https://github.com/AaronBallman updated https://github.com/llvm/llvm-project/pull/133472
>From f9268b3a331fd8caf2440d742a1f084c0f9648ce Mon Sep 17 00:00:00 2001 From: Aaron Ballman <aa...@aaronballman.com> Date: Fri, 28 Mar 2025 13:01:58 -0400 Subject: [PATCH 1/5] [C11] Implement WG14 N1285 (temporary lifetimes) This feature largely models the same behavior as in C++11. It is technically a breaking change between C99 and C11, so the paper is not being backported to older language modes. One difference between C++ and C is that things which are rvalues in C are often lvalues in C++ (such as the result of a ternary operator or a comma operator). --- clang/docs/ReleaseNotes.rst | 9 + clang/lib/CodeGen/CGExpr.cpp | 4 +- clang/lib/Sema/Sema.cpp | 5 +- clang/lib/Sema/SemaInit.cpp | 2 +- clang/test/C/C11/n1285.c | 83 ++++++-- clang/test/C/C11/n1285_1.c | 212 +++++++++++++++++++ clang/test/CodeGenObjC/property-array-type.m | 5 +- clang/www/c_status.html | 2 +- 8 files changed, 301 insertions(+), 21 deletions(-) create mode 100644 clang/test/C/C11/n1285_1.c diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index b96780cec75d9..c51b3c44f3b3b 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -160,6 +160,15 @@ C23 Feature Support treated as if the compound literal were within the body rather than at file scope. +C11 Feature Support +^^^^^^^^^^^^^^^^^^^ +- Implemented `WG14 N1285 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1285.htm>`_ + which introduces the notion of objects with a temporary lifetime. When an + expression resulting in an rvalue with structure or union type and that type + contains a member of array type, the expression result is an automatic storage + duration object with temporary lifetime which begins when the expression is + evaluated and ends at the evaluation of the containing full expression. + Non-comprehensive list of changes in this release ------------------------------------------------- diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp index 5943ff9294e1a..2328ad0def736 100644 --- a/clang/lib/CodeGen/CGExpr.cpp +++ b/clang/lib/CodeGen/CGExpr.cpp @@ -387,8 +387,8 @@ pushTemporaryCleanup(CodeGenFunction &CGF, const MaterializeTemporaryExpr *M, if (const RecordType *RT = E->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) { // Get the destructor for the reference temporary. - auto *ClassDecl = cast<CXXRecordDecl>(RT->getDecl()); - if (!ClassDecl->hasTrivialDestructor()) + if (auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl()); + ClassDecl && !ClassDecl->hasTrivialDestructor()) ReferenceTemporaryDtor = ClassDecl->getDestructor(); } diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp index 93a2d797679d4..4b573abb8efba 100644 --- a/clang/lib/Sema/Sema.cpp +++ b/clang/lib/Sema/Sema.cpp @@ -741,10 +741,11 @@ ExprResult Sema::ImpCastExprToType(Expr *E, QualType Ty, if (Kind == CK_ArrayToPointerDecay) { // C++1z [conv.array]: The temporary materialization conversion is applied. // We also use this to fuel C++ DR1213, which applies to C++11 onwards. - if (getLangOpts().CPlusPlus && E->isPRValue()) { + if ((getLangOpts().C11 || getLangOpts().CPlusPlus) && E->isPRValue()) { // The temporary is an lvalue in C++98 and an xvalue otherwise. ExprResult Materialized = CreateMaterializeTemporaryExpr( - E->getType(), E, !getLangOpts().CPlusPlus11); + E->getType(), E, + getLangOpts().CPlusPlus && !getLangOpts().CPlusPlus11); if (Materialized.isInvalid()) return ExprError(); E = Materialized.get(); diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp index 9814c3f456f0d..c47ea71cbafb5 100644 --- a/clang/lib/Sema/SemaInit.cpp +++ b/clang/lib/Sema/SemaInit.cpp @@ -7654,7 +7654,7 @@ ExprResult Sema::TemporaryMaterializationConversion(Expr *E) { // FIXME: This means that AST consumers need to deal with "prvalues" that // denote materialized temporaries. Maybe