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/MCRegisterInfo.h"
29 #include "llvm/MC/MCSectionELF.h"
30 #include "llvm/MC/MCSectionMachO.h"
31 #include "llvm/MC/MCSubtargetInfo.h"
32 #include "llvm/MC/MCValue.h"
33 #include "llvm/Support/Debug.h"
34 #include "llvm/Support/ELF.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/Format.h"
37 #include "llvm/Support/MachO.h"
38 #include "llvm/Support/TargetParser.h"
39 #include "llvm/Support/raw_ostream.h"
43 class ARMELFObjectWriter : public MCELFObjectTargetWriter {
45 ARMELFObjectWriter(uint8_t OSABI)
46 : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI, ELF::EM_ARM,
47 /*HasRelocationAddend*/ false) {}
49 } // end anonymous namespace
51 const MCFixupKindInfo &ARMAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
52 const static MCFixupKindInfo InfosLE[ARM::NumTargetFixupKinds] = {
53 // This table *must* be in the order that the fixup_* kinds are defined in
56 // Name Offset (bits) Size (bits) Flags
57 {"fixup_arm_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
58 {"fixup_t2_ldst_pcrel_12", 0, 32,
59 MCFixupKindInfo::FKF_IsPCRel |
60 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
61 {"fixup_arm_pcrel_10_unscaled", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
62 {"fixup_arm_pcrel_10", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
63 {"fixup_t2_pcrel_10", 0, 32,
64 MCFixupKindInfo::FKF_IsPCRel |
65 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
66 {"fixup_arm_pcrel_9", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
67 {"fixup_t2_pcrel_9", 0, 32,
68 MCFixupKindInfo::FKF_IsPCRel |
69 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
70 {"fixup_thumb_adr_pcrel_10", 0, 8,
71 MCFixupKindInfo::FKF_IsPCRel |
72 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
73 {"fixup_arm_adr_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
74 {"fixup_t2_adr_pcrel_12", 0, 32,
75 MCFixupKindInfo::FKF_IsPCRel |
76 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
77 {"fixup_arm_condbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
78 {"fixup_arm_uncondbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
79 {"fixup_t2_condbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
80 {"fixup_t2_uncondbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
81 {"fixup_arm_thumb_br", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
82 {"fixup_arm_uncondbl", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
83 {"fixup_arm_condbl", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
84 {"fixup_arm_blx", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
85 {"fixup_arm_thumb_bl", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
86 {"fixup_arm_thumb_blx", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
87 {"fixup_arm_thumb_cb", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
88 {"fixup_arm_thumb_cp", 0, 8,
89 MCFixupKindInfo::FKF_IsPCRel |
90 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
91 {"fixup_arm_thumb_bcc", 0, 8, MCFixupKindInfo::FKF_IsPCRel},
92 // movw / movt: 16-bits immediate but scattered into two chunks 0 - 12, 16
94 {"fixup_arm_movt_hi16", 0, 20, 0},
95 {"fixup_arm_movw_lo16", 0, 20, 0},
96 {"fixup_t2_movt_hi16", 0, 20, 0},
97 {"fixup_t2_movw_lo16", 0, 20, 0},
99 const static MCFixupKindInfo InfosBE[ARM::NumTargetFixupKinds] = {
100 // This table *must* be in the order that the fixup_* kinds are defined in
103 // Name Offset (bits) Size (bits) Flags
104 {"fixup_arm_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
105 {"fixup_t2_ldst_pcrel_12", 0, 32,
106 MCFixupKindInfo::FKF_IsPCRel |
107 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
108 {"fixup_arm_pcrel_10_unscaled", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
109 {"fixup_arm_pcrel_10", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
110 {"fixup_t2_pcrel_10", 0, 32,
111 MCFixupKindInfo::FKF_IsPCRel |
112 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
113 {"fixup_arm_pcrel_9", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
114 {"fixup_t2_pcrel_9", 0, 32,
115 MCFixupKindInfo::FKF_IsPCRel |
116 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
117 {"fixup_thumb_adr_pcrel_10", 8, 8,
118 MCFixupKindInfo::FKF_IsPCRel |
119 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
120 {"fixup_arm_adr_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
121 {"fixup_t2_adr_pcrel_12", 0, 32,
122 MCFixupKindInfo::FKF_IsPCRel |
123 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
124 {"fixup_arm_condbranch", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
125 {"fixup_arm_uncondbranch", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
126 {"fixup_t2_condbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
127 {"fixup_t2_uncondbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
128 {"fixup_arm_thumb_br", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
129 {"fixup_arm_uncondbl", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
130 {"fixup_arm_condbl", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
131 {"fixup_arm_blx", 8, 24, MCFixupKindInfo::FKF_IsPCRel},
