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Diffstat (limited to 'lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp')
| -rw-r--r-- | lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp b/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp new file mode 100644 index 0000000..5c86189 --- /dev/null +++ b/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp @@ -0,0 +1,396 @@ +//===-- AArch64MachObjectWriter.cpp - ARM Mach Object Writer --------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "MCTargetDesc/AArch64FixupKinds.h" +#include "MCTargetDesc/AArch64MCTargetDesc.h" +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCAsmLayout.h" +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCFixup.h" +#include "llvm/MC/MCMachObjectWriter.h" +#include "llvm/MC/MCSectionMachO.h" +#include "llvm/MC/MCValue.h" +#include "llvm/ADT/Twine.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/MachO.h" +using namespace llvm; + +namespace { +class AArch64MachObjectWriter : public MCMachObjectTargetWriter { + bool getAArch64FixupKindMachOInfo(const MCFixup &Fixup, unsigned &RelocType, + const MCSymbolRefExpr *Sym, + unsigned &Log2Size, const MCAssembler &Asm); + +public: + AArch64MachObjectWriter(uint32_t CPUType, uint32_t CPUSubtype) + : MCMachObjectTargetWriter(true /* is64Bit */, CPUType, CPUSubtype, + /*UseAggressiveSymbolFolding=*/true) {} + + void RecordRelocation(MachObjectWriter *Writer, const MCAssembler &Asm, + const MCAsmLayout &Layout, const MCFragment *Fragment, + const MCFixup &Fixup, MCValue Target, + uint64_t &FixedValue) override; +}; +} + +bool AArch64MachObjectWriter::getAArch64FixupKindMachOInfo( + const MCFixup &Fixup, unsigned &RelocType, const MCSymbolRefExpr *Sym, + unsigned &Log2Size, const MCAssembler &Asm) { + RelocType = unsigned(MachO::ARM64_RELOC_UNSIGNED); + Log2Size = ~0U; + + switch ((unsigned)Fixup.getKind()) { + default: + return false; + + case FK_Data_1: + Log2Size = llvm::Log2_32(1); + return true; + case FK_Data_2: + Log2Size = llvm::Log2_32(2); + return true; + case FK_Data_4: + Log2Size = llvm::Log2_32(4); + if (Sym->getKind() == MCSymbolRefExpr::VK_GOT) + RelocType = unsigned(MachO::ARM64_RELOC_POINTER_TO_GOT); + return true; + case FK_Data_8: + Log2Size = llvm::Log2_32(8); + if (Sym->getKind() == MCSymbolRefExpr::VK_GOT) + RelocType = unsigned(MachO::ARM64_RELOC_POINTER_TO_GOT); + return true; + case AArch64::fixup_aarch64_add_imm12: + case AArch64::fixup_aarch64_ldst_imm12_scale1: + case AArch64::fixup_aarch64_ldst_imm12_scale2: + case AArch64::fixup_aarch64_ldst_imm12_scale4: + case AArch64::fixup_aarch64_ldst_imm12_scale8: + case AArch64::fixup_aarch64_ldst_imm12_scale16: + Log2Size = llvm::Log2_32(4); + switch (Sym->getKind()) { + default: + assert(0 && "Unexpected symbol reference variant kind!"); + case MCSymbolRefExpr::VK_PAGEOFF: + RelocType = unsigned(MachO::ARM64_RELOC_PAGEOFF12); + return true; + case MCSymbolRefExpr::VK_GOTPAGEOFF: + RelocType = unsigned(MachO::ARM64_RELOC_GOT_LOAD_PAGEOFF12); + return true; + case MCSymbolRefExpr::VK_TLVPPAGEOFF: + RelocType = unsigned(MachO::ARM64_RELOC_TLVP_LOAD_PAGEOFF12); + return true; + } + case AArch64::fixup_aarch64_pcrel_adrp_imm21: + Log2Size = llvm::Log2_32(4); + // This encompasses the relocation for the whole 21-bit value. + switch (Sym->getKind()) { + default: + Asm.getContext().FatalError(Fixup.getLoc(), + "ADR/ADRP