Index: lib/Transforms/InstCombine/InstCombineCalls.cpp =================================================================== --- lib/Transforms/InstCombine/InstCombineCalls.cpp +++ lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -2242,11 +2242,18 @@ return eraseInstFromFunction(CI); break; } - case Intrinsic::lifetime_start: + case Intrinsic::lifetime_start: { + const Function *Func = II->getFunction(); + // Asan needs to poison memory to detect invalid access which is possible + // even for empty lifetime range. + if (Func && Func->hasFnAttribute(Attribute::SanitizeAddress)) + break; + if (removeTriviallyEmptyRange(*II, Intrinsic::lifetime_start, Intrinsic::lifetime_end, *this)) return nullptr; break; + } case Intrinsic::assume: { Value *IIOperand = II->getArgOperand(0); // Remove an assume if it is immediately followed by an identical assume. Index: test/Transforms/InstCombine/lifetime-asan.ll =================================================================== --- /dev/null +++ test/Transforms/InstCombine/lifetime-asan.ll @@ -0,0 +1,37 @@ +; RUN: opt < %s -instcombine -S | FileCheck %s + +declare void @llvm.lifetime.start(i64, i8* nocapture) +declare void @llvm.lifetime.end(i64, i8* nocapture) +declare void @foo(i8* nocapture) + +define void @asan() sanitize_address { +entry: + ; CHECK-LABEL: @asan( + %text = alloca [1 x i8], align 1 + %0 = getelementptr inbounds [1 x i8], [1 x i8]* %text, i64 0, i64 0 + + call void @llvm.lifetime.start(i64 1, i8* %0) + call void @llvm.lifetime.end(i64 1, i8* %0) + ; CHECK: call void @llvm.lifetime.start + ; CHECK-NEXT: call void @llvm.lifetime.end + + call void @foo(i8* %0) ; Keep alloca alive + + ret void +} + + +define void @no_asan() { +entry: + ; CHECK-LABEL: @no_asan( + %text = alloca [1 x i8], align 1 + %0 = getelementptr inbounds [1 x i8], [1 x i8]* %text, i64 0, i64 0 + + call void @llvm.lifetime.start(i64 1, i8* %0) + call void @llvm.lifetime.end(i64 1, i8* %0) + ; CHECK-NO: call void @llvm.lifetime + + call void @foo(i8* %0) ; Keep alloca alive + + ret void +}