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/ARMAsmBackend.h"
13 #include "MCTargetDesc/ARMAsmBackendDarwin.h"
14 #include "MCTargetDesc/ARMAsmBackendELF.h"
15 #include "MCTargetDesc/ARMAsmBackendWinCOFF.h"
16 #include "MCTargetDesc/ARMBaseInfo.h"
17 #include "MCTargetDesc/ARMFixupKinds.h"
18 #include "llvm/ADT/StringSwitch.h"
19 #include "llvm/MC/MCAsmBackend.h"
20 #include "llvm/MC/MCAssembler.h"
21 #include "llvm/MC/MCContext.h"
22 #include "llvm/MC/MCDirectives.h"
23 #include "llvm/MC/MCELFObjectWriter.h"
24 #include "llvm/MC/MCExpr.h"
25 #include "llvm/MC/MCFixupKindInfo.h"
26 #include "llvm/MC/MCMachObjectWriter.h"
27 #include "llvm/MC/MCObjectWriter.h"
28 #include "llvm/MC/MCSectionELF.h"
29 #include "llvm/MC/MCSectionMachO.h"
30 #include "llvm/MC/MCSubtargetInfo.h"
31 #include "llvm/MC/MCValue.h"
32 #include "llvm/Support/ELF.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/MachO.h"
35 #include "llvm/Support/TargetParser.h"
36 #include "llvm/Support/raw_ostream.h"
40 class ARMELFObjectWriter : public MCELFObjectTargetWriter {
42 ARMELFObjectWriter(uint8_t OSABI)
43 : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI, ELF::EM_ARM,
44 /*HasRelocationAddend*/ false) {}
47 const MCFixupKindInfo &ARMAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
48 const static MCFixupKindInfo InfosLE[ARM::NumTargetFixupKinds] = {
49 // This table *must* be in the order that the fixup_* kinds are defined in
52 // Name Offset (bits) Size (bits) Flags
53 {"fixup_arm_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
54 {"fixup_t2_ldst_pcrel_12", 0, 32,
55 MCFixupKindInfo::FKF_IsPCRel |
56 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
57 {"fixup_arm_pcrel_10_unscaled", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
58 {"fixup_arm_pcrel_10", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
59 {"fixup_t2_pcrel_10", 0, 32,
60 MCFixupKindInfo::FKF_IsPCRel |
61 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
62 {"fixup_thumb_adr_pcrel_10", 0, 8,
63 MCFixupKindInfo::FKF_IsPCRel |
64 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
65 {"fixup_arm_adr_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
66 {"fixup_t2_adr_pcrel_12", 0, 32,
67 MCFixupKindInfo::FKF_IsPCRel |
68 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
69 {"fixup_arm_condbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
70 {"fixup_arm_uncondbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
71 {"fixup_t2_condbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
72 {"fixup_t2_uncondbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
73 {"fixup_arm_thumb_br", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
74 {"fixup_arm_uncondbl", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
75 {"fixup_arm_condbl", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
76 {"fixup_arm_blx", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
77 {"fixup_arm_thumb_bl", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
78 {"fixup_arm_thumb_blx", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
79 {"fixup_arm_thumb_cb", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
80 {"fixup_arm_thumb_cp", 0, 8,
81 MCFixupKindInfo::FKF_IsPCRel |
82 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
83 {"fixup_arm_thumb_bcc", 0, 8, MCFixupKindInfo::FKF_IsPCRel},
84 // movw / movt: 16-bits immediate but scattered into two chunks 0 - 12, 16
86 {"fixup_arm_movt_hi16", 0, 20, 0},
87 {"fixup_arm_movw_lo16", 0, 20, 0},
88 {"fixup_t2_movt_hi16", 0, 20, 0},
89 {"fixup_t2_movw_lo16", 0, 20, 0},
91 const static MCFixupKindInfo InfosBE[ARM::NumTargetFixupKinds] = {
92 // This table *must* be in the order that the fixup_* kinds are defined in
95 // Name Offset (bits) Size (bits) Flags
