diff options
Diffstat (limited to 'lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp')
| -rw-r--r-- | lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp new file mode 100644 index 0000000000..9b293c1318 --- /dev/null +++ b/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp @@ -0,0 +1,515 @@ +//===-- ARMAsmBackend.cpp - ARM Assembler Backend -------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "MCTargetDesc/ARMBaseInfo.h" +#include "MCTargetDesc/ARMFixupKinds.h" +#include "MCTargetDesc/ARMAddressingModes.h" +#include "llvm/ADT/Twine.h" +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCDirectives.h" +#include "llvm/MC/MCELFObjectWriter.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCMachObjectWriter.h" +#include "llvm/MC/MCObjectWriter.h" +#include "llvm/MC/MCSectionELF.h" +#include "llvm/MC/MCSectionMachO.h" +#include "llvm/Object/MachOFormat.h" +#include "llvm/Support/ELF.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetAsmBackend.h" +using namespace llvm; + +namespace { +class ARMELFObjectWriter : public MCELFObjectTargetWriter { +public: + ARMELFObjectWriter(Triple::OSType OSType) + : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSType, ELF::EM_ARM, + /*HasRelocationAddend*/ false) {} +}; + +class ARMAsmBackend : public TargetAsmBackend { + bool isThumbMode; // Currently emitting Thumb code. +public: + ARMAsmBackend(const Target &T) : TargetAsmBackend(), isThumbMode(false) {} + + unsigned getNumFixupKinds() const { return ARM::NumTargetFixupKinds; } + + const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const { + const static MCFixupKindInfo Infos[ARM::NumTargetFixupKinds] = { +// This table *must* be in the order that the fixup_* kinds are defined in +// ARMFixupKinds.h. +// +// Name Offset (bits) Size (bits) Flags +{ "fixup_arm_ldst_pcrel_12", 1, 24, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_t2_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel | + MCFixupKindInfo::FKF_IsAlignedDownTo32Bits}, +{ "fixup_arm_pcrel_10", 1, 24, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_t2_pcrel_10", 0, 32, MCFixupKindInfo::FKF_IsPCRel | + MCFixupKindInfo::FKF_IsAlignedDownTo32Bits}, +{ "fixup_thumb_adr_pcrel_10",0, 8, MCFixupKindInfo::FKF_IsPCRel | + MCFixupKindInfo::FKF_IsAlignedDownTo32Bits}, +{ "fixup_arm_adr_pcrel_12", 1, 24, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_t2_adr_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel | + MCFixupKindInfo::FKF_IsAlignedDownTo32Bits}, +{ "fixup_arm_condbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_arm_uncondbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_t2_condbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_t2_uncondbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_arm_thumb_br", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_arm_thumb_bl", 0, 32, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_arm_thumb_blx", 7, 21, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_arm_thumb_cb", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_arm_thumb_cp", 1, 8, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_arm_thumb_bcc", 0, 8, MCFixupKindInfo::FKF_IsPCRel }, +// movw / movt: 16-bits immediate but scattered into two chunks 0 - 12, 16 - 19. +{ "fixup_arm_movt_hi16", 0, 20, 0 }, +{ "fixup_arm_movw_lo16", 0, 20, 0 }, +{ "fixup_t2_movt_hi16", 0, 20, 0 }, +{ "fixup_t2_movw_lo16", 0, 20, 0 }, +{ "fixup_arm_movt_hi16_pcrel", 0, 20, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_arm_movw_lo16_pcrel", 0, 20, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_t2_movt_hi16_pcrel", 0, 20, MCFixupKindInfo::FKF_IsPCRel }, +{ "fixup_t2_movw_lo16_pcrel", 0, 20, MCFixupKindInfo::FKF_IsPCRel }, + }; + + if (Kind < FirstTargetFixupKind) + return TargetAsmBackend::getFixupKindInfo(Kind); + + assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && + "Invalid kind!"); + return Infos[Kind - FirstTargetFixupKind]; + } + + bool MayNeedRelaxation(const MCInst &Inst) const; + + void RelaxInstruction(const MCInst &Inst, MCInst &Res) const; + + bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const; + + void HandleAssemblerFlag(MCAssemblerFlag Flag) { + switch (Flag) { + default: break; + case MCAF_Code16: + setIsThumb(true); + break; + case MCAF_Code32: + setIsThumb(false); + break; + } + } + + unsigned getPointerSize() const { return 4; } + bool isThumb() const { return isThumbMode; } + void setIsThumb(bool it) { isThumbMode = it; } +}; +} // end anonymous namespace + +bool ARMAsmBackend::MayNeedRelaxation(const MCInst &Inst) const { + // FIXME: Thumb targets, different move constant targets.. + return false; +} + +void ARMAsmBackend::RelaxInstruction(const MCInst &Inst, MCInst &Res) const { + assert(0 && "ARMAsmBackend::RelaxInstruction() unimplemented"); + return; +} + +bool ARMAsmBackend::WriteNopData(uint64_t Count, MCObjectWriter *OW) const { + if (isThumb()) { + // FIXME: 0xbf00 is the ARMv7 value. For v6 and before, we'll need to + // use 0x46c0 (which is a 'mov r8, r8' insn). + uint64_t NumNops = Count / 2; + for (uint64_t i = 0; i != NumNops; ++i) + OW->Write16(0xbf00); + if (Count & 1) + OW->Write8(0); + return true; + } + // ARM mode + uint64_t NumNops = Count / 4; + for (uint64_t i = 0; i != NumNops; ++i) + OW->Write32(0xe1a00000); + switch (Count % 4) { + default: break; // No leftover bytes to write + case 1: OW->Write8(0); break; + case 2: OW->Write16(0); break; + case 3: OW->Write16(0); OW->Write8(0xa0); break; + } + + return true; +} + +static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) { + switch (Kind) { + default: + llvm_unreachable("Unknown fixup kind!"); + case FK_Data_1: + case FK_Data_2: + case FK_Data_4: + return Value; + case ARM::fixup_arm_movt_hi16: + Value >>= 16; + // Fallthrough + case ARM::fixup_arm_movw_lo16: + case ARM::fixup_arm_movt_hi16_pcrel: + case ARM::fixup_arm_movw_lo16_pcrel: { + unsigned Hi4 = (Value & 0xF000) >> 12; + unsigned Lo12 = Value & 0x0FFF; + assert ((((int64_t)Value) >= -0x8000) && (((int64_t)Value) <= 0x7fff) && + "Out of range pc-relative fixup value!"); + // inst{19-16} = Hi4; + // inst{11-0} = Lo12; + Value = (Hi4 << 16) | (Lo12); + return Value; + } + case ARM::fixup_t2_movt_hi16: + Value >>= 16; + // Fallthrough + case ARM::fixup_t2_movw_lo16: + case ARM::fixup_t2_movt_hi16_pcrel: //FIXME: Shouldn't this be shifted like + // the other hi16 fixup? + case ARM::fixup_t2_movw_lo16_pcrel: { + unsigned Hi4 = (Value & 0xF000) >> 12; + unsigned i = (Value & 0x800) >> 11; + unsigned Mid3 = (Value & 0x700) >> 8; + unsigned Lo8 = Value & 0x0FF; + // inst{19-16} = Hi4; + // inst{26} = i; + // inst{14-12} = Mid3; + // inst{7-0} = Lo8; + // The value comes in as the whole thing, not just the portion required + // for this fixup, so we need to mask off the bits not handled by this + // portion (lo vs. hi). + Value &= 0xffff; + Value = (Hi4 << 16) | (i << 26) | (Mid3 << 