maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/lib/Target/X86/X86AsmPrinter.cpp

734 lines
25 KiB
C++
Raw Blame History

//===-- X86AsmPrinter.cpp - Convert X86 LLVM code to AT&T assembly --------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file contains a printer that converts from our internal representation
// of machine-dependent LLVM code to X86 machine code.
//
//===----------------------------------------------------------------------===//
#include "X86AsmPrinter.h"
#include "MCTargetDesc/X86ATTInstPrinter.h"
#include "MCTargetDesc/X86BaseInfo.h"
#include "MCTargetDesc/X86TargetStreamer.h"
#include "TargetInfo/X86TargetInfo.h"
#include "X86InstrInfo.h"
#include "X86MachineFunctionInfo.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineModuleInfoImpls.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MachineValueType.h"
#include "llvm/Support/TargetRegistry.h"
using namespace llvm;
X86AsmPrinter::X86AsmPrinter(TargetMachine &TM,
std::unique_ptr<MCStreamer> Streamer)
: AsmPrinter(TM, std::move(Streamer)), SM(*this), FM(*this) {}
//===----------------------------------------------------------------------===//
// Primitive Helper Functions.
//===----------------------------------------------------------------------===//
/// runOnMachineFunction - Emit the function body.
///
bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
Subtarget = &MF.getSubtarget<X86Subtarget>();
SMShadowTracker.startFunction(MF);
CodeEmitter.reset(TM.getTarget().createMCCodeEmitter(
*Subtarget->getInstrInfo(), *Subtarget->getRegisterInfo(),
MF.getContext()));
EmitFPOData =
Subtarget->isTargetWin32() && MF.getMMI().getModule()->getCodeViewFlag();
SetupMachineFunction(MF);
if (Subtarget->isTargetCOFF()) {
bool Local = MF.getFunction().hasLocalLinkage();
OutStreamer->BeginCOFFSymbolDef(CurrentFnSym);
OutStreamer->EmitCOFFSymbolStorageClass(
Local ? COFF::IMAGE_SYM_CLASS_STATIC : COFF::IMAGE_SYM_CLASS_EXTERNAL);
OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
<< COFF::SCT_COMPLEX_TYPE_SHIFT);
OutStreamer->EndCOFFSymbolDef();
}
// Emit the rest of the function body.
EmitFunctionBody();
// Emit the XRay table for this function.
emitXRayTable();
EmitFPOData = false;
// We didn't modify anything.
return false;
}
void X86AsmPrinter::EmitFunctionBodyStart() {
if (EmitFPOData) {
if (auto *XTS =
static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
XTS->emitFPOProc(
CurrentFnSym,
MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize());
}
}
void X86AsmPrinter::EmitFunctionBodyEnd() {
if (EmitFPOData) {
if (auto *XTS =
static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
XTS->emitFPOEndProc();
}
}
/// PrintSymbolOperand - Print a raw symbol reference operand. This handles
/// jump tables, constant pools, global address and external symbols, all of
/// which print to a label with various suffixes for relocation types etc.
void X86AsmPrinter::PrintSymbolOperand(const MachineOperand &MO,
raw_ostream &O) {
switch (MO.getType()) {
default: llvm_unreachable("unknown symbol type!");
case MachineOperand::MO_ConstantPoolIndex:
GetCPISymbol(MO.getIndex())->print(O, MAI);
printOffset(MO.getOffset(), O);
break;
case MachineOperand::MO_GlobalAddress: {
const GlobalValue *GV = MO.getGlobal();
MCSymbol *GVSym;
if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE)
GVSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
else
GVSym = getSymbol(GV);
// Handle dllimport linkage.
if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
GVSym = OutContext.getOrCreateSymbol(Twine("__imp_") + GVSym->getName());
else if (MO.getTargetFlags() == X86II::MO_COFFSTUB)
GVSym =
OutContext.getOrCreateSymbol(Twine(".refptr.") + GVSym->getName());
if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
MCSymbol *Sym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
MachineModuleInfoImpl::StubValueTy &StubSym =
MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(Sym);
if (!StubSym.getPointer())
StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
!GV->hasInternalLinkage());
}
// If the name begins with a dollar-sign, enclose it in parens. We do this
// to avoid having it look like an integer immediate to the assembler.
