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llvm-mirror/lib/MC/MCWinCOFFStreamer.cpp
Peter Smith 7d816e3012 [MC] Pass MCSubtargetInfo to fixupNeedsRelaxation and applyFixup
On targets like Arm some relaxations may only be performed when certain
architectural features are available. As functions can be compiled with
differing levels of architectural support we must make a judgement on
whether we can relax based on the MCSubtargetInfo for the function. This
change passes through the MCSubtargetInfo for the function to
fixupNeedsRelaxation so that the decision on whether to relax can be made
per function. In this patch, only the ARM backend makes use of this
information. We must also pass the MCSubtargetInfo to applyFixup because
some fixups skip error checking on the assumption that relaxation has
occurred, to prevent code-generation errors applyFixup must see the same
MCSubtargetInfo as fixupNeedsRelaxation.

Differential Revision: https://reviews.llvm.org/D44928

llvm-svn: 334078
2018-06-06 09:40:06 +00:00

307 lines
9.8 KiB
C++

//===- llvm/MC/MCWinCOFFStreamer.cpp --------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains an implementation of a Windows COFF object file streamer.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCFixup.h"
#include "llvm/MC/MCFragment.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSymbolCOFF.h"
#include "llvm/MC/MCWinCOFFStreamer.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/SMLoc.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
using namespace llvm;
#define DEBUG_TYPE "WinCOFFStreamer"
MCWinCOFFStreamer::MCWinCOFFStreamer(MCContext &Context,
std::unique_ptr<MCAsmBackend> MAB,
std::unique_ptr<MCCodeEmitter> CE,
std::unique_ptr<MCObjectWriter> OW)
: MCObjectStreamer(Context, std::move(MAB), std::move(OW), std::move(CE)),
CurSymbol(nullptr) {}
void MCWinCOFFStreamer::EmitInstToData(const MCInst &Inst,
const MCSubtargetInfo &STI) {
MCDataFragment *DF = getOrCreateDataFragment();
SmallVector<MCFixup, 4> Fixups;
SmallString<256> Code;
raw_svector_ostream VecOS(Code);
getAssembler().getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
// Add the fixups and data.
for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
DF->getFixups().push_back(Fixups[i]);
}
DF->setHasInstructions(STI);
DF->getContents().append(Code.begin(), Code.end());
}
void MCWinCOFFStreamer::InitSections(bool NoExecStack) {
// FIXME: this is identical to the ELF one.
// This emulates the same behavior of GNU as. This makes it easier
// to compare the output as the major sections are in the same order.
SwitchSection(getContext().getObjectFileInfo()->getTextSection());
EmitCodeAlignment(4);
SwitchSection(getContext().getObjectFileInfo()->getDataSection());
EmitCodeAlignment(4);
SwitchSection(getContext().getObjectFileInfo()->getBSSSection());
EmitCodeAlignment(4);
SwitchSection(getContext().getObjectFileInfo()->getTextSection());
}
void MCWinCOFFStreamer::EmitLabel(MCSymbol *S, SMLoc Loc) {
auto *Symbol = cast<MCSymbolCOFF>(S);
MCObjectStreamer::EmitLabel(Symbol, Loc);
}
void MCWinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
llvm_unreachable("not implemented");
}
void MCWinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
llvm_unreachable("not implemented");
}
bool MCWinCOFFStreamer::EmitSymbolAttribute(MCSymbol *S,
MCSymbolAttr Attribute) {
auto *Symbol = cast<MCSymbolCOFF>(S);
getAssembler().registerSymbol(*Symbol);
switch (Attribute) {
default: return false;
case MCSA_WeakReference:
case MCSA_Weak:
Symbol->setIsWeakExternal();
Symbol->setExternal(true);
break;
case MCSA_Global:
Symbol->setExternal(true);
break;
case MCSA_AltEntry:
llvm_unreachable("COFF doesn't support the .alt_entry attribute");
}
return true;
}
void MCWinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
llvm_unreachable("not implemented");
}
void MCWinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *S) {
auto *Symbol = cast<MCSymbolCOFF>(S);
if (CurSymbol)
Error("starting a new symbol definition without completing the "
"previous one");
CurSymbol = Symbol;
}
void MCWinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
if (!CurSymbol) {
Error("storage class specified outside of symbol definition");
return;
}
if (StorageClass & ~COFF::SSC_Invalid) {
Error("storage class value '" + Twine(StorageClass) +
"' out of range");
return;
}
getAssembler().registerSymbol(*CurSymbol);
cast<MCSymbolCOFF>(CurSymbol)->setClass((uint16_t)StorageClass);
}
void MCWinCOFFStreamer::EmitCOFFSymbolType(int Type) {
if (!CurSymbol) {