132 {"fixup_arm_thumb_bl", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
133 {"fixup_arm_thumb_blx", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
134 {"fixup_arm_thumb_cb", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
135 {"fixup_arm_thumb_cp", 8, 8,
136 MCFixupKindInfo::FKF_IsPCRel |
137 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
138 {"fixup_arm_thumb_bcc", 8, 8, MCFixupKindInfo::FKF_IsPCRel},
139 // movw / movt: 16-bits immediate but scattered into two chunks 0 - 12, 16
141 {"fixup_arm_movt_hi16", 12, 20, 0},
142 {"fixup_arm_movw_lo16", 12, 20, 0},
143 {"fixup_t2_movt_hi16", 12, 20, 0},
144 {"fixup_t2_movw_lo16", 12, 20, 0},
147 if (Kind < FirstTargetFixupKind)
148 return MCAsmBackend::getFixupKindInfo(Kind);
150 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
152 return (IsLittleEndian ? InfosLE : InfosBE)[Kind - FirstTargetFixupKind];
155 void ARMAsmBackend::handleAssemblerFlag(MCAssemblerFlag Flag) {
168 unsigned ARMAsmBackend::getRelaxedOpcode(unsigned Op) const {
169 bool HasThumb2 = STI->getFeatureBits()[ARM::FeatureThumb2];
170 bool HasV8MBaselineOps = STI->getFeatureBits()[ARM::HasV8MBaselineOps];
176 return HasThumb2 ? (unsigned)ARM::t2Bcc : Op;
178 return HasThumb2 ? (unsigned)ARM::t2LDRpci : Op;
180 return HasThumb2 ? (unsigned)ARM::t2ADR : Op;
182 return HasV8MBaselineOps ? (unsigned)ARM::t2B : Op;
190 bool ARMAsmBackend::mayNeedRelaxation(const MCInst &Inst) const {
191 if (getRelaxedOpcode(Inst.getOpcode()) != Inst.getOpcode())
196 const char *ARMAsmBackend::reasonForFixupRelaxation(const MCFixup &Fixup,
197 uint64_t Value) const {
198 switch ((unsigned)Fixup.getKind()) {
199 case ARM::fixup_arm_thumb_br: {
200 // Relaxing tB to t2B. tB has a signed 12-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 > 2046 || Offset < -2048)
208 return "out of range pc-relative fixup value";
211 case ARM::fixup_arm_thumb_bcc: {
212 // Relaxing tBcc to t2Bcc. tBcc has a signed 9-bit displacement with the
213 // low bit being an implied zero. There's an implied +4 offset for the
214 // branch, so we adjust the other way here to determine what's
217 // Relax if the value is too big for a (signed) i8.
218 int64_t Offset = int64_t(Value) - 4;
219 if (Offset > 254 || Offset < -256)
220 return "out of range pc-relative fixup value";
223 case ARM::fixup_thumb_adr_pcrel_10:
224 case ARM::fixup_arm_thumb_cp: {
225 // If the immediate is negative, greater than 1020, or not a multiple
226 // of four, the wide version of the instruction must be used.
227 int64_t Offset = int64_t(Value) - 4;
229 return "misaligned pc-relative fixup value";
230 else if (Offset > 1020 || Offset < 0)
231 return "out of range pc-relative fixup value";
234 case ARM::fixup_arm_thumb_cb: {
235 // If we have a Thumb CBZ or CBNZ instruction and its target is the next
236 // instruction it is is actually out of range for the instruction.
237 // It will be changed to a NOP.
238 int64_t Offset = (Value & ~1);
240 return "will be converted to nop";
244 llvm_unreachable("Unexpected fixup kind in reasonForFixupRelaxation()!");
249 bool ARMAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
250 const MCRelaxableFragment *DF,
251 const MCAsmLayout &Layout) const {
252 return reasonForFixupRelaxation(Fixup, Value);
255 void ARMAsmBackend::relaxInstruction(const MCInst &Inst, MCInst &Res) const {
256 unsigned RelaxedOp = getRelaxedOpcode(Inst.getOpcode());
258 // Sanity check w/ diagnostic if we get here w/ a bogus instruction.
259 if (RelaxedOp == Inst.getOpcode()) {
260 SmallString<256> Tmp;
261 raw_svector_ostream OS(Tmp);
262 Inst.dump_pretty(OS);
264 report_fatal_error("unexpected instruction to relax: " + OS.str());
267 // If we are changing Thumb CBZ or CBNZ instruction to a NOP, aka tHINT, we
268 // have to change the operands too.
269 if ((Inst.getOpcode() == ARM::tCBZ || Inst.getOpcode() == ARM::tCBNZ) &&
270 RelaxedOp == ARM::tHINT) {
271 Res.setOpcode(RelaxedOp);
272 Res.addOperand(MCOperand::createImm(0));
273 Res.addOperand(MCOperand::createImm(14));
274 Res.addOperand(MCOperand::createReg(0));
278 // The rest of instructions we're relaxing have the same operands.
279 // We just need to update to the proper opcode.
281 Res.setOpcode(RelaxedOp);
284 bool ARMAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
285 const uint16_t Thumb1_16bitNopEncoding = 0x46c0; // using MOV r8,r8
286 const uint16_t Thumb2_16bitNopEncoding = 0xbf00; // NOP
287 const uint32_t ARMv4_NopEncoding = 0xe1a00000; // using MOV r0,r0
288 const uint32_t ARMv6T2_NopEncoding = 0xe320f000; // NOP
290 const uint16_t nopEncoding =
291 hasNOP() ? Thumb2_16bitNopEncoding : Thumb1_16bitNopEncoding;
292 uint64_t NumNops = Count / 2;
293 for (uint64_t i = 0; i != NumNops; ++i)
294 OW->write16(nopEncoding);
300 const uint32_t nopEncoding =
301 hasNOP() ? ARMv6T2_NopEncoding : ARMv4_NopEncoding;
302 uint64_t NumNops = Count / 4;
303 for (uint64_t i = 0; i != NumNops; ++i)
304 OW->write32(nopEncoding);
305 // FIXME: should this function return false when unable to write exactly
306 // 'Count' bytes with NOP encodings?
