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Don't eliminate objc_retainBlock calls on stack objects if the
objc_retainBlock call is potentially responsible for copying the block to the heap to extend its lifetime. rdar://10209613. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140814 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
parent
026fa8782c
commit
597fece886
@ -2338,6 +2338,11 @@ ObjCARCOpt::VisitBottomUp(BasicBlock *BB,
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S.SetAtLeastOneRefCount();
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S.DecrementNestCount();
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// An objc_retainBlock call with just a use still needs to be kept,
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// because it may be copying a block from the stack to the heap.
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if (Class == IC_RetainBlock && S.GetSeq() == S_Use)
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S.SetSeq(S_CanRelease);
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switch (S.GetSeq()) {
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case S_Stop:
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case S_Release:
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@ -2406,14 +2411,14 @@ ObjCARCOpt::VisitBottomUp(BasicBlock *BB,
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case S_Release:
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case S_MovableRelease:
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if (CanUse(Inst, Ptr, PA, Class)) {
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S.RRI.ReverseInsertPts.clear();
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assert(S.RRI.ReverseInsertPts.empty());
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S.RRI.ReverseInsertPts.insert(Inst);
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S.SetSeq(S_Use);
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} else if (Seq == S_Release &&
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(Class == IC_User || Class == IC_CallOrUser)) {
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// Non-movable releases depend on any possible objc pointer use.
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S.SetSeq(S_Stop);
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S.RRI.ReverseInsertPts.clear();
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assert(S.RRI.ReverseInsertPts.empty());
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S.RRI.ReverseInsertPts.insert(Inst);
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}
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break;
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@ -2566,7 +2571,7 @@ ObjCARCOpt::VisitTopDown(BasicBlock *BB,
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switch (Seq) {
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case S_Retain:
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S.SetSeq(S_CanRelease);
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S.RRI.ReverseInsertPts.clear();
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assert(S.RRI.ReverseInsertPts.empty());
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S.RRI.ReverseInsertPts.insert(Inst);
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// One call can't cause a transition from S_Retain to S_CanRelease
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@ -2590,8 +2595,18 @@ ObjCARCOpt::VisitTopDown(BasicBlock *BB,
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if (CanUse(Inst, Ptr, PA, Class))
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S.SetSeq(S_Use);
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break;
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case S_Use:
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case S_Retain:
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// An objc_retainBlock call may be responsible for copying the block
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// data from the stack to the heap. Model this by moving it straight
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// from S_Retain to S_Use.
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if (S.RRI.IsRetainBlock &&
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CanUse(Inst, Ptr, PA, Class)) {
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assert(S.RRI.ReverseInsertPts.empty());
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S.RRI.ReverseInsertPts.insert(Inst);
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S.SetSeq(S_Use);
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}
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break;
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case S_Use:
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case S_None:
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break;
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case S_Stop:
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@ -2743,17 +2758,23 @@ ObjCARCOpt::PerformCodePlacement(DenseMap<const BasicBlock *, BBState>
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SmallVector<Instruction *, 8> DeadInsts;
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for (MapVector<Value *, RRInfo>::const_iterator I = Retains.begin(),
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E = Retains.end(); I != E; ) {
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Value *V = (I++)->first;
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E = Retains.end(); I != E; ++I) {
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Value *V = I->first;
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if (!V) continue; // blotted
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Instruction *Retain = cast<Instruction>(V);
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Value *Arg = GetObjCArg(Retain);
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// If the object being released is in static or stack storage, we know it's
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// If the object being released is in static storage, we know it's
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// not being managed by ObjC reference counting, so we can delete pairs
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// regardless of what possible decrements or uses lie between them.
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bool KnownSafe = isa<Constant>(Arg) || isa<AllocaInst>(Arg);
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bool KnownSafe = isa<Constant>(Arg);
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// Same for stack storage, unless this is an objc_retainBlock call,
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// which is responsible for copying the block data from the stack to
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// the heap.
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if (!I->second.IsRetainBlock && isa<AllocaInst>(Arg))
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KnownSafe = true;
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// A constant pointer can't be pointing to an object on the heap. It may
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// be reference-counted, but it won't be deleted.
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54
test/Transforms/ObjCARC/retain-block-alloca.ll
Normal file
54
test/Transforms/ObjCARC/retain-block-alloca.ll
Normal file
@ -0,0 +1,54 @@
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; RUN: opt -S -objc-arc < %s | FileCheck %s
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; rdar://10209613
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; CHECK: define void @test
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; CHECK: %3 = call i8* @objc_retainBlock(i8* %2) nounwind
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; CHECK: @objc_msgSend
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; CHECK-NEXT: @objc_release(i8* %3)
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%0 = type opaque
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%struct.__block_descriptor = type { i64, i64 }
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@_NSConcreteStackBlock = external global i8*
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@__block_descriptor_tmp = external hidden constant { i64, i64, i8*, i8*, i8*, i8* }
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@"\01L_OBJC_SELECTOR_REFERENCES_" = external hidden global i8*, section "__DATA, __objc_selrefs, literal_pointers, no_dead_strip"
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define void @test(%0* %array) uwtable {
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entry:
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%block = alloca <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>, align 8
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%0 = bitcast %0* %array to i8*
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%1 = tail call i8* @objc_retain(i8* %0) nounwind
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%block.isa = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>* %block, i64 0, i32 0
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store i8* bitcast (i8** @_NSConcreteStackBlock to i8*), i8** %block.isa, align 8
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%block.flags = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>* %block, i64 0, i32 1
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store i32 1107296256, i32* %block.flags, align 8
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%block.reserved = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>* %block, i64 0, i32 2
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store i32 0, i32* %block.reserved, align 4
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%block.invoke = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>* %block, i64 0, i32 3
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store i8* bitcast (void (i8*)* @__test_block_invoke_0 to i8*), i8** %block.invoke, align 8
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%block.descriptor = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>* %block, i64 0, i32 4
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store %struct.__block_descriptor* bitcast ({ i64, i64, i8*, i8*, i8*, i8* }* @__block_descriptor_tmp to %struct.__block_descriptor*), %struct.__block_descriptor** %block.descriptor, align 8
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%block.captured = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>* %block, i64 0, i32 5
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store %0* %array, %0** %block.captured, align 8
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%2 = bitcast <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>* %block to i8*
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%3 = call i8* @objc_retainBlock(i8* %2) nounwind
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%tmp2 = load i8** @"\01L_OBJC_SELECTOR_REFERENCES_", align 8
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call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*, i8*)*)(i8* %0, i8* %tmp2, i8* %3)
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call void @objc_release(i8* %3) nounwind
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%strongdestroy = load %0** %block.captured, align 8
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%4 = bitcast %0* %strongdestroy to i8*
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call void @objc_release(i8* %4) nounwind, !clang.imprecise_release !0
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ret void
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}
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declare i8* @objc_retain(i8*)
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declare void @__test_block_invoke_0(i8* nocapture) uwtable
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declare i8* @objc_retainBlock(i8*)
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declare i8* @objc_msgSend(i8*, i8*, ...) nonlazybind
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declare void @objc_release(i8*)
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!0 = metadata !{}
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