1 //===-- ARMAsmBackend.cpp - ARM Assembler Backend -------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "MCTargetDesc/ARMMCTargetDesc.h"
11 #include "MCTargetDesc/ARMAddressingModes.h"
12 #include "MCTargetDesc/ARMBaseInfo.h"
13 #include "MCTargetDesc/ARMFixupKinds.h"
14 #include "llvm/ADT/StringSwitch.h"
15 #include "llvm/MC/MCAsmBackend.h"
16 #include "llvm/MC/MCAssembler.h"
17 #include "llvm/MC/MCContext.h"
18 #include "llvm/MC/MCDirectives.h"
19 #include "llvm/MC/MCELFObjectWriter.h"
20 #include "llvm/MC/MCExpr.h"
21 #include "llvm/MC/MCFixupKindInfo.h"
22 #include "llvm/MC/MCMachObjectWriter.h"
23 #include "llvm/MC/MCObjectWriter.h"
24 #include "llvm/MC/MCSectionELF.h"
25 #include "llvm/MC/MCSectionMachO.h"
26 #include "llvm/MC/MCSubtargetInfo.h"
27 #include "llvm/MC/MCValue.h"
28 #include "llvm/Support/ELF.h"
29 #include "llvm/Support/ErrorHandling.h"
30 #include "llvm/Support/MachO.h"
31 #include "llvm/Support/raw_ostream.h"
35 class ARMELFObjectWriter : public MCELFObjectTargetWriter {
37 ARMELFObjectWriter(uint8_t OSABI)
38 : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI, ELF::EM_ARM,
39 /*HasRelocationAddend*/ false) {}
42 class ARMAsmBackend : public MCAsmBackend {
43 const MCSubtargetInfo* STI;
44 bool isThumbMode; // Currently emitting Thumb code.
46 ARMAsmBackend(const Target &T, const StringRef TT)
47 : MCAsmBackend(), STI(ARM_MC::createARMMCSubtargetInfo(TT, "", "")),
48 isThumbMode(TT.startswith("thumb")) {}
54 unsigned getNumFixupKinds() const override {
55 return ARM::NumTargetFixupKinds;
59 return (STI->getFeatureBits() & ARM::HasV6T2Ops) != 0;
62 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override {
63 const static MCFixupKindInfo Infos[ARM::NumTargetFixupKinds] = {
64 // This table *must* be in the order that the fixup_* kinds are defined in
67 // Name Offset (bits) Size (bits) Flags
68 { "fixup_arm_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
69 { "fixup_t2_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel |
70 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
71 { "fixup_arm_pcrel_10_unscaled", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
72 { "fixup_arm_pcrel_10", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
73 { "fixup_t2_pcrel_10", 0, 32, MCFixupKindInfo::FKF_IsPCRel |
74 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
75 { "fixup_thumb_adr_pcrel_10",0, 8, MCFixupKindInfo::FKF_IsPCRel |
76 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
77 { "fixup_arm_adr_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
78 { "fixup_t2_adr_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel |
79 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
80 { "fixup_arm_condbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
81 { "fixup_arm_uncondbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
82 { "fixup_t2_condbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
83 { "fixup_t2_uncondbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
84 { "fixup_arm_thumb_br", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
85 { "fixup_arm_uncondbl", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
86 { "fixup_arm_condbl", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
87 { "fixup_arm_blx", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
88 { "fixup_arm_thumb_bl", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
89 { "fixup_arm_thumb_blx", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
90 { "fixup_arm_thumb_cb", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
91 { "fixup_arm_thumb_cp", 0, 8, MCFixupKindInfo::FKF_IsPCRel |
92 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
93 { "fixup_arm_thumb_bcc", 0, 8, MCFixupKindInfo::FKF_IsPCRel },
94 // movw / movt: 16-bits immediate but scattered into two chunks 0 - 12, 16 - 19.
