rnk created this revision.
Herald added a subscriber: aprantl.
The MS ABI convention is that the 'this' pointer on entry is the address
of the vfptr that was used to make the virtual method call. In other
words, the pointer on entry always points to the base subobject that
introduced the virtual method. Consider this hierarchy:
struct A { virtual void f() = 0; };
struct B { virtual void g() = 0; };
struct C : A, B {
void f() override;
void g() override;
};
On entry to C::g, [ER]CX will contain the address of C's B subobject,
and C::g will have to subtract sizeof(A) to recover a pointer to C.
Before this change, we applied this adjustment in the prologue and
stored the new value into the "this" local variable alloca used for
debug info. However, MSVC does not do this, presumably because it is
often profitable to fold the adjustment into later field accesses. This
creates a problem, because the debugger expects the variable to be
unadjusted. Unfortunately, CodeView doesn't have anything like DWARF
expressions for computing variables that aren't in the program anymore,
so we have to declare 'this' to be the unadjusted value if we want the
debugger to see the right value.
This has the side benefit that, in optimized builds, the 'this' pointer
will usually be available on function entry because it doesn't require
any adjustment.
https://reviews.llvm.org/D40109
Files:
clang/lib/CodeGen/CGCXXABI.cpp
clang/lib/CodeGen/CGCXXABI.h
clang/lib/CodeGen/CGDecl.cpp
clang/lib/CodeGen/ItaniumCXXABI.cpp
clang/lib/CodeGen/MicrosoftCXXABI.cpp
clang/test/CodeGenCXX/microsoft-abi-multiple-nonvirtual-inheritance.cpp
clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp
clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp
clang/test/CodeGenCXX/microsoft-abi-vtables-multiple-nonvirtual-inheritance-this-adjustment.cpp
Index: clang/test/CodeGenCXX/microsoft-abi-vtables-multiple-nonvirtual-inheritance-this-adjustment.cpp
===================================================================
--- clang/test/CodeGenCXX/microsoft-abi-vtables-multiple-nonvirtual-inheritance-this-adjustment.cpp
+++ clang/test/CodeGenCXX/microsoft-abi-vtables-multiple-nonvirtual-inheritance-this-adjustment.cpp
@@ -196,7 +196,11 @@
}
// BITCODE-LABEL: define void @"\01?g@C@pr30293@@UAAXUNonTrivial@2@@Z"(<{ i8*, %"struct.pr30293::NonTrivial" }>* inalloca)
-// BITCODE: %[[this1:[^ ]*]] = load i8*, i8** %[[thisaddr:[^ ]*]], align 4
-// BITCODE-NEXT: %[[this2:[^ ]*]] = getelementptr inbounds i8, i8* %[[this1]], i32 -4
-// BITCODE-NEXT: store i8* %[[this2]], i8** %[[thisaddr]], align 4
+// BITCODE: %[[thisaddr:[^ ]*]] = getelementptr inbounds <{ i8*, %"struct.pr30293::NonTrivial" }>, <{ i8*, %"struct.pr30293::NonTrivial" }>* {{.*}}, i32 0, i32 0
+// BITCODE: %[[thisaddr1:[^ ]*]] = bitcast i8** %[[thisaddr]] to %"struct.pr30293::C"**
+// BITCODE: %[[this1:[^ ]*]] = load %"struct.pr30293::C"*, %"struct.pr30293::C"** %[[thisaddr1]], align 4
+// BITCODE: %[[this2:[^ ]*]] = bitcast %"struct.pr30293::C"* %[[this1]] to i8*
+// BITCODE: %[[this3:[^ ]*]] = getelementptr inbounds i8, i8* %[[this2]], i32 -4
+// BITCODE: %[[this4:[^ ]*]] = bitcast i8* %[[this3]] to %"struct.pr30293::C"*
+// BITCODE: store %"struct.pr30293::C"* %[[this4]], %"struct.pr30293::C"** @"\01?whatsthis@pr30293@@3PAUC@1@A", align 4
}
Index: clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp
===================================================================
--- clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp
+++ clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp
@@ -1,9 +1,9 @@
-// RUN: %clang_cc1 %s -fno-rtti -triple=i386-pc-win32 -emit-llvm -o %t
+// RUN: %clang_cc1 %s -fno-rtti -std=c++11 -Wno-inaccessible-base -triple=i386-pc-win32 -emit-llvm -o %t
// RUN: FileCheck %s < %t
// RUN: FileCheck --check-prefix=CHECK2 %s < %t
// For now, just make sure x86_64 doesn't crash.
