Generating assumption loads of vptr after ctor call (fixed)
Generating call assume(icmp %vtable, %global_vtable) after constructor
call for devirtualization purposes.
For more info go to:
http://lists.llvm.org/pipermail/cfe-dev/2015-July/044227.html
Edit:
Fixed version because of PR24479.
After this patch got reverted because of ScalarEvolution bug (D12719)
Merged after John McCall big patch (Added Address).
http://reviews.llvm.org/D11859
llvm-svn: 247199
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 0c6a6d7..e0add8f 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -243,10 +243,24 @@
void emitVTableDefinitions(CodeGenVTables &CGVT,
const CXXRecordDecl *RD) override;
+ bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
+ CodeGenFunction::VPtr Vptr) override;
+
+ bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {
+ return true;
+ }
+
+ llvm::Constant *
+ getVTableAddressPoint(BaseSubobject Base,
+ const CXXRecordDecl *VTableClass) override;
+
llvm::Value *getVTableAddressPointInStructor(
CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
- BaseSubobject Base, const CXXRecordDecl *NearestVBase,
- bool &NeedsVirtualOffset) override;
+ BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;
+
+ llvm::Value *getVTableAddressPointInStructorWithVTT(
+ CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
+ BaseSubobject Base, const CXXRecordDecl *NearestVBase);
llvm::Constant *
getVTableAddressPointForConstExpr(BaseSubobject Base,
@@ -267,7 +281,7 @@
void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
- bool canEmitAvailableExternallyVTable(const CXXRecordDecl *RD) const override;
+ bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override;
void setThunkLinkage(llvm::Function *Thunk, bool ForVTable, GlobalDecl GD,
bool ReturnAdjustment) override {
@@ -1459,41 +1473,29 @@
CGM.EmitVTableBitSetEntries(VTable, VTLayout);
}
-llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructor(
- CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
- const CXXRecordDecl *NearestVBase, bool &NeedsVirtualOffset) {
- bool NeedsVTTParam = CGM.getCXXABI().NeedsVTTParameter(CGF.CurGD);
- NeedsVirtualOffset = (NeedsVTTParam && NearestVBase);
-
- llvm::Value *VTableAddressPoint;
- if (NeedsVTTParam && (Base.getBase()->getNumVBases() || NearestVBase)) {
- // Get the secondary vpointer index.
- uint64_t VirtualPointerIndex =
- CGM.getVTables().getSecondaryVirtualPointerIndex(VTableClass, Base);
-
- /// Load the VTT.
- llvm::Value *VTT = CGF.LoadCXXVTT();
- if (VirtualPointerIndex)
- VTT = CGF.Builder.CreateConstInBoundsGEP1_64(VTT, VirtualPointerIndex);
-
- // And load the address point from the VTT.
- VTableAddressPoint = CGF.Builder.CreateAlignedLoad(VTT, CGF.getPointerAlign());
- } else {
- llvm::Constant *VTable =
- CGM.getCXXABI().getAddrOfVTable(VTableClass, CharUnits());
- uint64_t AddressPoint = CGM.getItaniumVTableContext()
- .getVTableLayout(VTableClass)
- .getAddressPoint(Base);
- VTableAddressPoint =
- CGF.Builder.CreateConstInBoundsGEP2_64(VTable, 0, AddressPoint);
- }
-
- return VTableAddressPoint;
+bool ItaniumCXXABI::isVirtualOffsetNeededForVTableField(
+ CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) {
+ if (Vptr.NearestVBase == nullptr)
+ return false;
+ return NeedsVTTParameter(CGF.CurGD);
}
-llvm::Constant *ItaniumCXXABI::getVTableAddressPointForConstExpr(
- BaseSubobject Base, const CXXRecordDecl *VTableClass) {
- auto *VTable = getAddrOfVTable(VTableClass, CharUnits());
+llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructor(
+ CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
+ const CXXRecordDecl *NearestVBase) {
+
+ if ((Base.getBase()->getNumVBases() || NearestVBase != nullptr) &&
+ NeedsVTTParameter(CGF.CurGD)) {
+ return getVTableAddressPointInStructorWithVTT(CGF, VTableClass, Base,
+ NearestVBase);
+ }
+ return getVTableAddressPoint(Base, VTableClass);
+}
+
+llvm::Constant *
+ItaniumCXXABI::getVTableAddressPoint(BaseSubobject Base,
+ const CXXRecordDecl *VTableClass) {
+ llvm::GlobalValue *VTable = getAddrOfVTable(VTableClass, CharUnits());
// Find the appropriate vtable within the vtable group.
uint64_t AddressPoint = CGM.getItaniumVTableContext()
@@ -1508,6 +1510,30 @@
VTable, Indices);
}
+llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructorWithVTT(
+ CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
+ const CXXRecordDecl *NearestVBase) {
+ assert((Base.getBase()->getNumVBases() || NearestVBase != nullptr) &&
+ NeedsVTTParameter(CGF.CurGD) && "This class doesn't have VTT");
+
+ // Get the secondary vpointer index.
+ uint64_t VirtualPointerIndex =
+ CGM.getVTables().getSecondaryVirtualPointerIndex(VTableClass, Base);
+
+ /// Load the VTT.
+ llvm::Value *VTT = CGF.LoadCXXVTT();
+ if (VirtualPointerIndex)
+ VTT = CGF.Builder.CreateConstInBoundsGEP1_64(VTT, VirtualPointerIndex);
+
+ // And load the address point from the VTT.
+ return CGF.Builder.CreateAlignedLoad(VTT, CGF.getPointerAlign());
+}
+
+llvm::Constant *ItaniumCXXABI::getVTableAddressPointForConstExpr(
+ BaseSubobject Base, const CXXRecordDecl *VTableClass) {
+ return getVTableAddressPoint(Base, VTableClass);
+}
+
llvm::GlobalVariable *ItaniumCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
CharUnits VPtrOffset) {
assert(VPtrOffset.isZero() && "Itanium ABI only supports zero vptr offsets");
@@ -1583,8 +1609,7 @@
VTables.EmitVTTDefinition(VTT, CGM.getVTableLinkage(RD), RD);
}
-bool ItaniumCXXABI::canEmitAvailableExternallyVTable(
- const CXXRecordDecl *RD) const {
+bool ItaniumCXXABI::canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const {
// We don't emit available_externally vtables if we are in -fapple-kext mode
// because kext mode does not permit devirtualization.
if (CGM.getLangOpts().AppleKext)