r342053 - [CodeGen] Align rtti and vtable data
David Green via cfe-commits
cfe-commits at lists.llvm.org
Wed Sep 12 07:09:07 PDT 2018
Author: dmgreen
Date: Wed Sep 12 07:09:06 2018
New Revision: 342053
URL: http://llvm.org/viewvc/llvm-project?rev=342053&view=rev
Log:
[CodeGen] Align rtti and vtable data
Previously the alignment on the newly created rtti/typeinfo data was largely
not set, meaning that DataLayout::getPreferredAlignment was free to overalign
it to 16 bytes. This causes unnecessary code bloat.
Differential Revision: https://reviews.llvm.org/D51416
Modified:
cfe/trunk/lib/CodeGen/CGVTT.cpp
cfe/trunk/lib/CodeGen/CGVTables.cpp
cfe/trunk/lib/CodeGen/CodeGenModule.cpp
cfe/trunk/lib/CodeGen/CodeGenModule.h
cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp
cfe/trunk/test/CodeGenCXX/microsoft-abi-vbtables.cpp
cfe/trunk/test/CodeGenCXX/vtable-align.cpp
cfe/trunk/test/CodeGenCXX/vtable-linkage.cpp
Modified: cfe/trunk/lib/CodeGen/CGVTT.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGVTT.cpp?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGVTT.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGVTT.cpp Wed Sep 12 07:09:06 2018
@@ -119,10 +119,10 @@ llvm::GlobalVariable *CodeGenVTables::Ge
llvm::ArrayType *ArrayType =
llvm::ArrayType::get(CGM.Int8PtrTy, Builder.getVTTComponents().size());
+ unsigned Align = CGM.getDataLayout().getABITypeAlignment(CGM.Int8PtrTy);
- llvm::GlobalVariable *GV =
- CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType,
- llvm::GlobalValue::ExternalLinkage);
+ llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(
+ Name, ArrayType, llvm::GlobalValue::ExternalLinkage, Align);
GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
return GV;
}
Modified: cfe/trunk/lib/CodeGen/CGVTables.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGVTables.cpp?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGVTables.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGVTables.cpp Wed Sep 12 07:09:06 2018
@@ -756,9 +756,11 @@ CodeGenVTables::GenerateConstructionVTab
if (Linkage == llvm::GlobalVariable::AvailableExternallyLinkage)
Linkage = llvm::GlobalVariable::InternalLinkage;
+ unsigned Align = CGM.getDataLayout().getABITypeAlignment(VTType);
+
// Create the variable that will hold the construction vtable.
llvm::GlobalVariable *VTable =
- CGM.CreateOrReplaceCXXRuntimeVariable(Name, VTType, Linkage);
+ CGM.CreateOrReplaceCXXRuntimeVariable(Name, VTType, Linkage, Align);
CGM.setGVProperties(VTable, RD);
// V-tables are always unnamed_addr.
Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Wed Sep 12 07:09:06 2018
@@ -3099,10 +3099,9 @@ CodeGenModule::GetAddrOfGlobal(GlobalDec
IsForDefinition);
}
-llvm::GlobalVariable *
-CodeGenModule::CreateOrReplaceCXXRuntimeVariable(StringRef Name,
- llvm::Type *Ty,
- llvm::GlobalValue::LinkageTypes Linkage) {
+llvm::GlobalVariable *CodeGenModule::CreateOrReplaceCXXRuntimeVariable(
+ StringRef Name, llvm::Type *Ty, llvm::GlobalValue::LinkageTypes Linkage,
+ unsigned Alignment) {
llvm::GlobalVariable *GV = getModule().getNamedGlobal(Name);
llvm::GlobalVariable *OldGV = nullptr;
@@ -3138,6 +3137,8 @@ CodeGenModule::CreateOrReplaceCXXRuntime
!GV->hasAvailableExternallyLinkage())
GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
+ GV->setAlignment(Alignment);
+
return GV;
}
Modified: cfe/trunk/lib/CodeGen/CodeGenModule.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.h?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenModule.h Wed Sep 12 07:09:06 2018
@@ -764,7 +764,8 @@ public:
/// bitcast to the new variable.
llvm::GlobalVariable *
CreateOrReplaceCXXRuntimeVariable(StringRef Name, llvm::Type *Ty,
- llvm::GlobalValue::LinkageTypes Linkage);
+ llvm::GlobalValue::LinkageTypes Linkage,
+ unsigned Alignment);
llvm::Function *
CreateGlobalInitOrDestructFunction(llvm::FunctionType *ty, const Twine &name,
Modified: cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp (original)
+++ cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp Wed Sep 12 07:09:06 2018
@@ -1598,12 +1598,6 @@ void ItaniumCXXABI::emitVTableDefinition
// Set the right visibility.
