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-rw-r--r--lib/Target/X86/X86MachObjectWriter.cpp554
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diff --git a/lib/Target/X86/X86MachObjectWriter.cpp b/lib/Target/X86/X86MachObjectWriter.cpp
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--- a/lib/Target/X86/X86MachObjectWriter.cpp
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-//===-- X86MachObjectWriter.cpp - X86 Mach-O Writer -----------------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "X86.h"
-#include "X86FixupKinds.h"
-#include "llvm/ADT/Twine.h"
-#include "llvm/MC/MCAssembler.h"
-#include "llvm/MC/MCAsmLayout.h"
-#include "llvm/MC/MCMachObjectWriter.h"
-#include "llvm/MC/MCSectionMachO.h"
-#include "llvm/MC/MCValue.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Object/MachOFormat.h"
-
-using namespace llvm;
-using namespace llvm::object;
-
-namespace {
-class X86MachObjectWriter : public MCMachObjectTargetWriter {
- void RecordScatteredRelocation(MachObjectWriter *Writer,
- const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- unsigned Log2Size,
- uint64_t &FixedValue);
- void RecordTLVPRelocation(MachObjectWriter *Writer,
- const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- uint64_t &FixedValue);
-
- void RecordX86Relocation(MachObjectWriter *Writer,
- const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- uint64_t &FixedValue);
- void RecordX86_64Relocation(MachObjectWriter *Writer,
- const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- uint64_t &FixedValue);
-public:
- X86MachObjectWriter(bool Is64Bit, uint32_t CPUType,
- uint32_t CPUSubtype)
- : MCMachObjectTargetWriter(Is64Bit, CPUType, CPUSubtype,
- /*UseAggressiveSymbolFolding=*/Is64Bit) {}
-
- void RecordRelocation(MachObjectWriter *Writer,
- const MCAssembler &Asm, const MCAsmLayout &Layout,
- const MCFragment *Fragment, const MCFixup &Fixup,
- MCValue Target, uint64_t &FixedValue) {
- if (Writer->is64Bit())
- RecordX86_64Relocation(Writer, Asm, Layout, Fragment, Fixup, Target,
- FixedValue);
- else
- RecordX86Relocation(Writer, Asm, Layout, Fragment, Fixup, Target,
- FixedValue);
- }
-};
-}
-
-static bool isFixupKindRIPRel(unsigned Kind) {
- return Kind == X86::reloc_riprel_4byte ||
- Kind == X86::reloc_riprel_4byte_movq_load;
-}
-
-static unsigned getFixupKindLog2Size(unsigned Kind) {
- switch (Kind) {
- default:
- llvm_unreachable("invalid fixup kind!");
- case FK_PCRel_1:
- case FK_Data_1: return 0;
- case FK_PCRel_2:
- case FK_Data_2: return 1;
- case FK_PCRel_4:
- // FIXME: Remove these!!!
- case X86::reloc_riprel_4byte:
- case X86::reloc_riprel_4byte_movq_load:
- case X86::reloc_signed_4byte:
- case FK_Data_4: return 2;
- case FK_Data_8: return 3;
- }
-}
-
-void X86MachObjectWriter::RecordX86_64Relocation(MachObjectWriter *Writer,
- const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- uint64_t &FixedValue) {
- unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind());
- unsigned IsRIPRel = isFixupKindRIPRel(Fixup.getKind());
- unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
-
- // See <reloc.h>.
- uint32_t FixupOffset =
- Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
- uint32_t FixupAddress =
- Writer->getFragmentAddress(Fragment, Layout) + Fixup.getOffset();
- int64_t Value = 0;
- unsigned Index = 0;
- unsigned IsExtern = 0;
- unsigned Type = 0;
-
- Value = Target.getConstant();
-
- if (IsPCRel) {
- // Compensate for the relocation offset, Darwin x86_64 relocations only have
- // the addend and appear to have attempted to define it to be the actual
- // expression addend without the PCrel bias. However, instructions with data
- // following the relocation are not accommodated for (see comment below
- // regarding SIGNED{1,2,4}), so it isn't exactly that either.
