r186799 - Tighten up the set of operator new/operator delete calls we're permitted to
Richard Smith
richard-llvm at metafoo.co.uk
Sun Jul 21 16:12:19 PDT 2013
Author: rsmith
Date: Sun Jul 21 18:12:18 2013
New Revision: 186799
URL: http://llvm.org/viewvc/llvm-project?rev=186799&view=rev
Log:
Tighten up the set of operator new/operator delete calls we're permitted to
optimize, to follow the permissions granted in N3664. Under those rules, only
calls generated by new-expressions and delete-expressions are permitted to be
optimized, and direct calls to ::operator new and ::operator delete must be
treated as normal calls.
Modified:
cfe/trunk/include/clang/AST/Decl.h
cfe/trunk/lib/AST/Decl.cpp
cfe/trunk/lib/CodeGen/CGExprCXX.cpp
cfe/trunk/lib/CodeGen/CodeGenModule.cpp
cfe/trunk/test/CodeGenCXX/new.cpp
cfe/trunk/www/cxx_status.html
Modified: cfe/trunk/include/clang/AST/Decl.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Decl.h?rev=186799&r1=186798&r2=186799&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Decl.h (original)
+++ cfe/trunk/include/clang/AST/Decl.h Sun Jul 21 18:12:18 2013
@@ -1720,6 +1720,21 @@ public:
/// This function must be an allocation or deallocation function.
bool isReservedGlobalPlacementOperator() const;
+ /// \brief Determines whether this function is one of the replaceable
+ /// global allocation functions:
+ /// void *operator new(size_t);
+ /// void *operator new(size_t, const std::nothrow_t &) noexcept;
+ /// void *operator new[](size_t);
+ /// void *operator new[](size_t, const std::nothrow_t &) noexcept;
+ /// void operator delete(void *) noexcept;
+ /// void operator delete(void *, const std::nothrow_t &) noexcept;
+ /// void operator delete[](void *) noexcept;
+ /// void operator delete[](void *, const std::nothrow_t &) noexcept;
+ /// These functions have special behavior under C++1y [expr.new]:
+ /// An implementation is allowed to omit a call to a replaceable global
+ /// allocation function. [...]
+ bool isReplaceableGlobalAllocationFunction() const;
+
/// Compute the language linkage.
LanguageLinkage getLanguageLinkage() const;
Modified: cfe/trunk/lib/AST/Decl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Decl.cpp?rev=186799&r1=186798&r2=186799&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Decl.cpp (original)
+++ cfe/trunk/lib/AST/Decl.cpp Sun Jul 21 18:12:18 2013
@@ -2132,13 +2132,18 @@ void FunctionDecl::setPure(bool P) {
Parent->markedVirtualFunctionPure();
}
+template<std::size_t Len>
+static bool isNamed(const NamedDecl *ND, const char (&Str)[Len]) {
+ IdentifierInfo *II = ND->getIdentifier();
+ return II && II->isStr(Str);
+}
+
bool FunctionDecl::isMain() const {
const TranslationUnitDecl *tunit =
dyn_cast<TranslationUnitDecl>(getDeclContext()->getRedeclContext());
return tunit &&
!tunit->getASTContext().getLangOpts().Freestanding &&
- getIdentifier() &&
- getIdentifier()->isStr("main");
+ isNamed(this, "main");
}
bool FunctionDecl::isReservedGlobalPlacementOperator() const {
@@ -2163,6 +2168,47 @@ bool FunctionDecl::isReservedGlobalPlace
return (proto->getArgType(1).getCanonicalType() == Context.VoidPtrTy);
}
+static bool isNamespaceStd(const DeclContext *DC) {
+ const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC->getRedeclContext());
+ return ND && isNamed(ND, "std") &&
+ ND->getParent()->getRedeclContext()->isTranslationUnit();
+}
+
+bool FunctionDecl::isReplaceableGlobalAllocationFunction() const {
+ if (getDeclName().getNameKind() != DeclarationName::CXXOperatorName)
+ return false;
+ if (getDeclName().getCXXOverloadedOperator() != OO_New &&
+ getDeclName().getCXXOverloadedOperator() != OO_Delete &&
+ getDeclName().getCXXOverloadedOperator() != OO_Array_New &&
+ getDeclName().getCXXOverloadedOperator() != OO_Array_Delete)
+ return false;
+
+ if (isa<CXXRecordDecl>(getDeclContext()))
+ return false;
+ assert(getDeclContext()->getRedeclContext()->isTranslationUnit());
+
+ const FunctionProtoType *FPT = getType()->castAs<FunctionProtoType>();
+ if (FPT->getNumArgs() > 2 || FPT->isVariadic())
+ return false;
+
+ // If this is a single-parameter function, it must be a replaceable global
+ // allocation or deallocation function.