CGM.setGVProperties(VTable, RD);
- // Use pointer alignment for the vtable. Otherwise we would align them based
- // on the size of the initializer which doesn't make sense as only single
- // values are read.
- unsigned PAlign = CGM.getTarget().getPointerAlign(0);
- VTable->setAlignment(getContext().toCharUnitsFromBits(PAlign).getQuantity());
-
// If this is the magic class __cxxabiv1::__fundamental_type_info,
// we will emit the typeinfo for the fundamental types. This is the
// same behaviour as GCC.
@@ -1703,8 +1697,14 @@ llvm::GlobalVariable *ItaniumCXXABI::get
CGM.getItaniumVTableContext().getVTableLayout(RD);
llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout);
+ // Use pointer alignment for the vtable. Otherwise we would align them based
+ // on the size of the initializer which doesn't make sense as only single
+ // values are read.
+ unsigned PAlign = CGM.getTarget().getPointerAlign(0);
+
VTable = CGM.CreateOrReplaceCXXRuntimeVariable(
- Name, VTableType, llvm::GlobalValue::ExternalLinkage);
+ Name, VTableType, llvm::GlobalValue::ExternalLinkage,
+ getContext().toCharUnitsFromBits(PAlign).getQuantity());
VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
CGM.setGVProperties(VTable, RD);
@@ -2725,9 +2725,10 @@ llvm::GlobalVariable *ItaniumRTTIBuilder
// get the mangled name of the type.
llvm::Constant *Init = llvm::ConstantDataArray::getString(VMContext,
Name.substr(4));
+ auto Align = CGM.getContext().getTypeAlignInChars(CGM.getContext().CharTy);
- llvm::GlobalVariable *GV =
- CGM.CreateOrReplaceCXXRuntimeVariable(Name, Init->getType(), Linkage);
+ llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(
+ Name, Init->getType(), Linkage, Align.getQuantity());
GV->setInitializer(Init);
@@ -3366,6 +3367,10 @@ llvm::Constant *ItaniumRTTIBuilder::Buil
if (CGM.supportsCOMDAT() && GV->isWeakForLinker())
GV->setComdat(M.getOrInsertComdat(GV->getName()));
+ CharUnits Align =
+ CGM.getContext().toCharUnitsFromBits(CGM.getTarget().getPointerAlign(0));
+ GV->setAlignment(Align.getQuantity());
+
// The Itanium ABI specifies that type_info objects must be globally
// unique, with one exception: if the type is an incomplete class
// type or a (possibly indirect) pointer to one. That exception
Modified: cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp (original)
+++ cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp Wed Sep 12 07:09:06 2018
@@ -2024,8 +2024,10 @@ MicrosoftCXXABI::getAddrOfVBTable(const
assert(!CGM.getModule().getNamedGlobal(Name) &&
"vbtable with this name already exists: mangling bug?");
- llvm::GlobalVariable *GV =
- CGM.CreateOrReplaceCXXRuntimeVariable(Name, VBTableType, Linkage);
+ CharUnits Alignment =
+ CGM.getContext().getTypeAlignInChars(CGM.getContext().IntTy);
+ llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(
+ Name, VBTableType, Linkage, Alignment.getQuantity());
GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
if (RD->hasAttr<DLLImportAttr>())
Modified: cfe/trunk/test/CodeGenCXX/microsoft-abi-vbtables.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/microsoft-abi-vbtables.cpp?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/microsoft-abi-vbtables.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/microsoft-abi-vbtables.cpp Wed Sep 12 07:09:06 2018
@@ -19,7 +19,7 @@ D d; // Force vbtable emission.