96 {"fixup_arm_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
97 {"fixup_t2_ldst_pcrel_12", 0, 32,
98 MCFixupKindInfo::FKF_IsPCRel |
99 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
100 {"fixup_arm_pcrel_10_unscaled", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
101 {"fixup_arm_pcrel_10", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
102 {"fixup_t2_pcrel_10", 0, 32,
103 MCFixupKindInfo::FKF_IsPCRel |
104 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
105 {"fixup_thumb_adr_pcrel_10", 8, 8,
106 MCFixupKindInfo::FKF_IsPCRel |
107 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
108 {"fixup_arm_adr_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
109 {"fixup_t2_adr_pcrel_12", 0, 32,
110 MCFixupKindInfo::FKF_IsPCRel |
111 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
112 {"fixup_arm_condbranch", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
113 {"fixup_arm_uncondbranch", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
114 {"fixup_t2_condbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
115 {"fixup_t2_uncondbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
116 {"fixup_arm_thumb_br", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
117 {"fixup_arm_uncondbl", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
118 {"fixup_arm_condbl", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
119 {"fixup_arm_blx", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
120 {"fixup_arm_thumb_bl", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
121 {"fixup_arm_thumb_blx", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
122 {"fixup_arm_thumb_cb", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
123 {"fixup_arm_thumb_cp", 8, 8,
124 MCFixupKindInfo::FKF_IsPCRel |
125 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
126 {"fixup_arm_thumb_bcc", 8, 8, MCFixupKindInfo::FKF_IsPCRel},
127 // movw / movt: 16-bits immediate but scattered into two chunks 0 - 12, 16
129 {"fixup_arm_movt_hi16", 12, 20, 0},
130 {"fixup_arm_movw_lo16", 12, 20, 0},
131 {"fixup_t2_movt_hi16", 12, 20, 0},
132 {"fixup_t2_movw_lo16", 12, 20, 0},
135 if (Kind < FirstTargetFixupKind)
136 return MCAsmBackend::getFixupKindInfo(Kind);
138 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
140 return (IsLittleEndian ? InfosLE : InfosBE)[Kind - FirstTargetFixupKind];
143 void ARMAsmBackend::handleAssemblerFlag(MCAssemblerFlag Flag) {
155 } // end anonymous namespace
157 unsigned ARMAsmBackend::getRelaxedOpcode(unsigned Op) const {
158 bool HasThumb2 = STI->getFeatureBits()[ARM::FeatureThumb2];
164 return HasThumb2 ? (unsigned)ARM::t2Bcc : Op;
166 return HasThumb2 ? (unsigned)ARM::t2LDRpci : Op;
168 return HasThumb2 ? (unsigned)ARM::t2ADR : Op;
170 return HasThumb2 ? (unsigned)ARM::t2B : Op;
178 bool ARMAsmBackend::mayNeedRelaxation(const MCInst &Inst) const {
179 if (getRelaxedOpcode(Inst.getOpcode()) != Inst.getOpcode())
184 const char *ARMAsmBackend::reasonForFixupRelaxation(const MCFixup &Fixup,
185 uint64_t Value) const {
186 switch ((unsigned)Fixup.getKind()) {
187 case ARM::fixup_arm_thumb_br: {
188 // Relaxing tB to t2B. tB has a signed 12-bit displacement with the
189 // low bit being an implied zero. There's an implied +4 offset for the
190 // branch, so we adjust the other way here to determine what's
193 // Relax if the value is too big for a (signed) i8.
194 int64_t Offset = int64_t(Value) - 4;
195 if (Offset > 2046 || Offset < -2048)
196 return "out of range pc-relative fixup value";
199 case ARM::fixup_arm_thumb_bcc: {
200 // Relaxing tBcc to t2Bcc. tBcc has a signed 9-bit displacement with the
201 // low bit being an implied zero. There's an implied +4 offset for the
202 // branch, so we adjust the other way here to determine what's
205 // Relax if the value is too big for a (signed) i8.
