| //===--- ConstantInitBuilder.cpp - Global initializer builder -------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines out-of-line routines for building initializers for |
| // global variables, in particular the kind of globals that are implicitly |
| // introduced by various language ABIs. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/CodeGen/ConstantInitBuilder.h" |
| #include "CodeGenModule.h" |
| |
| using namespace clang; |
| using namespace CodeGen; |
| |
| llvm::Type *ConstantInitFuture::getType() const { |
| assert(Data && "dereferencing null future"); |
| if (Data.is<llvm::Constant*>()) { |
| return Data.get<llvm::Constant*>()->getType(); |
| } else { |
| return Data.get<ConstantInitBuilderBase*>()->Buffer[0]->getType(); |
| } |
| } |
| |
| void ConstantInitFuture::abandon() { |
| assert(Data && "abandoning null future"); |
| if (auto builder = Data.dyn_cast<ConstantInitBuilderBase*>()) { |
| builder->abandon(0); |
| } |
| Data = nullptr; |
| } |
| |
| void ConstantInitFuture::installInGlobal(llvm::GlobalVariable *GV) { |
| assert(Data && "installing null future"); |
| if (Data.is<llvm::Constant*>()) { |
| GV->setInitializer(Data.get<llvm::Constant*>()); |
| } else { |
| auto &builder = *Data.get<ConstantInitBuilderBase*>(); |
| assert(builder.Buffer.size() == 1); |
| builder.setGlobalInitializer(GV, builder.Buffer[0]); |
| builder.Buffer.clear(); |
| Data = nullptr; |
| } |
| } |
| |
| ConstantInitFuture |
| ConstantInitBuilderBase::createFuture(llvm::Constant *initializer) { |
| assert(Buffer.empty() && "buffer not current empty"); |
| Buffer.push_back(initializer); |
| return ConstantInitFuture(this); |
| } |
| |
| // Only used in this file. |
| inline ConstantInitFuture::ConstantInitFuture(ConstantInitBuilderBase *builder) |
| : Data(builder) { |
| assert(!builder->Frozen); |
| assert(builder->Buffer.size() == 1); |
| assert(builder->Buffer[0] != nullptr); |
| } |
| |
| llvm::GlobalVariable * |
| ConstantInitBuilderBase::createGlobal(llvm::Constant *initializer, |
| const llvm::Twine &name, |
| CharUnits alignment, |
| bool constant, |
| llvm::GlobalValue::LinkageTypes linkage, |
| unsigned addressSpace) { |
| auto GV = new llvm::GlobalVariable(CGM.getModule(), |
| initializer->getType(), |
| constant, |
| linkage, |
| initializer, |
| name, |
| /*insert before*/ nullptr, |
| llvm::GlobalValue::NotThreadLocal, |
| addressSpace); |
| GV->setAlignment(alignment.getAsAlign()); |
| resolveSelfReferences(GV); |
| return GV; |
| } |
| |
| void ConstantInitBuilderBase::setGlobalInitializer(llvm::GlobalVariable *GV, |
| llvm::Constant *initializer){ |
| GV->setInitializer(initializer); |
| |
| if (!SelfReferences.empty()) |
| resolveSelfReferences(GV); |
| } |
| |
| void ConstantInitBuilderBase::resolveSelfReferences(llvm::GlobalVariable *GV) { |
| for (auto &entry : SelfReferences) { |
| llvm::Constant *resolvedReference = |
| llvm::ConstantExpr::getInBoundsGetElementPtr( |
| GV->getValueType(), GV, entry.Indices); |
| auto dummy = entry.Dummy; |
| dummy->replaceAllUsesWith(resolvedReference); |
| dummy->eraseFromParent(); |
| } |
| SelfReferences.clear(); |
| } |
| |
| void ConstantInitBuilderBase::abandon(size_t newEnd) { |
| // Remove all the entries we've added. |
| Buffer.erase(Buffer.begin() + newEnd, Buffer.end()); |
