Properly model precise lifetime when given an incomplete dataflow sequence.
The normal dataflow sequence in the ARC optimizer consists of the following
states:
Retain -> CanRelease -> Use -> Release
The optimizer before this patch stored the uses that determine the lifetime of
the retainable object pointer when it bottom up hits a retain or when top down
it hits a release. This is correct for an imprecise lifetime scenario since what
we are trying to do is remove retains/releases while making sure that no
``CanRelease'' (which is usually a call) deallocates the given pointer before we
get to the ``Use'' (since that would cause a segfault).
If we are considering the precise lifetime scenario though, this is not
correct. In such a situation, we *DO* care about the previous sequence, but
additionally, we wish to track the uses resulting from the following incomplete
sequences:
Retain -> CanRelease -> Release (TopDown)
Retain <- Use <- Release (BottomUp)
*NOTE* This patch looks large but the most of it consists of updating
test cases. Additionally this fix exposed an additional bug. I removed
the test case that expressed said bug and will recommit it with the fix
in a little bit.
llvm-svn: 178921
This commit is contained in:
Michael Gottesman
parent
3b59f5c804
commit
1d8d25777d
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@ -408,6 +408,10 @@ namespace {
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KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(0) {}
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void clear();
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bool IsTrackingImpreciseReleases() {
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return ReleaseMetadata != 0;
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}
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};
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}
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@ -1746,7 +1750,9 @@ ObjCARCOpt::VisitInstructionBottomUp(Instruction *Inst,
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bool NestingDetected = false;
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InstructionClass Class = GetInstructionClass(Inst);
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const Value *Arg = 0;
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DEBUG(dbgs() << "Class: " << Class << "\n");
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switch (Class) {
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case IC_Release: {
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Arg = GetObjCArg(Inst);
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@ -1794,7 +1800,10 @@ ObjCARCOpt::VisitInstructionBottomUp(Instruction *Inst,
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case S_Release:
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case S_MovableRelease:
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case S_Use:
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S.RRI.ReverseInsertPts.clear();
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// If OldSeq is not S_Use or OldSeq is S_Use and we are tracking an
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// imprecise release, clear our reverse insertion points.
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if (OldSeq != S_Use || S.RRI.IsTrackingImpreciseReleases())
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S.RRI.ReverseInsertPts.clear();
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// FALL THROUGH
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case S_CanRelease:
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// Don't do retain+release tracking for IC_RetainRV, because it's
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@ -2017,14 +2026,19 @@ ObjCARCOpt::VisitInstructionTopDown(Instruction *Inst,
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PtrState &S = MyStates.getPtrTopDownState(Arg);
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S.ClearKnownPositiveRefCount();
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switch (S.GetSeq()) {
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Sequence OldSeq = S.GetSeq();
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MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
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switch (OldSeq) {
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case S_Retain:
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case S_CanRelease:
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S.RRI.ReverseInsertPts.clear();
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if (OldSeq == S_Retain || ReleaseMetadata != 0)
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S.RRI.ReverseInsertPts.clear();
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// FALL THROUGH
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case S_Use:
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S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
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S.RRI.ReleaseMetadata = ReleaseMetadata;
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S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
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Releases[Inst] = S.RRI;
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ANNOTATE_TOPDOWN(Inst, Arg, S.GetSeq(), S_None);
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File diff suppressed because it is too large
Load Diff
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@ -34,7 +34,9 @@ declare void @test0_helper(i8*, i8**)
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; CHECK-NEXT: @objc_release(i8* [[VAL1]])
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; CHECK-NEXT: @objc_autorelease(i8* %x)
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; CHECK-NEXT: store i8* %x, i8** %out
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; CHECK-NEXT: @objc_retain(i8* %x)
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; CHECK-NEXT: @objc_release(i8* [[VAL2]])
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; CHECK-NEXT: @objc_release(i8* %x)
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; CHECK-NEXT: ret void
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define void @test0(i8** %out, i8* %x, i8* %y) {
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entry:
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@ -61,3 +63,52 @@ entry:
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call void @objc_release(i8* %x) nounwind
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ret void
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}
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; CHECK: define void @test0a(
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; CHECK: @objc_retain(i8* %x)
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; CHECK-NEXT: store i8* %y, i8** %temp0
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; CHECK-NEXT: @objc_retain(i8* %y)
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; CHECK-NEXT: call void @test0_helper
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; CHECK-NEXT: [[VAL1:%.*]] = load i8** %temp0
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; CHECK-NEXT: call void (...)* @clang.arc.use(i8* %y)
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; CHECK-NEXT: @objc_retain(i8* [[VAL1]])
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; CHECK-NEXT: @objc_release(i8* %y)
