From ebcdeef2f3efd820a57f0f0f9857a7cb2362b496 Mon Sep 17 00:00:00 2001 From: Erik Pilkington Date: Thu, 28 Feb 2019 00:47:55 +0000 Subject: [PATCH] [CodeGen] Fix some broken IR generated by -fsanitize=unsigned-integer-overflow I think the author of the function assumed that `GetInsertBlock()` wouldn't change from where `atomicPHI` was created, but this isn't true when `-fsanitize=unsigned-integer-overflow` is enabled (we generate an overflow/continuation label). Fix by keeping track of the block we want to return to to complete the cmpxchg loop. rdar://48406558 Differential revision: https://reviews.llvm.org/D58744 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@355054 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/CGExprScalar.cpp | 12 ++++---- test/CodeGen/sanitize-atomic-int-overflow.c | 33 +++++++++++++++++++++ 2 files changed, 39 insertions(+), 6 deletions(-) create mode 100644 test/CodeGen/sanitize-atomic-int-overflow.c diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp index bdc07f1776..e831c823da 100644 --- a/lib/CodeGen/CGExprScalar.cpp +++ b/lib/CodeGen/CGExprScalar.cpp @@ -2555,14 +2555,14 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV, } if (atomicPHI) { - llvm::BasicBlock *opBB = Builder.GetInsertBlock(); + llvm::BasicBlock *curBlock = Builder.GetInsertBlock(); llvm::BasicBlock *contBB = CGF.createBasicBlock("atomic_cont", CGF.CurFn); auto Pair = CGF.EmitAtomicCompareExchange( LV, RValue::get(atomicPHI), RValue::get(value), E->getExprLoc()); llvm::Value *old = CGF.EmitToMemory(Pair.first.getScalarVal(), type); llvm::Value *success = Pair.second; - atomicPHI->addIncoming(old, opBB); - Builder.CreateCondBr(success, contBB, opBB); + atomicPHI->addIncoming(old, curBlock); + Builder.CreateCondBr(success, contBB, atomicPHI->getParent()); Builder.SetInsertPoint(contBB); return isPre ? value : input; } @@ -2909,14 +2909,14 @@ LValue ScalarExprEmitter::EmitCompoundAssignLValue( Loc, ScalarConversionOpts(CGF.SanOpts)); if (atomicPHI) { - llvm::BasicBlock *opBB = Builder.GetInsertBlock(); + llvm::BasicBlock *curBlock = Builder.GetInsertBlock(); llvm::BasicBlock *contBB = CGF.createBasicBlock("atomic_cont", CGF.CurFn); auto Pair = CGF.EmitAtomicCompareExchange( LHSLV, RValue::get(atomicPHI), RValue::get(Result), E->getExprLoc()); llvm::Value *old = CGF.EmitToMemory(Pair.first.getScalarVal(), LHSTy); llvm::Value *success = Pair.second; - atomicPHI->addIncoming(old, opBB); - Builder.CreateCondBr(success, contBB, opBB); + atomicPHI->addIncoming(old, curBlock); + Builder.CreateCondBr(success, contBB, atomicPHI->getParent()); Builder.SetInsertPoint(contBB); return LHSLV; } diff --git a/test/CodeGen/sanitize-atomic-int-overflow.c b/test/CodeGen/sanitize-atomic-int-overflow.c new file mode 100644 index 0000000000..a1064f47c3 --- /dev/null +++ b/test/CodeGen/sanitize-atomic-int-overflow.c @@ -0,0 +1,33 @@ +// RUN: %clang_cc1 -triple x86_64-apple-macosx10.14.0 -fsanitize=unsigned-integer-overflow %s -emit-llvm -o - | FileCheck %s + +_Atomic(unsigned) atomic; + +// CHECK-LABEL: define void @cmpd_assign +void cmpd_assign() { + // CHECK: br label %[[LOOP_START:.*]] + + // CHECK: [[LOOP_START]]: + // CHECK-NEXT: phi i32 {{.*}}, [ {{.*}}, %[[INCOMING_BLOCK:.*]] ] + + // CHECK: [[INCOMING_BLOCK]]: + // CHECK-NEXT: cmpxchg + // CHECK-NEXT: extractvalue + // CHECK-NEXT: extractvalue + // CHECK-NEXT: br i1 %8, label %{{.*}}, label %[[LOOP_START]] + atomic += 1; +} + +// CHECK-LABEL: define void @inc +void inc() { + // CHECK: br label %[[LOOP_START:.*]] + + // CHECK: [[LOOP_START]]: + // CHECK-NEXT: phi i32 {{.*}}, [ {{.*}}, %[[INCOMING_BLOCK:.*]] ] + + // CHECK: [[INCOMING_BLOCK]]: + // CHECK-NEXT: cmpxchg + // CHECK-NEXT: extractvalue + // CHECK-NEXT: extractvalue + // CHECK-NEXT: br i1 %8, label %{{.*}}, label %[[LOOP_START]] + atomic++; +} -- 2.50.1