309 break; // No leftover bytes to write
325 static uint32_t swapHalfWords(uint32_t Value, bool IsLittleEndian) {
326 if (IsLittleEndian) {
327 // Note that the halfwords are stored high first and low second in thumb;
328 // so we need to swap the fixup value here to map properly.
329 uint32_t Swapped = (Value & 0xFFFF0000) >> 16;
330 Swapped |= (Value & 0x0000FFFF) << 16;
336 static uint32_t joinHalfWords(uint32_t FirstHalf, uint32_t SecondHalf,
337 bool IsLittleEndian) {
340 if (IsLittleEndian) {
341 Value = (SecondHalf & 0xFFFF) << 16;
342 Value |= (FirstHalf & 0xFFFF);
344 Value = (SecondHalf & 0xFFFF);
345 Value |= (FirstHalf & 0xFFFF) << 16;
351 unsigned ARMAsmBackend::adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
352 bool IsPCRel, MCContext *Ctx,
354 bool IsResolved) const {
355 unsigned Kind = Fixup.getKind();
358 llvm_unreachable("Unknown fixup kind!");
367 case ARM::fixup_arm_movt_hi16:
371 case ARM::fixup_arm_movw_lo16: {
372 unsigned Hi4 = (Value & 0xF000) >> 12;
373 unsigned Lo12 = Value & 0x0FFF;
374 // inst{19-16} = Hi4;
375 // inst{11-0} = Lo12;
376 Value = (Hi4 << 16) | (Lo12);
379 case ARM::fixup_t2_movt_hi16:
383 case ARM::fixup_t2_movw_lo16: {
384 unsigned Hi4 = (Value & 0xF000) >> 12;
385 unsigned i = (Value & 0x800) >> 11;
386 unsigned Mid3 = (Value & 0x700) >> 8;
387 unsigned Lo8 = Value & 0x0FF;
388 // inst{19-16} = Hi4;
390 // inst{14-12} = Mid3;
392 Value = (Hi4 << 16) | (i << 26) | (Mid3 << 12) | (Lo8);
393 return swapHalfWords(Value, IsLittleEndian);
395 case ARM::fixup_arm_ldst_pcrel_12:
396 // ARM PC-relative values are offset by 8.
399 case ARM::fixup_t2_ldst_pcrel_12: {
400 // Offset by 4, adjusted by two due to the half-word ordering of thumb.
403 if ((int64_t)Value < 0) {
407 if (Ctx && Value >= 4096) {
408 Ctx->reportError(Fixup.getLoc(), "out of range pc-relative fixup value");
411 Value |= isAdd << 23;
413 // Same addressing mode as fixup_arm_pcrel_10,
414 // but with 16-bit halfwords swapped.
415 if (Kind == ARM::fixup_t2_ldst_pcrel_12)
416 return swapHalfWords(Value, IsLittleEndian);
420 case ARM::fixup_arm_adr_pcrel_12: {
421 // ARM PC-relative values are offset by 8.
423 unsigned opc = 4; // bits {24-21}. Default to add: 0b0100
424 if ((int64_t)Value < 0) {
428 if (Ctx && ARM_AM::getSOImmVal(Value) == -1) {
429 Ctx->reportError(Fixup.getLoc(), "out of range pc-relative fixup value");
432 // Encode the immediate and shift the opcode into place.
433 return ARM_AM::getSOImmVal(Value) | (opc << 21);
436 case ARM::fixup_t2_adr_pcrel_12: {
439 if ((int64_t)Value < 0) {
444 uint32_t out = (opc << 21);
445 out |= (Value & 0x800) << 15;
446 out |= (Value & 0x700) << 4;
447 out |= (Value & 0x0FF);
449 return swapHalfWords(out, IsLittleEndian);
452 case ARM::fixup_arm_condbranch:
453 case ARM::fixup_arm_uncondbranch:
454 case ARM::fixup_arm_uncondbl:
455 case ARM::fixup_arm_condbl:
456 case ARM::fixup_arm_blx:
457 // These values don't encode the low two bits since they're always zero.
458 // Offset by 8 just as above.
459 if (const MCSymbolRefExpr *SRE =
460 dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
461 if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_TLSCALL)
463 return 0xffffff & ((Value - 8) >> 2);
464 case ARM::fixup_t2_uncondbranch: {
466 Value >>= 1; // Low bit is not encoded.
469 bool I = Value & 0x800000;
470 bool J1 = Value & 0x400000;
471 bool J2 = Value & 0x200000;
475 out |= I << 26; // S bit
476 out |= !J1 << 13; // J1 bit
477 out |= !J2 << 11; // J2 bit
478 out |= (Value & 0x1FF800) << 5; // imm6 field
479 out |= (Value & 0x0007FF); // imm11 field
481 return swapHalfWords(out, IsLittleEndian);
483 case ARM::fixup_t2_condbranch: {
485 Value >>= 1; // Low bit is not encoded.
488 out |= (Value & 0x80000) << 7; // S bit
489 out |= (Value & 0x40000) >> 7; // J2 bit
490 out |= (Value & 0x20000) >> 4; // J1 bit
491 out |= (Value & 0x1F800) << 5; // imm6 field
492 out |= (Value & 0x007FF); // imm11 field
494 return swapHalfWords(out, IsLittleEndian);
496 case ARM::fixup_arm_thumb_bl: {
497 // The value doesn't encode the low bit (always zero) and is offset by
498 // four. The 32-bit immediate value is encoded as
499 // imm32 = SignExtend(S:I1:I2:imm10:imm11:0)
500 // where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
501 // The value is encoded into disjoint bit positions in the destination
502 // opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
503 // J = either J1 or J2 bit
505 // BL: xxxxxSIIIIIIIIII xxJxJIIIIIIIIIII
507 // Note that the halfwords are stored high first, low second; so we need
508 // to transpose the fixup value here to map properly.
