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-rw-r--r--lib/CodeGen/CGCXXABI.h7
-rw-r--r--lib/CodeGen/CGCall.cpp25
-rw-r--r--lib/CodeGen/CGClass.cpp17
-rw-r--r--lib/CodeGen/CodeGenFunction.cpp7
-rw-r--r--lib/CodeGen/CodeGenFunction.h4
-rw-r--r--lib/CodeGen/ItaniumCXXABI.cpp11
-rw-r--r--lib/CodeGen/MicrosoftCXXABI.cpp5
-rw-r--r--test/CodeGenCXX/arm.cpp8
-rw-r--r--test/CodeGenCXX/constructor-destructor-return-this.cpp60
9 files changed, 128 insertions, 16 deletions
diff --git a/lib/CodeGen/CGCXXABI.h b/lib/CodeGen/CGCXXABI.h
index cdc87b70e5..d0384ecc12 100644
--- a/lib/CodeGen/CGCXXABI.h
+++ b/lib/CodeGen/CGCXXABI.h
@@ -91,6 +91,10 @@ public:
return *MangleCtx;
}
+ /// Returns true if the given instance method is one of the
+ /// kinds that the ABI says returns 'this'.
+ virtual bool HasThisReturn(GlobalDecl GD) const { return false; }
+
/// Find the LLVM type used to represent the given member pointer
/// type.
virtual llvm::Type *
@@ -209,7 +213,8 @@ public:
/// Emit the ABI-specific prolog for the function.
virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
- virtual void EmitConstructorCall(CodeGenFunction &CGF,
+ /// Emit the constructor call. Return the function that is called.
+ virtual llvm::Value *EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating,
diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 9e97bce6c3..9318973e64 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -1614,6 +1614,18 @@ static llvm::StoreInst *findDominatingStoreToReturnValue(CodeGenFunction &CGF) {
return store;
}
+/// Check whether 'this' argument of a callsite matches 'this' of the caller.
+static bool checkThisPointer(llvm::Value *ThisArg, llvm::Value *This) {
+ if (ThisArg == This)
+ return true;
+ // Check whether ThisArg is a bitcast of This.
+ llvm::BitCastInst *Bitcast;
+ if ((Bitcast = dyn_cast<llvm::BitCastInst>(ThisArg)) &&
+ Bitcast->getOperand(0) == This)
+ return true;
+ return false;
+}
+
void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI) {
// Functions with no result always return void.
if (ReturnValue == 0) {
@@ -1705,6 +1717,19 @@ void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI) {
llvm_unreachable("Invalid ABI kind for return argument");
}
+ // If this function returns 'this', the last instruction is a CallInst
+ // that returns 'this', and 'this' argument of the CallInst points to
+ // the same object as CXXThisValue, use the return value from the CallInst.
+ // We will not need to keep 'this' alive through the callsite. It also enables
+ // optimizations in the backend, such as tail call optimization.
+ if (CalleeWithThisReturn && CGM.getCXXABI().HasThisReturn(CurGD)) {
+ llvm::BasicBlock *IP = Builder.GetInsertBlock();
+ llvm::CallInst *Callsite;
+ if (!IP->empty() && (Callsite = dyn_cast<llvm::CallInst>(&IP->back())) &&
+ Callsite->getCalledFunction() == CalleeWithThisReturn &&
+ checkThisPointer(Callsite->getOperand(0), CXXThisValue))
+ RV = Builder.CreateBitCast(Callsite, RetAI.getCoerceToType());
+ }
llvm::Instruction *Ret = RV ? Builder.CreateRet(RV) : Builder.CreateRetVoid();
if (!RetDbgLoc.isUnknown())
Ret->setDebugLoc(RetDbgLoc);
diff --git a/lib/CodeGen/CGClass.cpp b/lib/CodeGen/CGClass.cpp
index 287d164cb9..2ececb0365 100644
--- a/lib/CodeGen/CGClass.cpp
+++ b/lib/CodeGen/CGClass.cpp
@@ -1666,8 +1666,11 @@ CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
}
// Non-trivial constructors are handled in an ABI-specific manner.
