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llvm-project/llvm/test/Transforms/ObjCARC/contract-replace-arg-use.ll

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[ObjCARC] Traverse chain downwards to replace uses of argument passed to ObjC library call with call return. ARC contraction tries to replace uses of an argument passed to an objective-c library call with the call return value. For example, in the following IR, it replaces uses of argument %9 and uses of the values discovered traversing the chain upwards (%7 and %8) with the call return %10, if they are dominated by the call to @objc_autoreleaseReturnValue. This transformation enables code-gen to tail-call the call to @objc_autoreleaseReturnValue, which is necessary to enable auto release return value optimization. %7 = tail call i8* @objc_loadWeakRetained(i8** %6) %8 = bitcast i8* %7 to %0* %9 = bitcast %0* %8 to i8* %10 = tail call i8* @objc_autoreleaseReturnValue(i8* %9) ret %0* %8 Since r276727, llvm started removing redundant bitcasts and as a result started feeding the following IR to ARC contraction: %7 = tail call i8* @objc_loadWeakRetained(i8** %6) %8 = bitcast i8* %7 to %0* %9 = tail call i8* @objc_autoreleaseReturnValue(i8* %7) ret %0* %8 ARC contraction no longer does the optimization described above since it only traverses the chain upwards and fails to recognize that the function return can be replaced by the call return. This commit changes ARC contraction to traverse the chain downwards too and replace uses of bitcasts with the call return. rdar://problem/28011339 Differential Revision: https://reviews.llvm.org/D24523 llvm-svn: 281419
2016-09-14 07:43:11 +08:00
; RUN: opt -objc-arc-contract -S < %s | FileCheck %s
declare i8* @objc_autoreleaseReturnValue(i8*)
declare i8* @foo1()
; Check that ARC contraction replaces the function return with the value
; returned by @objc_autoreleaseReturnValue.
[ObjCARC] Do not turn a call to @objc_autoreleaseReturnValue into a call to @objc_autorelease if its operand is a PHI and the PHI has an equivalent value that is used by a return instruction. For example, ARC optimizer shouldn't replace the call in the following example, as doing so breaks the AutoreleaseRV/RetainRV optimization: %v1 = bitcast i32* %v0 to i8* br label %bb3 bb2: %v3 = bitcast i32* %v2 to i8* br label %bb3 bb3: %p = phi i8* [ %v1, %bb1 ], [ %v3, %bb2 ] %retval = phi i32* [ %v0, %bb1 ], [ %v2, %bb2 ] ; equivalent to %p %v4 = tail call i8* @objc_autoreleaseReturnValue(i8* %p) ret i32* %retval Also, make sure ObjCARCContract replaces @objc_autoreleaseReturnValue's operand uses with its value so that the call gets tail-called. rdar://problem/15894705 llvm-svn: 323009
2018-01-20 07:51:13 +08:00
; CHECK-LABEL: define i32* @autoreleaseRVTailCall(
[ObjCARC] Traverse chain downwards to replace uses of argument passed to ObjC library call with call return. ARC contraction tries to replace uses of an argument passed to an objective-c library call with the call return value. For example, in the following IR, it replaces uses of argument %9 and uses of the values discovered traversing the chain upwards (%7 and %8) with the call return %10, if they are dominated by the call to @objc_autoreleaseReturnValue. This transformation enables code-gen to tail-call the call to @objc_autoreleaseReturnValue, which is necessary to enable auto release return value optimization. %7 = tail call i8* @objc_loadWeakRetained(i8** %6) %8 = bitcast i8* %7 to %0* %9 = bitcast %0* %8 to i8* %10 = tail call i8* @objc_autoreleaseReturnValue(i8* %9) ret %0* %8 Since r276727, llvm started removing redundant bitcasts and as a result started feeding the following IR to ARC contraction: %7 = tail call i8* @objc_loadWeakRetained(i8** %6) %8 = bitcast i8* %7 to %0* %9 = tail call i8* @objc_autoreleaseReturnValue(i8* %7) ret %0* %8 ARC contraction no longer does the optimization described above since it only traverses the chain upwards and fails to recognize that the function return can be replaced by the call return. This commit changes ARC contraction to traverse the chain downwards too and replace uses of bitcasts with the call return. rdar://problem/28011339 Differential Revision: https://reviews.llvm.org/D24523 llvm-svn: 281419
2016-09-14 07:43:11 +08:00
; CHECK: %[[V0:[0-9]+]] = tail call i8* @objc_autoreleaseReturnValue(
; CHECK: %[[V1:[0-9]+]] = bitcast i8* %[[V0]] to i32*
; CHECK: ret i32* %[[V1]]
define i32* @autoreleaseRVTailCall() {
%1 = call i8* @foo1()
%2 = bitcast i8* %1 to i32*
%3 = tail call i8* @objc_autoreleaseReturnValue(i8* %1)
ret i32* %2
}
[ObjCARC] Do not turn a call to @objc_autoreleaseReturnValue into a call to @objc_autorelease if its operand is a PHI and the PHI has an equivalent value that is used by a return instruction. For example, ARC optimizer shouldn't replace the call in the following example, as doing so breaks the AutoreleaseRV/RetainRV optimization: %v1 = bitcast i32* %v0 to i8* br label %bb3 bb2: %v3 = bitcast i32* %v2 to i8* br label %bb3 bb3: %p = phi i8* [ %v1, %bb1 ], [ %v3, %bb2 ] %retval = phi i32* [ %v0, %bb1 ], [ %v2, %bb2 ] ; equivalent to %p %v4 = tail call i8* @objc_autoreleaseReturnValue(i8* %p) ret i32* %retval Also, make sure ObjCARCContract replaces @objc_autoreleaseReturnValue's operand uses with its value so that the call gets tail-called. rdar://problem/15894705 llvm-svn: 323009
2018-01-20 07:51:13 +08:00
declare i32* @foo2(i32);
; CHECK-LABEL: define i32* @autoreleaseRVTailCallPhi(
; CHECK: %[[PHIVAL:.*]] = phi i8* [ %{{.*}}, %bb1 ], [ %{{.*}}, %bb2 ]
; CHECK: %[[RETVAL:.*]] = phi i32* [ %{{.*}}, %bb1 ], [ %{{.*}}, %bb2 ]
; CHECK: %[[V4:.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* %[[PHIVAL]])
; CHECK: %[[V0:.*]] = bitcast i8* %[[V4]] to i32*
; CHECK: ret i32* %[[V0]]
define i32* @autoreleaseRVTailCallPhi(i1 %cond) {
entry:
br i1 %cond, label %bb1, label %bb2
bb1:
%v0 = call i32* @foo2(i32 1)
%v1 = bitcast i32* %v0 to i8*
br label %bb3
bb2:
%v2 = call i32* @foo2(i32 2)
%v3 = bitcast i32* %v2 to i8*
br label %bb3
bb3:
%phival = phi i8* [ %v1, %bb1 ], [ %v3, %bb2 ]
%retval = phi i32* [ %v0, %bb1 ], [ %v2, %bb2 ]
%v4 = tail call i8* @objc_autoreleaseReturnValue(i8* %phival)
ret i32* %retval
}