relocations must be GOT relative"); + case MCSymbolRefExpr::VK_PAGE: + RelocType = unsigned(MachO::ARM64_RELOC_PAGE21); + return true; + case MCSymbolRefExpr::VK_GOTPAGE: + RelocType = unsigned(MachO::ARM64_RELOC_GOT_LOAD_PAGE21); + return true; + case MCSymbolRefExpr::VK_TLVPPAGE: + RelocType = unsigned(MachO::ARM64_RELOC_TLVP_LOAD_PAGE21); + return true; + } + return true; + case AArch64::fixup_aarch64_pcrel_branch26: + case AArch64::fixup_aarch64_pcrel_call26: + Log2Size = llvm::Log2_32(4); + RelocType = unsigned(MachO::ARM64_RELOC_BRANCH26); + return true; + } +} + +void AArch64MachObjectWriter::RecordRelocation( + 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()); + + // See <reloc.h>. + uint32_t FixupOffset = Layout.getFragmentOffset(Fragment); + unsigned Log2Size = 0; + int64_t Value = 0; + unsigned Index = 0; + unsigned IsExtern = 0; + unsigned Type = 0; + unsigned Kind = Fixup.getKind(); + + FixupOffset += Fixup.getOffset(); + + // AArch64 pcrel relocation addends do not include the section offset. + if (IsPCRel) + FixedValue += FixupOffset; + + // ADRP fixups use relocations for the whole symbol value and only + // put the addend in the instruction itself. Clear out any value the + // generic code figured out from the sybmol definition. + if (Kind == AArch64::fixup_aarch64_pcrel_adrp_imm21) + FixedValue = 0; + + // imm19 relocations are for conditional branches, which require + // assembler local symbols. If we got here, that's not what we have, + // so complain loudly. + if (Kind == AArch64::fixup_aarch64_pcrel_branch19) { + Asm.getContext().FatalError(Fixup.getLoc(), + "conditional branch requires assembler-local" + " label. '" + + Target.getSymA()->getSymbol().getName() + + "' is external."); + return; + } + + // 14-bit branch relocations should only target internal labels, and so + // should never get here. + if (Kind == AArch64::fixup_aarch64_pcrel_branch14) { + Asm.getContext().FatalError(Fixup.getLoc(), + "Invalid relocation on conditional branch!"); + return; + } + + if (!getAArch64FixupKindMachOInfo(Fixup, Type, Target.getSymA(), Log2Size, + Asm)) { + Asm.getContext().FatalError(Fixup.getLoc(), "unknown AArch64 fixup kind!"); + return; + } + + Value = Target.getConstant(); + + if (Target.isAbsolute()) { // constant + // FIXME: Should this always be extern? + // SymbolNum of 0 indicates the absolute section. + Type = MachO::ARM64_RELOC_UNSIGNED; + Index = 0; + + if (IsPCRel) { + IsExtern = 1; + Asm.getContext().FatalError(Fixup.getLoc(), + "PC relative absolute relocation!"); + + // FIXME: x86_64 sets the type to a branch reloc here. Should we do + // something similar? + } + } else if (Target.getSymB()) { // A - B + constant + const MCSymbol *A = &Target.getSymA()->getSymbol(); + const MCSymbolData &A_SD = Asm.getSymbolData(*A); + const MCSymbolData *A_Base = Asm.getAtom(&A_SD); + + const MCSymbol *B = &Target.getSymB()->getSymbol(); + const MCSymbolData &B_SD = Asm.getSymbolData(*B); + const MCSymbolData *B_Base = Asm.getAtom(&B_SD); + + // Check for "_foo@got - .", which comes through here as: + // Ltmp0: + // ... _foo@got - Ltmp0 + if (Target.getSymA()->getKind() == MCSymbolRefExpr::VK_GOT && + Target.getSymB()->getKind() == MCSymbolRefExpr::VK_None && + Layout.getSymbolOffset(&B_SD) == + Layout.getFragmentOffset(Fragment) + Fixup.getOffset()) { + // SymB is