509 uint32_t offset = (Value - 4) >> 1;
510 uint32_t signBit = (offset & 0x800000) >> 23;
511 uint32_t I1Bit = (offset & 0x400000) >> 22;
512 uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
513 uint32_t I2Bit = (offset & 0x200000) >> 21;
514 uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
515 uint32_t imm10Bits = (offset & 0x1FF800) >> 11;
516 uint32_t imm11Bits = (offset & 0x000007FF);
518 uint32_t FirstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10Bits);
519 uint32_t SecondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
520 (uint16_t)imm11Bits);
521 return joinHalfWords(FirstHalf, SecondHalf, IsLittleEndian);
523 case ARM::fixup_arm_thumb_blx: {
524 // The value doesn't encode the low two bits (always zero) and is offset by
525 // four (see fixup_arm_thumb_cp). The 32-bit immediate value is encoded as
526 // imm32 = SignExtend(S:I1:I2:imm10H:imm10L:00)
527 // where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
528 // The value is encoded into disjoint bit positions in the destination
529 // opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
530 // J = either J1 or J2 bit, 0 = zero.
532 // BLX: xxxxxSIIIIIIIIII xxJxJIIIIIIIIII0
534 // Note that the halfwords are stored high first, low second; so we need
535 // to transpose the fixup value here to map properly.
536 uint32_t offset = (Value - 2) >> 2;
537 if (const MCSymbolRefExpr *SRE =
538 dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
539 if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_TLSCALL)
541 uint32_t signBit = (offset & 0x400000) >> 22;
542 uint32_t I1Bit = (offset & 0x200000) >> 21;
543 uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
544 uint32_t I2Bit = (offset & 0x100000) >> 20;
545 uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
546 uint32_t imm10HBits = (offset & 0xFFC00) >> 10;
547 uint32_t imm10LBits = (offset & 0x3FF);
549 uint32_t FirstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10HBits);
550 uint32_t SecondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
551 ((uint16_t)imm10LBits) << 1);
552 return joinHalfWords(FirstHalf, SecondHalf, IsLittleEndian);
554 case ARM::fixup_thumb_adr_pcrel_10:
555 case ARM::fixup_arm_thumb_cp:
556 // On CPUs supporting Thumb2, this will be relaxed to an ldr.w, otherwise we
557 // could have an error on our hands.
558 if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2] && IsResolved) {
559 const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
560 if (FixupDiagnostic) {
561 Ctx->reportError(Fixup.getLoc(), FixupDiagnostic);
565 // Offset by 4, and don't encode the low two bits.
566 return ((Value - 4) >> 2) & 0xff;
567 case ARM::fixup_arm_thumb_cb: {
568 // Offset by 4 and don't encode the lower bit, which is always 0.
569 // FIXME: diagnose if no Thumb2
570 uint32_t Binary = (Value - 4) >> 1;
571 return ((Binary & 0x20) << 4) | ((Binary & 0x1f) << 3);
573 case ARM::fixup_arm_thumb_br:
574 // Offset by 4 and don't encode the lower bit, which is always 0.
575 if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2] &&
576 !STI->getFeatureBits()[ARM::HasV8MBaselineOps]) {
577 const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
578 if (FixupDiagnostic) {
579 Ctx->reportError(Fixup.getLoc(), FixupDiagnostic);
583 return ((Value - 4) >> 1) & 0x7ff;
584 case ARM::fixup_arm_thumb_bcc:
585 // Offset by 4 and don't encode the lower bit, which is always 0.
586 if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2]) {
587 const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value);
588 if (FixupDiagnostic) {
589 Ctx->reportError(Fixup.getLoc(), FixupDiagnostic);
593 return ((Value - 4) >> 1) & 0xff;
594 case ARM::fixup_arm_pcrel_10_unscaled: {
595 Value = Value - 8; // ARM fixups offset by an additional word and don't
596 // need to adjust for the half-word ordering.
598 if ((int64_t)Value < 0) {
602 // The value has the low 4 bits encoded in [3:0] and the high 4 in [11:8].
603 if (Ctx && Value >= 256) {
604 Ctx->reportError(Fixup.getLoc(), "out of range pc-relative fixup value");
607 Value = (Value & 0xf) | ((Value & 0xf0) << 4);
608 return Value | (isAdd << 23);
610 case ARM::fixup_arm_pcrel_10:
611 Value = Value - 4; // ARM fixups offset by an additional word and don't
612 // need to adjust for the half-word ordering.
614 case ARM::fixup_t2_pcrel_10: {
615 // Offset by 4, adjusted by two due to the half-word ordering of thumb.
618 if ((int64_t)Value < 0) {
622 // These values don't encode the low two bits since they're always zero.