206 int64_t Offset = int64_t(Value) - 4;
207 if (Offset > 254 || Offset < -256)
208 return "out of range pc-relative fixup value";
211 case ARM::fixup_thumb_adr_pcrel_10:
212 case ARM::fixup_arm_thumb_cp: {
213 // If the immediate is negative, greater than 1020, or not a multiple
214 // of four, the wide version of the instruction must be used.
215 int64_t Offset = int64_t(Value) - 4;
217 return "misaligned pc-relative fixup value";
218 else if (Offset > 1020 || Offset < 0)
219 return "out of range pc-relative fixup value";
222 case ARM::fixup_arm_thumb_cb: {
223 // If we have a Thumb CBZ or CBNZ instruction and its target is the next
224 // instruction it is is actually out of range for the instruction.
225 // It will be changed to a NOP.
226 int64_t Offset = (Value & ~1);
228 return "will be converted to nop";
232 llvm_unreachable("Unexpected fixup kind in reasonForFixupRelaxation()!");
237 bool ARMAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
238 const MCRelaxableFragment *DF,
239 const MCAsmLayout &Layout) const {
240 return reasonForFixupRelaxation(Fixup, Value);
243 void ARMAsmBackend::relaxInstruction(const MCInst &Inst, MCInst &Res) const {
244 unsigned RelaxedOp = getRelaxedOpcode(Inst.getOpcode());
246 // Sanity check w/ diagnostic if we get here w/ a bogus instruction.
247 if (RelaxedOp == Inst.getOpcode()) {
248 SmallString<256> Tmp;
249 raw_svector_ostream OS(Tmp);
250 Inst.dump_pretty(OS);
252 report_fatal_error("unexpected instruction to relax: " + OS.str());
255 // If we are changing Thumb CBZ or CBNZ instruction to a NOP, aka tHINT, we
256 // have to change the operands too.
257 if ((Inst.getOpcode() == ARM::tCBZ || Inst.getOpcode() == ARM::tCBNZ) &&
258 RelaxedOp == ARM::tHINT) {
259 Res.setOpcode(RelaxedOp);
260 Res.addOperand(MCOperand::createImm(0));
261 Res.addOperand(MCOperand::createImm(14));
262 Res.addOperand(MCOperand::createReg(0));
266 // The rest of instructions we're relaxing have the same operands.
267 // We just need to update to the proper opcode.
269 Res.setOpcode(RelaxedOp);
272 bool ARMAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
273 const uint16_t Thumb1_16bitNopEncoding = 0x46c0; // using MOV r8,r8
274 const uint16_t Thumb2_16bitNopEncoding = 0xbf00; // NOP
275 const uint32_t ARMv4_NopEncoding = 0xe1a00000; // using MOV r0,r0
276 const uint32_t ARMv6T2_NopEncoding = 0xe320f000; // NOP
278 const uint16_t nopEncoding =
279 hasNOP() ? Thumb2_16bitNopEncoding : Thumb1_16bitNopEncoding;
280 uint64_t NumNops = Count / 2;
281 for (uint64_t i = 0; i != NumNops; ++i)
282 OW->write16(nopEncoding);
288 const uint32_t nopEncoding =
289 hasNOP() ? ARMv6T2_NopEncoding : ARMv4_NopEncoding;
290 uint64_t NumNops = Count / 4;
291 for (uint64_t i = 0; i != NumNops; ++i)
292 OW->write32(nopEncoding);
293 // FIXME: should this function return false when unable to write exactly
294 // 'Count' bytes with NOP encodings?
297 break; // No leftover bytes to write
313 static uint32_t swapHalfWords(uint32_t Value, bool IsLittleEndian) {
314 if (IsLittleEndian) {
315 // Note that the halfwords are stored high first and low second in thumb;
316 // so we need to swap the fixup value here to map properly.