95 { "fixup_arm_movt_hi16", 0, 20, 0 },
96 { "fixup_arm_movw_lo16", 0, 20, 0 },
97 { "fixup_t2_movt_hi16", 0, 20, 0 },
98 { "fixup_t2_movw_lo16", 0, 20, 0 },
99 { "fixup_arm_movt_hi16_pcrel", 0, 20, MCFixupKindInfo::FKF_IsPCRel },
100 { "fixup_arm_movw_lo16_pcrel", 0, 20, MCFixupKindInfo::FKF_IsPCRel },
101 { "fixup_t2_movt_hi16_pcrel", 0, 20, MCFixupKindInfo::FKF_IsPCRel },
102 { "fixup_t2_movw_lo16_pcrel", 0, 20, MCFixupKindInfo::FKF_IsPCRel },
105 if (Kind < FirstTargetFixupKind)
106 return MCAsmBackend::getFixupKindInfo(Kind);
108 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
110 return Infos[Kind - FirstTargetFixupKind];
113 /// processFixupValue - Target hook to process the literal value of a fixup
115 void processFixupValue(const MCAssembler &Asm, const MCAsmLayout &Layout,
116 const MCFixup &Fixup, const MCFragment *DF,
117 MCValue &Target, uint64_t &Value,
118 bool &IsResolved) override;
121 void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
122 uint64_t Value) const override;
124 bool mayNeedRelaxation(const MCInst &Inst) const override;
126 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
127 const MCRelaxableFragment *DF,
128 const MCAsmLayout &Layout) const override;
130 void relaxInstruction(const MCInst &Inst, MCInst &Res) const override;
132 bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
134 void handleAssemblerFlag(MCAssemblerFlag Flag) override {
146 unsigned getPointerSize() const { return 4; }
147 bool isThumb() const { return isThumbMode; }
148 void setIsThumb(bool it) { isThumbMode = it; }
150 } // end anonymous namespace
152 static unsigned getRelaxedOpcode(unsigned Op) {
155 case ARM::tBcc: return ARM::t2Bcc;
156 case ARM::tLDRpci: return ARM::t2LDRpci;
157 case ARM::tADR: return ARM::t2ADR;
158 case ARM::tB: return ARM::t2B;
159 case ARM::tCBZ: return ARM::tHINT;
160 case ARM::tCBNZ: return ARM::tHINT;
164 bool ARMAsmBackend::mayNeedRelaxation(const MCInst &Inst) const {
165 if (getRelaxedOpcode(Inst.getOpcode()) != Inst.getOpcode())
170 bool ARMAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup,
172 const MCRelaxableFragment *DF,
173 const MCAsmLayout &Layout) const {
174 switch ((unsigned)Fixup.getKind()) {
175 case ARM::fixup_arm_thumb_br: {
176 // Relaxing tB to t2B. tB has a signed 12-bit displacement with the
177 // low bit being an implied zero. There's an implied +4 offset for the
178 // branch, so we adjust the other way here to determine what's
181 // Relax if the value is too big for a (signed) i8.
182 int64_t Offset = int64_t(Value) - 4;
183 return Offset > 2046 || Offset < -2048;
185 case ARM::fixup_arm_thumb_bcc: {
186 // Relaxing tBcc to t2Bcc. tBcc has a signed 9-bit displacement with the
187 // low bit being an implied zero. There's an implied +4 offset for the
188 // branch, so we adjust the other way here to determine what's
191 // Relax if the value is too big for a (signed) i8.
192 int64_t Offset = int64_t(Value) - 4;
193 return Offset > 254 || Offset < -256;
195 case ARM::fixup_thumb_adr_pcrel_10:
196 case ARM::fixup_arm_thumb_cp: {
197 // If the immediate is negative, greater than 1020, or not a multiple
198 // of four, the wide version of the instruction must be used.
199 int64_t Offset = int64_t(Value) - 4;
200 return Offset > 1020 || Offset < 0 || Offset & 3;
202 case ARM::fixup_arm_thumb_cb:
203 // If we have a Thumb CBZ or CBNZ instruction and its target is the next
204 // instruction it is is actually out of range for the instruction.
205 // It will be changed to a NOP.