+ if (FPT->getNumArgs() == 1)
+ return true;
+
+ // Otherwise, we're looking for a second parameter whose type is
+ // 'const std::nothrow_t &'.
+ QualType Ty = FPT->getArgType(1);
+ if (!Ty->isReferenceType())
+ return false;
+ Ty = Ty->getPointeeType();
+ if (Ty.getCVRQualifiers() != Qualifiers::Const)
+ return false;
+ // FIXME: Recognise nothrow_t in an inline namespace inside std?
+ const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
+ return RD && isNamed(RD, "nothrow_t") && isNamespaceStd(RD->getDeclContext());
+}
+
LanguageLinkage FunctionDecl::getLanguageLinkage() const {
// Users expect to be able to write
// extern "C" void *__builtin_alloca (size_t);
Modified: cfe/trunk/lib/CodeGen/CGExprCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprCXX.cpp?rev=186799&r1=186798&r2=186799&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprCXX.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprCXX.cpp Sun Jul 21 18:12:18 2013
@@ -1002,6 +1002,38 @@ static void EmitNewInitializer(CodeGenFu
StoreAnyExprIntoOneUnit(CGF, Init, E->getAllocatedType(), NewPtr);
}
+/// Emit a call to an operator new or operator delete function, as implicitly
+/// created by new-expressions and delete-expressions.
+static RValue EmitNewDeleteCall(CodeGenFunction &CGF,
+ const FunctionDecl *Callee,
+ const FunctionProtoType *CalleeType,
+ const CallArgList &Args) {
+ llvm::Instruction *CallOrInvoke;
+ RValue RV =
+ CGF.EmitCall(CGF.CGM.getTypes().arrangeFreeFunctionCall(Args, CalleeType),
+ CGF.CGM.GetAddrOfFunction(Callee), ReturnValueSlot(), Args,
+ Callee, &CallOrInvoke);
+
+ /// C++1y [expr.new]p10:
+ /// [In a new-expression,] an implementation is allowed to omit a call
+ /// to a replaceable global allocation function.
+ ///
+ /// We model such elidable calls with the 'builtin' attribute.
+ if (Callee->isReplaceableGlobalAllocationFunction()) {
+ // FIXME: Add addAttribute to CallSite.
+ if (llvm::CallInst *CI = dyn_cast<llvm::CallInst>(CallOrInvoke))
+ CI->addAttribute(llvm::AttributeSet::FunctionIndex,
+ llvm::Attribute::Builtin);
+ else if (llvm::InvokeInst *II = dyn_cast<llvm::InvokeInst>(CallOrInvoke))
+ II->addAttribute(llvm::AttributeSet::FunctionIndex,
+ llvm::Attribute::Builtin);
+ else
+ llvm_unreachable("unexpected kind of call instruction");
+ }
+
+ return RV;
+}
+
namespace {
/// A cleanup to call the given 'operator delete' function upon
/// abnormal exit from a new expression.
@@ -1051,9 +1083,7 @@ namespace {
DeleteArgs.add(getPlacementArgs()[I], *AI++);
// Call 'operator delete'.
- CGF.EmitCall(CGF.CGM.getTypes().arrangeFreeFunctionCall(DeleteArgs, FPT),
- CGF.CGM.GetAddrOfFunction(OperatorDelete),
- ReturnValueSlot(), DeleteArgs, OperatorDelete);
+ EmitNewDeleteCall(CGF, OperatorDelete, FPT, DeleteArgs);
}
};
@@ -1112,9 +1142,7 @@ namespace {
}
// Call 'operator delete'.
