diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 654a8e48cd104..aef14248b9022 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -86,6 +86,15 @@ Potentially Breaking Changes options-related code has been moved out of the Driver into a separate library. - The ``clangFrontend`` library no longer depends on ``clangDriver``, which may break downstream projects that relied on this transitive dependency. +- Clang is now more precise with regards to the lifetime of temporary objects + such as when aggregates are passed by value to a function, resulting in + better sharing of stack slots and reduced stack usage. This change can lead + to use-after-scope related issues in code that unintentionally relied on the + previous behavior. If recompiling with ``-fsanitize=address`` shows a + use-after-scope warning, then this is likely the case, and the report printed + should be able to help users pinpoint where the use-after-scope is occurring. + Users can use ``-Xclang -sloppy-temporary-lifetimes`` to retain the old + behavior until they are able to find and resolve issues in their code. C/C++ Language Potentially Breaking Changes ------------------------------------------- diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def index 76a6463881c6f..e7f5b4c9a08a9 100644 --- a/clang/include/clang/Basic/CodeGenOptions.def +++ b/clang/include/clang/Basic/CodeGenOptions.def @@ -475,6 +475,10 @@ ENUM_CODEGENOPT(ZeroCallUsedRegs, ZeroCallUsedRegsKind, /// non-deleting destructors. (No effect on Microsoft ABI.) CODEGENOPT(CtorDtorReturnThis, 1, 0, Benign) +/// Set via -Xclang -sloppy-temporary-lifetimes to disable emission of lifetime +/// marker intrinsic calls. +CODEGENOPT(NoLifetimeMarkersForTemporaries, 1, 0, Benign) + /// Enables emitting Import Call sections on supported targets that can be used /// by the Windows kernel to enable import call optimization. CODEGENOPT(ImportCallOptimization, 1, 0, Benign) diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td index c6841937c8d39..02396fb9b4d2d 100644 --- a/clang/include/clang/Options/Options.td +++ b/clang/include/clang/Options/Options.td @@ -8151,6 +8151,11 @@ def import_call_optimization : Flag<["-"], "import-call-optimization">, def replaceable_function: Joined<["-"], "loader-replaceable-function=">, MarshallingInfoStringVector>; +def sloppy_temporary_lifetimes + : Flag<["-"], "sloppy-temporary-lifetimes">, + HelpText<"Don't emit lifetime markers for temporary objects">, + MarshallingInfoFlag>; + } // let Visibility = [CC1Option] //===----------------------------------------------------------------------===// diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp index 4a9025b6e0b0f..84d3229863fe9 100644 --- a/clang/lib/CodeGen/CGCall.cpp +++ b/clang/lib/CodeGen/CGCall.cpp @@ -4960,7 +4960,27 @@ void CodeGenFunction::EmitCallArg(CallArgList &args, const Expr *E, return; } - args.add(EmitAnyExprToTemp(E), type); + AggValueSlot ArgSlot = AggValueSlot::ignored(); + // For arguments with aggregate type, create an alloca to store + // the value. If the argument's type has a destructor, that destructor + // will run at the end of the full-expression; emit matching lifetime + // markers. + // + // FIXME: For types which don't have a destructor, consider using a + // narrower lifetime bound. + if (hasAggregateEvaluationKind(E->getType())) { + RawAddress ArgSlotAlloca = Address::invalid(); + ArgSlot = CreateAggTemp(E->getType(), "agg.tmp", &ArgSlotAlloca); + + // Emit a lifetime