206 int64_t Offset = (Value & ~1);
209 llvm_unreachable("Unexpected fixup kind in fixupNeedsRelaxation()!");
212 void ARMAsmBackend::relaxInstruction(const MCInst &Inst, MCInst &Res) const {
213 unsigned RelaxedOp = getRelaxedOpcode(Inst.getOpcode());
215 // Sanity check w/ diagnostic if we get here w/ a bogus instruction.
216 if (RelaxedOp == Inst.getOpcode()) {
217 SmallString<256> Tmp;
218 raw_svector_ostream OS(Tmp);
219 Inst.dump_pretty(OS);
221 report_fatal_error("unexpected instruction to relax: " + OS.str());
224 // If we are changing Thumb CBZ or CBNZ instruction to a NOP, aka tHINT, we
225 // have to change the operands too.
226 if ((Inst.getOpcode() == ARM::tCBZ || Inst.getOpcode() == ARM::tCBNZ) &&
227 RelaxedOp == ARM::tHINT) {
228 Res.setOpcode(RelaxedOp);
229 Res.addOperand(MCOperand::CreateImm(0));
230 Res.addOperand(MCOperand::CreateImm(14));
231 Res.addOperand(MCOperand::CreateReg(0));
235 // The rest of instructions we're relaxing have the same operands.
236 // We just need to update to the proper opcode.
238 Res.setOpcode(RelaxedOp);
241 bool ARMAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
242 const uint16_t Thumb1_16bitNopEncoding = 0x46c0; // using MOV r8,r8
243 const uint16_t Thumb2_16bitNopEncoding = 0xbf00; // NOP
244 const uint32_t ARMv4_NopEncoding = 0xe1a00000; // using MOV r0,r0
245 const uint32_t ARMv6T2_NopEncoding = 0xe320f000; // NOP
247 const uint16_t nopEncoding = hasNOP() ? Thumb2_16bitNopEncoding
248 : Thumb1_16bitNopEncoding;
249 uint64_t NumNops = Count / 2;
250 for (uint64_t i = 0; i != NumNops; ++i)
251 OW->Write16(nopEncoding);
257 const uint32_t nopEncoding = hasNOP() ? ARMv6T2_NopEncoding
259 uint64_t NumNops = Count / 4;
260 for (uint64_t i = 0; i != NumNops; ++i)
261 OW->Write32(nopEncoding);
262 // FIXME: should this function return false when unable to write exactly
263 // 'Count' bytes with NOP encodings?
265 default: break; // No leftover bytes to write
266 case 1: OW->Write8(0); break;
267 case 2: OW->Write16(0); break;
268 case 3: OW->Write16(0); OW->Write8(0xa0); break;
274 static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
275 MCContext *Ctx = NULL) {
276 unsigned Kind = Fixup.getKind();
279 llvm_unreachable("Unknown fixup kind!");
284 case ARM::fixup_arm_movt_hi16:
287 case ARM::fixup_arm_movw_lo16:
288 case ARM::fixup_arm_movt_hi16_pcrel:
289 case ARM::fixup_arm_movw_lo16_pcrel: {
290 unsigned Hi4 = (Value & 0xF000) >> 12;
291 unsigned Lo12 = Value & 0x0FFF;
292 // inst{19-16} = Hi4;
293 // inst{11-0} = Lo12;
294 Value = (Hi4 << 16) | (Lo12);
297 case ARM::fixup_t2_movt_hi16:
300 case ARM::fixup_t2_movw_lo16:
301 case ARM::fixup_t2_movt_hi16_pcrel: //FIXME: Shouldn't this be shifted like
302 // the other hi16 fixup?
303 case ARM::fixup_t2_movw_lo16_pcrel: {
304 unsigned Hi4 = (Value & 0xF000) >> 12;
305 unsigned i = (Value & 0x800) >> 11;
306 unsigned Mid3 = (Value & 0x700) >> 8;
307 unsigned Lo8 = Value & 0x0FF;
308 // inst{19-16} = Hi4;
310 // inst{14-12} = Mid3;
312 Value = (Hi4 << 16) | (i << 26) | (Mid3 << 12) | (Lo8);
313 uint64_t swapped = (Value & 0xFFFF0000) >> 16;
314 swapped |= (Value & 0x0000FFFF) << 16;
317 case ARM::fixup_arm_ldst_pcrel_12:
318 // ARM PC-relative values are offset by 8.