we should add another ValueKind // for "xvalue pretending to be a prvalue" for C++98 support. - if (!E->isPRValue() || !getLangOpts().CPlusPlus11) + if (!E->isPRValue() || (!getLangOpts().CPlusPlus11 && !getLangOpts().C11)) return E; // C++1z [conv.rval]/1: T shall be a complete type. diff --git a/clang/test/C/C11/n1285.c b/clang/test/C/C11/n1285.c index e7a9463e68103..c4fb199e33ae5 100644 --- a/clang/test/C/C11/n1285.c +++ b/clang/test/C/C11/n1285.c @@ -1,24 +1,81 @@ -// RUN: %clang_cc1 -verify=wrong -std=c99 %s -// RUN: %clang_cc1 -verify=wrong -std=c11 %s -// RUN: %clang_cc1 -verify=cpp -std=c++11 -x c++ %s +// RUN: %clang_cc1 -fsyntax-only -verify=good -std=c99 %s +// RUN: %clang_cc1 -fsyntax-only -verify=expected,c -std=c11 %s +// RUN: %clang_cc1 -fsyntax-only -verify=expected,cpp -std=c++11 -x c++ %s -/* WG14 N1285: No +/* WG14 N1285: Clang 21 * Extending the lifetime of temporary objects (factored approach) * - * NB: we do not properly materialize temporary expressions in situations where - * it would be expected; that is why the "no-diagnostics" marking is named - * "wrong". We do issue the expected diagnostic in C++ mode. + * This paper introduced the notion of an object with a temporary lifetime. Any + * operation resulting in an rvalue of structure or union type which contains + * an array results in an object with temporary lifetime. */ -// wrong-no-diagnostics +// good-no-diagnostics + +// C11 6.2.4p8: A non-lvalue expression with structure or union type, where the +// structure or union contains a member with array type (including, +// recursively, members of all contained structures and unions) refers to an +// object with automatic storage duration and temporary lifetime. Its lifetime +// begins when the expression is evaluated and its initial value is the value +// of the expression. Its lifetime ends when the evaluation of the containing +// full expression or full declarator ends. Any attempt to modify an object +// with temporary lifetime results in undefined behavior. struct X { int a[5]; }; struct X f(void); -int foo(void) { - // FIXME: This diagnostic should be issued in C11 as well (though not in C99, - // as this paper was a breaking change between C99 and C11). - int *p = f().a; // cpp-warning {{temporary whose address is used as value of local variable 'p' will be destroyed at the end of the full-expression}} - return *p; +union U { int a[10]; double d; }; +union U g(void); + +void sink(int *); + +int func_return(void) { + int *p = f().a; // expected-warning {{temporary whose address is used as value of local variable 'p' will be destroyed at the end of the full-expression}} + p = f().a; // expected-warning {{object backing the pointer p will be destroyed at the end of the full-expression}} + p = g().a; // expected-warning {{object backing the pointer p will be destroyed at the end of the full-expression}} + sink(f().a); // Ok + return *f().a; // Ok +} + +int ternary(void) { + int *p = (1 ? (struct X){ 0 } : f()).a; // expected-warning {{temporary whose address is used as value of local variable 'p' will be destroyed at the end of the full-expression}} + int *r = (1 ? (union U){ 0 } : g()).a; // expected-warning {{temporary whose address is used as value of local variable 'r' will be destroyed at the end of the full-expression}} + p = (1 ? (struct X){ 0 } : f()).a; // expected-warning {{object backing the pointer p will be destroyed at the end of the full-expression}} + sink((1 ? (struct X){ 0 } : f()).a); // Ok + + // This intentionally gets one diagnostic in C and two in C++. In C, the + // compound literal results in an lvalue, not an rvalue as it does in C++. So + // only one branch results in a temporary in C but both branches do in C++. + int *q = 1 ? (struct X){ 0 }.a : f().a; // expected-warning {{temporary whose address is used as value of local