Move VTT builder to AST
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@140501 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/VTTBuilder.cpp b/lib/AST/VTTBuilder.cpp
new file mode 100644
index 0000000..f5ff624
--- /dev/null
+++ b/lib/AST/VTTBuilder.cpp
@@ -0,0 +1,212 @@
+//===--- VTTBuilder.cpp - C++ VTT layout builder --------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code dealing with generation of the layout of virtual table
+// tables (VTT).
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/VTTBuilder.h"
+#include "clang/AST/CXXInheritance.h"
+#include "clang/AST/RecordLayout.h"
+#include "clang/Basic/TargetInfo.h"
+#include "llvm/Support/Format.h"
+#include <algorithm>
+#include <cstdio>
+
+using namespace clang;
+
+#define DUMP_OVERRIDERS 0
+
+VTTBuilder::VTTBuilder(ASTContext &Ctx,
+ const CXXRecordDecl *MostDerivedClass,
+ bool GenerateDefinition)
+ : Ctx(Ctx), MostDerivedClass(MostDerivedClass),
+ MostDerivedClassLayout(Ctx.getASTRecordLayout(MostDerivedClass)),
+ GenerateDefinition(GenerateDefinition) {
+ // Lay out this VTT.
+ LayoutVTT(BaseSubobject(MostDerivedClass, CharUnits::Zero()),
+ /*BaseIsVirtual=*/false);
+}
+
+void VTTBuilder::AddVTablePointer(BaseSubobject Base, uint64_t VTableIndex,
+ const CXXRecordDecl *VTableClass) {
+ // Store the vtable pointer index if we're generating the primary VTT.
+ if (VTableClass == MostDerivedClass) {
+ assert(!SecondaryVirtualPointerIndices.count(Base) &&
+ "A virtual pointer index already exists for this base subobject!");
+ SecondaryVirtualPointerIndices[Base] = VTTComponents.size();
+ }
+
+ if (!GenerateDefinition) {
+ VTTComponents.push_back(VTTComponent());
+ return;
+ }
+
+ VTTComponents.push_back(VTTComponent(VTableIndex, Base));
+}
+
+void VTTBuilder::LayoutSecondaryVTTs(BaseSubobject Base) {
+ const CXXRecordDecl *RD = Base.getBase();
+
+ for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+ E = RD->bases_end(); I != E; ++I) {
+
+ // Don't layout virtual bases.
+ if (I->isVirtual())
+ continue;
+
+ const CXXRecordDecl *BaseDecl =
+ cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+ const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(RD);
+ CharUnits BaseOffset = Base.getBaseOffset() +
+ Layout.getBaseClassOffset(BaseDecl);
+
+ // Layout the VTT for this base.
+ LayoutVTT(BaseSubobject(BaseDecl, BaseOffset), /*BaseIsVirtual=*/false);
+ }
+}
+
+void
+VTTBuilder::LayoutSecondaryVirtualPointers(BaseSubobject Base,
+ bool BaseIsMorallyVirtual,
+ uint64_t VTableIndex,
+ const CXXRecordDecl *VTableClass,
+ VisitedVirtualBasesSetTy &VBases) {
+ const CXXRecordDecl *RD = Base.getBase();
+
+ // We're not interested in bases that don't have virtual bases, and not
+ // morally virtual bases.
+ if (!RD->getNumVBases() && !BaseIsMorallyVirtual)
+ return;
+
+ for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+ E = RD->bases_end(); I != E; ++I) {
+ const CXXRecordDecl *BaseDecl =
+ cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+ // Itanium C++ ABI 2.6.2:
+ // Secondary virtual pointers are present for all bases with either
+ // virtual bases or virtual function declarations overridden along a
+ // virtual path.
+ //
+ // If the base class is not dynamic, we don't want to add it, nor any
+ // of its base classes.
+ if (!BaseDecl->isDynamicClass())
+ continue;
+
+ bool BaseDeclIsMorallyVirtual = BaseIsMorallyVirtual;
+ bool BaseDeclIsNonVirtualPrimaryBase = false;
+ CharUnits BaseOffset;
+ if (I->isVirtual()) {
+ // Ignore virtual bases that we've already visited.
