llvm/lib/Target/Mips/MipsTargetObjectFile.cpp
Chris Lattner b71b909bc7 reintroduce support for Mips "small" section handling. This is
implemented somewhat differently than before, but it should have
the same functionality and the previous testcase passes again.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78900 91177308-0d34-0410-b5e6-96231b3b80d8
2009-08-13 06:28:06 +00:00

94 lines
3.3 KiB
C++

//===-- MipsTargetObjectFile.cpp - Mips object files ----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "MipsTargetObjectFile.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
static cl::opt<unsigned>
SSThreshold("mips-ssection-threshold", cl::Hidden,
cl::desc("Small data and bss section threshold size (default=8)"),
cl::init(8));
void MipsTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
TargetLoweringObjectFileELF::Initialize(Ctx, TM);
SmallDataSection =
getELFSection(".sdata", MCSectionELF::SHT_PROGBITS,
MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
SectionKind::getDataRel());
SmallBSSSection =
getELFSection(".sbss", MCSectionELF::SHT_NOBITS,
MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
SectionKind::getBSS());
}
// A address must be loaded from a small section if its size is less than the
// small section size threshold. Data in this section must be addressed using
// gp_rel operator.
static bool IsInSmallSection(uint64_t Size) {
return Size > 0 && Size <= SSThreshold;
}
bool MipsTargetObjectFile::IsGlobalInSmallSection(const GlobalValue *GV,
const TargetMachine &TM) const {
if (GV->isDeclaration() || GV->hasAvailableExternallyLinkage())
return false;
return IsGlobalInSmallSection(GV, TM, getKindForGlobal(GV, TM));
}
/// IsGlobalInSmallSection - Return true if this global address should be
/// placed into small data/bss section.
bool MipsTargetObjectFile::
IsGlobalInSmallSection(const GlobalValue *GV, const TargetMachine &TM,
SectionKind Kind) const {
// Only global variables, not functions.
const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV);
if (!GVA)
return false;
// We can only do this for datarel or BSS objects for now.
if (!Kind.isBSS() && !Kind.isDataRel())
return false;
// If this is a internal constant string, there is a special
// section for it, but not in small data/bss.
if (Kind.isMergeable1ByteCString())
return false;
const Type *Ty = GV->getType()->getElementType();
return IsInSmallSection(TM.getTargetData()->getTypeAllocSize(Ty));
}
const MCSection *MipsTargetObjectFile::
SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
Mangler *Mang, const TargetMachine &TM) const {
// TODO: Could also support "weak" symbols as well with ".gnu.linkonce.s.*"
// sections?
// Handle Small Section classification here.
if (Kind.isBSS() && IsGlobalInSmallSection(GV, TM, Kind))
return SmallBSSSection;
if (Kind.isDataNoRel() && IsGlobalInSmallSection(GV, TM, Kind))
return SmallDataSection;
// Otherwise, we work the same as ELF.
return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang,TM);
}