mirror of
https://github.com/RPCSX/llvm.git
synced 2024-11-30 23:20:54 +00:00
25efd6d556
Do some cleanup of the code while here. Inspired by patch by Logan Chien! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167904 91177308-0d34-0410-b5e6-96231b3b80d8
320 lines
12 KiB
C++
320 lines
12 KiB
C++
//===-- llvm/Target/TargetLoweringObjectFile.cpp - Object File Info -------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements classes used to handle lowerings specific to common
|
|
// object file formats.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Target/TargetLoweringObjectFile.h"
|
|
#include "llvm/Constants.h"
|
|
#include "llvm/DerivedTypes.h"
|
|
#include "llvm/Function.h"
|
|
#include "llvm/GlobalVariable.h"
|
|
#include "llvm/MC/MCContext.h"
|
|
#include "llvm/MC/MCExpr.h"
|
|
#include "llvm/MC/MCStreamer.h"
|
|
#include "llvm/MC/MCSymbol.h"
|
|
#include "llvm/Target/Mangler.h"
|
|
#include "llvm/DataLayout.h"
|
|
#include "llvm/Target/TargetMachine.h"
|
|
#include "llvm/Target/TargetOptions.h"
|
|
#include "llvm/Support/Dwarf.h"
|
|
#include "llvm/Support/ErrorHandling.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
using namespace llvm;
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Generic Code
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// Initialize - this method must be called before any actual lowering is
|
|
/// done. This specifies the current context for codegen, and gives the
|
|
/// lowering implementations a chance to set up their default sections.
|
|
void TargetLoweringObjectFile::Initialize(MCContext &ctx,
|
|
const TargetMachine &TM) {
|
|
Ctx = &ctx;
|
|
InitMCObjectFileInfo(TM.getTargetTriple(),
|
|
TM.getRelocationModel(), TM.getCodeModel(), *Ctx);
|
|
}
|
|
|
|
TargetLoweringObjectFile::~TargetLoweringObjectFile() {
|
|
}
|
|
|
|
static bool isSuitableForBSS(const GlobalVariable *GV, bool NoZerosInBSS) {
|
|
const Constant *C = GV->getInitializer();
|
|
|
|
// Must have zero initializer.
|
|
if (!C->isNullValue())
|
|
return false;
|
|
|
|
// Leave constant zeros in readonly constant sections, so they can be shared.
|
|
if (GV->isConstant())
|
|
return false;
|
|
|
|
// If the global has an explicit section specified, don't put it in BSS.
|
|
if (!GV->getSection().empty())
|
|
return false;
|
|
|
|
// If -nozero-initialized-in-bss is specified, don't ever use BSS.
|
|
if (NoZerosInBSS)
|
|
return false;
|
|
|
|
// Otherwise, put it in BSS!
|
|
return true;
|
|
}
|
|
|
|
/// IsNullTerminatedString - Return true if the specified constant (which is
|
|
/// known to have a type that is an array of 1/2/4 byte elements) ends with a
|
|
/// nul value and contains no other nuls in it. Note that this is more general
|
|
/// than ConstantDataSequential::isString because we allow 2 & 4 byte strings.
|
|
static bool IsNullTerminatedString(const Constant *C) {
|
|
// First check: is we have constant array terminated with zero
|
|
if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(C)) {
|
|
unsigned NumElts = CDS->getNumElements();
|
|
assert(NumElts != 0 && "Can't have an empty CDS");
|
|
|
|
if (CDS->getElementAsInteger(NumElts-1) != 0)
|
|
return false; // Not null terminated.
|
|
|
|
// Verify that the null doesn't occur anywhere else in the string.
|
|
for (unsigned i = 0; i != NumElts-1; ++i)
|
|
if (CDS->getElementAsInteger(i) == 0)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
// Another possibility: [1 x i8] zeroinitializer
|
|
if (isa<ConstantAggregateZero>(C))
|
|
return cast<ArrayType>(C->getType())->getNumElements() == 1;
|
|
|
|
return false;
|
|
}
|
|
|
|
MCSymbol *TargetLoweringObjectFile::
|
|
getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
|
|
MachineModuleInfo *MMI) const {
|
|
return Mang->getSymbol(GV);
|
|
}
|
|
|
|
void TargetLoweringObjectFile::emitPersonalityValue(MCStreamer &Streamer,
|
|
const TargetMachine &TM,
|
|
const MCSymbol *Sym) const {
|
|
}
|
|
|
|
|
|
/// getKindForGlobal - This is a top-level target-independent classifier for
|
|
/// a global variable. Given an global variable and information from TM, it
|
|
/// classifies the global in a variety of ways that make various target
|
|
/// implementations simpler. The target implementation is free to ignore this
|
|
/// extra info of course.