317 uint32_t Swapped = (Value & 0xFFFF0000) >> 16;
318 Swapped |= (Value & 0x0000FFFF) << 16;
324 static uint32_t joinHalfWords(uint32_t FirstHalf, uint32_t SecondHalf,
325 bool IsLittleEndian) {
328 if (IsLittleEndian) {
329 Value = (SecondHalf & 0xFFFF) << 16;
330 Value |= (FirstHalf & 0xFFFF);
332 Value = (SecondHalf & 0xFFFF);
333 Value |= (FirstHalf & 0xFFFF) << 16;
339 unsigned ARMAsmBackend::adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
340 bool IsPCRel, MCContext *Ctx,
342 bool IsResolved) const {
343 unsigned Kind = Fixup.getKind();
346 llvm_unreachable("Unknown fixup kind!");
355 case ARM::fixup_arm_movt_hi16:
359 case ARM::fixup_arm_movw_lo16: {
360 unsigned Hi4 = (Value & 0xF000) >> 12;
361 unsigned Lo12 = Value & 0x0FFF;
362 // inst{19-16} = Hi4;
363 // inst{11-0} = Lo12;
364 Value = (Hi4 << 16) | (Lo12);
367 case ARM::fixup_t2_movt_hi16:
371 case ARM::fixup_t2_movw_lo16: {
372 unsigned Hi4 = (Value & 0xF000) >> 12;
373 unsigned i = (Value & 0x800) >> 11;
374 unsigned Mid3 = (Value & 0x700) >> 8;
375 unsigned Lo8 = Value & 0x0FF;
376 // inst{19-16} = Hi4;
378 // inst{14-12} = Mid3;
380 Value = (Hi4 << 16) | (i << 26) | (Mid3 << 12) | (Lo8);
381 return swapHalfWords(Value, IsLittleEndian);
383 case ARM::fixup_arm_ldst_pcrel_12:
384 // ARM PC-relative values are offset by 8.
387 case ARM::fixup_t2_ldst_pcrel_12: {
388 // Offset by 4, adjusted by two due to the half-word ordering of thumb.
391 if ((int64_t)Value < 0) {
395 if (Ctx && Value >= 4096)
396 Ctx->reportFatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
397 Value |= isAdd << 23;
399 // Same addressing mode as fixup_arm_pcrel_10,
400 // but with 16-bit halfwords swapped.
401 if (Kind == ARM::fixup_t2_ldst_pcrel_12)
402 return swapHalfWords(Value, IsLittleEndian);
406 case ARM::fixup_arm_adr_pcrel_12: {
407 // ARM PC-relative values are offset by 8.
409 unsigned opc = 4; // bits {24-21}. Default to add: 0b0100
410 if ((int64_t)Value < 0) {
414 if (Ctx && ARM_AM::getSOImmVal(Value) == -1)
415 Ctx->reportFatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
416 // Encode the immediate and shift the opcode into place.
417 return ARM_AM::getSOImmVal(Value) | (opc << 21);
420 case ARM::fixup_t2_adr_pcrel_12: {
423 if ((int64_t)Value < 0) {
428 uint32_t out = (opc << 21);
429 out |= (Value & 0x800) << 15;
430 out |= (Value & 0x700) << 4;
431 out |= (Value & 0x0FF);
433 return swapHalfWords(out, IsLittleEndian);
436 case ARM::fixup_arm_condbranch:
437 case ARM::fixup_arm_uncondbranch:
438 case ARM::fixup_arm_uncondbl:
439 case ARM::fixup_arm_condbl:
440 case ARM::fixup_arm_blx:
441 // These values don't encode the low two bits since they're always zero.
442 // Offset by 8 just as above.