if (GVSym->getName()[0] != '$')
GVSym->print(O, MAI);
else {
O << '(';
GVSym->print(O, MAI);
O << ')';
}
printOffset(MO.getOffset(), O);
break;
}
}
switch (MO.getTargetFlags()) {
default:
llvm_unreachable("Unknown target flag on GV operand");
case X86II::MO_NO_FLAG: // No flag.
break;
case X86II::MO_DARWIN_NONLAZY:
case X86II::MO_DLLIMPORT:
case X86II::MO_COFFSTUB:
// These affect the name of the symbol, not any suffix.
break;
case X86II::MO_GOT_ABSOLUTE_ADDRESS:
O << " + [.-";
MF->getPICBaseSymbol()->print(O, MAI);
O << ']';
break;
case X86II::MO_PIC_BASE_OFFSET:
case X86II::MO_DARWIN_NONLAZY_PIC_BASE:
O << '-';
MF->getPICBaseSymbol()->print(O, MAI);
break;
case X86II::MO_TLSGD: O << "@TLSGD"; break;
case X86II::MO_TLSLD: O << "@TLSLD"; break;
case X86II::MO_TLSLDM: O << "@TLSLDM"; break;
case X86II::MO_GOTTPOFF: O << "@GOTTPOFF"; break;
case X86II::MO_INDNTPOFF: O << "@INDNTPOFF"; break;
case X86II::MO_TPOFF: O << "@TPOFF"; break;
case X86II::MO_DTPOFF: O << "@DTPOFF"; break;
case X86II::MO_NTPOFF: O << "@NTPOFF"; break;
case X86II::MO_GOTNTPOFF: O << "@GOTNTPOFF"; break;
case X86II::MO_GOTPCREL: O << "@GOTPCREL"; break;
case X86II::MO_GOT: O << "@GOT"; break;
case X86II::MO_GOTOFF: O << "@GOTOFF"; break;
case X86II::MO_PLT: O << "@PLT"; break;
case X86II::MO_TLVP: O << "@TLVP"; break;
case X86II::MO_TLVP_PIC_BASE:
O << "@TLVP" << '-';
MF->getPICBaseSymbol()->print(O, MAI);
break;
case X86II::MO_SECREL: O << "@SECREL32"; break;
}
}
void X86AsmPrinter::PrintOperand(const MachineInstr *MI, unsigned OpNo,
raw_ostream &O) {
const MachineOperand &MO = MI->getOperand(OpNo);
const bool IsATT = MI->getInlineAsmDialect() == InlineAsm::AD_ATT;
switch (MO.getType()) {
default: llvm_unreachable("unknown operand type!");
case MachineOperand::MO_Register: {
if (IsATT)
O << '%';
O << X86ATTInstPrinter::getRegisterName(MO.getReg());
return;
}
case MachineOperand::MO_Immediate:
if (IsATT)
O << '$';
O << MO.getImm();
return;
case MachineOperand::MO_GlobalAddress: {
if (IsATT)
O << '$';
PrintSymbolOperand(MO, O);
break;
}
case MachineOperand::MO_BlockAddress: {
MCSymbol *Sym = GetBlockAddressSymbol(MO.getBlockAddress());
Sym->print(O, MAI);
break;
}
}
}
/// PrintModifiedOperand - Print subregisters based on supplied modifier,
/// deferring to PrintOperand() if no modifier was supplied or if operand is not
/// a register.
void X86AsmPrinter::PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
raw_ostream &O, const char *Modifier) {
const MachineOperand &MO = MI->getOperand(OpNo);
if (!Modifier || MO.getType() != MachineOperand::MO_Register)
return PrintOperand(MI, OpNo, O);
if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
O << '%';
unsigned Reg = MO.getReg();
if (strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
unsigned Size = (strcmp(Modifier+6,"64") == 0) ? 64 :
(strcmp(Modifier+6,"32") == 0) ? 32 :
(strcmp(Modifier+6,"16") == 0) ? 16 : 8;
Reg = getX86SubSuperRegister(Reg, Size);
}
O << X86ATTInstPrinter::getRegisterName(Reg);
}
/// PrintPCRelImm - This is used to print an immediate value that ends up
/// being encoded as a pc-relative value. These print slightly differently, for
/// example, a $ is not emitted.