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; CHECK-NEXT: store i8* [[VAL1]], i8** %temp1
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; CHECK-NEXT: call void @test0_helper
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; CHECK-NEXT: [[VAL2:%.*]] = load i8** %temp1
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; CHECK-NEXT: call void (...)* @clang.arc.use(i8* [[VAL1]])
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; CHECK-NEXT: @objc_retain(i8* [[VAL2]])
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; CHECK-NEXT: @objc_release(i8* [[VAL1]])
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; CHECK-NEXT: @objc_autorelease(i8* %x)
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; CHECK-NEXT: @objc_release(i8* [[VAL2]])
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; CHECK-NEXT: store i8* %x, i8** %out
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; CHECK-NEXT: ret void
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define void @test0a(i8** %out, i8* %x, i8* %y) {
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entry:
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%temp0 = alloca i8*, align 8
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%temp1 = alloca i8*, align 8
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%0 = call i8* @objc_retain(i8* %x) nounwind
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%1 = call i8* @objc_retain(i8* %y) nounwind
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store i8* %y, i8** %temp0
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call void @test0_helper(i8* %x, i8** %temp0)
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%val1 = load i8** %temp0
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%2 = call i8* @objc_retain(i8* %val1) nounwind
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call void (...)* @clang.arc.use(i8* %y) nounwind
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call void @objc_release(i8* %y) nounwind, !clang.imprecise_release !0
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store i8* %val1, i8** %temp1
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call void @test0_helper(i8* %x, i8** %temp1)
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%val2 = load i8** %temp1
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%3 = call i8* @objc_retain(i8* %val2) nounwind
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call void (...)* @clang.arc.use(i8* %val1) nounwind
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call void @objc_release(i8* %val1) nounwind, !clang.imprecise_release !0
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%4 = call i8* @objc_retain(i8* %x) nounwind
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%5 = call i8* @objc_autorelease(i8* %x) nounwind
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store i8* %x, i8** %out
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call void @objc_release(i8* %val2) nounwind, !clang.imprecise_release !0
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call void @objc_release(i8* %x) nounwind, !clang.imprecise_release !0
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ret void
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}
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!0 = metadata !{}
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@ -21,6 +21,23 @@ declare i8* @objc_retainBlock(i8*)
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define void @bitcasttest(i8* %storage, void (...)* %block) {
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; CHECK: define void @bitcasttest
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entry:
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%t1 = bitcast void (...)* %block to i8*
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; CHECK: tail call i8* @objc_retain
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%t2 = tail call i8* @objc_retain(i8* %t1)
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; CHECK: tail call i8* @objc_retainBlock
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%t3 = tail call i8* @objc_retainBlock(i8* %t1), !clang.arc.copy_on_escape !0
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%t4 = bitcast i8* %storage to void (...)**
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%t5 = bitcast i8* %t3 to void (...)*
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store void (...)* %t5, void (...)** %t4, align 8
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; CHECK: call void @objc_release
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call void @objc_release(i8* %t1)
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ret void
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; CHECK: }
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}
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define void @bitcasttest_a(i8* %storage, void (...)* %block) {
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; CHECK: define void @bitcasttest_a
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entry:
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%t1 = bitcast void (...)* %block to i8*
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; CHECK-NOT: tail call i8* @objc_retain
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@ -31,12 +48,32 @@ entry:
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%t5 = bitcast i8* %t3 to void (...)*
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store void (...)* %t5, void (...)** %t4, align 8
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; CHECK-NOT: call void @objc_release
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call void @objc_release(i8* %t1)
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call void @objc_release(i8* %t1), !clang.imprecise_release !0
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ret void
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; CHECK: }
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}
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define void @geptest(void (...)** %storage_array, void (...)* %block) {
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; CHECK: define void @geptest
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entry:
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%t1 = bitcast void (...)* %block to i8*
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; CHECK: tail call i8* @objc_retain
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%t2 = tail call i8* @objc_retain(i8* %t1)
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; CHECK: tail call i8* @objc_retainBlock
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%t3 = tail call i8* @objc_retainBlock(i8* %t1), !clang.arc.copy_on_escape !0
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%t4 = bitcast i8* %t3 to void (...)*
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%storage = getelementptr inbounds void (...)** %storage_array, i64 0
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store void (...)* %t4, void (...)** %storage, align 8
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; CHECK: call void @objc_release
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call void @objc_release(i8* %t1)
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ret void
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; CHECK: }
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}
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define void @geptest_a(void (...)** %storage_array, void (...)* %block) {
