This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG5955a0f9375a: Allow flexible array initialization in C++.
(authored by efriedma).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D123649/new/
https://reviews.llvm.org/D123649
Files:
clang/include/clang/AST/Decl.h
clang/include/clang/Basic/DiagnosticASTKinds.td
clang/lib/AST/Decl.cpp
clang/lib/AST/ExprConstant.cpp
clang/lib/CodeGen/CGDecl.cpp
clang/lib/CodeGen/CodeGenModule.cpp
clang/lib/Sema/SemaInit.cpp
clang/test/CodeGenCXX/flexible-array-init.cpp
clang/test/SemaCXX/constant-expression-cxx11.cpp
Index: clang/test/SemaCXX/constant-expression-cxx11.cpp
===================================================================
--- clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -2383,9 +2383,11 @@
static_assert(b[2].x == 3, "");
static_assert(b[2].arr[0], ""); // expected-error {{constant expression}} expected-note {{array member without known bound}}
- // If we ever start to accept this, we'll need to ensure we can
- // constant-evaluate it properly.
- constexpr A c = {1, 2, 3}; // expected-error {{initialization of flexible array member}}
+ // Flexible array initialization is currently not supported by constant
+ // evaluation. Make sure we emit an error message, for now.
+ constexpr A c = {1, 2, 3}; // expected-error {{constexpr variable 'c' must be initialized by a constant expression}}
+ // expected-note@-1 {{flexible array initialization is not yet supported}}
+ // expected-warning@-2 {{flexible array initialization is a GNU extension}}
}
void local_constexpr_var() {
Index: clang/test/CodeGenCXX/flexible-array-init.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/flexible-array-init.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -triple i386-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple i386-unknown-unknown -emit-llvm-only -verify -DFAIL1 %s
+// RUN: %clang_cc1 -triple i386-unknown-unknown -emit-llvm-only -verify -DFAIL2 %s
+
+struct A { int x; int y[]; };
+A a = { 1, 7, 11 };
+// CHECK: @a ={{.*}} global { i32, [2 x i32] } { i32 1, [2 x i32] [i32 7, i32 11] }
+
+A b = { 1, { 13, 15 } };
+// CHECK: @b ={{.*}} global { i32, [2 x i32] } { i32 1, [2 x i32] [i32 13, i32 15] }
+
+int f();
+#ifdef FAIL1
+A c = { f(), { f(), f() } }; // expected-error {{cannot compile this flexible array initializer yet}}
+#endif
+#ifdef FAIL2
+void g() {
+ static A d = { f(), { f(), f() } }; // expected-error {{cannot compile this flexible array initializer yet}}
+}
+#endif
Index: clang/lib/Sema/SemaInit.cpp
===================================================================
--- clang/lib/Sema/SemaInit.cpp
+++ clang/lib/Sema/SemaInit.cpp
@@ -2004,10 +2004,6 @@
cast<InitListExpr>(InitExpr)->getNumInits() == 0) {
// Empty flexible array init always allowed as an extension
FlexArrayDiag = diag::ext_flexible_array_init;
- } else if (SemaRef.getLangOpts().CPlusPlus) {
- // Disallow flexible array init in C++; it is not required for gcc
- // compatibility, and it needs work to IRGen correctly in general.
- FlexArrayDiag = diag::err_flexible_array_init;
} else if (!TopLevelObject) {
// Disallow flexible array init on non-top-level object
FlexArrayDiag = diag::err_flexible_array_init;
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -4615,6 +4615,8 @@
T = D->getType();
if (getLangOpts().CPlusPlus) {
+ if (!InitDecl->getFlexibleArrayInitChars(getContext()).isZero())
+ ErrorUnsupported(D, "flexible array initializer");
Init = EmitNullConstant(T);
NeedsGlobalCtor = true;
} else {
@@ -4628,6 +4630,14 @@
// also don't need to register a destructor.
if (getLangOpts().CPlusPlus && !NeedsGlobalDtor)
DelayedCXXInitPosition.erase(D);
+
+#ifndef NDEBUG
+ CharUnits VarSize = getContext().getTypeSizeInChars(ASTTy) +
+ InitDecl->getFlexibleArrayInitChars(getContext());
+ CharUnits CstSize = CharUnits::fromQuantity(
+ getDataLayout().getTypeAllocSize(Init->getType()));
+ assert(VarSize == CstSize && "Emitted constant has unexpected size");
+#endif
}
}
Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -342,6 +342,8 @@
if (!Init) {
if (!getLangOpts().CPlusPlus)
CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
+ else if (!D.getFlexibleArrayInitChars(getContext()).isZero())
+ CGM.ErrorUnsupported(D.getInit(), "flexible array initializer");
else if (HaveInsertPoint()) {
// Since we have a static initializer, this global variable can't
// be constant.