-// RUN: %clang_cc1 %s -fno-rtti -triple=x86_64-pc-win32 -emit-llvm -o %t
+// RUN: %clang_cc1 %s -fno-rtti -std=c++11 -Wno-inaccessible-base -triple=x86_64-pc-win32 -emit-llvm -o %t
struct VBase {
virtual ~VBase();
@@ -52,12 +52,14 @@
B::~B() {
// CHECK-LABEL: define x86_thiscallcc void @"\01??1B@@UAE@XZ"
- // Adjust the this parameter:
- // CHECK: %[[THIS_PARAM_i8:.*]] = bitcast %struct.B* {{.*}} to i8*
- // CHECK: %[[THIS_i8:.*]] = getelementptr inbounds i8, i8* %[[THIS_PARAM_i8]], i32 -8
- // CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_i8]] to %struct.B*
- // CHECK: store %struct.B* %[[THIS]], %struct.B** %[[THIS_ADDR:.*]], align 4
- // CHECK: %[[THIS:.*]] = load %struct.B*, %struct.B** %[[THIS_ADDR]]
+ // Store initial this:
+ // CHECK: %[[THIS_ADDR:.*]] = alloca %struct.B*
+ // CHECK: store %struct.B* %{{.*}}, %struct.B** %[[THIS_ADDR]], align 4
+ // Reload and adjust the this parameter:
+ // CHECK: %[[THIS_RELOAD:.*]] = load %struct.B*, %struct.B** %[[THIS_ADDR]]
+ // CHECK: %[[THIS_UNADJ_i8:.*]] = bitcast %struct.B* %[[THIS_RELOAD]] to i8*
+ // CHECK: %[[THIS_ADJ_i8:.*]] = getelementptr inbounds i8, i8* %[[THIS_UNADJ_i8]], i32 -8
+ // CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_ADJ_i8]] to %struct.B*
// Restore the vfptr that could have been changed by a subclass.
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
@@ -97,11 +99,11 @@
// CHECK2: ret
// CHECK2-LABEL: define linkonce_odr x86_thiscallcc i8* @"\01??_GB@@UAEPAXI@Z"
- // CHECK2: %[[THIS_PARAM_i8:.*]] = bitcast %struct.B* {{.*}} to i8*
+ // CHECK2: store %struct.B* %{{.*}}, %struct.B** %[[THIS_ADDR:.*]], align 4
+ // CHECK2: %[[THIS:.*]] = load %struct.B*, %struct.B** %[[THIS_ADDR]]
+ // CHECK2: %[[THIS_PARAM_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK2: %[[THIS_i8:.*]] = getelementptr inbounds i8, i8* %[[THIS_PARAM_i8:.*]], i32 -8
// CHECK2: %[[THIS:.*]] = bitcast i8* %[[THIS_i8]] to %struct.B*
- // CHECK2: store %struct.B* %[[THIS]], %struct.B** %[[THIS_ADDR:.*]], align 4
- // CHECK2: %[[THIS:.*]] = load %struct.B*, %struct.B** %[[THIS_ADDR]]
// CHECK2: call x86_thiscallcc void @"\01??_DB@@QAEXXZ"(%struct.B* %[[THIS]])
// ...