12) | (Lo8); + uint64_t swapped = (Value & 0xFFFF0000) >> 16; + swapped |= (Value & 0x0000FFFF) << 16; + return swapped; + } + case ARM::fixup_arm_ldst_pcrel_12: + // ARM PC-relative values are offset by 8. + Value -= 4; + // FALLTHROUGH + case ARM::fixup_t2_ldst_pcrel_12: { + // Offset by 4, adjusted by two due to the half-word ordering of thumb. + Value -= 4; + bool isAdd = true; + if ((int64_t)Value < 0) { + Value = -Value; + isAdd = false; + } + assert ((Value < 4096) && "Out of range pc-relative fixup value!"); + Value |= isAdd << 23; + + // Same addressing mode as fixup_arm_pcrel_10, + // but with 16-bit halfwords swapped. + if (Kind == ARM::fixup_t2_ldst_pcrel_12) { + uint64_t swapped = (Value & 0xFFFF0000) >> 16; + swapped |= (Value & 0x0000FFFF) << 16; + return swapped; + } + + return Value; + } + case ARM::fixup_thumb_adr_pcrel_10: + return ((Value - 4) >> 2) & 0xff; + case ARM::fixup_arm_adr_pcrel_12: { + // ARM PC-relative values are offset by 8. + Value -= 8; + unsigned opc = 4; // bits {24-21}. Default to add: 0b0100 + if ((int64_t)Value < 0) { + Value = -Value; + opc = 2; // 0b0010 + } + assert(ARM_AM::getSOImmVal(Value) != -1 && + "Out of range pc-relative fixup value!"); + // Encode the immediate and shift the opcode into place. + return ARM_AM::getSOImmVal(Value) | (opc << 21); + } + + case ARM::fixup_t2_adr_pcrel_12: { + Value -= 4; + unsigned opc = 0; + if ((int64_t)Value < 0) { + Value = -Value; + opc = 5; + } + + uint32_t out = (opc << 21); + out |= (Value & 0x800) << 15; + out |= (Value & 0x700) << 4; + out |= (Value & 0x0FF); + + uint64_t swapped = (out & 0xFFFF0000) >> 16; + swapped |= (out & 0x0000FFFF) << 16; + return swapped; + } + + case ARM::fixup_arm_condbranch: + case ARM::fixup_arm_uncondbranch: + // These values don't encode the low two bits since they're always zero. + // Offset by 8 just as above. + return 0xffffff & ((Value - 8) >> 2); + case ARM::fixup_t2_uncondbranch: { + Value = Value - 4; + Value >>= 1; // Low bit is not encoded. + + uint32_t out = 0; + bool I = Value & 0x800000; + bool J1 = Value & 0x400000; + bool J2 = Value & 0x200000; + J1 ^= I; + J2 ^= I; + + out |= I << 26; // S bit + out |= !J1 << 13; // J1 bit + out |= !J2 << 11; // J2 bit + out |= (Value & 0x1FF800) << 5; // imm6 field + out |= (Value & 0x0007FF); // imm11 field + + uint64_t swapped = (out & 0xFFFF0000) >> 16; + swapped |= (out & 0x0000FFFF) << 16; + return swapped; + } + case ARM::fixup_t2_condbranch: { + Value = Value - 4; + Value >>= 1; // Low bit is not encoded. + + uint64_t out = 0; + out |= (Value & 0x80000) << 7; // S bit + out |= (Value & 0x40000) >> 7; // J2 bit + out |= (Value & 0x20000) >> 4; // J1 bit + out |= (Value & 0x1F800) << 5; // imm6 field + out |= (Value & 0x007FF); // imm11 field + + uint32_t swapped = (out & 0xFFFF0000) >> 16; + swapped |= (out & 0x0000FFFF) << 16; + return swapped; + } + case ARM::fixup_arm_thumb_bl: { + // The value doesn't encode the low bit (always zero) and is offset by + // four. The value is encoded into disjoint bit positions in the destination + // opcode. x = unchanged, I = immediate value bit, S = sign extension bit + // + // BL: xxxxxSIIIIIIIIII xxxxxIIIIIIIIIII + // + // Note that the halfwords are stored high first, low second; so we need + // to transpose the fixup value here to map properly. + unsigned isNeg = (int64_t(Value - 4) < 0) ? 