624 if (Ctx && Value >= 256) {
625 Ctx->reportError(Fixup.getLoc(), "out of range pc-relative fixup value");
628 Value |= isAdd << 23;
630 // Same addressing mode as fixup_arm_pcrel_10, but with 16-bit halfwords
632 if (Kind == ARM::fixup_t2_pcrel_10)
633 return swapHalfWords(Value, IsLittleEndian);
637 case ARM::fixup_arm_pcrel_9:
638 Value = Value - 4; // ARM fixups offset by an additional word and don't
639 // need to adjust for the half-word ordering.
641 case ARM::fixup_t2_pcrel_9: {
642 // Offset by 4, adjusted by two due to the half-word ordering of thumb.
645 if ((int64_t)Value < 0) {
649 // These values don't encode the low bit since it's always zero.
650 if (Ctx && (Value & 1)) {
651 Ctx->reportError(Fixup.getLoc(), "invalid value for this fixup");
655 if (Ctx && Value >= 256) {
656 Ctx->reportError(Fixup.getLoc(), "out of range pc-relative fixup value");
659 Value |= isAdd << 23;
661 // Same addressing mode as fixup_arm_pcrel_9, but with 16-bit halfwords
663 if (Kind == ARM::fixup_t2_pcrel_9)
664 return swapHalfWords(Value, IsLittleEndian);
671 void ARMAsmBackend::processFixupValue(const MCAssembler &Asm,
672 const MCAsmLayout &Layout,
673 const MCFixup &Fixup,
674 const MCFragment *DF,
675 const MCValue &Target, uint64_t &Value,
677 const MCSymbolRefExpr *A = Target.getSymA();
678 const MCSymbol *Sym = A ? &A->getSymbol() : nullptr;
679 // Some fixups to thumb function symbols need the low bit (thumb bit)
681 if ((unsigned)Fixup.getKind() != ARM::fixup_arm_ldst_pcrel_12 &&
682 (unsigned)Fixup.getKind() != ARM::fixup_t2_ldst_pcrel_12 &&
683 (unsigned)Fixup.getKind() != ARM::fixup_arm_adr_pcrel_12 &&
684 (unsigned)Fixup.getKind() != ARM::fixup_thumb_adr_pcrel_10 &&
685 (unsigned)Fixup.getKind() != ARM::fixup_t2_adr_pcrel_12 &&
686 (unsigned)Fixup.getKind() != ARM::fixup_arm_thumb_cp) {
688 if (Asm.isThumbFunc(Sym))
692 if (IsResolved && (unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_bl) {
693 assert(Sym && "How did we resolve this?");
695 // If the symbol is external the linker will handle it.
696 // FIXME: Should we handle it as an optimization?
698 // If the symbol is out of range, produce a relocation and hope the
699 // linker can handle it. GNU AS produces an error in this case.
700 if (Sym->isExternal() || Value >= 0x400004)
703 // We must always generate a relocation for BL/BLX instructions if we have
704 // a symbol to reference, as the linker relies on knowing the destination
705 // symbol's thumb-ness to get interworking right.
706 if (A && ((unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_blx ||
707 (unsigned)Fixup.getKind() == ARM::fixup_arm_blx ||
708 (unsigned)Fixup.getKind() == ARM::fixup_arm_uncondbl ||
709 (unsigned)Fixup.getKind() == ARM::fixup_arm_condbl))
712 // Try to get the encoded value for the fixup as-if we're mapping it into
713 // the instruction. This allows adjustFixupValue() to issue a diagnostic
714 // if the value aren't invalid.
715 (void)adjustFixupValue(Fixup, Value, false, &Asm.getContext(),
716 IsLittleEndian, IsResolved);
719 /// getFixupKindNumBytes - The number of bytes the fixup may change.
720 static unsigned getFixupKindNumBytes(unsigned Kind) {
723 llvm_unreachable("Unknown fixup kind!");
726 case ARM::fixup_arm_thumb_bcc:
727 case ARM::fixup_arm_thumb_cp:
728 case ARM::fixup_thumb_adr_pcrel_10:
732 case ARM::fixup_arm_thumb_br:
733 case ARM::fixup_arm_thumb_cb:
736 case ARM::fixup_arm_pcrel_10_unscaled:
737 case ARM::fixup_arm_ldst_pcrel_12:
738 case ARM::fixup_arm_pcrel_10:
739 case ARM::fixup_arm_pcrel_9:
740 case ARM::fixup_arm_adr_pcrel_12:
741 case ARM::fixup_arm_uncondbl:
742 case ARM::fixup_arm_condbl:
743 case ARM::fixup_arm_blx:
744 case ARM::fixup_arm_condbranch:
745 case ARM::fixup_arm_uncondbranch:
749 case ARM::fixup_t2_ldst_pcrel_12:
750 case ARM::fixup_t2_condbranch:
751 case ARM::fixup_t2_uncondbranch:
752 case ARM::fixup_t2_pcrel_10:
753 case ARM::fixup_t2_pcrel_9:
754 case ARM::fixup_t2_adr_pcrel_12:
755 case ARM::fixup_arm_thumb_bl:
756 case ARM::fixup_arm_thumb_blx:
757 case ARM::fixup_arm_movt_hi16:
758 case ARM::fixup_arm_movw_lo16:
759 case ARM::fixup_t2_movt_hi16:
760 case ARM::fixup_t2_movw_lo16:
770 /// getFixupKindContainerSizeBytes - The number of bytes of the
771 /// container involved in big endian.