- CGF.EmitCall(CGF.CGM.getTypes().arrangeFreeFunctionCall(DeleteArgs, FPT),
- CGF.CGM.GetAddrOfFunction(OperatorDelete),
- ReturnValueSlot(), DeleteArgs, OperatorDelete);
+ EmitNewDeleteCall(CGF, OperatorDelete, FPT, DeleteArgs);
}
};
}
@@ -1227,10 +1255,7 @@ llvm::Value *CodeGenFunction::EmitCXXNew
// TODO: kill any unnecessary computations done for the size
// argument.
} else {
- RV = EmitCall(CGM.getTypes().arrangeFreeFunctionCall(allocatorArgs,
- allocatorType),
- CGM.GetAddrOfFunction(allocator), ReturnValueSlot(),
- allocatorArgs, allocator);
+ RV = EmitNewDeleteCall(*this, allocator, allocatorType, allocatorArgs);
}
// Emit a null check on the allocation result if the allocation
@@ -1350,9 +1375,7 @@ void CodeGenFunction::EmitDeleteCall(con
DeleteArgs.add(RValue::get(Size), SizeTy);
// Emit the call to delete.
- EmitCall(CGM.getTypes().arrangeFreeFunctionCall(DeleteArgs, DeleteFTy),
- CGM.GetAddrOfFunction(DeleteFD), ReturnValueSlot(),
- DeleteArgs, DeleteFD);
+ EmitNewDeleteCall(*this, DeleteFD, DeleteFTy, DeleteArgs);
}
namespace {
@@ -1508,9 +1531,7 @@ namespace {
}
// Emit the call to delete.
- CGF.EmitCall(CGF.getTypes().arrangeFreeFunctionCall(Args, DeleteFTy),
- CGF.CGM.GetAddrOfFunction(OperatorDelete),
- ReturnValueSlot(), Args, OperatorDelete);
+ EmitNewDeleteCall(CGF, OperatorDelete, DeleteFTy, Args);
}
};
}
Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=186799&r1=186798&r2=186799&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Sun Jul 21 18:12:18 2013
@@ -744,6 +744,12 @@ void CodeGenModule::SetFunctionAttribute
if (const SectionAttr *SA = FD->getAttr<SectionAttr>())
F->setSection(SA->getName());
+
+ // A replaceable global allocation function does not act like a builtin by
+ // default, only if it is invoked by a new-expression or delete-expression.
+ if (FD->isReplaceableGlobalAllocationFunction())
+ F->addAttribute(llvm::AttributeSet::FunctionIndex,
+ llvm::Attribute::NoBuiltin);
}
void CodeGenModule::AddUsedGlobal(llvm::GlobalValue *GV) {
Modified: cfe/trunk/test/CodeGenCXX/new.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/new.cpp?rev=186799&r1=186798&r2=186799&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/new.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/new.cpp Sun Jul 21 18:12:18 2013
@@ -2,9 +2,24 @@
typedef __typeof__(sizeof(0)) size_t;
+// Ensure that this declaration doesn't cause operator new to lose its
+// 'noalias' attribute.
+void *operator new[](size_t);
+
void t1() {
- int* a = new int;
+ delete new int;
+ delete [] new int [3];
+}
+
+// CHECK: declare noalias i8* @_Znwm(i64) [[ATTR_NOBUILTIN:#[^ ]*]]
+// CHECK: declare void @_ZdlPv(i8*) [[ATTR_NOBUILTIN_NOUNWIND:#[^ ]*]]
+// CHECK: declare noalias i8* @_Znam(i64) [[ATTR_NOBUILTIN]]
+// CHECK: declare void @_ZdaPv(i8*) [[ATTR_NOBUILTIN_NOUNWIND]]
+
+namespace std {
+ struct nothrow_t {};
}
+std::nothrow_t nothrow;
// Declare the reserved placement operators.
void *operator new(size_t, void*) throw();
@@ -12,6 +27,13 @@ void operator delete(void*, void*) throw
void *operator new[](size_t, void*) throw();
void operator delete[](void*, void*) throw();
+// Declare the replaceable global allocation operators.