- CGM.getCXXABI().EmitConstructorCall(*this, D, Type, ForVirtualBase,
- Delegating, This, ArgBeg, ArgEnd);
+ llvm::Value *Callee = CGM.getCXXABI().EmitConstructorCall(*this, D, Type,
+ ForVirtualBase, Delegating, This, ArgBeg, ArgEnd);
+ if (CGM.getCXXABI().HasThisReturn(CurGD) &&
+ CGM.getCXXABI().HasThisReturn(GlobalDecl(D, Type)))
+ CalleeWithThisReturn = Callee;
}
void
@@ -1756,9 +1759,12 @@ CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
EmitDelegateCallArg(DelegateArgs, param);
}
+ llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(Ctor, CtorType);
EmitCall(CGM.getTypes().arrangeCXXConstructorDeclaration(Ctor, CtorType),
- CGM.GetAddrOfCXXConstructor(Ctor, CtorType),
- ReturnValueSlot(), DelegateArgs, Ctor);
+ Callee, ReturnValueSlot(), DelegateArgs, Ctor);
+ if (CGM.getCXXABI().HasThisReturn(CurGD) &&
+ CGM.getCXXABI().HasThisReturn(GlobalDecl(Ctor, CtorType)))
+ CalleeWithThisReturn = Callee;
}
namespace {
@@ -1825,6 +1831,9 @@ void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *DD,
EmitCXXMemberCall(DD, SourceLocation(), Callee, ReturnValueSlot(), This,
VTT, getContext().getPointerType(getContext().VoidPtrTy),
0, 0);
+ if (CGM.getCXXABI().HasThisReturn(CurGD) &&
+ CGM.getCXXABI().HasThisReturn(GlobalDecl(DD, Type)))
+ CalleeWithThisReturn = Callee;
}
namespace {
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 27ef65fa94..bd244355f0 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -564,6 +564,10 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
SourceRange BodyRange;
if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
+ // CalleeWithThisReturn keeps track of the last callee inside this function
+ // that returns 'this'. Before starting the function, we set it to null.
+ CalleeWithThisReturn = 0;
+
// Emit the standard function prologue.
StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin());
@@ -615,6 +619,9 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
// Emit the standard function epilogue.
FinishFunction(BodyRange.getEnd());
+ // CalleeWithThisReturn keeps track of the last callee inside this function
+ // that returns 'this'. After finishing the function, we set it to null.
+ CalleeWithThisReturn = 0;
// If we haven't marked the function nothrow through other means, do
// a quick pass now to see if we can.
diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index 55c21e80ee..19a4d571ee 100644
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -1131,6 +1131,10 @@ private:
CGDebugInfo *DebugInfo;
bool DisableDebugInfo;
+ /// If the current function returns 'this', use the field to keep track of
+ /// the callee that returns 'this'.
+ llvm::Value *CalleeWithThisReturn;
+
/// DidCallStackSave - Whether llvm.stacksave has been called. Used to avoid
/// calling llvm.stacksave for multiple VLAs in the same scope.
bool DidCallStackSave;
diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp
index 8c7a759a43..17e83a18b9 100644
--- a/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/lib/CodeGen/ItaniumCXXABI.cpp
@@ -112,7 +112,7 @@ public:
void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
- void EmitConstructorCall(CodeGenFunction &CGF,
+ llvm::Value *EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating,
@@ -177,11 +177,11 @@ public:
llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, llvm::Value *allocPtr,
CharUnits cookieSize);
-private:
/// \brief Returns true if the given instance method is one of the
/// kinds that the ARM ABI says returns 'this'.
- static bool HasThisReturn(GlobalDecl GD) {
- const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
+ bool HasThisReturn(GlobalDecl GD) const {
+ const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(GD.getDecl());
+ if (!MD) return false;
return ((isa<CXXDestructorDecl>(MD) && GD.getDtorType() != Dtor_Deleting) ||
(isa<CXXConstructorDecl>(MD)));
}
@@ -834,7 +834,7 @@ void ARMCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
}
-void ItaniumCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
+llvm::Value *ItaniumCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating,
@@ -849,6 +849,7 @@ void ItaniumCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
// FIXME: Provide a source location here.