@@ -352,6 +354,14 @@
return GV;
}
+#ifndef NDEBUG
+ CharUnits VarSize = CGM.getContext().getTypeSizeInChars(D.getType()) +
+ D.getFlexibleArrayInitChars(getContext());
+ CharUnits CstSize = CharUnits::fromQuantity(
+ CGM.getDataLayout().getTypeAllocSize(Init->getType()));
+ assert(VarSize == CstSize && "Emitted constant has unexpected size");
+#endif
+
// The initializer may differ in type from the global. Rewrite
// the global to match the initializer. (We have to do this
// because some types, like unions, can't be completely represented
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -9980,6 +9980,17 @@
ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType());
const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE;
+ if (Field->getType()->isIncompleteArrayType()) {
+ if (auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType())) {
+ if (!CAT->getSize().isZero()) {
+ // Bail out for now. This might sort of "work", but the rest of the
+ // code isn't really prepared to handle it.
+ Info.FFDiag(Init, diag::note_constexpr_unsupported_flexible_array);
+ return false;
+ }
+ }
+ }
+
// Temporarily override This, in case there's a CXXDefaultInitExpr in here.
ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
isa<CXXDefaultInitExpr>(Init));
Index: clang/lib/AST/Decl.cpp
===================================================================
--- clang/lib/AST/Decl.cpp
+++ clang/lib/AST/Decl.cpp
@@ -2722,6 +2722,21 @@
return getType().isDestructedType();
}
+CharUnits VarDecl::getFlexibleArrayInitChars(const ASTContext &Ctx) const {
+ assert(hasInit() && "Expect initializer to check for flexible array init");
+ auto *Ty = getType()->getAs<RecordType>();
+ if (!Ty || !Ty->getDecl()->hasFlexibleArrayMember())
+ return CharUnits::Zero();
+ auto *List = dyn_cast<InitListExpr>(getInit()->IgnoreParens());
+ if (!List)
+ return CharUnits::Zero();
+ auto FlexibleInit = List->getInit(List->getNumInits() - 1);
+ auto InitTy = Ctx.getAsConstantArrayType(FlexibleInit->getType());
+ if (!InitTy)
+ return CharUnits::Zero();
+ return Ctx.getTypeSizeInChars(InitTy);
+}
+
MemberSpecializationInfo *VarDecl::getMemberSpecializationInfo() const {
if (isStaticDataMember())
// FIXME: Remove ?
Index: clang/include/clang/Basic/DiagnosticASTKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticASTKinds.td
+++ clang/include/clang/Basic/DiagnosticASTKinds.td
@@ -364,6 +364,8 @@
"%plural{0:|: (along with %0 other memory leak%s0)}0">;
def note_constexpr_unsupported_layout : Note<
"type %0 has unexpected layout">;
+def note_constexpr_unsupported_flexible_array : Note<
+ "flexible array initialization is not yet supported">;
def err_experimental_clang_interp_failed : Error<
"the experimental clang interpreter failed to evaluate an expression">;
Index: clang/include/clang/AST/Decl.h
===================================================================
--- clang/include/clang/AST/Decl.h
+++ clang/include/clang/AST/Decl.h
@@ -1591,6 +1591,14 @@
/// kind?
QualType::DestructionKind needsDestruction(const ASTContext &Ctx) const;
+ /// If this variable declares a struct with a flexible array member, and
+ /// the flexible array member is initialized with one or more elements,
+ /// compute the number of bytes necessary to store those elements.
+ ///
+ /// (The standard doesn't allow initializing flexible array members; this is
+ /// a gcc/msvc extension.)
+ CharUnits getFlexibleArrayInitChars(const ASTContext &Ctx) const;
+
// Implement isa/cast/dyncast/etc.
static bool classof(const Decl *D) { return classofKind(D->getKind()); }
static bool classofKind(Kind K) { return K >= firstVar && K <= lastVar; }
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