void X86AsmPrinter::PrintPCRelImm(const MachineInstr *MI, unsigned OpNo,
raw_ostream &O) {
const MachineOperand &MO = MI->getOperand(OpNo);
switch (MO.getType()) {
default: llvm_unreachable("Unknown pcrel immediate operand");
case MachineOperand::MO_Register:
// pc-relativeness was handled when computing the value in the reg.
PrintOperand(MI, OpNo, O);
return;
case MachineOperand::MO_Immediate:
O << MO.getImm();
return;
case MachineOperand::MO_GlobalAddress:
PrintSymbolOperand(MO, O);
return;
}
}
void X86AsmPrinter::PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
raw_ostream &O, const char *Modifier) {
const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
// If we really don't want to print out (rip), don't.
bool HasBaseReg = BaseReg.getReg() != 0;
if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
BaseReg.getReg() == X86::RIP)
HasBaseReg = false;
// HasParenPart - True if we will print out the () part of the mem ref.
bool HasParenPart = IndexReg.getReg() || HasBaseReg;
switch (DispSpec.getType()) {
default:
llvm_unreachable("unknown operand type!");
case MachineOperand::MO_Immediate: {
int DispVal = DispSpec.getImm();
if (DispVal || !HasParenPart)
O << DispVal;
break;
}
case MachineOperand::MO_GlobalAddress:
case MachineOperand::MO_ConstantPoolIndex:
PrintSymbolOperand(DispSpec, O);
break;
}
if (Modifier && strcmp(Modifier, "H") == 0)
O << "+8";
if (HasParenPart) {
assert(IndexReg.getReg() != X86::ESP &&
"X86 doesn't allow scaling by ESP");
O << '(';
if (HasBaseReg)
PrintModifiedOperand(MI, OpNo + X86::AddrBaseReg, O, Modifier);
if (IndexReg.getReg()) {
O << ',';
PrintModifiedOperand(MI, OpNo + X86::AddrIndexReg, O, Modifier);
unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
if (ScaleVal != 1)
O << ',' << ScaleVal;
}
O << ')';
}
}
void X86AsmPrinter::PrintMemReference(const MachineInstr *MI, unsigned OpNo,
raw_ostream &O, const char *Modifier) {
assert(isMem(*MI, OpNo) && "Invalid memory reference!");
const MachineOperand &Segment = MI->getOperand(OpNo + X86::AddrSegmentReg);
if (Segment.getReg()) {
PrintModifiedOperand(MI, OpNo + X86::AddrSegmentReg, O, Modifier);
O << ':';
}
PrintLeaMemReference(MI, OpNo, O, Modifier);
}
void X86AsmPrinter::PrintIntelMemReference(const MachineInstr *MI,
unsigned OpNo, raw_ostream &O) {
const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
const MachineOperand &SegReg = MI->getOperand(OpNo + X86::AddrSegmentReg);
// If this has a segment register, print it.
if (SegReg.getReg()) {
PrintOperand(MI, OpNo + X86::AddrSegmentReg, O);
O << ':';
}
O << '[';
bool NeedPlus = false;
if (BaseReg.getReg()) {
PrintOperand(MI, OpNo + X86::AddrBaseReg, O);
NeedPlus = true;
}
if (IndexReg.getReg()) {
if (NeedPlus) O << " + ";
if (ScaleVal != 1)
O << ScaleVal << '*';
PrintOperand(MI, OpNo + X86::AddrIndexReg, O);
NeedPlus = true;
}
if (!DispSpec.isImm()) {
if (NeedPlus) O << " + ";
PrintOperand(MI, OpNo + X86::AddrDisp, O);
} else {
int64_t DispVal = DispSpec.getImm();
if (DispVal || (!IndexReg.getReg() && !BaseReg.getReg())) {
if (NeedPlus) {
if (DispVal > 0)
O << " + ";
else {
O << " - ";
DispVal = -DispVal;
}
}
O << DispVal;
}
}
O << ']';
}
static bool printAsmMRegister(X86AsmPrinter &P, const MachineOperand &MO,
char Mode, raw_ostream &O) {
unsigned Reg = MO.getReg();
bool EmitPercent = true;
if (!X86::GR8RegClass.contains(Reg) &&
!X86::GR16RegClass.contains(Reg) &&
!X86::GR32RegClass.contains(Reg) &&
!X86::GR64RegClass.contains(Reg))
return true;
switch (Mode) {
default: return true; // Unknown mode.