start/end for this temporary at the end of the full + // expression. + if (!CGM.getCodeGenOpts().NoLifetimeMarkersForTemporaries && + EmitLifetimeStart(ArgSlotAlloca.getPointer())) + pushFullExprCleanup(NormalEHLifetimeMarker, + ArgSlotAlloca); + } + + args.add(EmitAnyExpr(E, ArgSlot), type); } QualType CodeGenFunction::getVarArgType(const Expr *Arg) { diff --git a/clang/test/CodeGen/lifetime-call-temp.c b/clang/test/CodeGen/lifetime-call-temp.c new file mode 100644 index 0000000000000..3bc68b5e8024a --- /dev/null +++ b/clang/test/CodeGen/lifetime-call-temp.c @@ -0,0 +1,98 @@ +// RUN: %clang -cc1 -triple x86_64-apple-macos -O1 -disable-llvm-passes %s \ +// RUN: -emit-llvm -o - | FileCheck %s --implicit-check-not=llvm.lifetime +// RUN: %clang -cc1 -xc++ -std=c++17 -triple x86_64-apple-macos -O1 \ +// RUN: -disable-llvm-passes %s -emit-llvm -o - -Wno-return-type-c-linkage | \ +// RUN: FileCheck %s --implicit-check-not=llvm.lifetime --check-prefixes=CHECK,CXX +// RUN: %clang -cc1 -xobjective-c -triple x86_64-apple-macos -O1 \ +// RUN: -disable-llvm-passes %s -emit-llvm -o - | \ +// RUN: FileCheck %s --implicit-check-not=llvm.lifetime --check-prefixes=CHECK,OBJC +// RUN: %clang -cc1 -triple x86_64-apple-macos -O1 -disable-llvm-passes %s \ +// RUN: -emit-llvm -o - -sloppy-temporary-lifetimes | \ +// RUN: FileCheck %s --implicit-check-not=llvm.lifetime --check-prefixes=SLOPPY + +typedef struct { int x[100]; } aggregate; + +#ifdef __cplusplus +extern "C" { +#endif + +void takes_aggregate(aggregate); +aggregate gives_aggregate(); + +// CHECK-LABEL: define void @t1 +void t1() { + takes_aggregate(gives_aggregate()); + + // CHECK: [[AGGTMP:%.*]] = alloca %struct.aggregate, align 8 + // CHECK: call void @llvm.lifetime.start.p0(ptr [[AGGTMP]]) + // CHECK: call void{{.*}} @gives_aggregate(ptr{{.*}}sret(%struct.aggregate) align 4 [[AGGTMP]]) + // CHECK: call void @takes_aggregate(ptr noundef byval(%struct.aggregate) align 8 [[AGGTMP]]) + // CHECK: call void @llvm.lifetime.end.p0(ptr [[AGGTMP]]) + + // SLOPPY: [[AGGTMP:%.*]] = alloca %struct.aggregate, align 8 + // SLOPPY-NEXT: call void (ptr, ...) @gives_aggregate(ptr{{.*}}sret(%struct.aggregate) align 4 [[AGGTMP]]) + // SLOPPY-NEXT: call void @takes_aggregate(ptr noundef byval(%struct.aggregate) align 8 [[AGGTMP]]) +} + +// CHECK: declare {{.*}}llvm.lifetime.start +// CHECK: declare {{.*}}llvm.lifetime.end + +#ifdef __cplusplus +// CXX: define void @t2 +void t2() { + struct S { + S(aggregate) {} + }; + S{gives_aggregate()}; + + // CXX: [[AGG:%.*]] = alloca %struct.aggregate + // CXX: call void @llvm.lifetime.start.p0(ptr [[AGG]] + // CXX: call void @gives_aggregate(ptr{{.*}}sret(%struct.aggregate) align 4 [[AGG]]) + // CXX: call void @_ZZ2t2EN1SC1E9aggregate(ptr {{.*}}, ptr {{.*}} byval(%struct.aggregate) align 8 [[AGG]]) + // CXX: call void @llvm.lifetime.end.p0(ptr [[AGG]] +} + +struct Dtor { + ~Dtor(); +}; + +void takes_dtor(Dtor); +Dtor gives_dtor(); + +// CXX: define void @t3 +void t3() { + takes_dtor(gives_dtor()); + + // CXX: [[AGG:%.*]] = alloca %struct.Dtor + // CXX: call void @llvm.lifetime.start.p0(ptr [[AGG]]) + // CXX: call void @gives_dtor(ptr{{.*}}sret(%struct.Dtor) align 1 [[AGG]]) + // CXX: call void @takes_dtor(ptr noundef [[AGG]]) + // CXX: call void @_ZN4DtorD1Ev(ptr {{.*}} [[AGG]]) + // CXX: call void @llvm.lifetime.end.p0(ptr [[AGG]]) + // CXX: ret void +} + +#endif + +#ifdef __OBJC__ + +@interface X +-m:(aggregate)x; +@end + +// OBJC: define void @t4 +void t4(X *x) { + [x m: gives_aggregate()]; + + // OBJC: [[AGG:%.