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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@186799 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 0ad15fc..4ecb41b 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -2132,13 +2132,18 @@
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 @@
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);
diff --git a/lib/CodeGen/CGExprCXX.cpp b/lib/CodeGen/CGExprCXX.cpp
index 672e86d..1520656 100644
--- a/lib/CodeGen/CGExprCXX.cpp
+++ b/lib/CodeGen/CGExprCXX.cpp
@@ -1002,6 +1002,38 @@
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 @@
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 @@
}
// 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 @@
// 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 @@
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 @@
}
// Emit the call to delete.
- CGF.EmitCall(CGF.getTypes().arrangeFreeFunctionCall(Args, DeleteFTy),
- CGF.CGM.GetAddrOfFunction(OperatorDelete),
- ReturnValueSlot(), Args, OperatorDelete);
+ EmitNewDeleteCall(CGF, OperatorDelete, DeleteFTy, Args);
}
};
}
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index af6a011..53efaa6 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -744,6 +744,12 @@
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) {