// CHECK2: ret
@@ -113,13 +115,17 @@
// B::foo gets 'this' cast to VBase* in ECX (i.e. this+8) so we
// need to adjust 'this' before use.
//
-// CHECK: %[[THIS_ADDR:.*]] = alloca %struct.B*, align 4
-// CHECK: %[[THIS_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX:.*]], i32 -8
-// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_i8]] to %struct.B*
-// CHECK: store %struct.B* %[[THIS]], %struct.B** %[[THIS_ADDR]], align 4
+// Store initial this:
+// CHECK: %[[THIS_ADDR:.*]] = alloca %struct.B*
+// CHECK: store %struct.B* %{{.*}}, %struct.B** %[[THIS_ADDR]], align 4
+//
+// Reload and adjust the this parameter:
+// CHECK: %[[THIS_RELOAD:.*]] = load %struct.B*, %struct.B** %[[THIS_ADDR]]
+// CHECK: %[[THIS_UNADJ_i8:.*]] = bitcast %struct.B* %[[THIS_RELOAD]] to i8*
+// CHECK: %[[THIS_ADJ_i8:.*]] = getelementptr inbounds i8, i8* %[[THIS_UNADJ_i8]], i32 -8
+// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_ADJ_i8]] to %struct.B*
field = 42;
-// CHECK: %[[THIS:.*]] = load %struct.B*, %struct.B** %[[THIS_ADDR]]
// CHECK: %[[THIS8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VBPTR:.*]] = getelementptr inbounds i8, i8* %[[THIS8]], i32 0
// CHECK: %[[VBPTR8:.*]] = bitcast i8* %[[VBPTR]] to i32**
@@ -284,11 +290,16 @@
D::~D() {
// CHECK-LABEL: define x86_thiscallcc void @"\01??1D@diamond@@UAE@XZ"(%"struct.diamond::D"*{{.*}})
- // CHECK: %[[ARG_i8:.*]] = bitcast %"struct.diamond::D"* %{{.*}} to i8*
- // CHECK: %[[THIS_i8:.*]] = getelementptr inbounds i8, i8* %[[ARG_i8]], i32 -24
- // CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_i8]] to %"struct.diamond::D"*
- // CHECK: store %"struct.diamond::D"* %[[THIS]], %"struct.diamond::D"** %[[THIS_VAL:.*]], align 4
- // CHECK: %[[THIS:.*]] = load %"struct.diamond::D"*, %"struct.diamond::D"** %[[THIS_VAL]]
+ // Store initial this:
+ // CHECK: %[[THIS_ADDR:.*]] = alloca %"struct.diamond::D"*
+ // CHECK: store %"struct.diamond::D"* %{{.*}}, %"struct.diamond::D"** %[[THIS_ADDR]], align 4
+ //
+ // Reload and adjust the this parameter:
+ // CHECK: %[[THIS_RELOAD:.*]] = load %"struct.diamond::D"*, %"struct.diamond::D"** %[[THIS_ADDR]]
+ // CHECK: %[[THIS_UNADJ_i8:.*]] = bitcast %"struct.diamond::D"* %[[THIS_RELOAD]] to i8*
+ // CHECK: %[[THIS_ADJ_i8:.*]] = getelementptr inbounds i8, i8* %[[THIS_UNADJ_i8]], i32 -24
+ // CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_ADJ_i8]] to %"struct.diamond::D"*
+ //
// CHECK: %[[D_i8:.*]] = bitcast %"struct.diamond::D"* %[[THIS]] to i8*
// CHECK: %[[C_i8:.*]] = getelementptr inbounds i8, i8* %[[D_i8]], i32 4
// CHECK: %[[C:.*]] = bitcast i8* %[[C_i8]] to %"struct.diamond::C"*
Index: clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp
===================================================================
--- clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp
+++ clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp
@@ -24,8 +24,13 @@
D::D() {} // Forces vftable emission.
// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@D@@$4PPPPPPPM@A@AEXXZ"
-// CHECK: %[[ECX:.*]] = load %struct.D*, %struct.D** %{{.*}}
-// CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[ECX]] to i8*
+// Adjust 'this' to D*.
+// CHECK: %[[THIS_UNADJ:.*]] = load %struct.D*, %struct.D** %{{.*}}
+// CHECK: %[[THIS_UNADJ_i8:.*]] = bitcast %struct.D* %[[THIS_UNADJ]] to i8*
+// CHECK: %[[THIS_ADJ:.*]] = getelementptr inbounds i8, i8* %[[THIS_UNADJ_i8]], i32 -12
+// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_ADJ]] to %struct.D*
+//
+// CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[THIS]] to i8*
// CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX_i8]], i32 -4
// CHECK: %[[VTORDISP_PTR:.*]] = bitcast i8* %[[VTORDISP_PTR_i8]] to i32*
// CHECK: %[[VTORDISP:.*]] = load i32, i32* %[[VTORDISP_PTR]]
@@ -35,8 +40,13 @@
// CHECK: ret void
// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@D@@$4PPPPPPPI@3AEXXZ"
-// CHECK: %[[ECX:.*]] = load %struct.D*, %struct.D** %{{.*}}
-// CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[ECX]] to i8*
+// Adjust 'this' to D*.
+// CHECK: %[[THIS_UNADJ:.*]] = load %struct.D*, %struct.D** %{{.*}}
+// CHECK: %[[THIS_UNADJ_i8:.*]] = bitcast %struct.D* %[[THIS_UNADJ]] to i8*
+// CHECK: %[[THIS_ADJ:.*]] = getelementptr inbounds i8, i8* %[[THIS_UNADJ_i8]], i32 -12
+// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_ADJ]] to %struct.D*
+//
+// CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[THIS]] to i8*
// CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX_i8]], i32 -8
// CHECK: %[[VTORDISP_PTR:.*]] = bitcast i8* %[[VTORDISP_PTR_i8]] to i32*
// CHECK: %[[VTORDISP:.*]] = load i32, i32* %[[VTORDISP_PTR]]
@@ -64,8 +74,13 @@
G::G() {} // Forces vftable emission.
// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@E@@$R4BA@M@PPPPPPPM@7AEXXZ"(i8*)
-// CHECK: %[[ECX:.*]] = load %struct.E*, %struct.E** %{{.*}}
-// CHECK: %[[ECX_i8:.*]] = bitcast %struct.E* %[[ECX]] to i8*
+// Adjust 'this' to E*.
+// CHECK: %[[THIS_UNADJ:.*]] = load %struct.E*, %struct.E** %{{.*}}
+// CHECK: %[[THIS_UNADJ_i8:.*]] = bitcast %struct.E* %[[THIS_UNADJ]] to i8*
+// CHECK: %[[THIS_ADJ:.*]] = getelementptr inbounds i8, i8* %[[THIS_UNADJ_i8]], i32 -8
+// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_ADJ]] to %struct.E*
+//
+// CHECK: %[[ECX_i8:.*]] = bitcast %struct.E* %[[THIS]] to i8*
// CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX_i8]], i32 -4
// CHECK: %[[VTORDISP_PTR:.*]] = bitcast i8* %[[VTORDISP_PTR_i8]] to i32*
// CHECK: %[[VTORDISP:.*]] = load i32, i32* %[[VTORDISP_PTR]]
Index: clang/test/CodeGenCXX/microsoft-abi-multiple-nonvirtual-inheritance.cpp
===================================================================
--- clang/test/CodeGenCXX/microsoft-abi-multiple-nonvirtual-inheritance.cpp
+++ clang/test/CodeGenCXX/microsoft-abi-multiple-nonvirtual-inheritance.cpp
@@ -19,7 +19,7 @@
extern "C" void foo(void *);
void call_left_no_override(ChildNoOverride *child) {
-// CHECK: define void @"\01?call_left_no_override
+// CHECK-LABEL: define void @"\01?call_left_no_override
// CHECK: %[[CHILD:.*]] = load %struct.ChildNoOverride
child->left();
@@ -34,7 +34,8 @@
}
void ChildOverride::left() {
-// CHECK: define x86_thiscallcc void @"\01?left@ChildOverride@@UAEXXZ"(%struct.ChildOverride* %[[THIS:.*]])
+// CHECK-LABEL: define x86_thiscallcc void @"\01?left@ChildOverride@@UAEXXZ"
+// CHECK-SAME: (%struct.ChildOverride* %[[THIS:.*]])
//
// No need to adjust 'this' as the ChildOverride's layout begins with Left.
