diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp --- a/llvm/lib/Transforms/IPO/Attributor.cpp +++ b/llvm/lib/Transforms/IPO/Attributor.cpp @@ -4155,11 +4155,6 @@ continue; } - // NOTE: Right now, if a function that has malloc pointer as an argument - // frees memory, we assume that the malloc pointer is freed. - - // TODO: Add nofree callsite argument attribute to indicate that pointer - // argument is not freed. if (auto *CB = dyn_cast(UserI)) { if (!CB->isArgOperand(U)) continue; @@ -4180,15 +4175,16 @@ continue; } - // If a function does not free memory we are fine - const auto &NoFreeAA = - A.getAAFor(*this, IRPosition::callsite_function(*CB)); - unsigned ArgNo = CB->getArgOperandNo(U); + const auto &NoCaptureAA = A.getAAFor( *this, IRPosition::callsite_argument(*CB, ArgNo)); - if (!NoCaptureAA.isAssumedNoCapture() || !NoFreeAA.isAssumedNoFree()) { + // If a callsite argument use is nofree, we are fine. + const auto &ArgNoFreeAA = A.getAAFor( + *this, IRPosition::callsite_argument(*CB, ArgNo)); + + if (!NoCaptureAA.isAssumedNoCapture() || !ArgNoFreeAA.isAssumedNoFree()) { LLVM_DEBUG(dbgs() << "[H2S] Bad user: " << *UserI << "\n"); ValidUsesOnly = false; } diff --git a/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll b/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll --- a/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll +++ b/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll @@ -24,6 +24,13 @@ declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) nounwind +; CHECK: @nofree_arg_only(i8* nocapture nofree %p1, i8* nocapture %p2) +define void @nofree_arg_only(i8* %p1, i8* %p2) { + tail call void @free(i8* %p2) + tail call void @nofree_func(i8* %p1) + ret void +} + ; TEST 1 - negative, pointer freed in another function. define void @test1() { @@ -59,6 +66,16 @@ ret void } +define void @test3a(i8* %p) { + %1 = tail call noalias i8* @malloc(i64 4) + ; CHECK: %1 = alloca i8, i64 4 + ; CHECK-NEXT: tail call void @nofree_arg_only + tail call void @nofree_arg_only(i8* %1, i8* %p) + ; CHECK-NOT: @free(i8* %1) + tail call void @free(i8* %1) + ret void +} + declare noalias i8* @calloc(i64, i64) define void @test0() { @@ -85,7 +102,7 @@ ; TEST 5 - not all exit paths have a call to free, but all uses of malloc ; are in nofree functions and are not captured -define void @test5(i32) { +define void @test5(i32, i8* %p) { %2 = tail call noalias i8* @malloc(i64 4) ; CHECK: %2 = alloca i8, i64 4 ; CHECK-NEXT: icmp eq i32 %0, 0 @@ -97,6 +114,7 @@ br label %6 5: ; preds = %1 + tail call void @nofree_arg_only(i8* %2, i8* %p) tail call void @free(i8* %2) ; CHECK-NOT: @free(i8* %2) br label %6