// C: vbptr C
// int c
-// CHECK-DAG: @"??_8D at Test1@@7B01@@" = linkonce_odr unnamed_addr constant [4 x i32] [i32 0, i32 8, i32 12, i32 20]
+// CHECK-DAG: @"??_8D at Test1@@7B01@@" = linkonce_odr unnamed_addr constant [4 x i32] [i32 0, i32 8, i32 12, i32 20], comdat, align 4
// CHECK-DAG: @"??_8D at Test1@@7BB at 1@@" = {{.*}} [2 x i32] [i32 0, i32 -4]
// CHECK-DAG: @"??_8D at Test1@@7BC at 1@@" = {{.*}} [2 x i32] [i32 0, i32 -12]
// CHECK-DAG: @"??_8C at Test1@@7B@" = {{.*}} [2 x i32] [i32 0, i32 8]
Modified: cfe/trunk/test/CodeGenCXX/vtable-align.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/vtable-align.cpp?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/vtable-align.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/vtable-align.cpp Wed Sep 12 07:09:06 2018
@@ -10,5 +10,8 @@ struct A {
void A::f() {}
// CHECK-32: @_ZTV1A = unnamed_addr constant { [5 x i8*] } { [5 x i8*] [i8* null, i8* bitcast ({ i8*, i8* }* @_ZTI1A to i8*), i8* bitcast (void (%struct.A*)* @_ZN1A1fEv to i8*), i8* bitcast (void (%struct.A*)* @_ZN1A1gEv to i8*), i8* bitcast (void (%struct.A*)* @_ZN1A1hEv to i8*)] }, align 4
-
+// CHECK-32: @_ZTS1A = constant [3 x i8] c"1A\00", align 1
+// CHECK-32: @_ZTI1A = constant { i8*, i8* } { i8* bitcast (i8** getelementptr inbounds (i8*, i8** @_ZTVN10__cxxabiv117__class_type_infoE, i32 2) to i8*), i8* getelementptr inbounds ([3 x i8], [3 x i8]* @_ZTS1A, i32 0, i32 0) }, align 4
// CHECK-64: @_ZTV1A = unnamed_addr constant { [5 x i8*] } { [5 x i8*] [i8* null, i8* bitcast ({ i8*, i8* }* @_ZTI1A to i8*), i8* bitcast (void (%struct.A*)* @_ZN1A1fEv to i8*), i8* bitcast (void (%struct.A*)* @_ZN1A1gEv to i8*), i8* bitcast (void (%struct.A*)* @_ZN1A1hEv to i8*)] }, align 8
+// CHECK-64: @_ZTS1A = constant [3 x i8] c"1A\00", align 1
+// CHECK-64: @_ZTI1A = constant { i8*, i8* } { i8* bitcast (i8** getelementptr inbounds (i8*, i8** @_ZTVN10__cxxabiv117__class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([3 x i8], [3 x i8]* @_ZTS1A, i32 0, i32 0) }, align 8
Modified: cfe/trunk/test/CodeGenCXX/vtable-linkage.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/vtable-linkage.cpp?rev=342053&r1=342052&r2=342053&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/vtable-linkage.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/vtable-linkage.cpp Wed Sep 12 07:09:06 2018
@@ -98,10 +98,10 @@ void use_F() {
// C has no key function, so its vtable should have weak_odr linkage
// and hidden visibility (rdar://problem/7523229).
-// CHECK-DAG: @_ZTV1C = linkonce_odr unnamed_addr constant {{.*}}, comdat,
-// CHECK-DAG: @_ZTS1C = linkonce_odr constant {{.*}}, comdat{{$}}
-// CHECK-DAG: @_ZTI1C = linkonce_odr constant {{.*}}, comdat{{$}}
-// CHECK-DAG: @_ZTT1C = linkonce_odr unnamed_addr constant {{.*}}, comdat{{$}}
+// CHECK-DAG: @_ZTV1C = linkonce_odr unnamed_addr constant {{.*}}, comdat, align 8{{$}}
+// CHECK-DAG: @_ZTS1C = linkonce_odr constant {{.*}}, comdat, align 1{{$}}
+// CHECK-DAG: @_ZTI1C = linkonce_odr constant {{.*}}, comdat, align 8{{$}}
+// CHECK-DAG: @_ZTT1C = linkonce_odr unnamed_addr constant {{.*}}, comdat, align 8{{$}}
// D has a key function that is defined in this translation unit so its vtable is
// defined in the translation unit.
