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Diffstat (limited to 'gnu/llvm/lib/IR/Globals.cpp')
| -rw-r--r-- | gnu/llvm/lib/IR/Globals.cpp | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/gnu/llvm/lib/IR/Globals.cpp b/gnu/llvm/lib/IR/Globals.cpp new file mode 100644 index 00000000000..a61b62bd968 --- /dev/null +++ b/gnu/llvm/lib/IR/Globals.cpp @@ -0,0 +1,327 @@ +//===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the GlobalValue & GlobalVariable classes for the IR +// library. +// +//===----------------------------------------------------------------------===// + +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/Triple.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/GlobalAlias.h" +#include "llvm/IR/GlobalValue.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Operator.h" +#include "llvm/Support/ErrorHandling.h" +using namespace llvm; + +//===----------------------------------------------------------------------===// +// GlobalValue Class +//===----------------------------------------------------------------------===// + +bool GlobalValue::isMaterializable() const { + if (const Function *F = dyn_cast<Function>(this)) + return F->isMaterializable(); + return false; +} +std::error_code GlobalValue::materialize() { + return getParent()->materialize(this); +} + +/// Override destroyConstantImpl to make sure it doesn't get called on +/// GlobalValue's because they shouldn't be treated like other constants. +void GlobalValue::destroyConstantImpl() { + llvm_unreachable("You can't GV->destroyConstantImpl()!"); +} + +Value *GlobalValue::handleOperandChangeImpl(Value *From, Value *To, Use *U) { + llvm_unreachable("Unsupported class for handleOperandChange()!"); +} + +/// copyAttributesFrom - copy all additional attributes (those not needed to +/// create a GlobalValue) from the GlobalValue Src to this one. +void GlobalValue::copyAttributesFrom(const GlobalValue *Src) { + setVisibility(Src->getVisibility()); + setUnnamedAddr(Src->hasUnnamedAddr()); + setDLLStorageClass(Src->getDLLStorageClass()); +} + +unsigned GlobalValue::getAlignment() const { + if (auto *GA = dyn_cast<GlobalAlias>(this)) { + // In general we cannot compute this at the IR level, but we try. + if (const GlobalObject *GO = GA->getBaseObject()) + return GO->getAlignment(); + + // FIXME: we should also be able to handle: + // Alias = Global + Offset + // Alias = Absolute + return 0; + } + return cast<GlobalObject>(this)->getAlignment(); +} + +void GlobalObject::setAlignment(unsigned Align) { + assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!"); + assert(Align <= MaximumAlignment && + "Alignment is greater than MaximumAlignment!"); + unsigned AlignmentData = Log2_32(Align) + 1; + unsigned OldData = getGlobalValueSubClassData(); + setGlobalValueSubClassData((OldData & ~AlignmentMask) | AlignmentData); + assert(getAlignment() == Align && "Alignment representation error!"); +} + +unsigned GlobalObject::getGlobalObjectSubClassData() const { + unsigned ValueData = getGlobalValueSubClassData(); + return ValueData >> AlignmentBits; +} + +void GlobalObject::setGlobalObjectSubClassData(unsigned Val) { + unsigned OldData = getGlobalValueSubClassData(); + setGlobalValueSubClassData((OldData & AlignmentMask) | + (Val << AlignmentBits)); + assert(getGlobalObjectSubClassData() == Val && "representation error"); +} + +void GlobalObject::copyAttributesFrom(const GlobalValue *Src) { + GlobalValue::copyAttributesFrom(Src); + if (const auto *GV = dyn_cast<GlobalObject>(Src)) { + setAlignment(GV->getAlignment()); + setSection(GV->getSection()); + } +} + +const char *GlobalValue::getSection() const { + if (auto *GA = dyn_cast<GlobalAlias>(this)) { + // In general we cannot compute this at the IR level, but we try. + if (const GlobalObject *GO = GA->getBaseObject()) + return GO->getSection(); + return ""; + } + return cast<GlobalObject>(this)->getSection(); +} + +Comdat *GlobalValue::getComdat() { + if (auto *GA = dyn_cast<GlobalAlias>(this)) { + // In general we cannot compute this at the IR level, but we try. + if (const GlobalObject *GO = GA->getBaseObject()) + return const_cast<GlobalObject *>(GO)->getComdat(); + return nullptr; + } + return cast<GlobalObject>(this)->getComdat(); +} + +void GlobalObject::setSection(StringRef S) { Section = S; } + +bool GlobalValue::isDeclaration() const { + // Globals are definitions if they have an initializer. + if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this)) + return GV->getNumOperands() == 0; + + // Functions are definitions if they have a body. + if (const Function *F = dyn_cast<Function>(this)) + return F->empty() && !F->isMaterializable(); + + // Aliases are always definitions. + assert(isa<GlobalAlias>(this)); + return false; +} + +bool GlobalValue::canIncreaseAlignment() const { + // Firstly, can only increase the alignment of a global if it + // is a strong definition. + if (!isStrongDefinitionForLinker()) + return false; + + // It also has to either not have a section defined, or, not have + // alignment specified. (If it is assigned a section, the global + // could be densely packed with other objects in the section, and + // increasing the alignment could cause padding issues.) + if (hasSection() && getAlignment() > 0) + return false; + + // On ELF platforms, we're further restricted in that we can't + // increase the alignment of any variable which might be emitted + // into a shared library, and which is exported. If the main + // executable accesses a variable found in a shared-lib, the main + // exe actually allocates memory for and exports the symbol ITSELF, + // overriding the symbol found in the library. That is, at link + // time, the observed alignment of the variable is copied into the + // executable binary. (A COPY relocation is also generated, to copy + // the initial data from the