// CHECK: %[[THIS_ADDR:.*]] = alloca %struct.ChildOverride*, align 4
@@ -48,7 +49,7 @@
}
void call_left_override(ChildOverride *child) {
-// CHECK: define void @"\01?call_left_override
+// CHECK-LABEL: define void @"\01?call_left_override
// CHECK: %[[CHILD:.*]] = load %struct.ChildOverride
child->left();
@@ -62,7 +63,7 @@
}
void call_right_no_override(ChildNoOverride *child) {
-// CHECK: define void @"\01?call_right_no_override
+// CHECK-LABEL: define void @"\01?call_right_no_override
// CHECK: %[[CHILD:.*]] = load %struct.ChildNoOverride
child->right();
@@ -82,25 +83,27 @@
}
void ChildOverride::right() {
-// CHECK: define x86_thiscallcc void @"\01?right@ChildOverride@@UAEXXZ"(i8*
+// CHECK-LABEL: define x86_thiscallcc void @"\01?right@ChildOverride@@UAEXXZ"(i8*
//
// ChildOverride::right gets 'this' cast to Right* in ECX (i.e. this+4) so we
// need to adjust 'this' before use.
//
// CHECK: %[[THIS_ADDR:.*]] = alloca %struct.ChildOverride*, align 4
-// CHECK: %[[THIS_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX:.*]], i32 -4
-// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_i8]] to %struct.ChildOverride*
-// CHECK: store %struct.ChildOverride* %[[THIS]], %struct.ChildOverride** %[[THIS_ADDR]], align 4
+// CHECK: %[[THIS_INIT:.*]] = bitcast i8* %[[ECX:.*]] to %struct.ChildOverride*
+// CHECK: store %struct.ChildOverride* %[[THIS_INIT]], %struct.ChildOverride** %[[THIS_ADDR]], align 4
+// CHECK: %[[THIS_RELOAD:.*]] = load %struct.ChildOverride*, %struct.ChildOverride** %[[THIS_ADDR]]
+// CHECK: %[[THIS_i8:.*]] = bitcast %struct.ChildOverride* %[[THIS_RELOAD]] to i8*
+// CHECK: %[[THIS_ADJUSTED:.*]] = getelementptr inbounds i8, i8* %[[THIS_i8]], i32 -4
+// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_ADJUSTED]] to %struct.ChildOverride*
foo(this);
-// CHECK: %[[THIS:.*]] = load %struct.ChildOverride*, %struct.ChildOverride** %[[THIS_ADDR]]
// CHECK: %[[THIS_PARAM:.*]] = bitcast %struct.ChildOverride* %[[THIS]] to i8*
// CHECK: call void @foo(i8* %[[THIS_PARAM]])
// CHECK: ret
}
void call_right_override(ChildOverride *child) {
-// CHECK: define void @"\01?call_right_override
+// CHECK-LABEL: define void @"\01?call_right_override
// CHECK: %[[CHILD:.*]] = load %struct.ChildOverride
child->right();
@@ -127,15 +130,17 @@
};
void GrandchildOverride::right() {
-// CHECK: define x86_thiscallcc void @"\01?right@GrandchildOverride@@UAEXXZ"(i8*
+// CHECK-LABEL: define x86_thiscallcc void @"\01?right@GrandchildOverride@@UAEXXZ"(i8*
//
// CHECK: %[[THIS_ADDR:.*]] = alloca %struct.GrandchildOverride*, align 4
-// CHECK: %[[THIS_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX:.*]], i32 -4
-// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_i8]] to %struct.GrandchildOverride*
-// CHECK: store %struct.GrandchildOverride* %[[THIS]], %struct.GrandchildOverride** %[[THIS_ADDR]], align 4
+// CHECK: %[[THIS_INIT:.*]] = bitcast i8* %[[ECX:.*]] to %struct.GrandchildOverride*