@@ -120,27 +120,27 @@ void use_F() {
// defined in this translation unit, so its vtable should have
// weak_odr linkage.
// CHECK-DAG: @_ZTV1EIsE = weak_odr unnamed_addr constant {{.*}}, comdat,
-// CHECK-DAG: @_ZTS1EIsE = weak_odr constant {{.*}}, comdat{{$}}
-// CHECK-DAG: @_ZTI1EIsE = weak_odr constant {{.*}}, comdat{{$}}
+// CHECK-DAG: @_ZTS1EIsE = weak_odr constant {{.*}}, comdat, align 1{{$}}
+// CHECK-DAG: @_ZTI1EIsE = weak_odr constant {{.*}}, comdat, align 8{{$}}
// F<short> is an explicit template instantiation without a key
// function, so its vtable should have weak_odr linkage
// CHECK-DAG: @_ZTV1FIsE = weak_odr unnamed_addr constant {{.*}}, comdat,
-// CHECK-DAG: @_ZTS1FIsE = weak_odr constant {{.*}}, comdat{{$}}
-// CHECK-DAG: @_ZTI1FIsE = weak_odr constant {{.*}}, comdat{{$}}
+// CHECK-DAG: @_ZTS1FIsE = weak_odr constant {{.*}}, comdat, align 1{{$}}
+// CHECK-DAG: @_ZTI1FIsE = weak_odr constant {{.*}}, comdat, align 8{{$}}
// E<long> is an implicit template instantiation with a key function
// defined in this translation unit, so its vtable should have
// linkonce_odr linkage.
// CHECK-DAG: @_ZTV1EIlE = linkonce_odr unnamed_addr constant {{.*}}, comdat,
-// CHECK-DAG: @_ZTS1EIlE = linkonce_odr constant {{.*}}, comdat{{$}}
-// CHECK-DAG: @_ZTI1EIlE = linkonce_odr constant {{.*}}, comdat{{$}}
+// CHECK-DAG: @_ZTS1EIlE = linkonce_odr constant {{.*}}, comdat, align 1{{$}}
+// CHECK-DAG: @_ZTI1EIlE = linkonce_odr constant {{.*}}, comdat, align 8{{$}}
// F<long> is an implicit template instantiation with no key function,
// so its vtable should have linkonce_odr linkage.
// CHECK-DAG: @_ZTV1FIlE = linkonce_odr unnamed_addr constant {{.*}}, comdat,
-// CHECK-DAG: @_ZTS1FIlE = linkonce_odr constant {{.*}}, comdat{{$}}
-// CHECK-DAG: @_ZTI1FIlE = linkonce_odr constant {{.*}}, comdat{{$}}
+// CHECK-DAG: @_ZTS1FIlE = linkonce_odr constant {{.*}}, comdat, align 1{{$}}
+// CHECK-DAG: @_ZTI1FIlE = linkonce_odr constant {{.*}}, comdat, align 8{{$}}
// F<int> is an explicit template instantiation declaration without a
// key function, so its vtable should have external linkage.
@@ -171,8 +171,8 @@ void use_F() {
// F<char> is an explicit specialization without a key function, so
// its vtable should have linkonce_odr linkage.
// CHECK-DAG: @_ZTV1FIcE = linkonce_odr unnamed_addr constant {{.*}}, comdat,
-// CHECK-DAG: @_ZTS1FIcE = linkonce_odr constant {{.*}}, comdat{{$}}
-// CHECK-DAG: @_ZTI1FIcE = linkonce_odr constant {{.*}}, comdat{{$}}
+// CHECK-DAG: @_ZTS1FIcE = linkonce_odr constant {{.*}}, comdat, align 1{{$}}
+// CHECK-DAG: @_ZTI1FIcE = linkonce_odr constant {{.*}}, comdat, align 8{{$}}
// CHECK-DAG: @_ZTV1GIiE = linkonce_odr unnamed_addr constant {{.*}}, comdat,
template <typename T>
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