*]] = alloca %struct.aggregate + // OBJC: call void @llvm.lifetime.start.p0(ptr [[AGG]] + // OBJC: call void{{.*}} @gives_aggregate(ptr{{.*}}sret(%struct.aggregate) align 4 [[AGGTMP]]) + // OBJC: call {{.*}}@objc_msgSend + // OBJC: call void @llvm.lifetime.end.p0(ptr [[AGG]] +} + +#endif + +#ifdef __cplusplus +} +#endif diff --git a/clang/test/CodeGen/lifetime-invoke-c.c b/clang/test/CodeGen/lifetime-invoke-c.c new file mode 100644 index 0000000000000..f3573f4b2ec17 --- /dev/null +++ b/clang/test/CodeGen/lifetime-invoke-c.c @@ -0,0 +1,50 @@ +// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -o - %s -O1 -disable-llvm-passes -fexceptions | FileCheck %s + +struct Trivial { + int x[100]; +}; + +void cleanup(int *p) {} +void func(struct Trivial t); +struct Trivial gen(void); + +// CHECK-LABEL: define dso_local void @test() +void test() { + int x __attribute__((cleanup(cleanup))); + + // CHECK: %[[AGG1:.*]] = alloca %struct.Trivial + // CHECK: %[[AGG2:.*]] = alloca %struct.Trivial + + // CHECK: call void @llvm.lifetime.start.p0(ptr %[[AGG1]]) + // CHECK: invoke void @gen(ptr{{.*}} sret(%struct.Trivial){{.*}} %[[AGG1]]) + + // CHECK: invoke void @func(ptr{{.*}} %[[AGG1]]) + // CHECK-NEXT: to label %[[CONT1:.*]] unwind label %[[LPAD1:.*]] + + // CHECK: [[CONT1]]: + // CHECK-NOT: call void @llvm.lifetime.end.p0(ptr %[[AGG1]]) + + // CHECK: call void @llvm.lifetime.start.p0(ptr %[[AGG2]]) + // CHECK: invoke void @gen(ptr{{.*}} sret(%struct.Trivial){{.*}} %[[AGG2]]) + // CHECK: invoke void @func(ptr{{.*}} %[[AGG2]]) + // CHECK-NEXT: to label %[[CONT2:.*]] unwind label %[[LPAD2:.*]] + + // CHECK: [[CONT2]]: + // CHECK-DAG: call void @llvm.lifetime.end.p0(ptr %[[AGG2]]) + // CHECK-DAG: call void @llvm.lifetime.end.p0(ptr %[[AGG1]]) + + // CHECK: [[LPAD1]]: + // CHECK: landingpad + // CHECK: br label %[[EHCLEANUP:.*]] + + // CHECK: [[LPAD2]]: + // CHECK: landingpad + // CHECK: call void @llvm.lifetime.end.p0(ptr %[[AGG2]]) + // CHECK: br label %[[EHCLEANUP]] + + // CHECK: [[EHCLEANUP]]: + // CHECK: call void @llvm.lifetime.end.p0(ptr %[[AGG1]]) + // CHECK: call void @cleanup + func(gen()); + func(gen()); +} diff --git a/clang/test/CodeGenCXX/aggregate-lifetime-invoke.cpp b/clang/test/CodeGenCXX/aggregate-lifetime-invoke.cpp new file mode 100644 index 0000000000000..32af6b51fe9c8 --- /dev/null +++ b/clang/test/CodeGenCXX/aggregate-lifetime-invoke.cpp @@ -0,0 +1,47 @@ +// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -o - %s -O1 -fexceptions -fcxx-exceptions | FileCheck %s + +extern "C" { + +struct Trivial { + int x[100]; +}; + +void func_that_throws(Trivial t); + +// CHECK-LABEL: define{{.*}} void @test() +void test() { + // CHECK: %[[AGG1:.*]] = alloca %struct.Trivial + // CHECK: %[[AGG2:.*]] = alloca %struct.Trivial + + // CHECK: call void @llvm.lifetime.start.p0(ptr{{.*}} %[[AGG1]]) + // CHECK: invoke void @func_that_throws(ptr{{.*}} %[[AGG1]]) + // CHECK-NEXT: to label %[[CONT1:.*]] unwind label %[[LPAD1:.*]] + + // CHECK: [[CONT1]]: + // CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr{{.*}} %[[AGG2]]) + // CHECK: invoke void @func_that_throws(ptr{{.*}} %[[AGG2]]) + // CHECK-NEXT: to label %[[CONT2:.*]] unwind label %[[LPAD2:.*]] + + // CHECK: [[CONT2]]: + // CHECK-DAG: call void @llvm.lifetime.end.p0(ptr{{.*}} %[[AGG2]]) + // CHECK-DAG: call void @llvm.lifetime.end.p0(ptr{{.*}} %[[AGG1]]) + // CHECK: br label %[[TRY_CONT:.