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llvm-6502/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
Bill Wendling c3cee57f7d Generate compact unwind encoding from CFI directives. 
We used to generate the compact unwind encoding from the machine
instructions. However, this had the problem that if the user used `-save-temps'
or compiled their hand-written `.s' file (with CFI directives), we wouldn't
generate the compact unwind encoding.

Move the algorithm that generates the compact unwind encoding into the
MCAsmBackend. This way we can generate the encoding whether the code is from a
`.ll' or `.s' file.

<rdar://problem/13623355>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190290 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-09 02:37:14 +00:00

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25 KiB
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//===-- 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/ARMMCTargetDesc.h"
#include "MCTargetDesc/ARMAddressingModes.h"
#include "MCTargetDesc/ARMBaseInfo.h"
#include "MCTargetDesc/ARMFixupKinds.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDirectives.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCFixupKindInfo.h"
#include "llvm/MC/MCMachObjectWriter.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MachO.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class ARMELFObjectWriter : public MCELFObjectTargetWriter {
public:
ARMELFObjectWriter(uint8_t OSABI)
: MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI, ELF::EM_ARM,
/*HasRelocationAddend*/ false) {}
};
class ARMAsmBackend : public MCAsmBackend {
const MCSubtargetInfo* STI;
bool isThumbMode; // Currently emitting Thumb code.
public:
ARMAsmBackend(const Target &T, const StringRef TT)
: MCAsmBackend(), STI(ARM_MC::createARMMCSubtargetInfo(TT, "", "")),
isThumbMode(TT.startswith("thumb")) {}
~ARMAsmBackend() {
delete STI;
}
unsigned getNumFixupKinds() const { return ARM::NumTargetFixupKinds; }
bool hasNOP() const {
return (STI->getFeatureBits() & ARM::HasV6T2Ops) != 0;
}
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", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_t2_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel |
MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{ "fixup_arm_pcrel_10_unscaled", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_arm_pcrel_10", 0, 32, 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", 0, 32, 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_uncondbl", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_arm_condbl", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_arm_blx", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_arm_thumb_bl", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_arm_thumb_blx", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_arm_thumb_cb", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_arm_thumb_cp", 0, 8, MCFixupKindInfo::FKF_IsPCRel |
MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{ "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 MCAsmBackend::getFixupKindInfo(Kind);
assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
"Invalid kind!");
return Infos[Kind - FirstTargetFixupKind];
}
/// processFixupValue - Target hook to process the literal value of a fixup
/// if necessary.
void processFixupValue(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFixup &Fixup, const MCFragment *DF,
MCValue &Target, uint64_t &Value,
bool &IsResolved);
void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
uint64_t Value) const;
bool mayNeedRelaxation(const MCInst &Inst) const;
bool fixupNeedsRelaxation(const MCFixup &Fixup,
uint64_t Value,
const MCRelaxableFragment *DF,
const MCAsmLayout &Layout) 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
static unsigned getRelaxedOpcode(unsigned Op) {
switch (Op) {
default: return Op;
case ARM::tBcc: return ARM::t2Bcc;
case ARM::tLDRpci: return ARM::t2LDRpci;
case ARM::tADR: return ARM::t2ADR;
case ARM::tB: return ARM::t2B;
}
}
bool ARMAsmBackend::mayNeedRelaxation(const MCInst &Inst) const {
if (getRelaxedOpcode(Inst.getOpcode()) != Inst.getOpcode())
return true;
return false;
}
bool ARMAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup,
uint64_t Value,
const MCRelaxableFragment *DF,
const MCAsmLayout &Layout) const {
switch ((unsigned)Fixup.getKind()) {
case ARM::fixup_arm_thumb_br: {
// Relaxing tB to t2B. tB has a signed 12-bit displacement with the
// low bit being an implied zero. There's an implied +4 offset for the
// branch, so we adjust the other way here to determine what's
// encodable.
//
// Relax if the value is too big for a (signed) i8.
int64_t Offset = int64_t(Value) - 4;
return Offset > 2046 || Offset < -2048;
}
case ARM::fixup_arm_thumb_bcc: {
// Relaxing tBcc to t2Bcc. tBcc has a signed 9-bit displacement with the
// low bit being an implied zero. There's an implied +4 offset for the
// branch, so we adjust the other way here to determine what's
// encodable.
//
// Relax if the value is too big for a (signed) i8.
int64_t Offset = int64_t(Value) - 4;
return Offset > 254 || Offset < -256;
}
case ARM::fixup_thumb_adr_pcrel_10:
case ARM::fixup_arm_thumb_cp: {
// If the immediate is negative, greater than 1020, or not a multiple
// of four, the wide version of the instruction must be used.
int64_t Offset = int64_t(Value) - 4;
return Offset > 1020 || Offset < 0 || Offset & 3;
}
}
llvm_unreachable("Unexpected fixup kind in fixupNeedsRelaxation()!");
}
void ARMAsmBackend::relaxInstruction(const MCInst &Inst, MCInst &Res) const {
unsigned RelaxedOp = getRelaxedOpcode(Inst.getOpcode());
// Sanity check w/ diagnostic if we get here w/ a bogus instruction.
if (RelaxedOp == Inst.getOpcode()) {
SmallString<256> Tmp;
raw_svector_ostream OS(Tmp);
Inst.dump_pretty(OS);
OS << "\n";
report_fatal_error("unexpected instruction to relax: " + OS.str());
}
// The instructions we're relaxing have (so far) the same operands.