CGF.EmitCXXMemberCall(D, SourceLocation(), Callee, ReturnValueSlot(), This,
VTT, VTTTy, ArgBeg, ArgEnd);
+ return Callee;
}
RValue ItaniumCXXABI::EmitVirtualDestructorCall(CodeGenFunction &CGF,
diff --git a/lib/CodeGen/MicrosoftCXXABI.cpp b/lib/CodeGen/MicrosoftCXXABI.cpp
index fb6b86d878..85d926023f 100644
--- a/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -55,7 +55,7 @@ public:
void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
- void EmitConstructorCall(CodeGenFunction &CGF,
+ llvm::Value *EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating,
@@ -238,7 +238,7 @@ void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
}
}
-void MicrosoftCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
+llvm::Value *MicrosoftCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating,
@@ -259,6 +259,7 @@ void MicrosoftCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
CGF.EmitCXXMemberCall(D, SourceLocation(), Callee, ReturnValueSlot(), This,
ImplicitParam, ImplicitParamTy,
ArgBeg, ArgEnd);
+ return Callee;
}
RValue MicrosoftCXXABI::EmitVirtualDestructorCall(CodeGenFunction &CGF,
diff --git a/test/CodeGenCXX/arm.cpp b/test/CodeGenCXX/arm.cpp
index 3d3b147aa1..48f2f00840 100644
--- a/test/CodeGenCXX/arm.cpp
+++ b/test/CodeGenCXX/arm.cpp
@@ -56,15 +56,15 @@ namespace test1 {
// CHECK: [[THIS:%.*]] = alloca [[A]]*, align 4
// CHECK: store [[A]]* {{.*}}, [[A]]** [[THIS]]
// CHECK: [[THIS1:%.*]] = load [[A]]** [[THIS]]
- // CHECK: call [[A]]* @_ZN5test11AC2Ei(
- // CHECK: ret [[A]]* [[THIS1]]
+ // CHECK: [[THIS2:%.*]] = call [[A]]* @_ZN5test11AC2Ei(
+ // CHECK: ret [[A]]* [[THIS2]]
// CHECK: define linkonce_odr [[A]]* @_ZN5test11AD1Ev([[A]]* %this) unnamed_addr
// CHECK: [[THIS:%.*]] = alloca [[A]]*, align 4
// CHECK: store [[A]]* {{.*}}, [[A]]** [[THIS]]
// CHECK: [[THIS1:%.*]] = load [[A]]** [[THIS]]
- // CHECK: call [[A]]* @_ZN5test11AD2Ev(
- // CHECK: ret [[A]]* [[THIS1]]
+ // CHECK: [[THIS2:%.*]] = call [[A]]* @_ZN5test11AD2Ev(
+ // CHECK: ret [[A]]* [[THIS2]]
}
// Awkward virtual cases.
diff --git a/test/CodeGenCXX/constructor-destructor-return-this.cpp b/test/CodeGenCXX/constructor-destructor-return-this.cpp
new file mode 100644
index 0000000000..1ff922de60
--- /dev/null
+++ b/test/CodeGenCXX/constructor-destructor-return-this.cpp
@@ -0,0 +1,60 @@
+//RUN: %clang_cc1 %s -emit-llvm -o - -triple=thumbv7-apple-ios3.0 -target-abi apcs-gnu | FileCheck %s
+
+// For constructors/desctructors that return 'this', if there exists a callsite
+// that returns 'this' and is immediately before the return instruction, make
+// sure we are using the return value from the callsite.
+// rdar://12818789
+
+// CHECK: define linkonce_odr [[A:%.*]] @_ZN11ObjectCacheC1Ev([[A]] %this) unnamed_addr
+// CHECK: [[THIS1:%.*]] = call [[A]] @_ZN11ObjectCacheC2Ev(
+// CHECK-NEXT: ret [[A]] [[THIS1]]
+
+// CHECK: define linkonce_odr [[A:%.*]] @_ZN5TimerI11ObjectCacheEC1EPS0_MS0_FvPS1_E([[A]] %this
+// CHECK: [[THIS1:%.*]] = call [[A]] @_ZN5TimerI11ObjectCacheEC2EPS0_MS0_FvPS1_E(
+// CHECK-NEXT: ret [[A]] [[THIS1]]
+
+// CHECK: define linkonce_odr [[A:%.*]] @_ZN5TimerI11ObjectCacheED1Ev([[A]] %this) unnamed_addr
+// CHECK: [[THIS1:%.*]] = call [[A]] @_ZN5TimerI11ObjectCacheED2Ev(
+// CHECK-NEXT: ret [[A]] [[THIS1]]
+
+// CHECK: define linkonce_odr [[A:%.*]] @_ZN5TimerI11ObjectCacheED2Ev([[A]] %this) unnamed_addr
+// CHECK: [[THIS1:%.*]] = call [[B:%.*]] @_ZN9TimerBaseD2Ev(
+// CHECK-NEXT: [[THIS2:%.*]] = bitcast [[B]] [[THIS1]] to [[A]]
+// CHECK-NEXT: ret [[A]] [[THIS2]]
+
+class TimerBase {
+public:
+ TimerBase();
+ virtual ~TimerBase();
+};
+
+template <typename TimerFiredClass> class Timer : public TimerBase {
+public:
+ typedef void (TimerFiredClass::*TimerFiredFunction)(Timer*);
+
+ Timer(TimerFiredClass* o, TimerFiredFunction f)
+ : m_object(o), m_function(f) { }
+
+private:
+ virtual void fired() { (m_object->*m_function)(this); }
+
+ TimerFiredClass* m_object;
+ TimerFiredFunction m_function;
+};
+
+class ObjectCache {
+public:
+ explicit ObjectCache();
+ ~ObjectCache();
+
+private:
+ Timer<ObjectCache> m_notificationPostTimer;
+};
+
+inline ObjectCache::ObjectCache() : m_notificationPostTimer(this, 0) { }
+inline ObjectCache::~ObjectCache() { }
+
+ObjectCache *test() {
+ ObjectCache *dd = new ObjectCache();
+ return dd;
+}
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-07-01 18:45:44 +0000