case 'b': // Print QImode register
Reg = getX86SubSuperRegister(Reg, 8);
break;
case 'h': // Print QImode high register
Reg = getX86SubSuperRegister(Reg, 8, true);
break;
case 'w': // Print HImode register
Reg = getX86SubSuperRegister(Reg, 16);
break;
case 'k': // Print SImode register
Reg = getX86SubSuperRegister(Reg, 32);
break;
case 'V':
EmitPercent = false;
LLVM_FALLTHROUGH;
case 'q':
// Print 64-bit register names if 64-bit integer registers are available.
// Otherwise, print 32-bit register names.
Reg = getX86SubSuperRegister(Reg, P.getSubtarget().is64Bit() ? 64 : 32);
break;
}
if (EmitPercent)
O << '%';
O << X86ATTInstPrinter::getRegisterName(Reg);
return false;
}
/// PrintAsmOperand - Print out an operand for an inline asm expression.
///
bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
const char *ExtraCode, raw_ostream &O) {
// Does this asm operand have a single letter operand modifier?
if (ExtraCode && ExtraCode[0]) {
if (ExtraCode[1] != 0) return true; // Unknown modifier.
const MachineOperand &MO = MI->getOperand(OpNo);
switch (ExtraCode[0]) {
default:
// See if this is a generic print operand
return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
case 'a': // This is an address. Currently only 'i' and 'r' are expected.
switch (MO.getType()) {
default:
return true;
case MachineOperand::MO_Immediate:
O << MO.getImm();
return false;
case MachineOperand::MO_ConstantPoolIndex:
case MachineOperand::MO_JumpTableIndex:
case MachineOperand::MO_ExternalSymbol:
llvm_unreachable("unexpected operand type!");
case MachineOperand::MO_GlobalAddress:
PrintSymbolOperand(MO, O);
if (Subtarget->isPICStyleRIPRel())
O << "(%rip)";
return false;
case MachineOperand::MO_Register:
O << '(';
PrintOperand(MI, OpNo, O);
O << ')';
return false;
}
case 'c': // Don't print "$" before a global var name or constant.
switch (MO.getType()) {
default:
PrintOperand(MI, OpNo, O);
break;
case MachineOperand::MO_Immediate:
O << MO.getImm();
break;
case MachineOperand::MO_ConstantPoolIndex:
case MachineOperand::MO_JumpTableIndex:
case MachineOperand::MO_ExternalSymbol:
llvm_unreachable("unexpected operand type!");
case MachineOperand::MO_GlobalAddress:
PrintSymbolOperand(MO, O);
break;
}
return false;
case 'A': // Print '*' before a register (it must be a register)
if (MO.isReg()) {
O << '*';
PrintOperand(MI, OpNo, O);
return false;
}
return true;
case 'b': // Print QImode register
case 'h': // Print QImode high register
case 'w': // Print HImode register
case 'k': // Print SImode register
case 'q': // Print DImode register
case 'V': // Print native register without '%'
if (MO.isReg())
return printAsmMRegister(*this, MO, ExtraCode[0], O);
PrintOperand(MI, OpNo, O);
return false;
case 'P': // This is the operand of a call, treat specially.
PrintPCRelImm(MI, OpNo, O);
return false;
case 'n': // Negate the immediate or print a '-' before the operand.