// We just need to update to the proper opcode.
Res = Inst;
Res.setOpcode(RelaxedOp);
}
bool ARMAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
const uint16_t Thumb1_16bitNopEncoding = 0x46c0; // using MOV r8,r8
const uint16_t Thumb2_16bitNopEncoding = 0xbf00; // NOP
const uint32_t ARMv4_NopEncoding = 0xe1a00000; // using MOV r0,r0
const uint32_t ARMv6T2_NopEncoding = 0xe320f000; // NOP
if (isThumb()) {
const uint16_t nopEncoding = hasNOP() ? Thumb2_16bitNopEncoding
: Thumb1_16bitNopEncoding;
uint64_t NumNops = Count / 2;
for (uint64_t i = 0; i != NumNops; ++i)
OW->Write16(nopEncoding);
if (Count & 1)
OW->Write8(0);
return true;
}
// ARM mode
const uint32_t nopEncoding = hasNOP() ? ARMv6T2_NopEncoding
: ARMv4_NopEncoding;
uint64_t NumNops = Count / 4;
for (uint64_t i = 0; i != NumNops; ++i)
OW->Write32(nopEncoding);
// FIXME: should this function return false when unable to write exactly
// 'Count' bytes with NOP encodings?
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(const MCFixup &Fixup, uint64_t Value,
MCContext *Ctx = NULL) {
unsigned Kind = Fixup.getKind();
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;
// 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;
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;
}
if (Ctx && Value >= 4096)
Ctx->FatalError(Fixup.getLoc(), "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
}
if (Ctx && ARM_AM::getSOImmVal(Value) == -1)
Ctx->FatalError(Fixup.getLoc(), "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:
case ARM::fixup_arm_uncondbl:
case ARM::fixup_arm_condbl:
case ARM::fixup_arm_blx:
// 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 32-bit immediate value is encoded as
// imm32 = SignExtend(S:I1:I2:imm10:imm11:0)
// where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
// The value is encoded into disjoint bit positions in the destination
// opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
// J = either J1 or J2 bit
//
// BL: xxxxxSIIIIIIIIII xxJxJIIIIIIIIIII
//
// Note that the halfwords are stored high first, low second; so we need
// to transpose the fixup value here to map properly.
uint32_t offset = (Value - 4) >> 1;
uint32_t signBit = (offset & 0x800000) >> 23;
uint32_t I1Bit = (offset & 0x400000) >> 22;
uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
uint32_t I2Bit = (offset & 0x200000) >> 21;
uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
uint32_t imm10Bits = (offset & 0x1FF800) >> 11;
uint32_t imm11Bits = (offset & 0x000007FF);
uint32_t Binary = 0;
uint32_t firstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10Bits);
uint32_t secondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
(uint16_t)imm11Bits);
Binary |= secondHalf << 16;
Binary |= firstHalf;
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 32-bit immediate value is encoded as
// imm32 = SignExtend(S:I1:I2:imm10H:imm10L:00)
// where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
// The value is encoded into disjoint bit positions in the destination
// opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
// J = either J1 or J2 bit, 0 = zero.
//
// BLX: xxxxxSIIIIIIIIII xxJxJIIIIIIIIII0
//
// Note that the halfwords are stored high first, low second; so we need
// to transpose the fixup value here to map properly.
uint32_t offset = (Value - 2) >> 2;
uint32_t signBit = (offset & 0x400000) >> 22;
uint32_t I1Bit = (offset & 0x200000) >> 21;
uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
uint32_t I2Bit = (offset & 0x100000) >> 20;
uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
uint32_t imm10HBits = (offset & 0xFFC00) >> 10;
uint32_t imm10LBits = (offset & 0x3FF);
uint32_t Binary = 0;
uint32_t firstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10HBits);
uint32_t secondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
((uint16_t)imm10LBits) << 1);
Binary |= secondHalf << 16;
Binary |= firstHalf;
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_unscaled: {
Value = Value - 8; // ARM fixups offset by an additional word and don't
// need to adjust for the half-word ordering.
bool isAdd = true;
if ((int64_t)Value < 0) {
Value = -Value;
isAdd = false;
}
// The value has the low 4 bits encoded in [3:0] and the high 4 in [11:8].
if (Ctx && Value >= 256)
Ctx->FatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
Value = (Value & 0xf) | ((Value & 0xf0) << 4);
return Value | (isAdd << 23);
}
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;
if (Ctx && Value >= 256)
Ctx->FatalError(Fixup.getLoc(), "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;
}
}
}
void ARMAsmBackend::processFixupValue(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFixup &Fixup,
const MCFragment *DF,
MCValue &Target, uint64_t &Value,
bool &IsResolved) {
const MCSymbolRefExpr *A = Target.getSymA();
// Some fixups to thumb function symbols need the low bit (thumb bit)
// twiddled.
