoints().objc_autoreleaseRuntimeFunction,
-                                "objc_autorelease");
+  return emitObjCValueOperation(
+      *this, value, returnType,
+      CGM.getObjCEntrypoints().objc_autoreleaseRuntimeFunction,
+      "objc_autorelease", /*MayThrow=*/false);
 }
 
 /// Retain the given object, with normal retain semantics.
 ///   call i8* \@objc_retain(i8* %value)
 llvm::Value *CodeGenFunction::EmitObjCRetainNonBlock(llvm::Value *value,
                                                      llvm::Type *returnType) {
-  return emitObjCValueOperation(*this, value, returnType,
-                          CGM.getObjCEntrypoints().objc_retainRuntimeFunction,
-                                "objc_retain");
+  return emitObjCValueOperation(
+      *this, value, returnType,
+      CGM.getObjCEntrypoints().objc_retainRuntimeFunction, "objc_retain",
+      /*MayThrow=*/false);
 }
 
 /// Release the given object.
 ///   call void \@objc_release(i8* %value)
 void CodeGenFunction::EmitObjCRelease(llvm::Value *value,
                                       ARCPreciseLifetime_t precise) {
   if (isa<llvm::ConstantPointerNull>(value)) return;
 

clang/test/CodeGenObjC/convert-messages-to-runtime-calls.m

-// RUN: %clang_cc1 -fobjc-runtime=macosx-10.10.0 -emit-llvm -o - %s -fno-objc-convert-messages-to-runtime-calls | FileCheck %s --check-prefix=MSGS
-// RUN: %clang_cc1 -fobjc-runtime=macosx-10.10.0 -emit-llvm -o - %s | FileCheck %s --check-prefix=CALLS
-// RUN: %clang_cc1 -fobjc-runtime=macosx-10.9.0 -emit-llvm -o - %s | FileCheck %s --check-prefix=MSGS
-// RUN: %clang_cc1 -fobjc-runtime=macosx-fragile-10.10.0 -emit-llvm -o - %s | FileCheck %s --check-prefix=MSGS
-// RUN: %clang_cc1 -fobjc-runtime=ios-8.0 -emit-llvm -o - %s | FileCheck %s --check-prefix=CALLS
-// RUN: %clang_cc1 -fobjc-runtime=ios-7.0 -emit-llvm -o - %s | FileCheck %s --check-prefix=MSGS
+// RUN: %clang_cc1 -fobjc-runtime=macosx-10.10.0 -emit-llvm -o - %s -fno-objc-convert-messages-to-runtime-calls -fobjc-exceptions -fexceptions | FileCheck %s --check-prefix=MSGS
+// RUN: %clang_cc1 -fobjc-runtime=macosx-10.10.0 -emit-llvm -o - %s -fobjc-exceptions -fexceptions | FileCheck %s --check-prefix=CALLS
+// RUN: %clang_cc1 -fobjc-runtime=macosx-10.9.0 -emit-llvm -o - %s -fobjc-exceptions -fexceptions | FileCheck %s --check-prefix=MSGS
+// RUN: %clang_cc1 -fobjc-runtime=macosx-fragile-10.10.0 -emit-llvm -o - %s -fobjc-exceptions -fexceptions | FileCheck %s --check-prefix=MSGS
+// RUN: %clang_cc1 -fobjc-runtime=ios-8.0 -emit-llvm -o - %s -fobjc-exceptions -fexceptions | FileCheck %s --check-prefix=CALLS
+// RUN: %clang_cc1 -fobjc-runtime=ios-7.0 -emit-llvm -o - %s -fobjc-exceptions -fexceptions | FileCheck %s --check-prefix=MSGS
 // Note: This line below is for tvos for which the driver passes through to use the ios9.0 runtime.
-// RUN: %clang_cc1 -fobjc-runtime=ios-9.0 -emit-llvm -o - %s | FileCheck %s --check-prefix=CALLS
-// RUN: %clang_cc1 -fobjc-runtime=watchos-2.0 -emit-llvm -o - %s | FileCheck %s --check-prefix=CALLS
+// RUN: %clang_cc1 -fobjc-runtime=ios-9.0 -emit-llvm -o - %s -fobjc-exceptions -fexceptions | FileCheck %s --check-prefix=CALLS
+// RUN: %clang_cc1 -fobjc-runtime=watchos-2.0 -emit-llvm -o - %s -fobjc-exceptions -fexceptions | FileCheck %s --check-prefix=CALLS
 
 #define nil (id)0
 
 @interface NSObject
 + (id)alloc;
 + (id)allocWithZone:(void*)zone;
 + (id)alloc2;
 - (id)retain;
void test1(id x) {
   // CALLS: {{call.*@objc_autorelease}}
   [NSObject alloc];
   [NSObject allocWithZone:nil];
   [x retain];
   [x release];
   [x autorelease];
 }
 
+// CHECK-LABEL: define {{.*}}void @check_invoke
+void check_invoke() {
+  // MSGS: {{call.*@objc_msgSend}}
+  // MSGS: {{call.*@objc_msgSend}}
+  // CALLS: {{invoke.*@objc_alloc}}
+  // CALLS: {{invoke.*@objc_allocWithZone}}
+  @try {
+    [NSObject alloc];
+    [NSObject allocWithZone:nil];
+  } @catch (...) {
+  }
+}
+
 // CHECK-LABEL: define {{.*}}void @test2
 void test2(void* x) {
   // MSGS: {{call.*@objc_msgSend}}
   // MSGS: {{call.*@objc_msgSend}}
   // MSGS: {{call.*@objc_msgSend}}
   // CALLS: {{call.*@objc_msgSend}}
   // CALLS: {{call.*@objc_msgSend}}
   // CALLS: {{call.*@objc_msgSend}}