variable 'q' will be destroyed at the end of the full-expression}} \ + cpp-warning {{temporary whose address is used as value of local variable 'q' will be destroyed at the end of the full-expression}} + q = 1 ? (struct X){ 0 }.a : f().a; // expected-warning {{object backing the pointer q will be destroyed at the end of the full-expression}} \ + cpp-warning {{object backing the pointer q will be destroyed at the end of the full-expression}} + q = 1 ? (struct X){ 0 }.a : g().a; // expected-warning {{object backing the pointer q will be destroyed at the end of the full-expression}} \ + cpp-warning {{object backing the pointer q will be destroyed at the end of the full-expression}} + sink(1 ? (struct X){ 0 }.a : f().a); // Ok + return *(1 ? (struct X){ 0 }.a : f().a); // Ok } +int comma(void) { + struct X x; + int *p = ((void)0, x).a; // c-warning {{temporary whose address is used as value of local variable 'p' will be destroyed at the end of the full-expression}} + p = ((void)0, x).a; // c-warning {{object backing the pointer p will be destroyed at the end of the full-expression}} + sink(((void)0, x).a); // Ok + return *(((void)0, x).a);// Ok +} + +int cast(void) { + struct X x; + int *p = ((struct X)x).a; // expected-warning {{temporary whose address is used as value of local variable 'p' will be destroyed at the end of the full-expression}} + p = ((struct X)x).a; // expected-warning {{object backing the pointer p will be destroyed at the end of the full-expression}} + sink(((struct X)x).a); // Ok + return *(((struct X)x).a); // Ok +} + +int assign(void) { + struct X x, s; + int *p = (x = s).a; // c-warning {{temporary whose address is used as value of local variable 'p' will be destroyed at the end of the full-expression}} + p = (x = s).a; // c-warning {{object backing the pointer p will be destroyed at the end of the full-expression}} + sink((x = s).a); // Ok + return *((x = s).a); // Ok +} diff --git a/clang/test/C/C11/n1285_1.c b/clang/test/C/C11/n1285_1.c new file mode 100644 index 0000000000000..6a3df58e5a6a0 --- /dev/null +++ b/clang/test/C/C11/n1285_1.c @@ -0,0 +1,212 @@ +// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5 +// RUN: %clang_cc1 -std=c99 -Wno-dangling -emit-llvm -o - %s | FileCheck %s --check-prefix=C99 +// RUN: %clang_cc1 -std=c11 -Wno-dangling -emit-llvm -o - %s | FileCheck %s --check-prefix=C11 + +// Ensure that codegen for temporary lifetimes makes sense. + +struct X { int a[5]; }; +struct X f(void); + +// C99-LABEL: define dso_local i32 @func_return( +// C99-SAME: ) #[[ATTR0:[0-9]+]] { +// C99-NEXT: [[ENTRY:.*:]] +// C99-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C99-NEXT: [[TMP:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C99-NEXT: call void @f(ptr dead_on_unwind writable sret([[STRUCT_X]]) align 4 [[TMP]]) +// C99-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[TMP]], i32 0, i32 0 +// C99-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0 +// C99-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C99-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C99-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C99-NEXT: ret i32 [[TMP1]] +// +// C11-LABEL: define dso_local i32 @func_return( +// C11-SAME: ) #[[ATTR0:[0-9]+]] { +// C11-NEXT: [[ENTRY:.*:]] +// C11-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C11-NEXT: [[REF_TMP:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C11-NEXT: call void @f(ptr dead_on_unwind writable sret([[STRUCT_X]]) align 4 [[REF_TMP]]) +// C11-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[REF_TMP]], i32 0, i32 0 +// C11-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0 +// C11-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C11-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C11-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C11-NEXT: ret i32 [[TMP1]] +// +int func_return(void) { + int *p = f().a; + return *p; +} + +// C99-LABEL: define dso_local i32 @ternary( +// C99-SAME: ) #[[ATTR0]] { +// C99-NEXT: [[ENTRY:.