+// CHECK: store %struct.GrandchildOverride* %[[THIS_INIT]], %struct.GrandchildOverride** %[[THIS_ADDR]], align 4
+// CHECK: %[[THIS_RELOAD:.*]] = load %struct.GrandchildOverride*, %struct.GrandchildOverride** %[[THIS_ADDR]]
+// CHECK: %[[THIS_i8:.*]] = bitcast %struct.GrandchildOverride* %[[THIS_RELOAD]] to i8*
+// CHECK: %[[THIS_ADJUSTED:.*]] = getelementptr inbounds i8, i8* %[[THIS_i8]], i32 -4
+// CHECK: %[[THIS:.*]] = bitcast i8* %[[THIS_ADJUSTED]] to %struct.GrandchildOverride*
foo(this);
-// CHECK: %[[THIS:.*]] = load %struct.GrandchildOverride*, %struct.GrandchildOverride** %[[THIS_ADDR]]
// CHECK: %[[THIS_PARAM:.*]] = bitcast %struct.GrandchildOverride* %[[THIS]] to i8*
// CHECK: call void @foo(i8* %[[THIS_PARAM]])
// CHECK: ret
@@ -148,19 +153,19 @@
void emit_ctors() {
Left l;
- // CHECK: define {{.*}} @"\01??0Left@@QAE@XZ"
+ // CHECK-LABEL: define {{.*}} @"\01??0Left@@QAE@XZ"
// CHECK-NOT: getelementptr
// CHECK: store i32 (...)** bitcast ({ [1 x i8*] }* @"\01??_7Left@@6B@" to i32 (...)**)
// CHECK: ret
Right r;
- // CHECK: define {{.*}} @"\01??0Right@@QAE@XZ"
+ // CHECK-LABEL: define {{.*}} @"\01??0Right@@QAE@XZ"
// CHECK-NOT: getelementptr
// CHECK: store i32 (...)** bitcast ({ [1 x i8*] }* @"\01??_7Right@@6B@" to i32 (...)**)
// CHECK: ret
ChildOverride co;
- // CHECK: define {{.*}} @"\01??0ChildOverride@@QAE@XZ"
+ // CHECK-LABEL: define {{.*}} @"\01??0ChildOverride@@QAE@XZ"
// CHECK: %[[THIS:.*]] = load %struct.ChildOverride*, %struct.ChildOverride**
// CHECK: %[[VFPTR:.*]] = bitcast %struct.ChildOverride* %[[THIS]] to i32 (...)***
// CHECK: store i32 (...)** bitcast ({ [1 x i8*] }* @"\01??_7ChildOverride@@6BLeft@@@" to i32 (...)**), i32 (...)*** %[[VFPTR]]
@@ -171,7 +176,7 @@
// CHECK: ret
GrandchildOverride gc;
- // CHECK: define {{.*}} @"\01??0GrandchildOverride@@QAE@XZ"
+ // CHECK-LABEL: define {{.*}} @"\01??0GrandchildOverride@@QAE@XZ"
// CHECK: %[[THIS:.*]] = load %struct.GrandchildOverride*, %struct.GrandchildOverride**
// CHECK: %[[VFPTR:.*]] = bitcast %struct.GrandchildOverride* %[[THIS]] to i32 (...)***
// CHECK: store i32 (...)** bitcast ({ [1 x i8*] }* @"\01??_7GrandchildOverride@@6BLeft@@@" to i32 (...)**), i32 (...)*** %[[VFPTR]]
Index: clang/lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -244,9 +244,6 @@
void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
FunctionArgList &Params) override;
- llvm::Value *adjustThisParameterInVirtualFunctionPrologue(
- CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) override;
-
void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;
AddedStructorArgs
@@ -1433,50 +1430,48 @@
}
}
-llvm::Value *MicrosoftCXXABI::adjustThisParameterInVirtualFunctionPrologue(
- CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) {
- // In this ABI, every virtual function takes a pointer to one of the
- // subobjects that first defines it as the 'this' parameter, rather than a
- // pointer to the final overrider subobject. Thus, we need to adjust it back
- // to the final overrider subobject before use.
