[clang] 3d349ed - [CodeGen][ObjC] Fix broken IR generated when there is a nil receiver
Akira Hatanaka via cfe-commits
cfe-commits at lists.llvm.org
Thu Jan 21 17:38:57 PST 2021
Author: Akira Hatanaka
Date: 2021-01-21T17:38:46-08:00
New Revision: 3d349ed7e1108686271a09314dafaa356df4006d
URL: https://github.com/llvm/llvm-project/commit/3d349ed7e1108686271a09314dafaa356df4006d
DIFF: https://github.com/llvm/llvm-project/commit/3d349ed7e1108686271a09314dafaa356df4006d.diff
LOG: [CodeGen][ObjC] Fix broken IR generated when there is a nil receiver
check
This patch fixes a bug in emitARCOperationAfterCall where it inserts the
fall-back call after a bitcast instruction and then replaces the
bitcast's operand with the result of the fall-back call. The generated
IR without this patch looks like this:
msgSend.call: ; preds = %entry
%call = call i8* bitcast (i8* (i8*, i8*, ...)* @objc_msgSend
br label %msgSend.cont
msgSend.null-receiver: ; preds = %entry
call void @llvm.objc.release(i8* %4)
br label %msgSend.cont
msgSend.cont:
%8 = phi i8* [ %call, %msgSend.call ], [ null, %msgSend.null-receiver ]
%9 = bitcast i8* %10 to %0*
%10 = call i8* @llvm.objc.retain(i8* %8)
Notice that `%9 = bitcast i8* %10` to %0* is taking operand %10 which is
defined after it.
To fix the bug, this patch modifies the insert point to point to the
bitcast instruction so that the fall-back call is inserted before the
bitcast. In addition, it teaches the function to look at phi
instructions that are generated when there is a check for a null
receiver and insert the retainRV/claimRV instruction right after the
call instead of inserting a fall-back call right after the phi
instruction.
rdar://73360225
Differential Revision: https://reviews.llvm.org/D95181
Added:
Modified:
clang/lib/CodeGen/CGObjC.cpp
clang/test/CodeGenObjC/ns_consume_null_check.m
Removed:
################################################################################
diff --git a/clang/lib/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
index bdb9f4002f3c..3f930c76fe0a 100644
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -2894,45 +2894,57 @@ typedef llvm::function_ref<llvm::Value *(CodeGenFunction &CGF,
ValueTransform;
/// Insert code immediately after a call.
+
+// FIXME: We should find a way to emit the runtime call immediately
+// after the call is emitted to eliminate the need for this function.
static llvm::Value *emitARCOperationAfterCall(CodeGenFunction &CGF,
llvm::Value *value,
ValueTransform doAfterCall,
ValueTransform doFallback) {
- if (llvm::CallInst *call = dyn_cast<llvm::CallInst>(value)) {
- CGBuilderTy::InsertPoint ip = CGF.Builder.saveIP();
+ CGBuilderTy::InsertPoint ip = CGF.Builder.saveIP();
+ if (llvm::CallInst *call = dyn_cast<llvm::CallInst>(value)) {
// Place the retain immediately following the call.
CGF.Builder.SetInsertPoint(call->getParent(),
++llvm::BasicBlock::iterator(call));
value = doAfterCall(CGF, value);
-
- CGF.Builder.restoreIP(ip);
- return value;
} else if (llvm::InvokeInst *invoke = dyn_cast<llvm::InvokeInst>(value)) {
- CGBuilderTy::InsertPoint ip = CGF.Builder.saveIP();
-
// Place the retain at the beginning of the normal destination block.
llvm::BasicBlock *BB = invoke->getNormalDest();
CGF.Builder.SetInsertPoint(BB, BB->begin());
value = doAfterCall(CGF, value);
- CGF.Builder.restoreIP(ip);
- return value;
-
// Bitcasts can arise because of related-result returns. Rewrite
// the operand.