- Value += 1LL << Log2Size;
- }
-
- if (Target.isAbsolute()) { // constant
- // SymbolNum of 0 indicates the absolute section.
- Type = macho::RIT_X86_64_Unsigned;
- Index = 0;
-
- // FIXME: I believe this is broken, I don't think the linker can understand
- // it. I think it would require a local relocation, but I'm not sure if that
- // would work either. The official way to get an absolute PCrel relocation
- // is to use an absolute symbol (which we don't support yet).
- if (IsPCRel) {
- IsExtern = 1;
- Type = macho::RIT_X86_64_Branch;
- }
- } else if (Target.getSymB()) { // A - B + constant
- const MCSymbol *A = &Target.getSymA()->getSymbol();
- MCSymbolData &A_SD = Asm.getSymbolData(*A);
- const MCSymbolData *A_Base = Asm.getAtom(&A_SD);
-
- const MCSymbol *B = &Target.getSymB()->getSymbol();
- MCSymbolData &B_SD = Asm.getSymbolData(*B);
- const MCSymbolData *B_Base = Asm.getAtom(&B_SD);
-
- // Neither symbol can be modified.
- if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None ||
- Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None)
- report_fatal_error("unsupported relocation of modified symbol");
-
- // We don't support PCrel relocations of differences. Darwin 'as' doesn't
- // implement most of these correctly.
- if (IsPCRel)
- report_fatal_error("unsupported pc-relative relocation of difference");
-
- // The support for the situation where one or both of the symbols would
- // require a local relocation is handled just like if the symbols were
- // external. This is certainly used in the case of debug sections where the
- // section has only temporary symbols and thus the symbols don't have base
- // symbols. This is encoded using the section ordinal and non-extern
- // relocation entries.
-
- // Darwin 'as' doesn't emit correct relocations for this (it ends up with a
- // single SIGNED relocation); reject it for now. Except the case where both
- // symbols don't have a base, equal but both NULL.
- if (A_Base == B_Base && A_Base)
- report_fatal_error("unsupported relocation with identical base");
-
- Value += Writer->getSymbolAddress(&A_SD, Layout) -
- (A_Base == NULL ? 0 : Writer->getSymbolAddress(A_Base, Layout));
- Value -= Writer->getSymbolAddress(&B_SD, Layout) -
- (B_Base == NULL ? 0 : Writer->getSymbolAddress(B_Base, Layout));
-
- if (A_Base) {
- Index = A_Base->getIndex();
- IsExtern = 1;
- }
- else {
- Index = A_SD.getFragment()->getParent()->getOrdinal() + 1;
- IsExtern = 0;
- }
- Type = macho::RIT_X86_64_Unsigned;
-
- macho::RelocationEntry MRE;
- MRE.Word0 = FixupOffset;
- MRE.Word1 = ((Index << 0) |
- (IsPCRel << 24) |
- (Log2Size << 25) |
- (IsExtern << 27) |
- (Type << 28));
- Writer->addRelocation(Fragment->getParent(), MRE);
-
- if (B_Base) {
- Index = B_Base->getIndex();
- IsExtern = 1;
- }
- else {
- Index = B_SD.getFragment()->getParent()->getOrdinal() + 1;
- IsExtern = 0;
- }
- Type = macho::RIT_X86_64_Subtractor;
- } else {
- const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
- MCSymbolData &SD = Asm.getSymbolData(*Symbol);
- const MCSymbolData *Base = Asm.getAtom(&SD);
-
- // Relocations inside debug sections always use local relocations when
- // possible. This seems to be done because the debugger doesn't fully
- // understand x86_64 relocation entries, and expects to find values that
- // have already been fixed up.
- if (Symbol->isInSection()) {
- const MCSectionMachO &Section = static_cast<const MCSectionMachO&>(
- Fragment->getParent()->getSection());
- if (Section.hasAttribute(MCSectionMachO::S_ATTR_DEBUG))
- Base = 0;
- }
-
- // x86_64 almost always uses external relocations, except when there is no
- // symbol to use as a base address (a local symbol with no preceding
- // non-local symbol).