- // See comments in the MicrosoftVFTableContext implementation for the details.
- CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);
- if (Adjustment.isZero())
- return This;
-
- unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
- llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS),
- *thisTy = This->getType();
-
- This = CGF.Builder.CreateBitCast(This, charPtrTy);
- assert(Adjustment.isPositive());
- This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This,
- -Adjustment.getQuantity());
- return CGF.Builder.CreateBitCast(This, thisTy);
-}
-
void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
// Naked functions have no prolog.
if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())
return;
- EmitThisParam(CGF);
+ // Overridden virtual methods of non-primary bases need to adjust the incoming
+ // 'this' pointer in the prologue. Do this *after* storing the unadjusted
+ // value to the alloca we create. Microsoft debuggers actually *expect* and
+ // require this. This is slightly nicer after optimization because the
+ // adjustment can typically be folded into the uses of LoadCXXThis, but it
+ // muddies our -O0 codegen.
+ llvm::Value *This = loadIncomingCXXThis(CGF);
+ const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
+ if (MD->isVirtual()) {
+ CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(CGF.CurGD);
+ if (!Adjustment.isZero()) {
+ unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
+ llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS),
+ *thisTy = This->getType();
+ This = CGF.Builder.CreateBitCast(This, charPtrTy);
+ assert(Adjustment.isPositive());
+ This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This,
+ -Adjustment.getQuantity());
+ This = CGF.Builder.CreateBitCast(This, thisTy, "this.adjusted");
+ }
+ }
+ setCXXABIThisValue(CGF, This);
- /// If this is a function that the ABI specifies returns 'this', initialize
- /// the return slot to 'this' at the start of the function.
- ///
- /// Unlike the setting of return types, this is done within the ABI
- /// implementation instead of by clients of CGCXXABI because:
- /// 1) getThisValue is currently protected
- /// 2) in theory, an ABI could implement 'this' returns some other way;
- /// HasThisReturn only specifies a contract, not the implementation
+ // If this is a function that the ABI specifies returns 'this', initialize
+ // the return slot to 'this' at the start of the function.
+ //
+ // Unlike the setting of return types, this is done within the ABI
+ // implementation instead of by clients of CGCXXABI because:
+ // 1) getThisValue is currently protected
+ // 2) in theory, an ABI could implement 'this' returns some other way;
+ // HasThisReturn only specifies a contract, not the implementation
if (HasThisReturn(CGF.CurGD))
CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
else if (hasMostDerivedReturn(CGF.CurGD))
CGF.Builder.CreateStore(CGF.EmitCastToVoidPtr(getThisValue(CGF)),
CGF.ReturnValue);
- const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
assert(getStructorImplicitParamDecl(CGF) &&
"no implicit parameter for a constructor with virtual bases?");
@@ -1961,7 +1956,7 @@
// Start defining the function.
CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
FunctionArgs, MD->getLocation(), SourceLocation());
- EmitThisParam(CGF);
+ setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
// Load the vfptr and then callee from the vftable. The callee should have
// adjusted 'this' so that the vfptr is at offset zero.