} else if (llvm::BitCastInst *bitcast = dyn_cast<llvm::BitCastInst>(value)) {
+ // Change the insert point to avoid emitting the fall-back call after the
+ // bitcast.
+ CGF.Builder.SetInsertPoint(bitcast->getParent(), bitcast->getIterator());
llvm::Value *operand = bitcast->getOperand(0);
operand = emitARCOperationAfterCall(CGF, operand, doAfterCall, doFallback);
bitcast->setOperand(0, operand);
- return bitcast;
-
- // Generic fall-back case.
+ value = bitcast;
} else {
- // Retain using the non-block variant: we never need to do a copy
- // of a block that's been returned to us.
- return doFallback(CGF, value);
+ auto *phi = dyn_cast<llvm::PHINode>(value);
+ if (phi && phi->getNumIncomingValues() == 2 &&
+ isa<llvm::ConstantPointerNull>(phi->getIncomingValue(1)) &&
+ isa<llvm::CallBase>(phi->getIncomingValue(0))) {
+ // Handle phi instructions that are generated when it's necessary to check
+ // whether the receiver of a message is null.
+ llvm::Value *inVal = phi->getIncomingValue(0);
+ inVal = emitARCOperationAfterCall(CGF, inVal, doAfterCall, doFallback);
+ phi->setIncomingValue(0, inVal);
+ value = phi;
+ } else {
+ // Generic fall-back case.
+ // Retain using the non-block variant: we never need to do a copy
+ // of a block that's been returned to us.
+ value = doFallback(CGF, value);
+ }
}
+
+ CGF.Builder.restoreIP(ip);
+ return value;
}
/// Given that the given expression is some sort of call (which does
diff --git a/clang/test/CodeGenObjC/ns_consume_null_check.m b/clang/test/CodeGenObjC/ns_consume_null_check.m
index 3a0aa6f7c596..e02654d4e21b 100644
--- a/clang/test/CodeGenObjC/ns_consume_null_check.m
+++ b/clang/test/CodeGenObjC/ns_consume_null_check.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -fobjc-dispatch-method=mixed -fobjc-runtime-has-weak -fexceptions -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -fobjc-dispatch-method=mixed -fobjc-runtime-has-weak -fexceptions -fobjc-exceptions -o - %s | FileCheck %s
@interface NSObject
- (id) new;
@@ -7,6 +7,7 @@ - (id) new;
@interface MyObject : NSObject
- (char)isEqual:(id) __attribute__((ns_consumed)) object;
- (_Complex float) asComplexWithArg: (id) __attribute__((ns_consumed)) object;
++(instancetype)m0:(id) __attribute__((ns_consumed)) object;
@end
MyObject *x;
@@ -82,4 +83,27 @@ void test1(void) {
// CHECK: landingpad
// CHECK: call void @llvm.objc.destroyWeak(i8** [[WEAKOBJ]]) [[NUW]]
+void test2(id a) {
+ id obj = [MyObject m0:a];
+}
+
+// CHECK-LABEL: define{{.*}} void @test2(
+// CHECK: %[[CALL:.*]] = call i8* bitcast (i8* (i8*, i8*, ...)* @objc_msgSend
+// CHECK-NEXT: %[[V6:.*]] = {{.*}}call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %[[CALL]])
+
+// CHECK: phi i8* [ %[[V6]], %{{.*}} ], [ null, %{{.*}} ]
+
+void test3(id a) {
+ @try {
+ id obj = [MyObject m0:a];
+ } @catch (id x) {
+ }
+}
+
+// CHECK-LABEL: define{{.*}} void @test3(
+// CHECK: %[[CALL:.*]] = invoke i8* bitcast (i8* (i8*, i8*, ...)* @objc_msgSend
+// CHECK: %[[V6:.*]] = {{.*}}call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %[[CALL]])
+
+// CHECK: phi i8* [ %[[V6]], %{{.*}} ], [ null, %{{.*}} ]
+
// CHECK: attributes [[NUW]] = { nounwind }
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