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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
130 lines
4.9 KiB
C++
130 lines
4.9 KiB
C++
//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "LanaiTargetObjectFile.h"
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#include "LanaiSubtarget.h"
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#include "LanaiTargetMachine.h"
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#include "llvm/BinaryFormat/ELF.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCSectionELF.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Target/TargetMachine.h"
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using namespace llvm;
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static cl::opt<unsigned> SSThreshold(
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"lanai-ssection-threshold", cl::Hidden,
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cl::desc("Small data and bss section threshold size (default=0)"),
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cl::init(0));
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void LanaiTargetObjectFile::Initialize(MCContext &Ctx,
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const TargetMachine &TM) {
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TargetLoweringObjectFileELF::Initialize(Ctx, TM);
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InitializeELF(TM.Options.UseInitArray);
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SmallDataSection = getContext().getELFSection(
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".sdata", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
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SmallBSSSection = getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
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ELF::SHF_WRITE | ELF::SHF_ALLOC);
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}
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// A address must be loaded from a small section if its size is less than the
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// small section size threshold. Data in this section must be addressed using
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// gp_rel operator.
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static bool isInSmallSection(uint64_t Size) {
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// gcc has traditionally not treated zero-sized objects as small data, so this
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// is effectively part of the ABI.
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return Size > 0 && Size <= SSThreshold;
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}
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// Return true if this global address should be placed into small data/bss
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// section.
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bool LanaiTargetObjectFile::isGlobalInSmallSection(
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const GlobalObject *GO, const TargetMachine &TM) const {
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if (GO == nullptr) return TM.getCodeModel() == CodeModel::Small;
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// We first check the case where global is a declaration, because finding
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// section kind using getKindForGlobal() is only allowed for global
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// definitions.
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if (GO->isDeclaration() || GO->hasAvailableExternallyLinkage())
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return isGlobalInSmallSectionImpl(GO, TM);
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return isGlobalInSmallSection(GO, TM, getKindForGlobal(GO, TM));
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}
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// Return true if this global address should be placed into small data/bss
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// section.
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bool LanaiTargetObjectFile::isGlobalInSmallSection(const GlobalObject *GO,
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const TargetMachine &TM,
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SectionKind Kind) const {
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return isGlobalInSmallSectionImpl(GO, TM);
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}
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// Return true if this global address should be placed into small data/bss
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// section. This method does all the work, except for checking the section
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// kind.
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bool LanaiTargetObjectFile::isGlobalInSmallSectionImpl(
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const GlobalObject *GO, const TargetMachine &TM) const {
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const auto *GVA = dyn_cast<GlobalVariable>(GO);
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// If not a GlobalVariable, only consider the code model.
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if (!GVA) return TM.getCodeModel() == CodeModel::Small;
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// Global values placed in sections starting with .ldata do not fit in
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// 21-bits, so always use large memory access for them. FIXME: This is a
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// workaround for a tool limitation.
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if (GVA->getSection().startswith(".ldata"))
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return false;
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if (TM.getCodeModel() == CodeModel::Small)
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return true;
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if (GVA->hasLocalLinkage())
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return false;
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if (((GVA->hasExternalLinkage() && GVA->isDeclaration()) ||
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GVA->hasCommonLinkage()))
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return false;
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Type *Ty = GVA->getValueType();
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return isInSmallSection(
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GVA->getParent()->getDataLayout().getTypeAllocSize(Ty));
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}
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MCSection *LanaiTargetObjectFile::SelectSectionForGlobal(
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const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
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// Handle Small Section classification here.
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if (Kind.isBSS() && isGlobalInSmallSection(GO, TM, Kind))
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return SmallBSSSection;
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if (Kind.isData() && isGlobalInSmallSection(GO, TM, Kind))
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return SmallDataSection;
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// Otherwise, we work the same as ELF.
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return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
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}
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/// Return true if this constant should be placed into small data section.
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bool LanaiTargetObjectFile::isConstantInSmallSection(const DataLayout &DL,
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const Constant *CN) const {
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return isInSmallSection(DL.getTypeAllocSize(CN->getType()));
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}
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MCSection *LanaiTargetObjectFile::getSectionForConstant(const DataLayout &DL,
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SectionKind Kind,
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const Constant *C,
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unsigned &Align) const {
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if (isConstantInSmallSection(DL, C))
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return SmallDataSection;
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// Otherwise, we work the same as ELF.
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return TargetLoweringObjectFileELF::getSectionForConstant(DL, Kind, C, Align);
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}
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