|
|
SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV,
|
|
const TargetMachine &TM){
|
|
assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
|
|
"Can only be used for global definitions");
|
|
|
|
Reloc::Model ReloModel = TM.getRelocationModel();
|
|
|
|
// Early exit - functions should be always in text sections.
|
|
const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
|
|
if (GVar == 0)
|
|
return SectionKind::getText();
|
|
|
|
// Handle thread-local data first.
|
|
if (GVar->isThreadLocal()) {
|
|
if (isSuitableForBSS(GVar, TM.Options.NoZerosInBSS))
|
|
return SectionKind::getThreadBSS();
|
|
return SectionKind::getThreadData();
|
|
}
|
|
|
|
// Variables with common linkage always get classified as common.
|
|
if (GVar->hasCommonLinkage())
|
|
return SectionKind::getCommon();
|
|
|
|
// Variable can be easily put to BSS section.
|
|
if (isSuitableForBSS(GVar, TM.Options.NoZerosInBSS)) {
|
|
if (GVar->hasLocalLinkage())
|
|
return SectionKind::getBSSLocal();
|
|
else if (GVar->hasExternalLinkage())
|
|
return SectionKind::getBSSExtern();
|
|
return SectionKind::getBSS();
|
|
}
|
|
|
|
const Constant *C = GVar->getInitializer();
|
|
|
|
// If the global is marked constant, we can put it into a mergable section,
|
|
// a mergable string section, or general .data if it contains relocations.
|
|
if (GVar->isConstant()) {
|
|
// If the initializer for the global contains something that requires a
|
|
// relocation, then we may have to drop this into a writable data section
|
|
// even though it is marked const.
|
|
switch (C->getRelocationInfo()) {
|
|
case Constant::NoRelocation:
|
|
// If the global is required to have a unique address, it can't be put
|
|
// into a mergable section: just drop it into the general read-only
|
|
// section instead.
|
|
if (!GVar->hasUnnamedAddr())
|
|
return SectionKind::getReadOnly();
|
|
|
|
// If initializer is a null-terminated string, put it in a "cstring"
|
|
// section of the right width.
|
|
if (ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) {
|
|
if (IntegerType *ITy =
|
|
dyn_cast<IntegerType>(ATy->getElementType())) {
|
|
if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 ||
|
|
ITy->getBitWidth() == 32) &&
|
|
IsNullTerminatedString(C)) {
|
|
if (ITy->getBitWidth() == 8)
|
|
return SectionKind::getMergeable1ByteCString();
|
|
if (ITy->getBitWidth() == 16)
|
|
return SectionKind::getMergeable2ByteCString();
|
|
|
|
assert(ITy->getBitWidth() == 32 && "Unknown width");
|
|
return SectionKind::getMergeable4ByteCString();
|
|
}
|
|
}
|
|
}
|
|
|
|
// Otherwise, just drop it into a mergable constant section. If we have
|
|
// a section for this size, use it, otherwise use the arbitrary sized
|
|
// mergable section.
|
|
switch (TM.getDataLayout()->getTypeAllocSize(C->getType())) {
|
|
case 4: return SectionKind::getMergeableConst4();
|
|
case 8: return SectionKind::getMergeableConst8();
|
|
case 16: return SectionKind::getMergeableConst16();
|
|
default: return SectionKind::getMergeableConst();
|
|
}
|
|
|
|
case Constant::LocalRelocation:
|
|
// In static relocation model, the linker will resolve all addresses, so
|
|
// the relocation entries will actually be constants by the time the app
|
|
// starts up. However, we can't put this into a mergable section, because
|
|
// the linker doesn't take relocations into consideration when it tries to
|
|
// merge entries in the section.
|
|
if (ReloModel == Reloc::Static)
|
|
return SectionKind::getReadOnly();
|
|
|
|
// Otherwise, the dynamic linker needs to fix it up, put it in the
|
|
// writable data.rel.local section.
|
|
return SectionKind::getReadOnlyWithRelLocal();
|
|
|
|
case Constant::GlobalRelocations:
|
|
// In static relocation model, the linker will resolve all addresses, so
|
|
// the relocation entries will actually be constants by the time the app
|
|
// starts up. However, we can't put this into a mergable section, because
|
|
// the linker doesn't take relocations into consideration when it tries to
|
|
// merge entries in the section.