321 case ARM::fixup_t2_ldst_pcrel_12: {
322 // Offset by 4, adjusted by two due to the half-word ordering of thumb.
325 if ((int64_t)Value < 0) {
329 if (Ctx && Value >= 4096)
330 Ctx->FatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
331 Value |= isAdd << 23;
333 // Same addressing mode as fixup_arm_pcrel_10,
334 // but with 16-bit halfwords swapped.
335 if (Kind == ARM::fixup_t2_ldst_pcrel_12) {
336 uint64_t swapped = (Value & 0xFFFF0000) >> 16;
337 swapped |= (Value & 0x0000FFFF) << 16;
343 case ARM::fixup_thumb_adr_pcrel_10:
344 return ((Value - 4) >> 2) & 0xff;
345 case ARM::fixup_arm_adr_pcrel_12: {
346 // ARM PC-relative values are offset by 8.
348 unsigned opc = 4; // bits {24-21}. Default to add: 0b0100
349 if ((int64_t)Value < 0) {
353 if (Ctx && ARM_AM::getSOImmVal(Value) == -1)
354 Ctx->FatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
355 // Encode the immediate and shift the opcode into place.
356 return ARM_AM::getSOImmVal(Value) | (opc << 21);
359 case ARM::fixup_t2_adr_pcrel_12: {
362 if ((int64_t)Value < 0) {
367 uint32_t out = (opc << 21);
368 out |= (Value & 0x800) << 15;
369 out |= (Value & 0x700) << 4;
370 out |= (Value & 0x0FF);
372 uint64_t swapped = (out & 0xFFFF0000) >> 16;
373 swapped |= (out & 0x0000FFFF) << 16;
377 case ARM::fixup_arm_condbranch:
378 case ARM::fixup_arm_uncondbranch:
379 case ARM::fixup_arm_uncondbl:
380 case ARM::fixup_arm_condbl:
381 case ARM::fixup_arm_blx:
382 // These values don't encode the low two bits since they're always zero.
383 // Offset by 8 just as above.
384 if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
385 if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_TLSCALL)
387 return 0xffffff & ((Value - 8) >> 2);
388 case ARM::fixup_t2_uncondbranch: {
390 Value >>= 1; // Low bit is not encoded.
393 bool I = Value & 0x800000;
394 bool J1 = Value & 0x400000;
395 bool J2 = Value & 0x200000;
399 out |= I << 26; // S bit
400 out |= !J1 << 13; // J1 bit
401 out |= !J2 << 11; // J2 bit
402 out |= (Value & 0x1FF800) << 5; // imm6 field
403 out |= (Value & 0x0007FF); // imm11 field
405 uint64_t swapped = (out & 0xFFFF0000) >> 16;
406 swapped |= (out & 0x0000FFFF) << 16;
409 case ARM::fixup_t2_condbranch: {
411 Value >>= 1; // Low bit is not encoded.
414 out |= (Value & 0x80000) << 7; // S bit
415 out |= (Value & 0x40000) >> 7; // J2 bit
416 out |= (Value & 0x20000) >> 4; // J1 bit
417 out |= (Value & 0x1F800) << 5; // imm6 field
418 out |= (Value & 0x007FF); // imm11 field
420 uint32_t swapped = (out & 0xFFFF0000) >> 16;
421 swapped |= (out & 0x0000FFFF) << 16;
424 case ARM::fixup_arm_thumb_bl: {
425 // The value doesn't encode the low bit (always zero) and is offset by
426 // four. The 32-bit immediate value is encoded as
427 // imm32 = SignExtend(S:I1:I2:imm10:imm11:0)
428 // where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
429 // The value is encoded into disjoint bit positions in the destination
430 // opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
431 // J = either J1 or J2 bit
433 // BL: xxxxxSIIIIIIIIII xxJxJIIIIIIIIIII
435 // Note that the halfwords are stored high first, low second; so we need
436 // to transpose the fixup value here to map properly.