- if (Base) {
- Index = Base->getIndex();
- IsExtern = 1;
-
- // Add the local offset, if needed.
- if (Base != &SD)
- Value += Layout.getSymbolOffset(&SD) - Layout.getSymbolOffset(Base);
- } else if (Symbol->isInSection() && !Symbol->isVariable()) {
- // The index is the section ordinal (1-based).
- Index = SD.getFragment()->getParent()->getOrdinal() + 1;
- IsExtern = 0;
- Value += Writer->getSymbolAddress(&SD, Layout);
-
- if (IsPCRel)
- Value -= FixupAddress + (1 << Log2Size);
- } else if (Symbol->isVariable()) {
- const MCExpr *Value = Symbol->getVariableValue();
- int64_t Res;
- bool isAbs = Value->EvaluateAsAbsolute(Res, Layout,
- Writer->getSectionAddressMap());
- if (isAbs) {
- FixedValue = Res;
- return;
- } else {
- report_fatal_error("unsupported relocation of variable '" +
- Symbol->getName() + "'");
- }
- } else {
- report_fatal_error("unsupported relocation of undefined symbol '" +
- Symbol->getName() + "'");
- }
-
- MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind();
- if (IsPCRel) {
- if (IsRIPRel) {
- if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
- // x86_64 distinguishes movq foo@GOTPCREL so that the linker can
- // rewrite the movq to an leaq at link time if the symbol ends up in
- // the same linkage unit.
- if (unsigned(Fixup.getKind()) == X86::reloc_riprel_4byte_movq_load)
- Type = macho::RIT_X86_64_GOTLoad;
- else
- Type = macho::RIT_X86_64_GOT;
- } else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
- Type = macho::RIT_X86_64_TLV;
- } else if (Modifier != MCSymbolRefExpr::VK_None) {
- report_fatal_error("unsupported symbol modifier in relocation");
- } else {
- Type = macho::RIT_X86_64_Signed;
-
- // The Darwin x86_64 relocation format has a problem where it cannot
- // encode an address (L<foo> + <constant>) which is outside the atom
- // containing L<foo>. Generally, this shouldn't occur but it does
- // happen when we have a RIPrel instruction with data following the
- // relocation entry (e.g., movb $012, L0(%rip)). Even with the PCrel
- // adjustment Darwin x86_64 uses, the offset is still negative and the
- // linker has no way to recognize this.
- //
- // To work around this, Darwin uses several special relocation types
- // to indicate the offsets. However, the specification or
- // implementation of these seems to also be incomplete; they should
- // adjust the addend as well based on the actual encoded instruction
- // (the additional bias), but instead appear to just look at the final
- // offset.
- switch (-(Target.getConstant() + (1LL << Log2Size))) {
- case 1: Type = macho::RIT_X86_64_Signed1; break;
- case 2: Type = macho::RIT_X86_64_Signed2; break;
- case 4: Type = macho::RIT_X86_64_Signed4; break;
- }
- }
- } else {
- if (Modifier != MCSymbolRefExpr::VK_None)
- report_fatal_error("unsupported symbol modifier in branch "
- "relocation");
-
- Type = macho::RIT_X86_64_Branch;
- }
- } else {
- if (Modifier == MCSymbolRefExpr::VK_GOT) {
- Type = macho::RIT_X86_64_GOT;
- } else if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
- // GOTPCREL is allowed as a modifier on non-PCrel instructions, in which
- // case all we do is set the PCrel bit in the relocation entry; this is
- // used with exception handling, for example. The source is required to
- // include any necessary offset directly.
- Type = macho::RIT_X86_64_GOT;
- IsPCRel = 1;
- } else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
- report_fatal_error("TLVP symbol modifier should have been rip-rel");
- } else if (Modifier != MCSymbolRefExpr::VK_None)
- report_fatal_error("unsupported symbol modifier in relocation");
- else
- Type = macho::RIT_X86_64_Unsigned;
- }
- }
-
- // x86_64 always writes custom values into the fixups.