*:]] +// C99-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C99-NEXT: [[TMP:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C99-NEXT: [[Q:%.*]] = alloca ptr, align 8 +// C99-NEXT: [[DOTCOMPOUNDLITERAL:%.*]] = alloca [[STRUCT_X]], align 4 +// C99-NEXT: br i1 true, label %[[COND_TRUE:.*]], label %[[COND_FALSE:.*]] +// C99: [[COND_TRUE]]: +// C99-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[TMP]], i8 0, i64 20, i1 false) +// C99-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[TMP]], i32 0, i32 0 +// C99-NEXT: br label %[[COND_END:.*]] +// C99: [[COND_FALSE]]: +// C99-NEXT: call void @f(ptr dead_on_unwind writable sret([[STRUCT_X]]) align 4 [[TMP]]) +// C99-NEXT: br label %[[COND_END]] +// C99: [[COND_END]]: +// C99-NEXT: [[A1:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[TMP]], i32 0, i32 0 +// C99-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A1]], i64 0, i64 0 +// C99-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C99-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[DOTCOMPOUNDLITERAL]], i8 0, i64 20, i1 false) +// C99-NEXT: [[A2:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[DOTCOMPOUNDLITERAL]], i32 0, i32 0 +// C99-NEXT: [[A3:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[DOTCOMPOUNDLITERAL]], i32 0, i32 0 +// C99-NEXT: [[ARRAYDECAY4:%.*]] = getelementptr inbounds [5 x i32], ptr [[A3]], i64 0, i64 0 +// C99-NEXT: store ptr [[ARRAYDECAY4]], ptr [[Q]], align 8 +// C99-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C99-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C99-NEXT: [[TMP2:%.*]] = load ptr, ptr [[Q]], align 8 +// C99-NEXT: [[TMP3:%.*]] = load i32, ptr [[TMP2]], align 4 +// C99-NEXT: [[ADD:%.*]] = add nsw i32 [[TMP1]], [[TMP3]] +// C99-NEXT: ret i32 [[ADD]] +// +// C11-LABEL: define dso_local i32 @ternary( +// C11-SAME: ) #[[ATTR0]] { +// C11-NEXT: [[ENTRY:.*:]] +// C11-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C11-NEXT: [[REF_TMP:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C11-NEXT: [[Q:%.*]] = alloca ptr, align 8 +// C11-NEXT: [[DOTCOMPOUNDLITERAL:%.*]] = alloca [[STRUCT_X]], align 4 +// C11-NEXT: br i1 true, label %[[COND_TRUE:.*]], label %[[COND_FALSE:.*]] +// C11: [[COND_TRUE]]: +// C11-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[REF_TMP]], i8 0, i64 20, i1 false) +// C11-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[REF_TMP]], i32 0, i32 0 +// C11-NEXT: br label %[[COND_END:.*]] +// C11: [[COND_FALSE]]: +// C11-NEXT: call void @f(ptr dead_on_unwind writable sret([[STRUCT_X]]) align 4 [[REF_TMP]]) +// C11-NEXT: br label %[[COND_END]] +// C11: [[COND_END]]: +// C11-NEXT: [[A1:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[REF_TMP]], i32 0, i32 0 +// C11-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A1]], i64 0, i64 0 +// C11-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C11-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[DOTCOMPOUNDLITERAL]], i8 0, i64 20, i1 false) +// C11-NEXT: [[A2:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[DOTCOMPOUNDLITERAL]], i32 0, i32 0 +// C11-NEXT: [[A3:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[DOTCOMPOUNDLITERAL]], i32 0, i32 0 +// C11-NEXT: [[ARRAYDECAY4:%.*]] = getelementptr inbounds [5 x i32], ptr [[A3]], i64 0, i64 0 +// C11-NEXT: store ptr [[ARRAYDECAY4]], ptr [[Q]], align 8 +// C11-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C11-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C11-NEXT: [[TMP2:%.*]] = load ptr, ptr [[Q]], align 8 +// C11-NEXT: [[TMP3:%.*]] = load i32, ptr [[TMP2]], align 4 +// C11-NEXT: [[ADD:%.