443 if (const MCSymbolRefExpr *SRE =
444 dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
445 if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_TLSCALL)
447 return 0xffffff & ((Value - 8) >> 2);
448 case ARM::fixup_t2_uncondbranch: {
450 Value >>= 1; // Low bit is not encoded.
453 bool I = Value & 0x800000;
454 bool J1 = Value & 0x400000;
455 bool J2 = Value & 0x200000;
459 out |= I << 26; // S bit
460 out |= !J1 << 13; // J1 bit
461 out |= !J2 << 11; // J2 bit
462 out |= (Value & 0x1FF800) << 5; // imm6 field
463 out |= (Value & 0x0007FF); // imm11 field
465 return swapHalfWords(out, IsLittleEndian);
467 case ARM::fixup_t2_condbranch: {
469 Value >>= 1; // Low bit is not encoded.
472 out |= (Value & 0x80000) << 7; // S bit
473 out |= (Value & 0x40000) >> 7; // J2 bit
474 out |= (Value & 0x20000) >> 4; // J1 bit
475 out |= (Value & 0x1F800) << 5; // imm6 field
476 out |= (Value & 0x007FF); // imm11 field
478 return swapHalfWords(out, IsLittleEndian);
480 case ARM::fixup_arm_thumb_bl: {
481 // The value doesn't encode the low bit (always zero) and is offset by
482 // four. The 32-bit immediate value is encoded as
483 // imm32 = SignExtend(S:I1:I2:imm10:imm11:0)
484 // where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
485 // The value is encoded into disjoint bit positions in the destination
486 // opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
487 // J = either J1 or J2 bit
489 // BL: xxxxxSIIIIIIIIII xxJxJIIIIIIIIIII
491 // Note that the halfwords are stored high first, low second; so we need
492 // to transpose the fixup value here to map properly.
493 uint32_t offset = (Value - 4) >> 1;
494 uint32_t signBit = (offset & 0x800000) >> 23;
495 uint32_t I1Bit = (offset & 0x400000) >> 22;
496 uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
497 uint32_t I2Bit = (offset & 0x200000) >> 21;
498 uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
499 uint32_t imm10Bits = (offset & 0x1FF800) >> 11;
500 uint32_t imm11Bits = (offset & 0x000007FF);
502 uint32_t FirstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10Bits);
503 uint32_t SecondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
504 (uint16_t)imm11Bits);
505 return joinHalfWords(FirstHalf, SecondHalf, IsLittleEndian);
507 case ARM::fixup_arm_thumb_blx: {
508 // The value doesn't encode the low two bits (always zero) and is offset by
509 // four (see fixup_arm_thumb_cp). The 32-bit immediate value is encoded as
510 // imm32 = SignExtend(S:I1:I2:imm10H:imm10L:00)
511 // where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
512 // The value is encoded into disjoint bit positions in the destination
513 // opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
514 // J = either J1 or J2 bit, 0 = zero.
516 // BLX: xxxxxSIIIIIIIIII xxJxJIIIIIIIIII0
518 // Note that the halfwords are stored high first, low second; so we need
519 // to transpose the fixup value here to map properly.
520 uint32_t offset = (Value - 2) >> 2;
521 if (const MCSymbolRefExpr *SRE =
522 dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
523 if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_TLSCALL)
525 uint32_t signBit = (offset & 0x400000) >> 22;
526 uint32_t I1Bit = (offset & 0x200000) >> 21;
527 uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
528 uint32_t I2Bit = (offset & 0x100000) >> 20;
529 uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
530 uint32_t imm10HBits = (offset & 0xFFC00) >> 10;
531 uint32_t imm10LBits = (offset & 0x3FF);
533 uint32_t FirstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10HBits);
534 uint32_t SecondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
535 ((uint16_t)imm10LBits) << 1);
536 return joinHalfWords(FirstHalf, SecondHalf, IsLittleEndian);
538 case ARM::fixup_thumb_adr_pcrel_10:
539 case ARM::fixup_arm_thumb_cp:
540 // On CPUs supporting Thumb2, this will be relaxed to an ldr.w, otherwise we
541 // could have an error on our hands.
542 if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2] && IsResolved) {
543 const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
545 Ctx->reportFatalError(Fixup.getLoc(), FixupDiagnostic);
547 // Offset by 4, and don't encode the low two bits.
548 return ((Value - 4) >> 2) & 0xff;
549 case ARM::fixup_arm_thumb_cb: {
550 // Offset by 4 and don't encode the lower bit, which is always 0.