| |
| // If we're abandoning all the way to the beginning, destroy |
| // all the self-references, because we might not get another |
| // opportunity. |
| if (newEnd == 0) { |
| for (auto &entry : SelfReferences) { |
| auto dummy = entry.Dummy; |
| dummy->replaceAllUsesWith(llvm::UndefValue::get(dummy->getType())); |
| dummy->eraseFromParent(); |
| } |
| SelfReferences.clear(); |
| } |
| } |
| |
| void ConstantAggregateBuilderBase::addSize(CharUnits size) { |
| add(Builder.CGM.getSize(size)); |
| } |
| |
| llvm::Constant * |
| ConstantAggregateBuilderBase::getRelativeOffset(llvm::IntegerType *offsetType, |
| llvm::Constant *target) { |
| return getRelativeOffsetToPosition(offsetType, target, |
| Builder.Buffer.size() - Begin); |
| } |
| |
| llvm::Constant *ConstantAggregateBuilderBase::getRelativeOffsetToPosition( |
| llvm::IntegerType *offsetType, llvm::Constant *target, size_t position) { |
| // Compute the address of the relative-address slot. |
| auto base = getAddrOfPosition(offsetType, position); |
| |
| // Subtract. |
| base = llvm::ConstantExpr::getPtrToInt(base, Builder.CGM.IntPtrTy); |
| target = llvm::ConstantExpr::getPtrToInt(target, Builder.CGM.IntPtrTy); |
| llvm::Constant *offset = llvm::ConstantExpr::getSub(target, base); |
| |
| // Truncate to the relative-address type if necessary. |
| if (Builder.CGM.IntPtrTy != offsetType) { |
| offset = llvm::ConstantExpr::getTrunc(offset, offsetType); |
| } |
| |
| return offset; |
| } |
| |
| llvm::Constant * |
| ConstantAggregateBuilderBase::getAddrOfPosition(llvm::Type *type, |
| size_t position) { |
| // Make a global variable. We will replace this with a GEP to this |
| // position after installing the initializer. |
| auto dummy = new llvm::GlobalVariable(Builder.CGM.getModule(), type, true, |
| llvm::GlobalVariable::PrivateLinkage, |
| nullptr, ""); |
| Builder.SelfReferences.emplace_back(dummy); |
| auto &entry = Builder.SelfReferences.back(); |
| (void)getGEPIndicesTo(entry.Indices, position + Begin); |
| return dummy; |
| } |
| |
| llvm::Constant * |
| ConstantAggregateBuilderBase::getAddrOfCurrentPosition(llvm::Type *type) { |
| // Make a global variable. We will replace this with a GEP to this |
| // position after installing the initializer. |
| auto dummy = |
| new llvm::GlobalVariable(Builder.CGM.getModule(), type, true, |
| llvm::GlobalVariable::PrivateLinkage, |
| nullptr, ""); |
| Builder.SelfReferences.emplace_back(dummy); |
| auto &entry = Builder.SelfReferences.back(); |
| (void) getGEPIndicesToCurrentPosition(entry.Indices); |
| return dummy; |
| } |
| |
| void ConstantAggregateBuilderBase::getGEPIndicesTo( |
| llvm::SmallVectorImpl<llvm::Constant*> &indices, |
| size_t position) const { |
| // Recurse on the parent builder if present. |
| if (Parent) { |
| Parent->getGEPIndicesTo(indices, Begin); |
| |
| // Otherwise, add an index to drill into the first level of pointer. |
| } else { |
| assert(indices.empty()); |
| indices.push_back(llvm::ConstantInt::get(Builder.CGM.Int32Ty, 0)); |
| } |
| |
| assert(position >= Begin); |
| // We have to use i32 here because struct GEPs demand i32 indices. |
| // It's rather unlikely to matter in practice. |
| indices.push_back(llvm::ConstantInt::get(Builder.CGM.Int32Ty, |
| position - Begin)); |