if ((unsigned)Fixup.getKind() != ARM::fixup_arm_ldst_pcrel_12 &&
(unsigned)Fixup.getKind() != ARM::fixup_t2_ldst_pcrel_12 &&
(unsigned)Fixup.getKind() != ARM::fixup_arm_adr_pcrel_12 &&
(unsigned)Fixup.getKind() != ARM::fixup_thumb_adr_pcrel_10 &&
(unsigned)Fixup.getKind() != ARM::fixup_t2_adr_pcrel_12 &&
(unsigned)Fixup.getKind() != ARM::fixup_arm_thumb_cp) {
if (A) {
const MCSymbol &Sym = A->getSymbol().AliasedSymbol();
if (Asm.isThumbFunc(&Sym))
Value |= 1;
}
}
// We must always generate a relocation for BL/BLX instructions if we have
// a symbol to reference, as the linker relies on knowing the destination
// symbol's thumb-ness to get interworking right.
if (A && ((unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_blx ||
(unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_bl ||
(unsigned)Fixup.getKind() == ARM::fixup_arm_blx ||
(unsigned)Fixup.getKind() == ARM::fixup_arm_uncondbl ||
(unsigned)Fixup.getKind() == ARM::fixup_arm_condbl))
IsResolved = false;
// Try to get the encoded value for the fixup as-if we're mapping it into
// the instruction. This allows adjustFixupValue() to issue a diagnostic
// if the value aren't invalid.
(void)adjustFixupValue(Fixup, Value, &Asm.getContext());
}
/// 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_pcrel_10_unscaled:
case ARM::fixup_arm_ldst_pcrel_12:
case ARM::fixup_arm_pcrel_10:
case ARM::fixup_arm_adr_pcrel_12:
case ARM::fixup_arm_uncondbl:
case ARM::fixup_arm_condbl:
case ARM::fixup_arm_blx:
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 ARMAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
unsigned DataSize, uint64_t Value) const {
unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind());
Value = adjustFixupValue(Fixup, 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. 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);
}
namespace {
// FIXME: This should be in a separate file.
// ELF is an ELF of course...
class ELFARMAsmBackend : public ARMAsmBackend {
public:
uint8_t OSABI;
ELFARMAsmBackend(const Target &T, const StringRef TT,
uint8_t _OSABI)
: ARMAsmBackend(T, TT), OSABI(_OSABI) { }
MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
return createARMELFObjectWriter(OS, OSABI);
}
};
// FIXME: This should be in a separate file.
class DarwinARMAsmBackend : public ARMAsmBackend {
public:
const MachO::CPUSubTypeARM Subtype;
DarwinARMAsmBackend(const Target &T, const StringRef TT,
MachO::CPUSubTypeARM st)
: ARMAsmBackend(T, TT), Subtype(st) {
HasDataInCodeSupport = true;
}
MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
return createARMMachObjectWriter(OS, /*Is64Bit=*/false,
MachO::CPU_TYPE_ARM,
Subtype);
}
virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
return false;
}
};
} // end anonymous namespace
MCAsmBackend *llvm::createARMAsmBackend(const Target &T,
const MCRegisterInfo &MRI,
StringRef TT, StringRef CPU) {
Triple TheTriple(TT);
if (TheTriple.isOSDarwin()) {
MachO::CPUSubTypeARM CS =
StringSwitch<MachO::CPUSubTypeARM>(TheTriple.getArchName())
.Cases("armv4t", "thumbv4t", MachO::CPU_SUBTYPE_ARM_V4T)
.Cases("armv5e", "thumbv5e", MachO::CPU_SUBTYPE_ARM_V5TEJ)
.Cases("armv6", "thumbv6", MachO::CPU_SUBTYPE_ARM_V6)
.Cases("armv6m", "thumbv6m", MachO::CPU_SUBTYPE_ARM_V6M)
.Cases("armv7em", "thumbv7em", MachO::CPU_SUBTYPE_ARM_V7EM)
.Cases("armv7f", "thumbv7f", MachO::CPU_SUBTYPE_ARM_V7F)
.Cases("armv7k", "thumbv7k", MachO::CPU_SUBTYPE_ARM_V7K)
.Cases("armv7m", "thumbv7m", MachO::CPU_SUBTYPE_ARM_V7M)
.Cases("armv7s", "thumbv7s", MachO::CPU_SUBTYPE_ARM_V7S)
.Default(MachO::CPU_SUBTYPE_ARM_V7);
return new DarwinARMAsmBackend(T, TT, CS);
}
#if 0
// FIXME: Introduce yet another checker but assert(0).
if (TheTriple.isOSBinFormatCOFF())
assert(0 && "Windows not supported on ARM");
#endif
uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(Triple(TT).getOS());
return new ELFARMAsmBackend(T, TT, OSABI);
}
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