551 // FIXME: diagnose if no Thumb2
552 uint32_t Binary = (Value - 4) >> 1;
553 return ((Binary & 0x20) << 4) | ((Binary & 0x1f) << 3);
555 case ARM::fixup_arm_thumb_br:
556 // Offset by 4 and don't encode the lower bit, which is always 0.
557 if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2]) {
558 const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
560 Ctx->reportFatalError(Fixup.getLoc(), FixupDiagnostic);
562 return ((Value - 4) >> 1) & 0x7ff;
563 case ARM::fixup_arm_thumb_bcc:
564 // Offset by 4 and don't encode the lower bit, which is always 0.
565 if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2]) {
566 const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
568 Ctx->reportFatalError(Fixup.getLoc(), FixupDiagnostic);
570 return ((Value - 4) >> 1) & 0xff;
571 case ARM::fixup_arm_pcrel_10_unscaled: {
572 Value = Value - 8; // ARM fixups offset by an additional word and don't
573 // need to adjust for the half-word ordering.
575 if ((int64_t)Value < 0) {
579 // The value has the low 4 bits encoded in [3:0] and the high 4 in [11:8].
580 if (Ctx && Value >= 256)
581 Ctx->reportFatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
582 Value = (Value & 0xf) | ((Value & 0xf0) << 4);
583 return Value | (isAdd << 23);
585 case ARM::fixup_arm_pcrel_10:
586 Value = Value - 4; // ARM fixups offset by an additional word and don't
587 // need to adjust for the half-word ordering.
589 case ARM::fixup_t2_pcrel_10: {
590 // Offset by 4, adjusted by two due to the half-word ordering of thumb.
593 if ((int64_t)Value < 0) {
597 // These values don't encode the low two bits since they're always zero.
599 if (Ctx && Value >= 256)
600 Ctx->reportFatalError(Fixup.getLoc(), "out of range pc-relative fixup value");
601 Value |= isAdd << 23;
603 // Same addressing mode as fixup_arm_pcrel_10, but with 16-bit halfwords
605 if (Kind == ARM::fixup_t2_pcrel_10)
606 return swapHalfWords(Value, IsLittleEndian);
613 void ARMAsmBackend::processFixupValue(const MCAssembler &Asm,
614 const MCAsmLayout &Layout,
615 const MCFixup &Fixup,
616 const MCFragment *DF,
617 const MCValue &Target, uint64_t &Value,
619 const MCSymbolRefExpr *A = Target.getSymA();
620 // Some fixups to thumb function symbols need the low bit (thumb bit)
622 if ((unsigned)Fixup.getKind() != ARM::fixup_arm_ldst_pcrel_12 &&
623 (unsigned)Fixup.getKind() != ARM::fixup_t2_ldst_pcrel_12 &&
624 (unsigned)Fixup.getKind() != ARM::fixup_arm_adr_pcrel_12 &&
625 (unsigned)Fixup.getKind() != ARM::fixup_thumb_adr_pcrel_10 &&
626 (unsigned)Fixup.getKind() != ARM::fixup_t2_adr_pcrel_12 &&
627 (unsigned)Fixup.getKind() != ARM::fixup_arm_thumb_cp) {
629 const MCSymbol &Sym = A->getSymbol();
630 if (Asm.isThumbFunc(&Sym))
634 // For Thumb1 BL instruction, it is possible to be a long jump between
635 // the basic blocks of the same function. Thus, we would like to resolve
636 // the offset when the destination has the same MCFragment.
637 if (A && (unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_bl) {
638 const MCSymbol &Sym = A->getSymbol();
639 IsResolved = (Sym.getFragment() == DF);
641 // We must always generate a relocation for BL/BLX instructions if we have
642 // a symbol to reference, as the linker relies on knowing the destination
643 // symbol's thumb-ness to get interworking right.