shadowed variable in the shared-lib + // into the location in the main binary, before running code.) + // + // And thus, even though you might think you are defining the + // global, and allocating the memory for the global in your object + // file, and thus should be able to set the alignment arbitrarily, + // that's not actually true. Doing so can cause an ABI breakage; an + // executable might have already been built with the previous + // alignment of the variable, and then assuming an increased + // alignment will be incorrect. + + // Conservatively assume ELF if there's no parent pointer. + bool isELF = + (!Parent || Triple(Parent->getTargetTriple()).isOSBinFormatELF()); + if (isELF && hasDefaultVisibility() && !hasLocalLinkage()) + return false; + + return true; +} + +//===----------------------------------------------------------------------===// +// GlobalVariable Implementation +//===----------------------------------------------------------------------===// + +GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link, + Constant *InitVal, const Twine &Name, + ThreadLocalMode TLMode, unsigned AddressSpace, + bool isExternallyInitialized) + : GlobalObject(Ty, Value::GlobalVariableVal, + OperandTraits<GlobalVariable>::op_begin(this), + InitVal != nullptr, Link, Name, AddressSpace), + isConstantGlobal(constant), + isExternallyInitializedConstant(isExternallyInitialized) { + setThreadLocalMode(TLMode); + if (InitVal) { + assert(InitVal->getType() == Ty && + "Initializer should be the same type as the GlobalVariable!"); + Op<0>() = InitVal; + } +} + +GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant, + LinkageTypes Link, Constant *InitVal, + const Twine &Name, GlobalVariable *Before, + ThreadLocalMode TLMode, unsigned AddressSpace, + bool isExternallyInitialized) + : GlobalObject(Ty, Value::GlobalVariableVal, + OperandTraits<GlobalVariable>::op_begin(this), + InitVal != nullptr, Link, Name, AddressSpace), + isConstantGlobal(constant), + isExternallyInitializedConstant(isExternallyInitialized) { + setThreadLocalMode(TLMode); + if (InitVal) { + assert(InitVal->getType() == Ty && + "Initializer should be the same type as the GlobalVariable!"); + Op<0>() = InitVal; + } + + if (Before) + Before->getParent()->getGlobalList().insert(Before->getIterator(), this); + else + M.getGlobalList().push_back(this); +} + +void GlobalVariable::setParent(Module *parent) { + Parent = parent; +} + +void GlobalVariable::removeFromParent() { + getParent()->getGlobalList().remove(getIterator()); +} + +void GlobalVariable::eraseFromParent() { + getParent()->getGlobalList().erase(getIterator()); +} + +void GlobalVariable::setInitializer(Constant *InitVal) { + if (!InitVal) { + if (hasInitializer()) { + // Note, the num operands is used to compute the offset of the operand, so + // the order here matters. Clearing the operand then clearing the num + // operands ensures we have the correct offset to the operand. + Op<0>().set(nullptr); + setGlobalVariableNumOperands(0); + } + } else { + assert(InitVal->getType() == getType()->getElementType() && + "Initializer type must match GlobalVariable type"); + // Note, the num operands is used to compute the offset of the operand, so + // the order here matters. We need to set num operands to 1 first so that + // we get the correct offset to the first operand when we set it. + if (!hasInitializer()) + setGlobalVariableNumOperands(1); + Op<0>().set(InitVal); + } +} + +/// Copy all additional attributes (those not needed to create a GlobalVariable) +/// from the GlobalVariable Src to this one. +void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) { + GlobalObject::copyAttributesFrom(Src); + if (const GlobalVariable *SrcVar = dyn_cast<GlobalVariable>(Src)) { + setThreadLocalMode(SrcVar->getThreadLocalMode()); + setExternallyInitialized(SrcVar->isExternallyInitialized()); + } +} + + +//===----------------------------------------------------------------------===// +// GlobalAlias Implementation +//===----------------------------------------------------------------------===// + +GlobalAlias::GlobalAlias(Type *Ty, unsigned AddressSpace, LinkageTypes Link, + const Twine &Name, Constant *Aliasee, + Module *ParentModule) + : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name, + AddressSpace) { + Op<0>() = Aliasee; + + if (ParentModule) + ParentModule->getAliasList().push_back(this); +} + +GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace, + LinkageTypes Link, const Twine &Name, + Constant *Aliasee, Module *ParentModule) { + return new GlobalAlias(Ty, AddressSpace, Link, Name, Aliasee, ParentModule); +} + +GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace, + LinkageTypes Linkage, const Twine &Name, + Module *Parent) { + return create(Ty, AddressSpace, Linkage, Name, nullptr, Parent); +} + +GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace, + LinkageTypes Linkage, const Twine &Name, + GlobalValue *Aliasee) { + return create(Ty, AddressSpace, Linkage, Name, Aliasee, Aliasee->getParent()); +} + +GlobalAlias *GlobalAlias::create(LinkageTypes Link, const Twine &Name, + GlobalValue *Aliasee) { + PointerType *PTy = Aliasee->getType(); + return create(PTy->getElementType(), PTy->getAddressSpace(), Link, Name, + Aliasee); +} + +GlobalAlias *GlobalAlias::create(const Twine &Name, GlobalValue *Aliasee) { + return create(Aliasee->getLinkage(), Name, Aliasee); +} + +void GlobalAlias::setParent(Module *parent) { + Parent = parent; +} + +void GlobalAlias::removeFromParent() { + getParent()->getAliasList().remove(getIterator()); +} + +void GlobalAlias::eraseFromParent() { + getParent()->getAliasList().erase(getIterator()); +} + +void GlobalAlias::setAliasee(Constant *Aliasee) { + assert((!Aliasee || Aliasee->getType() == getType()) && + "Alias and aliasee types should match!"); + setOperand(0, Aliasee); +} |