115 lines
4.1 KiB
C++
115 lines
4.1 KiB
C++
//===-- RISCVTargetObjectFile.cpp - RISCV Object Info -----------------===//
|
|
//
|
|
// 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
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "RISCVTargetObjectFile.h"
|
|
#include "RISCVTargetMachine.h"
|
|
#include "llvm/BinaryFormat/ELF.h"
|
|
#include "llvm/MC/MCContext.h"
|
|
#include "llvm/MC/MCSectionELF.h"
|
|
|
|
using namespace llvm;
|
|
|
|
void RISCVELFTargetObjectFile::Initialize(MCContext &Ctx,
|
|
const TargetMachine &TM) {
|
|
TargetLoweringObjectFileELF::Initialize(Ctx, TM);
|
|
InitializeELF(TM.Options.UseInitArray);
|
|
|
|
SmallDataSection = getContext().getELFSection(
|
|
".sdata", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
|
|
SmallBSSSection = getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
|
|
ELF::SHF_WRITE | ELF::SHF_ALLOC);
|
|
}
|
|
|
|
// A address must be loaded from a small section if its size is less than the
|
|
// small section size threshold. Data in this section could be addressed by
|
|
// using gp_rel operator.
|
|
bool RISCVELFTargetObjectFile::isInSmallSection(uint64_t Size) const {
|
|
// gcc has traditionally not treated zero-sized objects as small data, so this
|
|
// is effectively part of the ABI.
|
|
return Size > 0 && Size <= SSThreshold;
|
|
}
|
|
|
|
// Return true if this global address should be placed into small data/bss
|
|
// section.
|
|
bool RISCVELFTargetObjectFile::isGlobalInSmallSection(
|
|
const GlobalObject *GO, const TargetMachine &TM) const {
|
|
// Only global variables, not functions.
|
|
const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GO);
|
|
if (!GVA)
|
|
return false;
|
|
|
|
// If the variable has an explicit section, it is placed in that section.
|
|
if (GVA->hasSection()) {
|
|
StringRef Section = GVA->getSection();
|
|
|
|
// Explicitly placing any variable in the small data section overrides
|
|
// the global -G value.
|
|
if (Section == ".sdata" || Section == ".sbss")
|
|
return true;
|
|
|
|
// Otherwise reject putting the variable to small section if it has an
|
|
// explicit section name.
|
|
return false;
|
|
}
|
|
|
|
if (((GVA->hasExternalLinkage() && GVA->isDeclaration()) ||
|
|
GVA->hasCommonLinkage()))
|
|
return false;
|
|
|
|
Type *Ty = GVA->getValueType();
|
|
// It is possible that the type of the global is unsized, i.e. a declaration
|
|
// of a extern struct. In this case don't presume it is in the small data
|
|
// section. This happens e.g. when building the FreeBSD kernel.
|
|
if (!Ty->isSized())
|
|
return false;
|
|
|
|
return isInSmallSection(
|
|
GVA->getParent()->getDataLayout().getTypeAllocSize(Ty));
|
|
}
|
|
|
|
MCSection *RISCVELFTargetObjectFile::SelectSectionForGlobal(
|
|
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
|
|
// Handle Small Section classification here.
|
|
if (Kind.isBSS() && isGlobalInSmallSection(GO, TM))
|
|
return SmallBSSSection;
|
|
if (Kind.isData() && isGlobalInSmallSection(GO, TM))
|
|
return SmallDataSection;
|
|
|
|
// Otherwise, we work the same as ELF.
|
|
return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
|
|
}
|
|
|
|
void RISCVELFTargetObjectFile::getModuleMetadata(Module &M) {
|
|
SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
|
|
M.getModuleFlagsMetadata(ModuleFlags);
|
|
|
|
for (const auto &MFE : ModuleFlags) {
|
|
StringRef Key = MFE.Key->getString();
|
|
if (Key == "SmallDataLimit") {
|
|
SSThreshold = mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue();
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Return true if this constant should be placed into small data section.
|
|
bool RISCVELFTargetObjectFile::isConstantInSmallSection(
|
|
const DataLayout &DL, const Constant *CN) const {
|
|
return isInSmallSection(DL.getTypeAllocSize(CN->getType()));
|
|
}
|
|
|
|
MCSection *RISCVELFTargetObjectFile::getSectionForConstant(
|
|
const DataLayout &DL, SectionKind Kind, const Constant *C,
|
|
unsigned &Align) const {
|
|
if (isConstantInSmallSection(DL, C))
|
|
return SmallDataSection;
|
|
|
|
// Otherwise, we work the same as ELF.
|
|
return TargetLoweringObjectFileELF::getSectionForConstant(DL, Kind, C, Align);
|
|
}
|