- FixedValue = Value;
-
- // struct relocation_info (8 bytes)
- macho::RelocationEntry MRE;
- MRE.Word0 = FixupOffset;
- MRE.Word1 = ((Index << 0) |
- (IsPCRel << 24) |
- (Log2Size << 25) |
- (IsExtern << 27) |
- (Type << 28));
- Writer->addRelocation(Fragment->getParent(), MRE);
-}
-
-void X86MachObjectWriter::RecordScatteredRelocation(MachObjectWriter *Writer,
- const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- unsigned Log2Size,
- uint64_t &FixedValue) {
- uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
- unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind());
- unsigned Type = macho::RIT_Vanilla;
-
- // See <reloc.h>.
- const MCSymbol *A = &Target.getSymA()->getSymbol();
- MCSymbolData *A_SD = &Asm.getSymbolData(*A);
-
- if (!A_SD->getFragment())
- report_fatal_error("symbol '" + A->getName() +
- "' can not be undefined in a subtraction expression");
-
- uint32_t Value = Writer->getSymbolAddress(A_SD, Layout);
- uint64_t SecAddr = Writer->getSectionAddress(A_SD->getFragment()->getParent());
- FixedValue += SecAddr;
- uint32_t Value2 = 0;
-
- if (const MCSymbolRefExpr *B = Target.getSymB()) {
- MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
-
- if (!B_SD->getFragment())
- report_fatal_error("symbol '" + B->getSymbol().getName() +
- "' can not be undefined in a subtraction expression");
-
- // Select the appropriate difference relocation type.
- //
- // Note that there is no longer any semantic difference between these two
- // relocation types from the linkers point of view, this is done solely for
- // pedantic compatibility with 'as'.
- Type = A_SD->isExternal() ? (unsigned)macho::RIT_Difference :
- (unsigned)macho::RIT_Generic_LocalDifference;
- Value2 = Writer->getSymbolAddress(B_SD, Layout);
- FixedValue -= Writer->getSectionAddress(B_SD->getFragment()->getParent());
- }
-
- // Relocations are written out in reverse order, so the PAIR comes first.
- if (Type == macho::RIT_Difference ||
- Type == macho::RIT_Generic_LocalDifference) {
- macho::RelocationEntry MRE;
- MRE.Word0 = ((0 << 0) |
- (macho::RIT_Pair << 24) |
- (Log2Size << 28) |
- (IsPCRel << 30) |
- macho::RF_Scattered);
- MRE.Word1 = Value2;
- Writer->addRelocation(Fragment->getParent(), MRE);
- }
-
- macho::RelocationEntry MRE;
- MRE.Word0 = ((FixupOffset << 0) |
- (Type << 24) |
- (Log2Size << 28) |
- (IsPCRel << 30) |
- macho::RF_Scattered);
- MRE.Word1 = Value;
- Writer->addRelocation(Fragment->getParent(), MRE);
-}
-
-void X86MachObjectWriter::RecordTLVPRelocation(MachObjectWriter *Writer,
- const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- uint64_t &FixedValue) {
- assert(Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP &&
- !is64Bit() &&
- "Should only be called with a 32-bit TLVP relocation!");
-
- unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
- uint32_t Value = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
- unsigned IsPCRel = 0;
-
- // Get the symbol data.
- MCSymbolData *SD_A = &Asm.getSymbolData(Target.getSymA()->getSymbol());
- unsigned Index = SD_A->getIndex();
-
- // We're only going to have a second symbol in pic mode and it'll be a
- // subtraction from the picbase. For 32-bit pic the addend is the difference
- // between the picbase and the next address. For 32-bit static the addend is
- // zero.
- if (Target.getSymB()) {
- // If this is a subtraction then we're pcrel.