*]] = add nsw i32 [[TMP1]], [[TMP3]] +// C11-NEXT: ret i32 [[ADD]] +// +int ternary(void) { + int *p; + p = (1 ? (struct X){ 0 } : f()).a; + int *q = 1 ? (struct X){ 0 }.a : f().a; + + return *p + *q; +} + +// C99-LABEL: define dso_local i32 @comma( +// C99-SAME: ) #[[ATTR0]] { +// C99-NEXT: [[ENTRY:.*:]] +// C99-NEXT: [[X:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C99-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C99-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[X]], i32 0, i32 0 +// C99-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0 +// C99-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C99-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C99-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C99-NEXT: ret i32 [[TMP1]] +// +// C11-LABEL: define dso_local i32 @comma( +// C11-SAME: ) #[[ATTR0]] { +// C11-NEXT: [[ENTRY:.*:]] +// C11-NEXT: [[X:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C11-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C11-NEXT: [[REF_TMP:%.*]] = alloca [[STRUCT_X]], align 4 +// C11-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[REF_TMP]], ptr align 4 [[X]], i64 20, i1 false) +// C11-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[REF_TMP]], i32 0, i32 0 +// C11-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0 +// C11-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C11-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C11-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C11-NEXT: ret i32 [[TMP1]] +// +int comma(void) { + struct X x; + int *p = ((void)0, x).a; + return *p; +} + +// C99-LABEL: define dso_local i32 @cast( +// C99-SAME: ) #[[ATTR0]] { +// C99-NEXT: [[ENTRY:.*:]] +// C99-NEXT: [[X:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C99-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C99-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[X]], i32 0, i32 0 +// C99-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0 +// C99-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C99-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C99-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C99-NEXT: ret i32 [[TMP1]] +// +// C11-LABEL: define dso_local i32 @cast( +// C11-SAME: ) #[[ATTR0]] { +// C11-NEXT: [[ENTRY:.*:]] +// C11-NEXT: [[X:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C11-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C11-NEXT: [[REF_TMP:%.*]] = alloca [[STRUCT_X]], align 4 +// C11-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[REF_TMP]], ptr align 4 [[X]], i64 20, i1 false) +// C11-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[REF_TMP]], i32 0, i32 0 +// C11-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0 +// C11-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C11-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C11-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C11-NEXT: ret i32 [[TMP1]] +// +int cast(void) { + struct X x; + int *p; + p = ((struct X)x).a; + return *p; +} + +// C99-LABEL: define dso_local i32 @assign( +// C99-SAME: ) #[[ATTR0]] { +// C99-NEXT: [[ENTRY:.*:]] +// C99-NEXT: [[X:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C99-NEXT: [[S:%.*]] = alloca [[STRUCT_X]], align 4 +// C99-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C99-NEXT: [[TMP:%.*]] = alloca [[STRUCT_X]], align 4 +// C99-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[X]], ptr align 4 [[S]], i64 20, i1 false) +// C99-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[TMP]], ptr align 4 [[X]], i64 20, i1 false) +// C99-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[TMP]], i32 0, i32 0 +// C99-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0 +// C99-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C99-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C99-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C99-NEXT: ret i32 [[TMP1]] +// +// C11-LABEL: define dso_local i32 @assign( +// C11-SAME: ) #[[ATTR0]] { +// C11-NEXT: [[ENTRY:.