644 if (A && ((unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_blx ||
645 (unsigned)Fixup.getKind() == ARM::fixup_arm_blx ||
646 (unsigned)Fixup.getKind() == ARM::fixup_arm_uncondbl ||
647 (unsigned)Fixup.getKind() == ARM::fixup_arm_condbl))
650 // Try to get the encoded value for the fixup as-if we're mapping it into
651 // the instruction. This allows adjustFixupValue() to issue a diagnostic
652 // if the value aren't invalid.
653 (void)adjustFixupValue(Fixup, Value, false, &Asm.getContext(),
654 IsLittleEndian, IsResolved);
657 /// getFixupKindNumBytes - The number of bytes the fixup may change.
658 static unsigned getFixupKindNumBytes(unsigned Kind) {
661 llvm_unreachable("Unknown fixup kind!");
664 case ARM::fixup_arm_thumb_bcc:
665 case ARM::fixup_arm_thumb_cp:
666 case ARM::fixup_thumb_adr_pcrel_10:
670 case ARM::fixup_arm_thumb_br:
671 case ARM::fixup_arm_thumb_cb:
674 case ARM::fixup_arm_pcrel_10_unscaled:
675 case ARM::fixup_arm_ldst_pcrel_12:
676 case ARM::fixup_arm_pcrel_10:
677 case ARM::fixup_arm_adr_pcrel_12:
678 case ARM::fixup_arm_uncondbl:
679 case ARM::fixup_arm_condbl:
680 case ARM::fixup_arm_blx:
681 case ARM::fixup_arm_condbranch:
682 case ARM::fixup_arm_uncondbranch:
686 case ARM::fixup_t2_ldst_pcrel_12:
687 case ARM::fixup_t2_condbranch:
688 case ARM::fixup_t2_uncondbranch:
689 case ARM::fixup_t2_pcrel_10:
690 case ARM::fixup_t2_adr_pcrel_12:
691 case ARM::fixup_arm_thumb_bl:
692 case ARM::fixup_arm_thumb_blx:
693 case ARM::fixup_arm_movt_hi16:
694 case ARM::fixup_arm_movw_lo16:
695 case ARM::fixup_t2_movt_hi16:
696 case ARM::fixup_t2_movw_lo16:
706 /// getFixupKindContainerSizeBytes - The number of bytes of the
707 /// container involved in big endian.
708 static unsigned getFixupKindContainerSizeBytes(unsigned Kind) {
711 llvm_unreachable("Unknown fixup kind!");
720 case ARM::fixup_arm_thumb_bcc:
721 case ARM::fixup_arm_thumb_cp:
722 case ARM::fixup_thumb_adr_pcrel_10:
723 case ARM::fixup_arm_thumb_br:
724 case ARM::fixup_arm_thumb_cb:
725 // Instruction size is 2 bytes.
728 case ARM::fixup_arm_pcrel_10_unscaled:
729 case ARM::fixup_arm_ldst_pcrel_12:
730 case ARM::fixup_arm_pcrel_10:
731 case ARM::fixup_arm_adr_pcrel_12:
732 case ARM::fixup_arm_uncondbl:
733 case ARM::fixup_arm_condbl:
734 case ARM::fixup_arm_blx:
735 case ARM::fixup_arm_condbranch:
736 case ARM::fixup_arm_uncondbranch:
737 case ARM::fixup_t2_ldst_pcrel_12:
738 case ARM::fixup_t2_condbranch:
739 case ARM::fixup_t2_uncondbranch:
740 case ARM::fixup_t2_pcrel_10:
741 case ARM::fixup_t2_adr_pcrel_12:
742 case ARM::fixup_arm_thumb_bl:
743 case ARM::fixup_arm_thumb_blx:
744 case ARM::fixup_arm_movt_hi16:
745 case ARM::fixup_arm_movw_lo16:
746 case ARM::fixup_t2_movt_hi16:
747 case ARM::fixup_t2_movw_lo16:
748 // Instruction size is 4 bytes.
753 void ARMAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
754 unsigned DataSize, uint64_t Value,
755 bool IsPCRel) const {
756 unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind());
758 adjustFixupValue(Fixup, Value, IsPCRel, nullptr, IsLittleEndian, true);
760 return; // Doesn't change encoding.