@@ -3900,7 +3895,7 @@
FunctionArgs, CD->getLocation(), SourceLocation());
// Create a scope with an artificial location for the body of this function.
auto AL = ApplyDebugLocation::CreateArtificial(CGF);
- EmitThisParam(CGF);
+ setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
llvm::Value *This = getThisValue(CGF);
llvm::Value *SrcVal =
Index: clang/lib/CodeGen/ItaniumCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -1443,8 +1443,9 @@
if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())
return;
- /// Initialize the 'this' slot.
- EmitThisParam(CGF);
+ /// Initialize the 'this' slot. In the Itanium C++ ABI, no prologue
+ /// adjustments are required, becuase they are all handled by thunks.
+ setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
/// Initialize the 'vtt' slot if needed.
if (getStructorImplicitParamDecl(CGF)) {
Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -1796,24 +1796,6 @@
setBlockContextParameter(IPD, ArgNo, Arg.getDirectValue());
return;
}
-
- // Apply any prologue 'this' adjustments required by the ABI. Be careful to
- // handle the case where 'this' is passed indirectly as part of an inalloca
- // struct.
- if (const CXXMethodDecl *MD =
- dyn_cast_or_null<CXXMethodDecl>(CurCodeDecl)) {
- if (MD->isVirtual() && IPD == CXXABIThisDecl) {
- llvm::Value *This = Arg.isIndirect()
- ? Builder.CreateLoad(Arg.getIndirectAddress())
- : Arg.getDirectValue();
- This = CGM.getCXXABI().adjustThisParameterInVirtualFunctionPrologue(
- *this, CurGD, This);
- if (Arg.isIndirect())
- Builder.CreateStore(This, Arg.getIndirectAddress());
- else
- Arg = ParamValue::forDirect(This);
- }
- }
}
Address DeclPtr = Address::invalid();
Index: clang/lib/CodeGen/CGCXXABI.h
===================================================================
--- clang/lib/CodeGen/CGCXXABI.h
+++ clang/lib/CodeGen/CGCXXABI.h
@@ -73,9 +73,10 @@
return CGF.CXXStructorImplicitParamValue;
}
- /// Perform prolog initialization of the parameter variable suitable
- /// for 'this' emitted by buildThisParam.
- void EmitThisParam(CodeGenFunction &CGF);
+ /// Loads the incoming C++ this pointer as it was passed by the caller.
+ llvm::Value *loadIncomingCXXThis(CodeGenFunction &CGF);
+
+ void setCXXABIThisValue(CodeGenFunction &CGF, llvm::Value *ThisPtr);
ASTContext &getContext() const { return CGM.getContext(); }
@@ -358,13 +359,6 @@
return CharUnits::Zero();
}
- /// Perform ABI-specific "this" parameter adjustment in a virtual function
- /// prologue.
- virtual llvm::Value *adjustThisParameterInVirtualFunctionPrologue(
- CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) {
- return This;
- }
-
/// Emit the ABI-specific prolog for the function.
virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
Index: clang/lib/CodeGen/CGCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/CGCXXABI.cpp
+++ clang/lib/CodeGen/CGCXXABI.cpp
@@ -149,12 +149,15 @@
}
}
-void CGCXXABI::EmitThisParam(CodeGenFunction &CGF) {
+llvm::Value *CGCXXABI::loadIncomingCXXThis(CodeGenFunction &CGF) {
+ return CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
+ "this");
+}
+
+void CGCXXABI::setCXXABIThisValue(CodeGenFunction &CGF, llvm::Value *ThisPtr) {
/// Initialize the 'this' slot.
assert(getThisDecl(CGF) && "no 'this' variable for function");
- CGF.CXXABIThisValue
- = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
- "this");
+ CGF.CXXABIThisValue = ThisPtr;
}
void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
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