*:]] +// C11-NEXT: [[X:%.*]] = alloca [[STRUCT_X:%.*]], align 4 +// C11-NEXT: [[S:%.*]] = alloca [[STRUCT_X]], align 4 +// C11-NEXT: [[P:%.*]] = alloca ptr, align 8 +// C11-NEXT: [[REF_TMP:%.*]] = alloca [[STRUCT_X]], align 4 +// C11-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[X]], ptr align 4 [[S]], i64 20, i1 false) +// C11-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[REF_TMP]], ptr align 4 [[X]], i64 20, i1 false) +// C11-NEXT: [[A:%.*]] = getelementptr inbounds nuw [[STRUCT_X]], ptr [[REF_TMP]], i32 0, i32 0 +// C11-NEXT: [[ARRAYDECAY:%.*]] = getelementptr inbounds [5 x i32], ptr [[A]], i64 0, i64 0 +// C11-NEXT: store ptr [[ARRAYDECAY]], ptr [[P]], align 8 +// C11-NEXT: [[TMP0:%.*]] = load ptr, ptr [[P]], align 8 +// C11-NEXT: [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4 +// C11-NEXT: ret i32 [[TMP1]] +// +int assign(void) { + struct X x, s; + int *p = (x = s).a; + return *p; +} diff --git a/clang/test/CodeGenObjC/property-array-type.m b/clang/test/CodeGenObjC/property-array-type.m index a0ad8db2630fa..3bb1e3c63334e 100644 --- a/clang/test/CodeGenObjC/property-array-type.m +++ b/clang/test/CodeGenObjC/property-array-type.m @@ -23,7 +23,8 @@ - (void)viewDidLoad { } @end -// CHECK: [[M:%.*]] = getelementptr inbounds nuw %struct._GLKMatrix4, ptr [[TMP:%.*]], i32 0, i32 0 +// CHECK: [[REF_TEMP:%.*]] = alloca %struct._GLKMatrix4, align 4 +// CHECK: [[M:%.*]] = getelementptr inbounds nuw %struct._GLKMatrix4, ptr [[REF_TEMP:%.*]], i32 0, i32 0 // CHECK: [[ARRAYDECAY:%.*]] = getelementptr inbounds [16 x float], ptr [[M]], i64 0, i64 0 // CHECK: [[SIX:%.*]] = load ptr, ptr @OBJC_SELECTOR_REFERENCES -// CHECK: call void @objc_msgSend(ptr noundef [[SEVEN:%.*]], ptr noundef [[SIX]], ptr noundef [[ARRAYDECAY]]) +// CHECK: call void @objc_msgSend(ptr noundef [[SEVEN:%.*]], ptr noundef [[SIX]], ptr noundef [[ARRAYDECAY]]) diff --git a/clang/www/c_status.html b/clang/www/c_status.html index f4f00ac6dd808..0a5de40efe6dc 100644 --- a/clang/www/c_status.html +++ b/clang/www/c_status.html @@ -941,7 +941,7 @@ <h2 id="c11">C11 implementation status</h2> <tr> <td>Extending the lifetime of temporary objects (factored approach)</td> <td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1285.htm";>N1285</a></td> - <td class="none" align="center">No</td> + <td class="unreleased" align="center">Clang 21</td> </tr> <tr> <td>Requiring signed char to have no padding bits</td> >From 54a7a06472d767ffac6ff6730ba8349e0a5a88e4 Mon Sep 17 00:00:00 2001 From: Aaron Ballman <aa...@aaronballman.com> Date: Mon, 31 Mar 2025 07:42:37 -0400 Subject: [PATCH 2/5] Fix codegen --- clang/lib/CodeGen/CGDecl.cpp | 11 +++- clang/lib/CodeGen/CGExpr.cpp | 86 ++++++++++++++--------------- clang/lib/CodeGen/CodeGenFunction.h | 2 + clang/test/CodeGen/xcore-abi.c | 3 +- 4 files changed, 53 insertions(+), 49 deletions(-) diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp index eab1ebfb2369b..3ba0b970554a6 100644 --- a/clang/lib/CodeGen/CGDecl.cpp +++ b/clang/lib/CodeGen/CGDecl.cpp @@ -2269,11 +2269,18 @@ void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind, cleanupKind & EHCleanup); } + void CodeGenFunction::pushLifetimeExtendedDestroy( + QualType::DestructionKind dtorKind, Address addr, QualType type) { + CleanupKind cleanupKind = getCleanupKind(dtorKind); + pushLifetimeExtendedDestroy(cleanupKind, addr, type, getDestroyer(dtorKind), + cleanupKind & EHCleanup); +} + void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, Address addr, QualType type, Destroyer *destroyer, bool useEHCleanupForArray) { - pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type, - destroyer, useEHCleanupForArray); + pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type, destroyer, + useEHCleanupForArray); } // Pushes a destroy and defers its deactivation until its diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp index 2328ad0def736..1066d4f79718b 100644 --- a/clang/lib/CodeGen/CGExpr.cpp +++ b/clang/lib/CodeGen/CGExpr.cpp @@ -383,55 +383,49 @@ pushTemporaryCleanup(CodeGenFunction &CGF, const MaterializeTemporaryExpr *M, } } - CXXDestructorDecl *ReferenceTemporaryDtor = nullptr; - if (const RecordType *RT = - E->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) { - // Get the destructor for the reference temporary. - if (auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl()); - ClassDecl && !ClassDecl->hasTrivialDestructor()) - ReferenceTemporaryDtor = ClassDecl->getDestructor(); - } + QualType::DestructionKind DK = E->getType().isDestructedType(); + if (DK != QualType::DK_none) { + switch (M->getStorageDuration()) { + case SD_Static: + case SD_Thread: { + CXXDestructorDecl *ReferenceTemporaryDtor = nullptr; + if (const RecordType *RT = + E->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) { + // Get the destructor for the reference temporary. + if (auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl()); + ClassDecl && !ClassDecl->hasTrivialDestructor()) + ReferenceTemporaryDtor = ClassDecl->getDestructor(); + } - if (!ReferenceTemporaryDtor) - return; + if (!ReferenceTemporaryDtor) + return; - // Call the destructor for the temporary. - switch (M->getStorageDuration()) { - case SD_Static: - case SD_Thread: { - llvm::FunctionCallee CleanupFn; - llvm::Constant *CleanupArg; - if (E->getType()->isArrayType()) { - CleanupFn = CodeGenFunction(CGF.CGM).generateDestroyHelper( - ReferenceTemporary, E->getType(), - CodeGenFunction::destroyCXXObject, CGF.getLangOpts().Exceptions, - dyn_cast_or_null<VarDecl>(M->getExtendingDecl())); - CleanupArg = llvm::Constant::getNullValue(CGF.Int8PtrTy); - } else { - CleanupFn = CGF.CGM.getAddrAndTypeOfCXXStructor( - GlobalDecl(ReferenceTemporaryDtor, Dtor_Complete)); - CleanupArg = cast<llvm::Constant>(ReferenceTemporary.emitRawPointer(CGF)); + llvm::FunctionCallee CleanupFn; + llvm::Constant *CleanupArg; + if (E->getType()->isArrayType()) { + CleanupFn = CodeGenFunction(CGF.CGM).generateDestroyHelper( + ReferenceTemporary, E->getType(), CodeGenFunction::destroyCXXObject, + CGF.getLangOpts().Exceptions, + dyn_cast_or_null<VarDecl>(M->getExtendingDecl())); + CleanupArg = llvm::Constant::getNullValue(CGF.Int8PtrTy); + } else { + CleanupFn = CGF.CGM.getAddrAndTypeOfCXXStructor( + GlobalDecl(ReferenceTemporaryDtor, Dtor_Complete)); + CleanupArg = + cast<llvm::Constant>(ReferenceTemporary.emitRawPointer(CGF)); + } + CGF.CGM.getCXXABI().registerGlobalDtor( + CGF, *cast<VarDecl>(M->getExtendingDecl()), CleanupFn, CleanupArg); + } break; + case SD_FullExpression: + CGF.pushDestroy(DK, ReferenceTemporary, E->getType()); + break; + case SD_Automatic: + CGF.pushLifetimeExtendedDestroy(DK, ReferenceTemporary, E->getType()); + break; + case SD_Dynamic: + llvm_unreachable("temporary cannot have dynamic storage duration"); } - CGF.CGM.getCXXABI().registerGlobalDtor( - CGF, *cast<VarDecl>(M->getExtendingDecl()), CleanupFn, CleanupArg); - break; - } - - case SD_FullExpression: - CGF.pushDestroy(NormalAndEHCleanup, ReferenceTemporary, E->getType(), - CodeGenFunction::destroyCXXObject, - CGF.getLangOpts().Exceptions); - break; - - case SD_Automatic: - CGF.pushLifetimeExtendedDestroy(NormalAndEHCleanup, - ReferenceTemporary, E->getType(), - CodeGenFunction::destroyCXXObject, - CGF.getLangOpts().Exceptions); - break; - - case SD_Dynamic: - llvm_unreachable("temporary cannot have dynamic storage duration"); } } diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h index ca00a0e8c6cf4..12425d817b5f0 100644 --- a/clang/lib/CodeGen/CodeGenFunction.h +++ b/clang/lib/CodeGen/CodeGenFunction.h @@ -2273,6 +2273,8 @@ class CodeGenFunction : public CodeGenTypeCache { void pushLifetimeExtendedDestroy(CleanupKind kind, Address