the PC, so use a PC-rel pointer-to-GOT relocation. + Index = A_Base->getIndex(); + IsExtern = 1; + Type = MachO::ARM64_RELOC_POINTER_TO_GOT; + IsPCRel = 1; + MachO::any_relocation_info MRE; + MRE.r_word0 = FixupOffset; + MRE.r_word1 = ((Index << 0) | (IsPCRel << 24) | (Log2Size << 25) | + (IsExtern << 27) | (Type << 28)); + Writer->addRelocation(Fragment->getParent(), MRE); + return; + } else if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None || + Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None) + // Otherwise, neither symbol can be modified. + Asm.getContext().FatalError(Fixup.getLoc(), + "unsupported relocation of modified symbol"); + + // We don't support PCrel relocations of differences. + if (IsPCRel) + Asm.getContext().FatalError(Fixup.getLoc(), + "unsupported pc-relative relocation of " + "difference"); + + // AArch64 always uses external relocations. If there is no symbol to use as + // a base address (a local symbol with no preceding non-local symbol), + // error out. + // + // FIXME: We should probably just synthesize an external symbol and use + // that. + if (!A_Base) + Asm.getContext().FatalError( + Fixup.getLoc(), + "unsupported relocation of local symbol '" + A->getName() + + "'. Must have non-local symbol earlier in section."); + if (!B_Base) + Asm.getContext().FatalError( + Fixup.getLoc(), + "unsupported relocation of local symbol '" + B->getName() + + "'. Must have non-local symbol earlier in section."); + + if (A_Base == B_Base && A_Base) + Asm.getContext().FatalError(Fixup.getLoc(), + "unsupported relocation with identical base"); + + Value += (!A_SD.getFragment() ? 0 + : Writer->getSymbolAddress(&A_SD, Layout)) - + (!A_Base || !A_Base->getFragment() + ? 0 + : Writer->getSymbolAddress(A_Base, Layout)); + Value -= (!B_SD.getFragment() ? 0 + : Writer->getSymbolAddress(&B_SD, Layout)) - + (!B_Base || !B_Base->getFragment() + ? 0 + : Writer->getSymbolAddress(B_Base, Layout)); + + Index = A_Base->getIndex(); + IsExtern = 1; + Type = MachO::ARM64_RELOC_UNSIGNED; + + MachO::any_relocation_info MRE; + MRE.r_word0 = FixupOffset; + MRE.r_word1 = ((Index << 0) | (IsPCRel << 24) | (Log2Size << 25) | + (IsExtern << 27) | (Type << 28)); + Writer->addRelocation(Fragment->getParent(), MRE); + + Index = B_Base->getIndex(); + IsExtern = 1; + Type = MachO::ARM64_RELOC_SUBTRACTOR; + } else { // A + constant + const MCSymbol *Symbol = &Target.getSymA()->getSymbol(); + const MCSymbolData &SD = Asm.getSymbolData(*Symbol); + const MCSymbolData *Base = Asm.getAtom(&SD); + const MCSectionMachO &Section = static_cast<const MCSectionMachO &>( + Fragment->getParent()->getSection()); + + // If the symbol is a variable and we weren't able to get a Base for it + // (i.e., it's not in the symbol table associated with a section) resolve + // the relocation based its expansion instead. + if (Symbol->isVariable() && !Base) { + // If the evaluation is an absolute value, just use that directly + // to keep things easy. + int64_t Res; + if (SD.getSymbol().getVariableValue()->EvaluateAsAbsolute( + Res, Layout, Writer->getSectionAddressMap())) { + FixedValue = Res; + return; + } + + // FIXME: Will the Target we already have ever have any data in it + // we need to preserve and merge with the new Target? How about + // the FixedValue? + if (!Symbol->getVariableValue()->EvaluateAsRelocatable(Target, &Layout)) + Asm.getContext().FatalError(Fixup.getLoc(), + "unable