| } |
| |
| ConstantAggregateBuilderBase::PlaceholderPosition |
| ConstantAggregateBuilderBase::addPlaceholderWithSize(llvm::Type *type) { |
| // Bring the offset up to the last field. |
| CharUnits offset = getNextOffsetFromGlobal(); |
| |
| // Create the placeholder. |
| auto position = addPlaceholder(); |
| |
| // Advance the offset past that field. |
| auto &layout = Builder.CGM.getDataLayout(); |
| if (!Packed) |
| offset = offset.alignTo(CharUnits::fromQuantity( |
| layout.getABITypeAlignment(type))); |
| offset += CharUnits::fromQuantity(layout.getTypeStoreSize(type)); |
| |
| CachedOffsetEnd = Builder.Buffer.size(); |
| CachedOffsetFromGlobal = offset; |
| |
| return position; |
| } |
| |
| CharUnits ConstantAggregateBuilderBase::getOffsetFromGlobalTo(size_t end) const{ |
| size_t cacheEnd = CachedOffsetEnd; |
| assert(cacheEnd <= end); |
| |
| // Fast path: if the cache is valid, just use it. |
| if (cacheEnd == end) { |
| return CachedOffsetFromGlobal; |
| } |
| |
| // If the cached range ends before the index at which the current |
| // aggregate starts, recurse for the parent. |
| CharUnits offset; |
| if (cacheEnd < Begin) { |
| assert(cacheEnd == 0); |
| assert(Parent && "Begin != 0 for root builder"); |
| cacheEnd = Begin; |
| offset = Parent->getOffsetFromGlobalTo(Begin); |
| } else { |
| offset = CachedOffsetFromGlobal; |
| } |
| |
| // Perform simple layout on the elements in cacheEnd..<end. |
| if (cacheEnd != end) { |
| auto &layout = Builder.CGM.getDataLayout(); |
| do { |
| llvm::Constant *element = Builder.Buffer[cacheEnd]; |
| assert(element != nullptr && |
| "cannot compute offset when a placeholder is present"); |
| llvm::Type *elementType = element->getType(); |
| if (!Packed) |
| offset = offset.alignTo(CharUnits::fromQuantity( |
| layout.getABITypeAlignment(elementType))); |
| offset += CharUnits::fromQuantity(layout.getTypeStoreSize(elementType)); |
| } while (++cacheEnd != end); |
| } |
| |
| // Cache and return. |
| CachedOffsetEnd = cacheEnd; |
| CachedOffsetFromGlobal = offset; |
| return offset; |
| } |
| |
| llvm::Constant *ConstantAggregateBuilderBase::finishArray(llvm::Type *eltTy) { |
| markFinished(); |
| |
| auto &buffer = getBuffer(); |
| assert((Begin < buffer.size() || |
| (Begin == buffer.size() && eltTy)) |
| && "didn't add any array elements without element type"); |
| auto elts = llvm::makeArrayRef(buffer).slice(Begin); |
| if (!eltTy) eltTy = elts[0]->getType(); |
| auto type = llvm::ArrayType::get(eltTy, elts.size()); |
| auto constant = llvm::ConstantArray::get(type, elts); |
| buffer.erase(buffer.begin() + Begin, buffer.end()); |
| return constant; |
| } |
| |
| llvm::Constant * |
| ConstantAggregateBuilderBase::finishStruct(llvm::StructType *ty) { |
| markFinished(); |
| |
| auto &buffer = getBuffer(); |
| auto elts = llvm::makeArrayRef(buffer).slice(Begin); |
| |
| if (ty == nullptr && elts.empty()) |
| ty = llvm::StructType::get(Builder.CGM.getLLVMContext(), {}, Packed); |
| |
| llvm::Constant *constant; |
| if (ty) { |
| assert(ty->isPacked() == Packed); |
| constant = llvm::ConstantStruct::get(ty, elts); |
| } else { |
| constant = llvm::ConstantStruct::getAnon(elts, Packed); |
| } |
| |
| buffer.erase(buffer.begin() + Begin, buffer.end()); |
| return constant; |
| } |