addr, QualType type, Destroyer *destroyer, bool useEHCleanupForArray); + void pushLifetimeExtendedDestroy(QualType::DestructionKind dtorKind, + Address addr, QualType type); void pushCallObjectDeleteCleanup(const FunctionDecl *OperatorDelete, llvm::Value *CompletePtr, QualType ElementType); diff --git a/clang/test/CodeGen/xcore-abi.c b/clang/test/CodeGen/xcore-abi.c index 40e2f418f7304..5a6849cd2e2e4 100644 --- a/clang/test/CodeGen/xcore-abi.c +++ b/clang/test/CodeGen/xcore-abi.c @@ -77,7 +77,8 @@ void testva (int n, ...) { // CHECK: call void @f(ptr noundef [[V5]]) // an unusual aggregate type - int* v6 = va_arg (ap, int[4]); // expected-warning{{second argument to 'va_arg' is of array type 'int[4]'}} + int* v6 = va_arg (ap, int[4]); // expected-warning{{second argument to 'va_arg' is of array type 'int[4]'}} \ + expected-warning{{temporary whose address is used as value of local variable 'v6' will be destroyed at the end of the full-expression}} f(v6); // CHECK: [[I:%[a-z0-9]+]] = load ptr, ptr [[AP]] // CHECK: [[P:%[a-z0-9]+]] = load ptr, ptr [[I]] >From 22b87ac21f924975e1ec9d3c8db74019e58008b4 Mon Sep 17 00:00:00 2001 From: Aaron Ballman <aa...@aaronballman.com> Date: Mon, 31 Mar 2025 07:58:26 -0400 Subject: [PATCH 3/5] Fix formatting; NFC --- clang/lib/CodeGen/CGDecl.cpp | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp index 3ba0b970554a6..853f448c387a5 100644 --- a/clang/lib/CodeGen/CGDecl.cpp +++ b/clang/lib/CodeGen/CGDecl.cpp @@ -2269,7 +2269,7 @@ void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind, cleanupKind & EHCleanup); } - void CodeGenFunction::pushLifetimeExtendedDestroy( +void CodeGenFunction::pushLifetimeExtendedDestroy( QualType::DestructionKind dtorKind, Address addr, QualType type) { CleanupKind cleanupKind = getCleanupKind(dtorKind); pushLifetimeExtendedDestroy(cleanupKind, addr, type, getDestroyer(dtorKind), >From 15b3f7b1bedb48dc2428ce4ec40488e3784efdf5 Mon Sep 17 00:00:00 2001 From: Aaron Ballman <aa...@aaronballman.com> Date: Mon, 31 Mar 2025 08:23:01 -0400 Subject: [PATCH 4/5] Back out unnecessary changes --- clang/lib/Sema/Sema.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp index 4b573abb8efba..daf48e84f1413 100644 --- a/clang/lib/Sema/Sema.cpp +++ b/clang/lib/Sema/Sema.cpp @@ -741,11 +741,11 @@ ExprResult Sema::ImpCastExprToType(Expr *E, QualType Ty, if (Kind == CK_ArrayToPointerDecay) { // C++1z [conv.array]: The temporary materialization conversion is applied. // We also use this to fuel C++ DR1213, which applies to C++11 onwards. - if ((getLangOpts().C11 || getLangOpts().CPlusPlus) && E->isPRValue()) { + if (getLangOpts().CPlusPlus && E->isPRValue()) { // The temporary is an lvalue in C++98 and an xvalue otherwise. ExprResult Materialized = CreateMaterializeTemporaryExpr( E->getType(), E, - getLangOpts().CPlusPlus && !getLangOpts().CPlusPlus11); + !getLangOpts().CPlusPlus11); if (Materialized.isInvalid()) return ExprError(); E = Materialized.get(); >From 94b396c86549f778f35fcb6100639a4de15d873d Mon Sep 17 00:00:00 2001 From: Aaron Ballman <aa...@aaronballman.com> Date: Mon, 31 Mar 2025 08:31:32 -0400 Subject: [PATCH 5/5] Speculative fix for codegen test --- clang/test/CodeGen/xcore-abi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/clang/test/CodeGen/xcore-abi.c b/clang/test/CodeGen/xcore-abi.c index 5a6849cd2e2e4..9f7026648d036 100644 --- a/clang/test/CodeGen/xcore-abi.c +++ b/clang/test/CodeGen/xcore-abi.c @@ -27,7 +27,7 @@ void testva (int n, ...) { va_start(ap,n); // CHECK: [[AP:%[a-z0-9]+]] = alloca ptr, align 4 // CHECK: [[V5:%[a-z0-9]+]] = alloca %struct.x, align 4 - // CHECK: [[TMP:%[a-z0-9]+]] = alloca [4 x i32], align 4 + // CHECK: [[TMP:%[a-z0-9\.]+]] = alloca [4 x i32], align 4 // CHECK: call void @llvm.va_start.p0(ptr [[AP]]) char* v1 = va_arg (ap, char*); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