772 static unsigned getFixupKindContainerSizeBytes(unsigned Kind) {
775 llvm_unreachable("Unknown fixup kind!");
784 case ARM::fixup_arm_thumb_bcc:
785 case ARM::fixup_arm_thumb_cp:
786 case ARM::fixup_thumb_adr_pcrel_10:
787 case ARM::fixup_arm_thumb_br:
788 case ARM::fixup_arm_thumb_cb:
789 // Instruction size is 2 bytes.
792 case ARM::fixup_arm_pcrel_10_unscaled:
793 case ARM::fixup_arm_ldst_pcrel_12:
794 case ARM::fixup_arm_pcrel_10:
795 case ARM::fixup_arm_adr_pcrel_12:
796 case ARM::fixup_arm_uncondbl:
797 case ARM::fixup_arm_condbl:
798 case ARM::fixup_arm_blx:
799 case ARM::fixup_arm_condbranch:
800 case ARM::fixup_arm_uncondbranch:
801 case ARM::fixup_t2_ldst_pcrel_12:
802 case ARM::fixup_t2_condbranch:
803 case ARM::fixup_t2_uncondbranch:
804 case ARM::fixup_t2_pcrel_10:
805 case ARM::fixup_t2_adr_pcrel_12:
806 case ARM::fixup_arm_thumb_bl:
807 case ARM::fixup_arm_thumb_blx:
808 case ARM::fixup_arm_movt_hi16:
809 case ARM::fixup_arm_movw_lo16:
810 case ARM::fixup_t2_movt_hi16:
811 case ARM::fixup_t2_movw_lo16:
812 // Instruction size is 4 bytes.
817 void ARMAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
818 unsigned DataSize, uint64_t Value,
819 bool IsPCRel) const {
820 unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind());
822 adjustFixupValue(Fixup, Value, IsPCRel, nullptr, IsLittleEndian, true);
824 return; // Doesn't change encoding.
826 unsigned Offset = Fixup.getOffset();
827 assert(Offset + NumBytes <= DataSize && "Invalid fixup offset!");
829 // Used to point to big endian bytes.
830 unsigned FullSizeBytes;
831 if (!IsLittleEndian) {
832 FullSizeBytes = getFixupKindContainerSizeBytes(Fixup.getKind());
833 assert((Offset + FullSizeBytes) <= DataSize && "Invalid fixup size!");
834 assert(NumBytes <= FullSizeBytes && "Invalid fixup size!");
837 // For each byte of the fragment that the fixup touches, mask in the bits from
838 // the fixup value. The Value has been "split up" into the appropriate
840 for (unsigned i = 0; i != NumBytes; ++i) {
841 unsigned Idx = IsLittleEndian ? i : (FullSizeBytes - 1 - i);
842 Data[Offset + Idx] |= uint8_t((Value >> (i * 8)) & 0xff);
848 /// \brief Compact unwind encoding values.
849 enum CompactUnwindEncodings {
850 UNWIND_ARM_MODE_MASK = 0x0F000000,
851 UNWIND_ARM_MODE_FRAME = 0x01000000,
852 UNWIND_ARM_MODE_FRAME_D = 0x02000000,
853 UNWIND_ARM_MODE_DWARF = 0x04000000,
855 UNWIND_ARM_FRAME_STACK_ADJUST_MASK = 0x00C00000,
857 UNWIND_ARM_FRAME_FIRST_PUSH_R4 = 0x00000001,
858 UNWIND_ARM_FRAME_FIRST_PUSH_R5 = 0x00000002,
859 UNWIND_ARM_FRAME_FIRST_PUSH_R6 = 0x00000004,
861 UNWIND_ARM_FRAME_SECOND_PUSH_R8 = 0x00000008,
862 UNWIND_ARM_FRAME_SECOND_PUSH_R9 = 0x00000010,
863 UNWIND_ARM_FRAME_SECOND_PUSH_R10 = 0x00000020,
864 UNWIND_ARM_FRAME_SECOND_PUSH_R11 = 0x00000040,
865 UNWIND_ARM_FRAME_SECOND_PUSH_R12 = 0x00000080,
867 UNWIND_ARM_FRAME_D_REG_COUNT_MASK = 0x00000F00,
869 UNWIND_ARM_DWARF_SECTION_OFFSET = 0x00FFFFFF
872 } // end CU namespace
874 /// Generate compact unwind encoding for the function based on the CFI
875 /// instructions. If the CFI instructions describe a frame that cannot be
876 /// encoded in compact unwind, the method returns UNWIND_ARM_MODE_DWARF which
877 /// tells the runtime to fallback and unwind using dwarf.
878 uint32_t ARMAsmBackendDarwin::generateCompactUnwindEncoding(
879 ArrayRef<MCCFIInstruction> Instrs) const {
880 DEBUG_WITH_TYPE("compact-unwind", llvm::dbgs() << "generateCU()\n");
881 // Only armv7k uses CFI based unwinding.
882 if (Subtype != MachO::CPU_SUBTYPE_ARM_V7K)
884 // No .cfi directives means no frame.
887 // Start off assuming CFA is at SP+0.
888 int CFARegister = ARM::SP;
889 int CFARegisterOffset = 0;
890 // Mark savable registers as initially unsaved
891 DenseMap<unsigned, int> RegOffsets;
892 int FloatRegCount = 0;
893 // Process each .cfi directive and build up compact unwind info.