- uint32_t FixupAddress =
- Writer->getFragmentAddress(Fragment, Layout) + Fixup.getOffset();
- MCSymbolData *SD_B = &Asm.getSymbolData(Target.getSymB()->getSymbol());
- IsPCRel = 1;
- FixedValue = (FixupAddress - Writer->getSymbolAddress(SD_B, Layout) +
- Target.getConstant());
- FixedValue += 1ULL << Log2Size;
- } else {
- FixedValue = 0;
- }
-
- // struct relocation_info (8 bytes)
- macho::RelocationEntry MRE;
- MRE.Word0 = Value;
- MRE.Word1 = ((Index << 0) |
- (IsPCRel << 24) |
- (Log2Size << 25) |
- (1 << 27) | // Extern
- (macho::RIT_Generic_TLV << 28)); // Type
- Writer->addRelocation(Fragment->getParent(), MRE);
-}
-
-void X86MachObjectWriter::RecordX86Relocation(MachObjectWriter *Writer,
- const MCAssembler &Asm,
- const MCAsmLayout &Layout,
- const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- uint64_t &FixedValue) {
- unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind());
- unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
-
- // If this is a 32-bit TLVP reloc it's handled a bit differently.
- if (Target.getSymA() &&
- Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP) {
- RecordTLVPRelocation(Writer, Asm, Layout, Fragment, Fixup, Target,
- FixedValue);
- return;
- }
-
- // If this is a difference or a defined symbol plus an offset, then we need a
- // scattered relocation entry. Differences always require scattered
- // relocations.
- if (Target.getSymB())
- return RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup,
- Target, Log2Size, FixedValue);
-
- // Get the symbol data, if any.
- MCSymbolData *SD = 0;
- if (Target.getSymA())
- SD = &Asm.getSymbolData(Target.getSymA()->getSymbol());
-
- // If this is an internal relocation with an offset, it also needs a scattered
- // relocation entry.
- uint32_t Offset = Target.getConstant();
- if (IsPCRel)
- Offset += 1 << Log2Size;
- if (Offset && SD && !Writer->doesSymbolRequireExternRelocation(SD))
- return RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup,
- Target, Log2Size, FixedValue);
-
- // See <reloc.h>.
- uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
- unsigned Index = 0;
- unsigned IsExtern = 0;
- unsigned Type = 0;
-
- if (Target.isAbsolute()) { // constant
- // SymbolNum of 0 indicates the absolute section.
- //
- // FIXME: Currently, these are never generated (see code below). I cannot
- // find a case where they are actually emitted.
- Type = macho::RIT_Vanilla;
- } else {
- // Resolve constant variables.
- if (SD->getSymbol().isVariable()) {
- int64_t Res;
- if (SD->getSymbol().getVariableValue()->EvaluateAsAbsolute(
- Res, Layout, Writer->getSectionAddressMap())) {
- FixedValue = Res;
- return;
- }
- }
-
- // Check whether we need an external or internal relocation.
- if (Writer->doesSymbolRequireExternRelocation(SD)) {
- IsExtern = 1;
- Index = SD->getIndex();
- // For external relocations, make sure to offset the fixup value to
- // compensate for the addend of the symbol address, if it was
- // undefined. This occurs with weak definitions, for example.
- if (!SD->Symbol->isUndefined())
- FixedValue -= Layout.getSymbolOffset(SD);
- } else {
- // The index is the section ordinal (1-based).
- const MCSectionData &SymSD = Asm.getSectionData(
- SD->getSymbol().getSection());
- Index = SymSD.getOrdinal() + 1;
- FixedValue += Writer->getSectionAddress(&SymSD);
- }
- if (IsPCRel)
- FixedValue -= Writer->getSectionAddress(Fragment->getParent());
-
- Type = macho::RIT_Vanilla;
- }
-
- // struct relocation_info (8 bytes)
- macho::RelocationEntry MRE;
- MRE.Word0 = FixupOffset;
- MRE.Word1 = ((Index << 0) |
- (IsPCRel << 24) |
- (Log2Size << 25) |
- (IsExtern << 27) |
- (Type << 28));
- Writer->addRelocation(Fragment->getParent(), MRE);
-}
-
-MCObjectWriter *llvm::createX86MachObjectWriter(raw_ostream &OS,
- bool Is64Bit,
- uint32_t CPUType,
- uint32_t CPUSubtype) {
- return createMachObjectWriter(new X86MachObjectWriter(Is64Bit,
- CPUType,
- CPUSubtype),
- OS, /*IsLittleEndian=*/true);
-}
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