Revert "[InstCombine] avoid crash from deleting an instruction that still has uses (PR43723)" (b0ac26a6) · Commits · llvm-doe / llvm-project

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

+4 −17

Original line number	Diff line number	Diff line
		@@ -2330,21 +2330,13 @@ static bool isAllocSiteRemovable(Instruction *AI,
		return false;
		LLVM_FALLTHROUGH;
		}
		case Intrinsic::invariant_start:
		case Intrinsic::invariant_end:
		case Intrinsic::lifetime_start:
		case Intrinsic::lifetime_end:
		case Intrinsic::objectsize:
		Users.emplace_back(I);
		continue;
		case Intrinsic::invariant_start:
		// Only delete this if it has no uses or a single 'end' use.
		if (I->use_empty())
		Users.emplace_back(I);
		else if (I->hasOneUse() &&
		match(I->user_back(),
		m_Intrinsic<Intrinsic::invariant_end>()))
		Users.emplace_back(I);
		continue;
		}
		}

		@@ -2392,13 +2384,14 @@ Instruction *InstCombiner::visitAllocSite(Instruction &MI) {

		if (isAllocSiteRemovable(&MI, Users, &TLI)) {
		for (unsigned i = 0, e = Users.size(); i != e; ++i) {
		// Lowering all @llvm.objectsize calls first because they may
		// use a bitcast/GEP of the alloca we are removing.
		if (!Users[i])
		continue;

		Instruction I = cast<Instruction>(&Users[i]);

		if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
		// Lowering all @llvm.objectsize calls first because they may
		// use a bitcast/GEP of the alloca we are removing.
		if (II->getIntrinsicID() == Intrinsic::objectsize) {
		Value *Result =
		lowerObjectSizeCall(II, DL, &TLI, /MustSucceed=/true);
		@@ -2406,12 +2399,6 @@ Instruction *InstCombiner::visitAllocSite(Instruction &MI) {
		eraseInstFromFunction(*I);
		Users[i] = nullptr; // Skip examining in the next loop.
		}
		// Erase llvm.invariant.end because we expect that it uses an
		// llvm.invariant.start that we will remove below.
		if (II->getIntrinsicID() == Intrinsic::invariant_end) {
		eraseInstFromFunction(*I);
		Users[i] = nullptr; // Skip examining in the next loop.
		}
		}
		}
		for (unsigned i = 0, e = Users.size(); i != e; ++i) {

llvm/test/Transforms/InstCombine/builtin-object-size-ptr.ll

+0 −35

Original line number	Diff line number	Diff line
		@@ -28,41 +28,6 @@ define i32 @foo() #0 {
		ret i32 %conv
		}

		; This used to crash while erasing instructions:
		; https://bugs.llvm.org/show_bug.cgi?id=43723

		define void @PR43723() {
		; CHECK-LABEL: @PR43723(
		; CHECK-NEXT: ret void
		;
		%tab = alloca [10 x i8], align 16
		%t0 = bitcast [10 x i8]* %tab to i8*
		call void @llvm.memset.p0i8.i64(i8* align 16 %t0, i8 9, i64 10, i1 false)
		%t1 = call {}* @llvm.invariant.start.p0i8(i64 10, i8* align 16 %t0)
		call void @llvm.invariant.end.p0i8({}* %t1, i64 10, i8* align 16 %t0)
		ret void

		uselistorder i8* %t0, { 1, 0, 2 }
		}

		define void @unknown_use_of_invariant_start({}** %p) {
		; CHECK-LABEL: @unknown_use_of_invariant_start(
		; CHECK-NEXT: [[T1:%.]] = call {} @llvm.invariant.start.p0i8(i64 10, i8* align 16 undef)
		; CHECK-NEXT: store {}* [[T1]], {}** [[P:%.*]], align 8
		; CHECK-NEXT: ret void
		;
		%tab = alloca [10 x i8], align 16
		%t0 = bitcast [10 x i8]* %tab to i8*
		call void @llvm.memset.p0i8.i64(i8* align 16 %t0, i8 9, i64 10, i1 false)
		%t1 = call {}* @llvm.invariant.start.p0i8(i64 10, i8* align 16 %t0)
		call void @llvm.invariant.end.p0i8({}* %t1, i64 10, i8* align 16 %t0)
		store {}* %t1, {}** %p
		ret void
		}

		declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #1
		declare i64 @llvm.objectsize.i64.p0i8(i8*, i1) #2
		declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #1
		declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg) #0
		declare {}* @llvm.invariant.start.p0i8(i64 immarg, i8* nocapture) #0
		declare void @llvm.invariant.end.p0i8({}, i64 immarg, i8 nocapture) #0