+ if (!VBases.insert(BaseDecl))
+ continue;
+
+ BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
+ BaseDeclIsMorallyVirtual = true;
+ } else {
+ const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(RD);
+
+ BaseOffset = Base.getBaseOffset() +
+ Layout.getBaseClassOffset(BaseDecl);
+
+ if (!Layout.isPrimaryBaseVirtual() &&
+ Layout.getPrimaryBase() == BaseDecl)
+ BaseDeclIsNonVirtualPrimaryBase = true;
+ }
+
+ // Itanium C++ ABI 2.6.2:
+ // Secondary virtual pointers: for each base class X which (a) has virtual
+ // bases or is reachable along a virtual path from D, and (b) is not a
+ // non-virtual primary base, the address of the virtual table for X-in-D
+ // or an appropriate construction virtual table.
+ if (!BaseDeclIsNonVirtualPrimaryBase &&
+ (BaseDecl->getNumVBases() || BaseDeclIsMorallyVirtual)) {
+ // Add the vtable pointer.
+ AddVTablePointer(BaseSubobject(BaseDecl, BaseOffset), VTableIndex,
+ VTableClass);
+ }
+
+ // And lay out the secondary virtual pointers for the base class.
+ LayoutSecondaryVirtualPointers(BaseSubobject(BaseDecl, BaseOffset),
+ BaseDeclIsMorallyVirtual, VTableIndex,
+ VTableClass, VBases);
+ }
+}
+
+void
+VTTBuilder::LayoutSecondaryVirtualPointers(BaseSubobject Base,
+ uint64_t VTableIndex) {
+ VisitedVirtualBasesSetTy VBases;
+ LayoutSecondaryVirtualPointers(Base, /*BaseIsMorallyVirtual=*/false,
+ VTableIndex, Base.getBase(), VBases);
+}
+
+void VTTBuilder::LayoutVirtualVTTs(const CXXRecordDecl *RD,
+ VisitedVirtualBasesSetTy &VBases) {
+ for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+ E = RD->bases_end(); I != E; ++I) {
+ const CXXRecordDecl *BaseDecl =
+ cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+ // Check if this is a virtual base.
+ if (I->isVirtual()) {
+ // Check if we've seen this base before.
+ if (!VBases.insert(BaseDecl))
+ continue;
+
+ CharUnits BaseOffset =
+ MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
+
+ LayoutVTT(BaseSubobject(BaseDecl, BaseOffset), /*BaseIsVirtual=*/true);
+ }
+
+ // We only need to layout virtual VTTs for this base if it actually has
+ // virtual bases.
+ if (BaseDecl->getNumVBases())
+ LayoutVirtualVTTs(BaseDecl, VBases);
+ }
+}
+
+void VTTBuilder::LayoutVTT(BaseSubobject Base, bool BaseIsVirtual) {
+ const CXXRecordDecl *RD = Base.getBase();
+
+ // Itanium C++ ABI 2.6.2:
+ // An array of virtual table addresses, called the VTT, is declared for
+ // each class type that has indirect or direct virtual base classes.
+ if (RD->getNumVBases() == 0)
+ return;
+
+ bool IsPrimaryVTT = Base.getBase() == MostDerivedClass;
+
+ if (!IsPrimaryVTT) {
+ // Remember the sub-VTT index.
+ SubVTTIndicies[Base] = VTTComponents.size();
+ }
+
+ uint64_t VTableIndex = VTTVTables.size();
+ VTTVTables.push_back(VTTVTable(Base, BaseIsVirtual));
+
+ // Add the primary vtable pointer.
+ AddVTablePointer(Base, VTableIndex, RD);
+
+ // Add the secondary VTTs.
+ LayoutSecondaryVTTs(Base);
+
+ // Add the secondary virtual pointers.
+ LayoutSecondaryVirtualPointers(Base, VTableIndex);
+
+ // If this is the primary VTT, we want to lay out virtual VTTs as well.
+ if (IsPrimaryVTT) {
+ VisitedVirtualBasesSetTy VBases;
+ LayoutVirtualVTTs(Base.getBase(), VBases);
+ }
+}