894 for (size_t i = 0, e = Instrs.size(); i != e; ++i) {
896 const MCCFIInstruction &Inst = Instrs[i];
897 switch (Inst.getOperation()) {
898 case MCCFIInstruction::OpDefCfa: // DW_CFA_def_cfa
899 CFARegisterOffset = -Inst.getOffset();
900 CFARegister = MRI.getLLVMRegNum(Inst.getRegister(), true);
902 case MCCFIInstruction::OpDefCfaOffset: // DW_CFA_def_cfa_offset
903 CFARegisterOffset = -Inst.getOffset();
905 case MCCFIInstruction::OpDefCfaRegister: // DW_CFA_def_cfa_register
906 CFARegister = MRI.getLLVMRegNum(Inst.getRegister(), true);
908 case MCCFIInstruction::OpOffset: // DW_CFA_offset
909 Reg = MRI.getLLVMRegNum(Inst.getRegister(), true);
910 if (ARMMCRegisterClasses[ARM::GPRRegClassID].contains(Reg))
911 RegOffsets[Reg] = Inst.getOffset();
912 else if (ARMMCRegisterClasses[ARM::DPRRegClassID].contains(Reg)) {
913 RegOffsets[Reg] = Inst.getOffset();
916 DEBUG_WITH_TYPE("compact-unwind",
917 llvm::dbgs() << ".cfi_offset on unknown register="
918 << Inst.getRegister() << "\n");
919 return CU::UNWIND_ARM_MODE_DWARF;
922 case MCCFIInstruction::OpRelOffset: // DW_CFA_advance_loc
926 // Directive not convertable to compact unwind, bail out.
927 DEBUG_WITH_TYPE("compact-unwind",
929 << "CFI directive not compatiable with comact "
930 "unwind encoding, opcode=" << Inst.getOperation()
932 return CU::UNWIND_ARM_MODE_DWARF;
937 // If no frame set up, return no unwind info.
938 if ((CFARegister == ARM::SP) && (CFARegisterOffset == 0))
941 // Verify standard frame (lr/r7) was used.
942 if (CFARegister != ARM::R7) {
943 DEBUG_WITH_TYPE("compact-unwind", llvm::dbgs() << "frame register is "
945 << " instead of r7\n");
946 return CU::UNWIND_ARM_MODE_DWARF;
948 int StackAdjust = CFARegisterOffset - 8;
949 if (RegOffsets.lookup(ARM::LR) != (-4 - StackAdjust)) {
950 DEBUG_WITH_TYPE("compact-unwind",
952 << "LR not saved as standard frame, StackAdjust="
954 << ", CFARegisterOffset=" << CFARegisterOffset
955 << ", lr save at offset=" << RegOffsets[14] << "\n");
956 return CU::UNWIND_ARM_MODE_DWARF;
958 if (RegOffsets.lookup(ARM::R7) != (-8 - StackAdjust)) {
959 DEBUG_WITH_TYPE("compact-unwind",
960 llvm::dbgs() << "r7 not saved as standard frame\n");
961 return CU::UNWIND_ARM_MODE_DWARF;
963 uint32_t CompactUnwindEncoding = CU::UNWIND_ARM_MODE_FRAME;
965 // If var-args are used, there may be a stack adjust required.
966 switch (StackAdjust) {
970 CompactUnwindEncoding |= 0x00400000;
973 CompactUnwindEncoding |= 0x00800000;
976 CompactUnwindEncoding |= 0x00C00000;
979 DEBUG_WITH_TYPE("compact-unwind", llvm::dbgs()
980 << ".cfi_def_cfa stack adjust ("
981 << StackAdjust << ") out of range\n");
982 return CU::UNWIND_ARM_MODE_DWARF;
985 // If r6 is saved, it must be right below r7.
989 } GPRCSRegs[] = {{ARM::R6, CU::UNWIND_ARM_FRAME_FIRST_PUSH_R6},
990 {ARM::R5, CU::UNWIND_ARM_FRAME_FIRST_PUSH_R5},
991 {ARM::R4, CU::UNWIND_ARM_FRAME_FIRST_PUSH_R4},
992 {ARM::R12, CU::UNWIND_ARM_FRAME_SECOND_PUSH_R12},
993 {ARM::R11, CU::UNWIND_ARM_FRAME_SECOND_PUSH_R11},
994 {ARM::R10, CU::UNWIND_ARM_FRAME_SECOND_PUSH_R10},
995 {ARM::R9, CU::UNWIND_ARM_FRAME_SECOND_PUSH_R9},
996 {ARM::R8, CU::UNWIND_ARM_FRAME_SECOND_PUSH_R8}};
998 int CurOffset = -8 - StackAdjust;
999 for (auto CSReg : GPRCSRegs) {
1000 auto Offset = RegOffsets.find(CSReg.Reg);
1001 if (Offset == RegOffsets.end())
1004 int RegOffset = Offset->second;
1005 if (RegOffset != CurOffset - 4) {
1006 DEBUG_WITH_TYPE("compact-unwind",
1007 llvm::dbgs() << MRI.getName(CSReg.Reg) << " saved at "
1008 << RegOffset << " but only supported at "
1009 << CurOffset << "\n");
1010 return CU::UNWIND_ARM_MODE_DWARF;
1012 CompactUnwindEncoding |= CSReg.Encoding;
1016 // If no floats saved, we are done.
1017 if (FloatRegCount == 0)
1018 return CompactUnwindEncoding;
1020 // Switch mode to include D register saving.