*]] + + // CHECK: [[LPAD1]]: + // CHECK: landingpad + // CHECK: br label %[[EHCLEANUP:.*]] + + // CHECK: [[LPAD2]]: + // CHECK: landingpad + // CHECK: call void @llvm.lifetime.end.p0(ptr{{.*}} %[[AGG2]]) + // CHECK: br label %[[EHCLEANUP]] + + // CHECK: [[EHCLEANUP]]: + // CHECK: call void @llvm.lifetime.end.p0(ptr{{.*}} %[[AGG1]]) + try { + func_that_throws(Trivial{0}); + func_that_throws(Trivial{0}); + } catch (...) { + } +} +} // end extern "C" diff --git a/clang/test/CodeGenCXX/amdgcn-call-with-aggarg.cc b/clang/test/CodeGenCXX/amdgcn-call-with-aggarg.cc new file mode 100644 index 0000000000000..9b598a48f6436 --- /dev/null +++ b/clang/test/CodeGenCXX/amdgcn-call-with-aggarg.cc @@ -0,0 +1,19 @@ +// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -emit-llvm -O3 -disable-llvm-passes -o - %s | FileCheck %s + +struct A { + float x, y, z, w; +}; + +void foo(A a); + +// CHECK-LABEL: @_Z4testv +// CHECK: [[A:%.*]] = alloca [[STRUCT_A:%.*]], align 4, addrspace(5) +// CHECK-NEXT: [[AGG_TMP:%.*]] = alloca [[STRUCT_A]], align 4, addrspace(5) +// CHECK-NEXT: [[A_ASCAST:%.*]] = addrspacecast ptr addrspace(5) [[A]] to ptr +// CHECK-NEXT: [[AGG_TMP_ASCAST:%.*]] = addrspacecast ptr addrspace(5) [[AGG_TMP]] to ptr +// CHECK-NEXT: call void @llvm.lifetime.start.p5(i64 16, ptr addrspace(5) [[A]]) #[[ATTR4:[0-9]+]] +// CHECK-NEXT: call void @llvm.lifetime.start.p5(i64 16, ptr addrspace(5) [[AGG_TMP]]) #[[ATTR4]] +void test() { + A a; + foo(a); +} diff --git a/clang/test/CodeGenCXX/stack-reuse-miscompile.cpp b/clang/test/CodeGenCXX/stack-reuse-miscompile.cpp index 67fa9f9c9cd98..50c374d2710f4 100644 --- a/clang/test/CodeGenCXX/stack-reuse-miscompile.cpp +++ b/clang/test/CodeGenCXX/stack-reuse-miscompile.cpp @@ -26,6 +26,8 @@ const char * f(S s) // CHECK: [[T2:%.*]] = alloca %class.T, align 4 // CHECK: [[T3:%.*]] = alloca %class.T, align 4 // +// CHECK: [[AGG:%.*]] = alloca %class.S, align 4 +// // FIXME: We could defer starting the lifetime of the return object of concat // until the call. // CHECK: call void @llvm.lifetime.start.p0(ptr [[T1]]) @@ -34,10 +36,12 @@ const char * f(S s) // CHECK: [[T4:%.*]] = call noundef ptr @_ZN1TC1EPKc(ptr {{[^,]*}} [[T2]], ptr noundef @.str) // // CHECK: call void @llvm.lifetime.start.p0(ptr [[T3]]) +// CHECK: call void @llvm.lifetime.start.p0(ptr [[AGG]]) // CHECK: [[T5:%.*]] = call noundef ptr @_ZN1TC1E1S(ptr {{[^,]*}} [[T3]], [2 x i32] %{{.*}}) // // CHECK: call void @_ZNK1T6concatERKS_(ptr dead_on_unwind writable sret(%class.T) align 4 [[T1]], ptr {{[^,]*}} [[T2]], ptr noundef nonnull align 4 dereferenceable(16) [[T3]]) // CHECK: [[T6:%.*]] = call noundef ptr @_ZNK1T3strEv(ptr {{[^,]*}} [[T1]]) +// CHECK: call void @llvm.lifetime.end.p0(ptr [[AGG]]) // // CHECK: call void @llvm.lifetime.end.p0( // CHECK: call void @llvm.lifetime.end.p0( diff --git a/clang/test/CodeGenCoroutines/pr59181.cpp b/clang/test/CodeGenCoroutines/pr59181.cpp index 21e784e0031de..a68a61984f981 100644 --- a/clang/test/CodeGenCoroutines/pr59181.cpp +++ b/clang/test/CodeGenCoroutines/pr59181.cpp @@ -49,6 +49,7 @@ void foo() { } // CHECK: cleanup.cont:{{.*}} +// CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr [[AGG:%agg.tmp]]) // CHECK-NEXT: load i8 // CHECK-NEXT: trunc // CHECK-NEXT: store i1 false @@ -57,3 +58,6 @@ void foo() { // CHECK-NOT: call void @llvm.lifetime // CHECK: call void @llvm.coro.await.suspend.void( // CHECK-NEXT: %{{[0-9]+}} = call i8 @llvm.coro.suspend( + +// CHECK-LABEL: cond.end: +// check call @llvm.lifetime.end.p0(ptr [[AGG]])