1 : 0; + uint32_t Binary = 0; + Value = 0x3fffff & ((Value - 4) >> 1); + Binary = (Value & 0x7ff) << 16; // Low imm11 value. + Binary |= (Value & 0x1ffc00) >> 11; // High imm10 value. + Binary |= isNeg << 10; // Sign bit. + return Binary; + } + case ARM::fixup_arm_thumb_blx: { + // The value doesn't encode the low two bits (always zero) and is offset by + // four (see fixup_arm_thumb_cp). The value is encoded into disjoint bit + // positions in the destination opcode. x = unchanged, I = immediate value + // bit, S = sign extension bit, 0 = zero. + // + // BLX: xxxxxSIIIIIIIIII xxxxxIIIIIIIIII0 + // + // Note that the halfwords are stored high first, low second; so we need + // to transpose the fixup value here to map properly. + unsigned isNeg = (int64_t(Value-4) < 0) ? 1 : 0; + uint32_t Binary = 0; + Value = 0xfffff & ((Value - 2) >> 2); + Binary = (Value & 0x3ff) << 17; // Low imm10L value. + Binary |= (Value & 0xffc00) >> 10; // High imm10H value. + Binary |= isNeg << 10; // Sign bit. + return Binary; + } + case ARM::fixup_arm_thumb_cp: + // Offset by 4, and don't encode the low two bits. Two bytes of that + // 'off by 4' is implicitly handled by the half-word ordering of the + // Thumb encoding, so we only need to adjust by 2 here. + return ((Value - 2) >> 2) & 0xff; + case ARM::fixup_arm_thumb_cb: { + // Offset by 4 and don't encode the lower bit, which is always 0. + uint32_t Binary = (Value - 4) >> 1; + return ((Binary & 0x20) << 4) | ((Binary & 0x1f) << 3); + } + case ARM::fixup_arm_thumb_br: + // Offset by 4 and don't encode the lower bit, which is always 0. + return ((Value - 4) >> 1) & 0x7ff; + case ARM::fixup_arm_thumb_bcc: + // Offset by 4 and don't encode the lower bit, which is always 0. + return ((Value - 4) >> 1) & 0xff; + case ARM::fixup_arm_pcrel_10: + Value = Value - 4; // ARM fixups offset by an additional word and don't + // need to adjust for the half-word ordering. + // Fall through. + case ARM::fixup_t2_pcrel_10: { + // Offset by 4, adjusted by two due to the half-word ordering of thumb. + Value = Value - 4; + bool isAdd = true; + if ((int64_t)Value < 0) { + Value = -Value; + isAdd = false; + } + // These values don't encode the low two bits since they're always zero. + Value >>= 2; + assert ((Value < 256) && "Out of range pc-relative fixup value!"); + Value |= isAdd << 23; + + // Same addressing mode as fixup_arm_pcrel_10, + // but with 16-bit halfwords swapped. + if (Kind == ARM::fixup_t2_pcrel_10) { + uint32_t swapped = (Value & 0xFFFF0000) >> 16; + swapped |= (Value & 0x0000FFFF) << 16; + return swapped; + } + + return Value; + } + } +} + +namespace { + +// FIXME: This should be in a separate file. +// ELF is an ELF of course... +class ELFARMAsmBackend : public ARMAsmBackend { +public: + Triple::OSType OSType; + ELFARMAsmBackend(const Target &T, Triple::OSType _OSType) + : ARMAsmBackend(T), OSType(_OSType) { } + + void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize, + uint64_t Value) const; + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return createELFObjectWriter(new ARMELFObjectWriter(OSType), OS, + /*IsLittleEndian*/ true); + } +}; + +// FIXME: Raise this to share code between Darwin and ELF. +void ELFARMAsmBackend::ApplyFixup(const MCFixup &Fixup, char *Data, + unsigned DataSize, uint64_t Value) const { + unsigned NumBytes = 4; // FIXME: 2 for Thumb + Value = adjustFixupValue(Fixup.getKind(), Value); + if (!Value) return; // Doesn't change encoding. + + unsigned Offset = Fixup.getOffset(); + + // For each byte of the fragment that the fixup