|
|
if (ReloModel == Reloc::Static)
|
|
return SectionKind::getReadOnly();
|
|
|
|
// Otherwise, the dynamic linker needs to fix it up, put it in the
|
|
// writable data.rel section.
|
|
return SectionKind::getReadOnlyWithRel();
|
|
}
|
|
}
|
|
|
|
// Okay, this isn't a constant. If the initializer for the global is going
|
|
// to require a runtime relocation by the dynamic linker, put it into a more
|
|
// specific section to improve startup time of the app. This coalesces these
|
|
// globals together onto fewer pages, improving the locality of the dynamic
|
|
// linker.
|
|
if (ReloModel == Reloc::Static)
|
|
return SectionKind::getDataNoRel();
|
|
|
|
switch (C->getRelocationInfo()) {
|
|
case Constant::NoRelocation:
|
|
return SectionKind::getDataNoRel();
|
|
case Constant::LocalRelocation:
|
|
return SectionKind::getDataRelLocal();
|
|
case Constant::GlobalRelocations:
|
|
return SectionKind::getDataRel();
|
|
}
|
|
llvm_unreachable("Invalid relocation");
|
|
}
|
|
|
|
/// SectionForGlobal - This method computes the appropriate section to emit
|
|
/// the specified global variable or function definition. This should not
|
|
/// be passed external (or available externally) globals.
|
|
const MCSection *TargetLoweringObjectFile::
|
|
SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang,
|
|
const TargetMachine &TM) const {
|
|
// Select section name.
|
|
if (GV->hasSection())
|
|
return getExplicitSectionGlobal(GV, Kind, Mang, TM);
|
|
|
|
|
|
// Use default section depending on the 'type' of global
|
|
return SelectSectionForGlobal(GV, Kind, Mang, TM);
|
|
}
|
|
|
|
|
|
// Lame default implementation. Calculate the section name for global.
|
|
const MCSection *
|
|
TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
|
|
SectionKind Kind,
|
|
Mangler *Mang,
|
|
const TargetMachine &TM) const{
|
|
assert(!Kind.isThreadLocal() && "Doesn't support TLS");
|
|
|
|
if (Kind.isText())
|
|
return getTextSection();
|
|
|
|
if (Kind.isBSS() && BSSSection != 0)
|
|
return BSSSection;
|
|
|
|
if (Kind.isReadOnly() && ReadOnlySection != 0)
|
|
return ReadOnlySection;
|
|
|
|
return getDataSection();
|
|
}
|
|
|
|
/// getSectionForConstant - Given a mergable constant with the
|
|
/// specified size and relocation information, return a section that it
|
|
/// should be placed in.
|
|
const MCSection *
|
|
TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const {
|
|
if (Kind.isReadOnly() && ReadOnlySection != 0)
|
|
return ReadOnlySection;
|
|
|
|
return DataSection;
|
|
}
|
|
|
|
/// getTTypeGlobalReference - Return an MCExpr to use for a
|
|
/// reference to the specified global variable from exception
|
|
/// handling information.
|
|
const MCExpr *TargetLoweringObjectFile::
|
|
getTTypeGlobalReference(const GlobalValue *GV, Mangler *Mang,
|
|
MachineModuleInfo *MMI, unsigned Encoding,
|
|
MCStreamer &Streamer) const {
|
|
const MCSymbolRefExpr *Ref =
|
|
MCSymbolRefExpr::Create(Mang->getSymbol(GV), getContext());
|
|
|
|
return getTTypeReference(Ref, Encoding, Streamer);
|
|
}
|
|
|
|
const MCExpr *TargetLoweringObjectFile::
|
|
getTTypeReference(const MCSymbolRefExpr *Sym, unsigned Encoding,
|
|
MCStreamer &Streamer) const {
|
|
switch (Encoding & 0x70) {
|
|
default:
|
|
report_fatal_error("We do not support this DWARF encoding yet!");
|
|
case dwarf::DW_EH_PE_absptr:
|
|
// Do nothing special
|
|
return Sym;
|
|
case dwarf::DW_EH_PE_pcrel: {
|
|
// Emit a label to the streamer for the current position. This gives us
|
|
// .-foo addressing.
|
|
MCSymbol *PCSym = getContext().CreateTempSymbol();
|
|
Streamer.EmitLabel(PCSym);
|
|
const MCExpr *PC = MCSymbolRefExpr::Create(PCSym, getContext());
|
|
return MCBinaryExpr::CreateSub(Sym, PC, getContext());
|
|
}
|
|
}
|
|
}
|