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; CHECK: define void @geptest_a
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entry:
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%t1 = bitcast void (...)* %block to i8*
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; CHECK-NOT: tail call i8* @objc_retain
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@ -49,13 +86,32 @@ entry:
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store void (...)* %t4, void (...)** %storage, align 8
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; CHECK-NOT: call void @objc_release
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call void @objc_release(i8* %t1)
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call void @objc_release(i8* %t1), !clang.imprecise_release !0
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ret void
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; CHECK: }
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}
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define void @selecttest(void (...)** %store1, void (...)** %store2,
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void (...)* %block) {
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; CHECK: define void @selecttest
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entry:
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%t1 = bitcast void (...)* %block to i8*
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; CHECK: tail call i8* @objc_retain
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%t2 = tail call i8* @objc_retain(i8* %t1)
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; CHECK: tail call i8* @objc_retainBlock
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%t3 = tail call i8* @objc_retainBlock(i8* %t1), !clang.arc.copy_on_escape !0
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%t4 = bitcast i8* %t3 to void (...)*
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%store = select i1 undef, void (...)** %store1, void (...)** %store2
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store void (...)* %t4, void (...)** %store, align 8
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; CHECK: call void @objc_release
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call void @objc_release(i8* %t1)
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ret void
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; CHECK: }
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}
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define void @selecttest_a(void (...)** %store1, void (...)** %store2,
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void (...)* %block) {
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; CHECK: define void @selecttest_a
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entry:
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%t1 = bitcast void (...)* %block to i8*
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; CHECK-NOT: tail call i8* @objc_retain
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@ -66,14 +122,45 @@ entry:
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%store = select i1 undef, void (...)** %store1, void (...)** %store2
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store void (...)* %t4, void (...)** %store, align 8
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; CHECK-NOT: call void @objc_release
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call void @objc_release(i8* %t1)
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call void @objc_release(i8* %t1), !clang.imprecise_release !0
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ret void
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; CHECK: }
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}
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define void @phinodetest(void (...)** %storage1,
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void (...)** %storage2,
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void (...)* %block) {
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; CHECK: define void @phinodetest
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entry:
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%t1 = bitcast void (...)* %block to i8*
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; CHECK: tail call i8* @objc_retain
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%t2 = tail call i8* @objc_retain(i8* %t1)
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; CHECK: tail call i8* @objc_retainBlock
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%t3 = tail call i8* @objc_retainBlock(i8* %t1), !clang.arc.copy_on_escape !0
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%t4 = bitcast i8* %t3 to void (...)*
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br i1 undef, label %store1_set, label %store2_set
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; CHECK: store1_set:
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store1_set:
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br label %end
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store2_set:
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br label %end
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end:
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; CHECK: end:
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%storage = phi void (...)** [ %storage1, %store1_set ], [ %storage2, %store2_set]
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store void (...)* %t4, void (...)** %storage, align 8
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; CHECK: call void @objc_release
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call void @objc_release(i8* %t1)
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ret void
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; CHECK: }
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}
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define void @phinodetest_a(void (...)** %storage1,
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void (...)** %storage2,
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void (...)* %block) {
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; CHECK: define void @phinodetest_a
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entry:
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%t1 = bitcast void (...)* %block to i8*
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; CHECK-NOT: tail call i8* @objc_retain
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@ -93,10 +180,11 @@ end:
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%storage = phi void (...)** [ %storage1, %store1_set ], [ %storage2, %store2_set]
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store void (...)* %t4, void (...)** %storage, align 8
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; CHECK-NOT: call void @objc_release
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call void @objc_release(i8* %t1)
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call void @objc_release(i8* %t1), !clang.imprecise_release !0
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ret void
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}
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; This test makes sure that we do not hang clang when visiting a use ;
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; cycle caused by phi nodes during objc-arc analysis. *NOTE* This ;
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