// Note: this is a temporary solution. It should be handled target
// independently as part of the 'MC' work.
if (MO.isImm()) {
O << -MO.getImm();
return false;
}
O << '-';
}
}
PrintOperand(MI, OpNo, O);
return false;
}
bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
const char *ExtraCode,
raw_ostream &O) {
if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
PrintIntelMemReference(MI, OpNo, O);
return false;
}
if (ExtraCode && ExtraCode[0]) {
if (ExtraCode[1] != 0) return true; // Unknown modifier.
switch (ExtraCode[0]) {
default: return true; // Unknown modifier.
case 'b': // Print QImode register
case 'h': // Print QImode high register
case 'w': // Print HImode register
case 'k': // Print SImode register
case 'q': // Print SImode register
// These only apply to registers, ignore on mem.
break;
case 'H':
PrintMemReference(MI, OpNo, O, "H");
return false;
case 'P': // Don't print @PLT, but do print as memory.
PrintMemReference(MI, OpNo, O, "no-rip");
return false;
}
}
PrintMemReference(MI, OpNo, O, nullptr);
return false;
}
void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
const Triple &TT = TM.getTargetTriple();
if (TT.isOSBinFormatELF()) {
// Assemble feature flags that may require creation of a note section.
unsigned FeatureFlagsAnd = 0;
if (M.getModuleFlag("cf-protection-branch"))
FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
if (M.getModuleFlag("cf-protection-return"))
FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
if (FeatureFlagsAnd) {
// Emit a .note.gnu.property section with the flags.
if (!TT.isArch32Bit() && !TT.isArch64Bit())
llvm_unreachable("CFProtection used on invalid architecture!");
MCSection *Cur = OutStreamer->getCurrentSectionOnly();
MCSection *Nt = MMI->getContext().getELFSection(
".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
OutStreamer->SwitchSection(Nt);
// Emitting note header.
int WordSize = TT.isArch64Bit() ? 8 : 4;
EmitAlignment(WordSize == 4 ? 2 : 3);
OutStreamer->EmitIntValue(4, 4 /*size*/); // data size for "GNU\0"
OutStreamer->EmitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
OutStreamer->EmitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
OutStreamer->EmitBytes(StringRef("GNU", 4)); // note name
// Emitting an Elf_Prop for the CET properties.
OutStreamer->EmitIntValue(ELF::GNU_PROPERTY_X86_FEATURE_1_AND, 4);
OutStreamer->EmitIntValue(4, 4); // data size
OutStreamer->EmitIntValue(FeatureFlagsAnd, 4); // data
EmitAlignment(WordSize == 4 ? 2 : 3); // padding
OutStreamer->endSection(Nt);
OutStreamer->SwitchSection(Cur);
}
}
if (TT.isOSBinFormatMachO())
OutStreamer->SwitchSection(getObjFileLowering().getTextSection());
if (TT.isOSBinFormatCOFF()) {
// Emit an absolute @feat.00 symbol. This appears to be some kind of
// compiler features bitfield read by link.exe.
MCSymbol *S = MMI->getContext().getOrCreateSymbol(StringRef("@feat.00"));
OutStreamer->BeginCOFFSymbolDef(S);
OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
OutStreamer->EndCOFFSymbolDef();
int64_t Feat00Flags = 0;
if (TT.getArch() == Triple::x86) {
// According to the PE-COFF spec, the LSB of this value marks the object
// for "registered SEH". This means that all SEH handler entry points
// must be registered in .sxdata. Use of any unregistered handlers will
// cause the process to terminate immediately. LLVM does not know how to
// register any SEH handlers, so its object files should be safe.
Feat00Flags |= 1;
}
if (M.getModuleFlag("cfguardtable"))
Feat00Flags |= 0x800; // Object is CFG-aware.
OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
OutStreamer->EmitAssignment(
S, MCConstantExpr::create(Feat00Flags, MMI->getContext()));
}
OutStreamer->EmitSyntaxDirective();
// If this is not inline asm and we're in 16-bit
// mode prefix assembly with .code16.
bool is16 = TT.getEnvironment() == Triple::CODE16;
if (M.getModuleInlineAsm().empty() && is16)
OutStreamer->EmitAssemblerFlag(MCAF_Code16);
}
static void
emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
MachineModuleInfoImpl::StubValueTy &MCSym) {
// L_foo$stub:
OutStreamer.EmitLabel(StubLabel);
// .indirect_symbol _foo
OutStreamer.EmitSymbolAttribute(MCSym.getPointer(), MCSA_IndirectSymbol);
if (MCSym.getInt())
// External to current translation unit.
OutStreamer.EmitIntValue(0, 4/*size*/);
else
// Internal to current translation unit.
//
// When we place the LSDA into the TEXT section, the type info
// pointers need to be indirect and pc-rel. We accomplish this by
// using NLPs; however, sometimes the types are local to the file.
// We need to fill in the value for the NLP in those cases.
OutStreamer.EmitValue(
MCSymbolRefExpr::create(MCSym.getPointer(), OutStreamer.getContext()),
4 /*size*/);
}
static void emitNonLazyStubs(MachineModuleInfo *MMI, MCStreamer &OutStreamer) {
MachineModuleInfoMachO &MMIMacho =
MMI->getObjFileInfo<MachineModuleInfoMachO>();
// Output stubs for dynamically-linked functions.
MachineModuleInfoMachO::SymbolListTy Stubs;
// Output stubs for external and common global variables.
Stubs = MMIMacho.GetGVStubList();
if (!Stubs.empty()) {
OutStreamer.SwitchSection(MMI->getContext().getMachOSection(
"__IMPORT", "__pointers", MachO::S_NON_LAZY_SYMBOL_POINTERS,
SectionKind::getMetadata()));
for (auto &Stub : Stubs)
emitNonLazySymbolPointer(OutStreamer, Stub.first, Stub.second);
Stubs.clear();
OutStreamer.AddBlankLine();
}
}
void X86AsmPrinter::EmitEndOfAsmFile(Module &M) {
const Triple &TT = TM.getTargetTriple();
if (TT.isOSBinFormatMachO()) {
// Mach-O uses non-lazy symbol stubs to encode per-TU information into
// global table for symbol lookup.
emitNonLazyStubs(MMI, *OutStreamer);
// Emit stack and fault map information.
emitStackMaps(SM);
FM.serializeToFaultMapSection();
// This flag tells the linker that no global symbols contain code that fall
// through to other global symbols (e.g. an implementation of multiple entry
// points). If this doesn't occur, the linker can safely perform dead code
// stripping. Since LLVM never generates code that does this, it is always
// safe to set.
OutStreamer->EmitAssemblerFlag(MCAF_SubsectionsViaSymbols);
} else if (TT.isOSBinFormatCOFF()) {
if (MMI->usesMSVCFloatingPoint()) {
// In Windows' libcmt.lib, there is a file which is linked in only if the
// symbol _fltused is referenced. Linking this in causes some
// side-effects:
//
// 1. For x86-32, it will set the x87 rounding mode to 53-bit instead of
// 64-bit mantissas at program start.
//
// 2. It links in support routines for floating-point in scanf and printf.
//
// MSVC emits an undefined reference to _fltused when there are any
// floating point operations in the program (including calls). A program
// that only has: `scanf("%f", &global_float);` may fail to trigger this,
// but oh well...that's a documented issue.
StringRef SymbolName =
(TT.getArch() == Triple::x86) ? "__fltused" : "_fltused";
MCSymbol *S = MMI->getContext().getOrCreateSymbol(SymbolName);
OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
return;
}
emitStackMaps(SM);
} else if (TT.isOSBinFormatELF()) {
emitStackMaps(SM);
FM.serializeToFaultMapSection();
}
}
//===----------------------------------------------------------------------===//
// Target Registry Stuff
//===----------------------------------------------------------------------===//
// Force static initialization.
extern "C" void LLVMInitializeX86AsmPrinter() {
RegisterAsmPrinter<X86AsmPrinter> X(getTheX86_32Target());
RegisterAsmPrinter<X86AsmPrinter> Y(getTheX86_64Target());
}
Reference in New Issue View Git Blame Copy Permalink