+void *operator new(size_t, const std::nothrow_t &) throw();
+void *operator new[](size_t, const std::nothrow_t &) throw();
+void operator delete(void *, const std::nothrow_t &) throw();
+void operator delete[](void *, const std::nothrow_t &) throw();
+
+
void t2(int* a) {
int* b = new (a) int;
}
@@ -77,10 +99,6 @@ void t8(int n) {
new U[n];
}
-// noalias
-// CHECK: declare noalias i8* @_Znam
-void *operator new[](size_t);
-
void t9() {
bool b;
@@ -260,3 +278,63 @@ namespace PR13380 {
// CHECK-NEXT: call void @_ZN7PR133801BC1Ev
void* f() { return new B[2](); }
}
+
+struct MyPlacementType {} mpt;
+void *operator new(size_t, MyPlacementType);
+
+namespace N3664 {
+ struct S { S() throw(int); };
+
+ // CHECK-LABEL: define void @_ZN5N36641fEv
+ void f() {
+ // CHECK: call noalias i8* @_Znwm(i64 4) [[ATTR_BUILTIN_NEW:#[^ ]*]]
+ int *p = new int;
+ // CHECK: call void @_ZdlPv({{.*}}) [[ATTR_BUILTIN_DELETE:#[^ ]*]]
+ delete p;
+
+ // CHECK: call noalias i8* @_Znam(i64 12) [[ATTR_BUILTIN_NEW]]
+ int *q = new int[3];
+ // CHECK: call void @_ZdaPv({{.*}}) [[ATTR_BUILTIN_DELETE]]
+ delete [] p;
+
+ // CHECK: call i8* @_ZnamRKSt9nothrow_t(i64 3, {{.*}}) [[ATTR_BUILTIN_NOTHROW_NEW:#[^ ]*]]
+ (void) new (nothrow) S[3];
+
+ // CHECK: call i8* @_Znwm15MyPlacementType(i64 4){{$}}
+ (void) new (mpt) int;
+ }
+
+ // FIXME: Can we mark this noalias?
+ // CHECK: declare i8* @_ZnamRKSt9nothrow_t(i64, {{.*}}) [[ATTR_NOBUILTIN_NOUNWIND]]
+
+ // CHECK-LABEL: define void @_ZN5N36641gEv
+ void g() {
+ // It's OK for there to be attributes here, so long as we don't have a
+ // 'builtin' attribute.
+ // CHECK: call noalias i8* @_Znwm(i64 4){{$}}
+ int *p = (int*)operator new(4);
+ // CHECK: call void @_ZdlPv({{.*}}) [[ATTR_NOUNWIND:#[^ ]*]]
+ operator delete(p);
+
+ // CHECK: call noalias i8* @_Znam(i64 12){{$}}
+ int *q = (int*)operator new[](12);
+ // CHECK: call void @_ZdaPv({{.*}}) [[ATTR_NOUNWIND]]
+ operator delete [](p);
+
+ // CHECK: call i8* @_ZnamRKSt9nothrow_t(i64 3, {{.*}}) [[ATTR_NOUNWIND]]
+ (void) operator new[](3, nothrow);
+ }
+}
+
+// CHECK-DAG: attributes [[ATTR_NOBUILTIN]] = {{[{].*}} nobuiltin {{.*[}]}}
+// CHECK-DAG: attributes [[ATTR_NOBUILTIN_NOUNWIND]] = {{[{].*}} nobuiltin nounwind {{.*[}]}}
+
+// CHECK: attributes [[ATTR_NOUNWIND]] =
+// CHECK-NOT: builtin
+// CHECK-NOT: attributes
+// CHECK: nounwind
+// CHECK-NOT: builtin
+// CHECK: attributes
+
+// CHECK-DAG: attributes [[ATTR_BUILTIN_NEW]] = {{[{].*}} builtin {{.*[}]}}
+// CHECK-DAG: attributes [[ATTR_BUILTIN_DELETE]] = {{[{].*}} builtin {{.*[}]}}
Modified: cfe/trunk/www/cxx_status.html
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/www/cxx_status.html?rev=186799&r1=186798&r2=186799&view=diff
==============================================================================
--- cfe/trunk/www/cxx_status.html (original)
+++ cfe/trunk/www/cxx_status.html Sun Jul 21 18:12:18 2013
@@ -467,7 +467,7 @@ available.</p>
<tr>
<td>Clarifying memory allocation</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3664.html">N3664</a></td>
- <td class="partial" align="center">Partial</td>
+ <td class="svn" align="center">SVN</td>
</tr>
</table>
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