1021 CompactUnwindEncoding &= ~CU::UNWIND_ARM_MODE_MASK;
1022 CompactUnwindEncoding |= CU::UNWIND_ARM_MODE_FRAME_D;
1024 // FIXME: supporting more than 4 saved D-registers compactly would be trivial,
1025 // but needs coordination with the linker and libunwind.
1026 if (FloatRegCount > 4) {
1027 DEBUG_WITH_TYPE("compact-unwind",
1028 llvm::dbgs() << "unsupported number of D registers saved ("
1029 << FloatRegCount << ")\n");
1030 return CU::UNWIND_ARM_MODE_DWARF;
1033 // Floating point registers must either be saved sequentially, or we defer to
1034 // DWARF. No gaps allowed here so check that each saved d-register is
1035 // precisely where it should be.
1036 static unsigned FPRCSRegs[] = { ARM::D8, ARM::D10, ARM::D12, ARM::D14 };
1037 for (int Idx = FloatRegCount - 1; Idx >= 0; --Idx) {
1038 auto Offset = RegOffsets.find(FPRCSRegs[Idx]);
1039 if (Offset == RegOffsets.end()) {
1040 DEBUG_WITH_TYPE("compact-unwind",
1041 llvm::dbgs() << FloatRegCount << " D-regs saved, but "
1042 << MRI.getName(FPRCSRegs[Idx])
1044 return CU::UNWIND_ARM_MODE_DWARF;
1045 } else if (Offset->second != CurOffset - 8) {
1046 DEBUG_WITH_TYPE("compact-unwind",
1047 llvm::dbgs() << FloatRegCount << " D-regs saved, but "
1048 << MRI.getName(FPRCSRegs[Idx])
1049 << " saved at " << Offset->second
1050 << ", expected at " << CurOffset - 8
1052 return CU::UNWIND_ARM_MODE_DWARF;
1057 return CompactUnwindEncoding | ((FloatRegCount - 1) << 8);
1060 static MachO::CPUSubTypeARM getMachOSubTypeFromArch(StringRef Arch) {
1061 unsigned AK = ARM::parseArch(Arch);
1064 return MachO::CPU_SUBTYPE_ARM_V7;
1065 case ARM::AK_ARMV4T:
1066 return MachO::CPU_SUBTYPE_ARM_V4T;
1067 case ARM::AK_ARMV5T:
1068 case ARM::AK_ARMV5TE:
1069 case ARM::AK_ARMV5TEJ:
1070 return MachO::CPU_SUBTYPE_ARM_V5;
1072 case ARM::AK_ARMV6K:
1073 return MachO::CPU_SUBTYPE_ARM_V6;
1074 case ARM::AK_ARMV7A:
1075 return MachO::CPU_SUBTYPE_ARM_V7;
1076 case ARM::AK_ARMV7S:
1077 return MachO::CPU_SUBTYPE_ARM_V7S;
1078 case ARM::AK_ARMV7K:
1079 return MachO::CPU_SUBTYPE_ARM_V7K;
1080 case ARM::AK_ARMV6M:
1081 return MachO::CPU_SUBTYPE_ARM_V6M;
1082 case ARM::AK_ARMV7M:
1083 return MachO::CPU_SUBTYPE_ARM_V7M;
1084 case ARM::AK_ARMV7EM:
1085 return MachO::CPU_SUBTYPE_ARM_V7EM;
1089 MCAsmBackend *llvm::createARMAsmBackend(const Target &T,
1090 const MCRegisterInfo &MRI,
1091 const Triple &TheTriple, StringRef CPU,
1093 switch (TheTriple.getObjectFormat()) {
1095 llvm_unreachable("unsupported object format");
1096 case Triple::MachO: {
1097 MachO::CPUSubTypeARM CS = getMachOSubTypeFromArch(TheTriple.getArchName());
1098 return new ARMAsmBackendDarwin(T, TheTriple, MRI, CS);
1101 assert(TheTriple.isOSWindows() && "non-Windows ARM COFF is not supported");
1102 return new ARMAsmBackendWinCOFF(T, TheTriple);
1104 assert(TheTriple.isOSBinFormatELF() && "using ELF for non-ELF target");
1105 uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TheTriple.getOS());
1106 return new ARMAsmBackendELF(T, TheTriple, OSABI, isLittle);
1110 MCAsmBackend *llvm::createARMLEAsmBackend(const Target &T,
1111 const MCRegisterInfo &MRI,
1112 const Triple &TT, StringRef CPU) {
1113 return createARMAsmBackend(T, MRI, TT, CPU, true);
1116 MCAsmBackend *llvm::createARMBEAsmBackend(const Target &T,
1117 const MCRegisterInfo &MRI,
1118 const Triple &TT, StringRef CPU) {
1119 return createARMAsmBackend(T, MRI, TT, CPU, false);
1122 MCAsmBackend *llvm::createThumbLEAsmBackend(const Target &T,
1123 const MCRegisterInfo &MRI,
1124 const Triple &TT, StringRef CPU) {
1125 return createARMAsmBackend(T, MRI, TT, CPU, true);
1128 MCAsmBackend *llvm::createThumbBEAsmBackend(const Target &T,
1129 const MCRegisterInfo &MRI,
1130 const Triple &TT, StringRef CPU) {
1131 return createARMAsmBackend(T, MRI, TT, CPU, false);