762 unsigned Offset = Fixup.getOffset();
763 assert(Offset + NumBytes <= DataSize && "Invalid fixup offset!");
765 // Used to point to big endian bytes.
766 unsigned FullSizeBytes;
767 if (!IsLittleEndian) {
768 FullSizeBytes = getFixupKindContainerSizeBytes(Fixup.getKind());
769 assert((Offset + FullSizeBytes) <= DataSize && "Invalid fixup size!");
770 assert(NumBytes <= FullSizeBytes && "Invalid fixup size!");
773 // For each byte of the fragment that the fixup touches, mask in the bits from
774 // the fixup value. The Value has been "split up" into the appropriate
776 for (unsigned i = 0; i != NumBytes; ++i) {
777 unsigned Idx = IsLittleEndian ? i : (FullSizeBytes - 1 - i);
778 Data[Offset + Idx] |= uint8_t((Value >> (i * 8)) & 0xff);
782 static MachO::CPUSubTypeARM getMachOSubTypeFromArch(StringRef Arch) {
783 unsigned AK = ARM::parseArch(Arch);
786 return MachO::CPU_SUBTYPE_ARM_V7;
788 return MachO::CPU_SUBTYPE_ARM_V4T;
791 return MachO::CPU_SUBTYPE_ARM_V6;
793 return MachO::CPU_SUBTYPE_ARM_V5;
796 case ARM::AK_ARMV5TE:
797 case ARM::AK_ARMV5TEJ:
798 return MachO::CPU_SUBTYPE_ARM_V5TEJ;
800 return MachO::CPU_SUBTYPE_ARM_V7;
802 return MachO::CPU_SUBTYPE_ARM_V7S;
804 return MachO::CPU_SUBTYPE_ARM_V7K;
806 case ARM::AK_ARMV6SM:
807 return MachO::CPU_SUBTYPE_ARM_V6M;
809 return MachO::CPU_SUBTYPE_ARM_V7M;
810 case ARM::AK_ARMV7EM:
811 return MachO::CPU_SUBTYPE_ARM_V7EM;
815 MCAsmBackend *llvm::createARMAsmBackend(const Target &T,
816 const MCRegisterInfo &MRI,
817 const Triple &TheTriple, StringRef CPU,
819 switch (TheTriple.getObjectFormat()) {
821 llvm_unreachable("unsupported object format");
822 case Triple::MachO: {
823 MachO::CPUSubTypeARM CS = getMachOSubTypeFromArch(TheTriple.getArchName());
824 return new ARMAsmBackendDarwin(T, TheTriple, CS);
827 assert(TheTriple.isOSWindows() && "non-Windows ARM COFF is not supported");
828 return new ARMAsmBackendWinCOFF(T, TheTriple);
830 assert(TheTriple.isOSBinFormatELF() && "using ELF for non-ELF target");
831 uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TheTriple.getOS());
832 return new ARMAsmBackendELF(T, TheTriple, OSABI, isLittle);
836 MCAsmBackend *llvm::createARMLEAsmBackend(const Target &T,
837 const MCRegisterInfo &MRI,
838 const Triple &TT, StringRef CPU) {
839 return createARMAsmBackend(T, MRI, TT, CPU, true);
842 MCAsmBackend *llvm::createARMBEAsmBackend(const Target &T,
843 const MCRegisterInfo &MRI,
844 const Triple &TT, StringRef CPU) {
845 return createARMAsmBackend(T, MRI, TT, CPU, false);
848 MCAsmBackend *llvm::createThumbLEAsmBackend(const Target &T,
849 const MCRegisterInfo &MRI,
850 const Triple &TT, StringRef CPU) {
851 return createARMAsmBackend(T, MRI, TT, CPU, true);
854 MCAsmBackend *llvm::createThumbBEAsmBackend(const Target &T,
855 const MCRegisterInfo &MRI,
856 const Triple &TT, StringRef CPU) {
857 return createARMAsmBackend(T, MRI, TT, CPU, false);