437 uint32_t offset = (Value - 4) >> 1;
438 uint32_t signBit = (offset & 0x800000) >> 23;
439 uint32_t I1Bit = (offset & 0x400000) >> 22;
440 uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
441 uint32_t I2Bit = (offset & 0x200000) >> 21;
442 uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
443 uint32_t imm10Bits = (offset & 0x1FF800) >> 11;
444 uint32_t imm11Bits = (offset & 0x000007FF);
447 uint32_t firstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10Bits);
448 uint32_t secondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
449 (uint16_t)imm11Bits);
450 Binary |= secondHalf << 16;
454 case ARM::fixup_arm_thumb_blx: {
455 // The value doesn't encode the low two bits (always zero) and is offset by
456 // four (see fixup_arm_thumb_cp). The 32-bit immediate value is encoded as
457 // imm32 = SignExtend(S:I1:I2:imm10H:imm10L:00)
458 // where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
459 // The value is encoded into disjoint bit positions in the destination
460 // opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
461 // J = either J1 or J2 bit, 0 = zero.
463 // BLX: xxxxxSIIIIIIIIII xxJxJIIIIIIIIII0
465 // Note that the halfwords are stored high first, low second; so we need
466 // to transpose the fixup value here to map properly.
467 uint32_t offset = (Value - 2) >> 2;
468 if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
469 if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_TLSCALL)
471 uint32_t signBit = (offset & 0x400000) >> 22;
472 uint32_t I1Bit = (offset & 0x200000) >> 21;
473 uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
474 uint32_t I2Bit = (offset & 0x100000) >> 20;
475 uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
476 uint32_t imm10HBits = (offset & 0xFFC00) >> 10;
477 uint32_t imm10LBits = (offset & 0x3FF);
480 uint32_t firstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10HBits);
481 uint32_t secondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
482 ((uint16_t)imm10LBits) << 1);
483 Binary |= secondHalf << 16;
487 case ARM::fixup_arm_thumb_cp:
488 // Offset by 4, and don't encode the low two bits. Two bytes of that
489 // 'off by 4' is implicitly handled by the half-word ordering of the
490 // Thumb encoding, so we only need to adjust by 2 here.
491 return ((Value - 2) >> 2) & 0xff;
492 case ARM::fixup_arm_thumb_cb: {
493 // Offset by 4 and don't encode the lower bit, which is always 0.
494 uint32_t Binary = (Value - 4) >> 1;
495 return ((Binary & 0x20) << 4) | ((Binary & 0x1f) << 3);
497 case ARM::fixup_arm_thumb_br:
498 // Offset by 4 and don't encode the lower bit, which is always 0.
499 return ((Value - 4) >> 1) & 0x7ff;
500 case ARM::fixup_arm_thumb_bcc:
501 // Offset by 4 and don't encode the lower bit, which is always 0.
502 return ((Value - 4) >> 1) & 0xff;
503 case ARM::fixup_arm_pcrel_10_unscaled: {
504 Value = Value - 8; // ARM fixups offset by an additional word and don't
505 // need to adjust for the half-word ordering.
507 if ((int64_t)Value < 0) {
511 // The value has the low 4 bits encoded in [3:0] and the high 4 in [11:8].
512 if (Ctx && Value >= 256)
513 Ctx->FatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
514 Value = (Value & 0xf) | ((Value & 0xf0) << 4);
515 return Value | (isAdd << 23);
517 case ARM::fixup_arm_pcrel_10:
518 Value = Value - 4; // ARM fixups offset by an additional word and don't
519 // need to adjust for the half-word ordering.
521 case ARM::fixup_t2_pcrel_10: {
522 // Offset by 4, adjusted by two due to the half-word ordering of thumb.
525 if ((int64_t)Value < 0) {
529 // These values don't encode the low two bits since they're always zero.