Error("symbol type specified outside of a symbol definition");
return;
}
if (Type & ~0xffff) {
Error("type value '" + Twine(Type) + "' out of range");
return;
}
getAssembler().registerSymbol(*CurSymbol);
cast<MCSymbolCOFF>(CurSymbol)->setType((uint16_t)Type);
}
void MCWinCOFFStreamer::EndCOFFSymbolDef() {
if (!CurSymbol)
Error("ending symbol definition without starting one");
CurSymbol = nullptr;
}
void MCWinCOFFStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {
// SafeSEH is a feature specific to 32-bit x86. It does not exist (and is
// unnecessary) on all platforms which use table-based exception dispatch.
if (getContext().getObjectFileInfo()->getTargetTriple().getArch() !=
Triple::x86)
return;
const MCSymbolCOFF *CSymbol = cast<MCSymbolCOFF>(Symbol);
if (CSymbol->isSafeSEH())
return;
MCSection *SXData = getContext().getObjectFileInfo()->getSXDataSection();
getAssembler().registerSection(*SXData);
if (SXData->getAlignment() < 4)
SXData->setAlignment(4);
new MCSymbolIdFragment(Symbol, SXData);
getAssembler().registerSymbol(*Symbol);
CSymbol->setIsSafeSEH();
// The Microsoft linker requires that the symbol type of a handler be
// function. Go ahead and oblige it here.
CSymbol->setType(COFF::IMAGE_SYM_DTYPE_FUNCTION
<< COFF::SCT_COMPLEX_TYPE_SHIFT);
}
void MCWinCOFFStreamer::EmitCOFFSymbolIndex(MCSymbol const *Symbol) {
MCSection *Sec = getCurrentSectionOnly();
getAssembler().registerSection(*Sec);
if (Sec->getAlignment() < 4)
Sec->setAlignment(4);
new MCSymbolIdFragment(Symbol, getCurrentSectionOnly());
getAssembler().registerSymbol(*Symbol);
}
void MCWinCOFFStreamer::EmitCOFFSectionIndex(const MCSymbol *Symbol) {
visitUsedSymbol(*Symbol);
MCDataFragment *DF = getOrCreateDataFragment();
const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_2);
DF->getFixups().push_back(Fixup);
DF->getContents().resize(DF->getContents().size() + 2, 0);
}
void MCWinCOFFStreamer::EmitCOFFSecRel32(const MCSymbol *Symbol,
uint64_t Offset) {
visitUsedSymbol(*Symbol);
MCDataFragment *DF = getOrCreateDataFragment();
// Create Symbol A for the relocation relative reference.
const MCExpr *MCE = MCSymbolRefExpr::create(Symbol, getContext());
// Add the constant offset, if given.
if (Offset)
MCE = MCBinaryExpr::createAdd(
MCE, MCConstantExpr::create(Offset, getContext()), getContext());
// Build the secrel32 relocation.
MCFixup Fixup = MCFixup::create(DF->getContents().size(), MCE, FK_SecRel_4);
// Record the relocation.
DF->getFixups().push_back(Fixup);
// Emit 4 bytes (zeros) to the object file.
DF->getContents().resize(DF->getContents().size() + 4, 0);
}
void MCWinCOFFStreamer::EmitCommonSymbol(MCSymbol *S, uint64_t Size,
unsigned ByteAlignment) {
auto *Symbol = cast<MCSymbolCOFF>(S);
const Triple &T = getContext().getObjectFileInfo()->getTargetTriple();
if (T.isKnownWindowsMSVCEnvironment()) {
if (ByteAlignment > 32)
report_fatal_error("alignment is limited to 32-bytes");
// Round size up to alignment so that we will honor the alignment request.
Size = std::max(Size, static_cast<uint64_t>(ByteAlignment));
}
getAssembler().registerSymbol(*Symbol);
Symbol->setExternal(true);
Symbol->setCommon(Size, ByteAlignment);
if (!T.isKnownWindowsMSVCEnvironment() && ByteAlignment > 1) {
SmallString<128> Directive;
raw_svector_ostream OS(Directive);
const MCObjectFileInfo *MFI = getContext().getObjectFileInfo();
OS << " -aligncomm:\"" << Symbol->getName() << "\","
<< Log2_32_Ceil(ByteAlignment);
PushSection();
SwitchSection(MFI->getDrectveSection());
EmitBytes(Directive);
PopSection();
}
}
void MCWinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
unsigned ByteAlignment) {
auto *Symbol = cast<MCSymbolCOFF>(S);
MCSection *Section = getContext().getObjectFileInfo()->getBSSSection();
PushSection();
SwitchSection(Section);
EmitValueToAlignment(ByteAlignment, 0, 1, 0);
EmitLabel(Symbol);
Symbol->setExternal(false);
EmitZeros(Size);
PopSection();
}
void MCWinCOFFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) {
llvm_unreachable("not implemented");
}
void MCWinCOFFStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) {
llvm_unreachable("not implemented");
}
// TODO: Implement this if you want to emit .comment section in COFF obj files.
void MCWinCOFFStreamer::EmitIdent(StringRef IdentString) {
llvm_unreachable("not implemented");
}
void MCWinCOFFStreamer::EmitWinEHHandlerData(SMLoc Loc) {
llvm_unreachable("not implemented");
}
void MCWinCOFFStreamer::FinishImpl() {
MCObjectStreamer::FinishImpl();
}
void MCWinCOFFStreamer::Error(const Twine &Msg) const {
getContext().reportError(SMLoc(), Msg);
}