to resolve variable '" + + Symbol->getName() + "'"); + return RecordRelocation(Writer, Asm, Layout, Fragment, Fixup, Target, + FixedValue); + } + + // Relocations inside debug sections always use local relocations when + // possible. This seems to be done because the debugger doesn't fully + // understand relocation entries and expects to find values that + // have already been fixed up. + if (Symbol->isInSection()) { + if (Section.hasAttribute(MachO::S_ATTR_DEBUG)) + Base = nullptr; + } + + // AArch64 uses external relocations as much as possible. For debug + // sections, and for pointer-sized relocations (.quad), we allow section + // relocations. It's code sections that run into trouble. + 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()) { + // Pointer-sized relocations can use a local relocation. Otherwise, + // we have to be in a debug info section. + if (!Section.hasAttribute(MachO::S_ATTR_DEBUG) && Log2Size != 3) + Asm.getContext().FatalError( + Fixup.getLoc(), + "unsupported relocation of local symbol '" + Symbol->getName() + + "'. Must have non-local symbol earlier in section."); + // Adjust the relocation to be section-relative. + // The index is the section ordinal (1-based). + const MCSectionData &SymSD = + Asm.getSectionData(SD.getSymbol().getSection()); + Index = SymSD.getOrdinal() + 1; + IsExtern = 0; + Value += Writer->getSymbolAddress(&SD, Layout); + + if (IsPCRel) + Value -= Writer->getFragmentAddress(Fragment, Layout) + + Fixup.getOffset() + (1ULL << Log2Size); + } else { + // Resolve constant variables. + if (SD.getSymbol().isVariable()) { + int64_t Res; + if (SD.getSymbol().getVariableValue()->EvaluateAsAbsolute( + Res, Layout, Writer->getSectionAddressMap())) { + FixedValue = Res; + return; + } + } + Asm.getContext().FatalError(Fixup.getLoc(), + "unsupported relocation of variable '" + + Symbol->getName() + "'"); + } + } + + // If the relocation kind is Branch26, Page21, or Pageoff12, any addend + // is represented via an Addend relocation, not encoded directly into + // the instruction. + if ((Type == MachO::ARM64_RELOC_BRANCH26 || + Type == MachO::ARM64_RELOC_PAGE21 || + Type == MachO::ARM64_RELOC_PAGEOFF12) && + Value) { + assert((Value & 0xff000000) == 0 && "Added relocation out of range!"); + + MachO::any_relocation_info MRE; + MRE.r_word0 = FixupOffset; + MRE.r_word1 = ((Index << 0) | (IsPCRel << 24) | (Log2Size << 25) | + (IsExtern << 27) | (Type << 28)); + Writer->addRelocation(Fragment->getParent(), MRE); + + // Now set up the Addend relocation. + Type = MachO::ARM64_RELOC_ADDEND; + Index = Value; + IsPCRel = 0; + Log2Size = 2; + IsExtern = 0; + + // Put zero into the instruction itself. The addend is in the relocation. + Value = 0; + } + + // If there's any addend left to handle, encode it in the instruction. + FixedValue = Value; + + // struct relocation_info (8 bytes) + MachO::any_relocation_info MRE; + MRE.r_word0 = FixupOffset; + MRE.r_word1 = ((Index << 0) | (IsPCRel << 24) | (Log2Size << 25) | + (IsExtern << 27) | (Type << 28)); + Writer->addRelocation(Fragment->getParent(), MRE); +} + +MCObjectWriter *llvm::createAArch64MachObjectWriter(raw_ostream &OS, + uint32_t CPUType, + uint32_t CPUSubtype) { + return createMachObjectWriter( + new AArch64MachObjectWriter(CPUType, CPUSubtype), OS, + /*IsLittleEndian=*/true); +} |