531 if (Ctx && Value >= 256)
532 Ctx->FatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
533 Value |= isAdd << 23;
535 // Same addressing mode as fixup_arm_pcrel_10, but with 16-bit halfwords
537 if (Kind == ARM::fixup_t2_pcrel_10) {
538 uint32_t swapped = (Value & 0xFFFF0000) >> 16;
539 swapped |= (Value & 0x0000FFFF) << 16;
548 void ARMAsmBackend::processFixupValue(const MCAssembler &Asm,
549 const MCAsmLayout &Layout,
550 const MCFixup &Fixup,
551 const MCFragment *DF,
552 MCValue &Target, uint64_t &Value,
554 const MCSymbolRefExpr *A = Target.getSymA();
555 // Some fixups to thumb function symbols need the low bit (thumb bit)
557 if ((unsigned)Fixup.getKind() != ARM::fixup_arm_ldst_pcrel_12 &&
558 (unsigned)Fixup.getKind() != ARM::fixup_t2_ldst_pcrel_12 &&
559 (unsigned)Fixup.getKind() != ARM::fixup_arm_adr_pcrel_12 &&
560 (unsigned)Fixup.getKind() != ARM::fixup_thumb_adr_pcrel_10 &&
561 (unsigned)Fixup.getKind() != ARM::fixup_t2_adr_pcrel_12 &&
562 (unsigned)Fixup.getKind() != ARM::fixup_arm_thumb_cp) {
564 const MCSymbol &Sym = A->getSymbol().AliasedSymbol();
565 if (Asm.isThumbFunc(&Sym))
569 // For Thumb1 BL instruction, it is possible to be a long jump between
570 // the basic blocks of the same function. Thus, we would like to resolve
571 // the offset when the destination has the same MCFragment.
572 if (A && (unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_bl) {
573 const MCSymbol &Sym = A->getSymbol().AliasedSymbol();
574 MCSymbolData &SymData = Asm.getSymbolData(Sym);
575 IsResolved = (SymData.getFragment() == DF);
577 // We must always generate a relocation for BL/BLX instructions if we have
578 // a symbol to reference, as the linker relies on knowing the destination
579 // symbol's thumb-ness to get interworking right.
580 if (A && ((unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_blx ||
581 (unsigned)Fixup.getKind() == ARM::fixup_arm_blx ||
582 (unsigned)Fixup.getKind() == ARM::fixup_arm_uncondbl ||
583 (unsigned)Fixup.getKind() == ARM::fixup_arm_condbl))
586 // Try to get the encoded value for the fixup as-if we're mapping it into
587 // the instruction. This allows adjustFixupValue() to issue a diagnostic
588 // if the value aren't invalid.
589 (void)adjustFixupValue(Fixup, Value, &Asm.getContext());
592 /// getFixupKindNumBytes - The number of bytes the fixup may change.
593 static unsigned getFixupKindNumBytes(unsigned Kind) {
596 llvm_unreachable("Unknown fixup kind!");
599 case ARM::fixup_arm_thumb_bcc:
600 case ARM::fixup_arm_thumb_cp:
601 case ARM::fixup_thumb_adr_pcrel_10:
605 case ARM::fixup_arm_thumb_br:
606 case ARM::fixup_arm_thumb_cb:
609 case ARM::fixup_arm_pcrel_10_unscaled:
610 case ARM::fixup_arm_ldst_pcrel_12:
611 case ARM::fixup_arm_pcrel_10:
612 case ARM::fixup_arm_adr_pcrel_12:
613 case ARM::fixup_arm_uncondbl:
614 case ARM::fixup_arm_condbl:
615 case ARM::fixup_arm_blx:
616 case ARM::fixup_arm_condbranch:
617 case ARM::fixup_arm_uncondbranch:
621 case ARM::fixup_t2_ldst_pcrel_12:
622 case ARM::fixup_t2_condbranch:
623 case ARM::fixup_t2_uncondbranch:
624 case ARM::fixup_t2_pcrel_10:
625 case ARM::fixup_t2_adr_pcrel_12:
626 case ARM::fixup_arm_thumb_bl:
627 case ARM::fixup_arm_thumb_blx:
628 case ARM::fixup_arm_movt_hi16:
629 case ARM::fixup_arm_movw_lo16:
630 case ARM::fixup_arm_movt_hi16_pcrel:
631 case ARM::fixup_arm_movw_lo16_pcrel:
632 case ARM::fixup_t2_movt_hi16:
633 case ARM::fixup_t2_movw_lo16:
634 case ARM::fixup_t2_movt_hi16_pcrel:
635 case ARM::fixup_t2_movw_lo16_pcrel:
640 void ARMAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
641 unsigned DataSize, uint64_t Value) const {
642 unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind());
643 Value = adjustFixupValue(Fixup, Value);
644 if (!Value) return; // Doesn't change encoding.