touches, mask in the bits from + // the fixup value. The Value has been "split up" into the appropriate + // bitfields above. + for (unsigned i = 0; i != NumBytes; ++i) + Data[Offset + i] |= uint8_t((Value >> (i * 8)) & 0xff); +} + +// FIXME: This should be in a separate file. +class DarwinARMAsmBackend : public ARMAsmBackend { +public: + const object::mach::CPUSubtypeARM Subtype; + DarwinARMAsmBackend(const Target &T, object::mach::CPUSubtypeARM st) + : ARMAsmBackend(T), Subtype(st) { } + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return createARMMachObjectWriter(OS, /*Is64Bit=*/false, + object::mach::CTM_ARM, + Subtype); + } + + void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize, + uint64_t Value) const; + + virtual bool doesSectionRequireSymbols(const MCSection &Section) const { + return false; + } +}; + +/// getFixupKindNumBytes - The number of bytes the fixup may change. +static unsigned getFixupKindNumBytes(unsigned Kind) { + switch (Kind) { + default: + llvm_unreachable("Unknown fixup kind!"); + + case FK_Data_1: + case ARM::fixup_arm_thumb_bcc: + case ARM::fixup_arm_thumb_cp: + case ARM::fixup_thumb_adr_pcrel_10: + return 1; + + case FK_Data_2: + case ARM::fixup_arm_thumb_br: + case ARM::fixup_arm_thumb_cb: + return 2; + + case ARM::fixup_arm_ldst_pcrel_12: + case ARM::fixup_arm_pcrel_10: + case ARM::fixup_arm_adr_pcrel_12: + case ARM::fixup_arm_condbranch: + case ARM::fixup_arm_uncondbranch: + return 3; + + case FK_Data_4: + case ARM::fixup_t2_ldst_pcrel_12: + case ARM::fixup_t2_condbranch: + case ARM::fixup_t2_uncondbranch: + case ARM::fixup_t2_pcrel_10: + case ARM::fixup_t2_adr_pcrel_12: + case ARM::fixup_arm_thumb_bl: + case ARM::fixup_arm_thumb_blx: + case ARM::fixup_arm_movt_hi16: + case ARM::fixup_arm_movw_lo16: + case ARM::fixup_arm_movt_hi16_pcrel: + case ARM::fixup_arm_movw_lo16_pcrel: + case ARM::fixup_t2_movt_hi16: + case ARM::fixup_t2_movw_lo16: + case ARM::fixup_t2_movt_hi16_pcrel: + case ARM::fixup_t2_movw_lo16_pcrel: + return 4; + } +} + +void DarwinARMAsmBackend::ApplyFixup(const MCFixup &Fixup, char *Data, + unsigned DataSize, uint64_t Value) const { + unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind()); + Value = adjustFixupValue(Fixup.getKind(), Value); + if (!Value) return; // Doesn't change encoding. + + unsigned Offset = Fixup.getOffset(); + assert(Offset + NumBytes <= DataSize && "Invalid fixup offset!"); + + // For each byte of the fragment that the fixup touches, mask in the + // bits from the fixup value. + for (unsigned i = 0; i != NumBytes; ++i) + Data[Offset + i] |= uint8_t((Value >> (i * 8)) & 0xff); +} + +} // end anonymous namespace + +TargetAsmBackend *llvm::createARMAsmBackend(const Target &T, + const std::string &TT) { + Triple TheTriple(TT); + + if (TheTriple.isOSDarwin()) { + if (TheTriple.getArchName() == "armv4t" || + TheTriple.getArchName() == "thumbv4t") + return new DarwinARMAsmBackend(T, object::mach::CSARM_V4T); + else if (TheTriple.getArchName() == "armv5e" || + TheTriple.getArchName() == "thumbv5e") + return new DarwinARMAsmBackend(T, object::mach::CSARM_V5TEJ); + else if (TheTriple.getArchName() == "armv6" || + TheTriple.getArchName() == "thumbv6") + return new DarwinARMAsmBackend(T, object::mach::CSARM_V6); + return new DarwinARMAsmBackend(T, object::mach::CSARM_V7); + } + + if (TheTriple.isOSWindows()) + assert(0 && "Windows not supported on ARM"); + + return new ELFARMAsmBackend(T, Triple(TT).getOS()); +} |