646 unsigned Offset = Fixup.getOffset();
647 assert(Offset + NumBytes <= DataSize && "Invalid fixup offset!");
649 // For each byte of the fragment that the fixup touches, mask in the bits from
650 // the fixup value. The Value has been "split up" into the appropriate
652 for (unsigned i = 0; i != NumBytes; ++i)
653 Data[Offset + i] |= uint8_t((Value >> (i * 8)) & 0xff);
658 // FIXME: This should be in a separate file.
659 // ELF is an ELF of course...
660 class ELFARMAsmBackend : public ARMAsmBackend {
663 ELFARMAsmBackend(const Target &T, const StringRef TT,
665 : ARMAsmBackend(T, TT), OSABI(_OSABI) { }
667 MCObjectWriter *createObjectWriter(raw_ostream &OS) const override {
668 return createARMELFObjectWriter(OS, OSABI);
672 // FIXME: This should be in a separate file.
673 class DarwinARMAsmBackend : public ARMAsmBackend {
675 const MachO::CPUSubTypeARM Subtype;
676 DarwinARMAsmBackend(const Target &T, const StringRef TT,
677 MachO::CPUSubTypeARM st)
678 : ARMAsmBackend(T, TT), Subtype(st) {
679 HasDataInCodeSupport = true;
682 MCObjectWriter *createObjectWriter(raw_ostream &OS) const override {
683 return createARMMachObjectWriter(OS, /*Is64Bit=*/false,
689 } // end anonymous namespace
691 MCAsmBackend *llvm::createARMAsmBackend(const Target &T,
692 const MCRegisterInfo &MRI,
693 StringRef TT, StringRef CPU) {
694 Triple TheTriple(TT);
696 if (TheTriple.isOSBinFormatMachO()) {
697 MachO::CPUSubTypeARM CS =
698 StringSwitch<MachO::CPUSubTypeARM>(TheTriple.getArchName())
699 .Cases("armv4t", "thumbv4t", MachO::CPU_SUBTYPE_ARM_V4T)
700 .Cases("armv5e", "thumbv5e", MachO::CPU_SUBTYPE_ARM_V5TEJ)
701 .Cases("armv6", "thumbv6", MachO::CPU_SUBTYPE_ARM_V6)
702 .Cases("armv6m", "thumbv6m", MachO::CPU_SUBTYPE_ARM_V6M)
703 .Cases("armv7em", "thumbv7em", MachO::CPU_SUBTYPE_ARM_V7EM)
704 .Cases("armv7k", "thumbv7k", MachO::CPU_SUBTYPE_ARM_V7K)
705 .Cases("armv7m", "thumbv7m", MachO::CPU_SUBTYPE_ARM_V7M)
706 .Cases("armv7s", "thumbv7s", MachO::CPU_SUBTYPE_ARM_V7S)
707 .Default(MachO::CPU_SUBTYPE_ARM_V7);
709 return new DarwinARMAsmBackend(T, TT, CS);
713 // FIXME: Introduce yet another checker but assert(0).
714 if (TheTriple.isOSBinFormatCOFF())
715 assert(0 && "Windows not supported on ARM");
718 uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(Triple(TT).getOS());
719 return new ELFARMAsmBackend(T, TT, OSABI);