6670dc208552fdb363feee613c7879121c26bc90
1 //===-- MipsAsmBackend.cpp - Mips Asm Backend ----------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the MipsAsmBackend class.
11 //
12 //===----------------------------------------------------------------------===//
13 //
15 #include "MCTargetDesc/MipsFixupKinds.h"
16 #include "MCTargetDesc/MipsAsmBackend.h"
17 #include "MCTargetDesc/MipsMCTargetDesc.h"
18 #include "llvm/MC/MCAsmBackend.h"
19 #include "llvm/MC/MCAssembler.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/MC/MCDirectives.h"
22 #include "llvm/MC/MCELFObjectWriter.h"
23 #include "llvm/MC/MCFixupKindInfo.h"
24 #include "llvm/MC/MCObjectWriter.h"
25 #include "llvm/MC/MCSubtargetInfo.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/MathExtras.h"
28 #include "llvm/Support/raw_ostream.h"
30 using namespace llvm;
32 // Prepare value for the target space for it
33 static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
34 MCContext *Ctx = nullptr) {
36 unsigned Kind = Fixup.getKind();
38 // Add/subtract and shift
39 switch (Kind) {
40 default:
41 return 0;
42 case FK_Data_2:
43 case FK_GPRel_4:
44 case FK_Data_4:
45 case FK_Data_8:
46 case Mips::fixup_Mips_LO16:
47 case Mips::fixup_Mips_GPREL16:
48 case Mips::fixup_Mips_GPOFF_HI:
49 case Mips::fixup_Mips_GPOFF_LO:
50 case Mips::fixup_Mips_GOT_PAGE:
51 case Mips::fixup_Mips_GOT_OFST:
52 case Mips::fixup_Mips_GOT_DISP:
53 case Mips::fixup_Mips_GOT_LO16:
54 case Mips::fixup_Mips_CALL_LO16:
55 case Mips::fixup_MICROMIPS_LO16:
56 case Mips::fixup_MICROMIPS_GOT_PAGE:
57 case Mips::fixup_MICROMIPS_GOT_OFST:
58 case Mips::fixup_MICROMIPS_GOT_DISP:
59 case Mips::fixup_MIPS_PCLO16:
60 break;
61 case Mips::fixup_Mips_PC16:
62 // So far we are only using this type for branches.
63 // For branches we start 1 instruction after the branch
64 // so the displacement will be one instruction size less.
65 Value -= 4;
66 // The displacement is then divided by 4 to give us an 18 bit
67 // address range. Forcing a signed division because Value can be negative.
68 Value = (int64_t)Value / 4;
69 // We now check if Value can be encoded as a 16-bit signed immediate.
70 if (!isIntN(16, Value) && Ctx)
71 Ctx->FatalError(Fixup.getLoc(), "out of range PC16 fixup");
72 break;
73 case Mips::fixup_MIPS_PC19_S2:
74 // Forcing a signed division because Value can be negative.
75 Value = (int64_t)Value / 4;
76 // We now check if Value can be encoded as a 19-bit signed immediate.
77 if (!isIntN(19, Value) && Ctx)
78 Ctx->FatalError(Fixup.getLoc(), "out of range PC19 fixup");
79 break;
80 case Mips::fixup_Mips_26:
81 // So far we are only using this type for jumps.
82 // The displacement is then divided by 4 to give us an 28 bit
83 // address range.
84 Value >>= 2;
85 break;
86 case Mips::fixup_Mips_HI16:
87 case Mips::fixup_Mips_GOT_Local:
88 case Mips::fixup_Mips_GOT_HI16:
89 case Mips::fixup_Mips_CALL_HI16:
90 case Mips::fixup_MICROMIPS_HI16:
91 case Mips::fixup_MIPS_PCHI16:
92 // Get the 2nd 16-bits. Also add 1 if bit 15 is 1.
93 Value = ((Value + 0x8000) >> 16) & 0xffff;
94 break;
95 case Mips::fixup_Mips_HIGHER:
96 // Get the 3rd 16-bits.
97 Value = ((Value + 0x80008000LL) >> 32) & 0xffff;
98 break;
99 case Mips::fixup_Mips_HIGHEST:
100 // Get the 4th 16-bits.
101 Value = ((Value + 0x800080008000LL) >> 48) & 0xffff;
102 break;
103 case Mips::fixup_MICROMIPS_26_S1:
104 Value >>= 1;
105 break;
106 case Mips::fixup_MICROMIPS_PC7_S1:
107 Value -= 4;
108 // Forcing a signed division because Value can be negative.
109 Value = (int64_t) Value / 2;
110 // We now check if Value can be encoded as a 7-bit signed immediate.
111 if (!isIntN(7, Value) && Ctx)
112 Ctx->FatalError(Fixup.getLoc(), "out of range PC7 fixup");
113 break;
114 case Mips::fixup_MICROMIPS_PC16_S1:
115 Value -= 4;
116 // Forcing a signed division because Value can be negative.
117 Value = (int64_t)Value / 2;
118 // We now check if Value can be encoded as a 16-bit signed immediate.
119 if (!isIntN(16, Value) && Ctx)
120 Ctx->FatalError(Fixup.getLoc(), "out of range PC16 fixup");
121 break;
122 case Mips::fixup_MIPS_PC18_S3:
123 // Forcing a signed division because Value can be negative.
124 Value = (int64_t)Value / 8;
125 // We now check if Value can be encoded as a 18-bit signed immediate.
126 if (!isIntN(18, Value) && Ctx)
127 Ctx->FatalError(Fixup.getLoc(), "out of range PC18 fixup");
128 break;
129 case Mips::fixup_MIPS_PC21_S2:
130 Value -= 4;
131 // Forcing a signed division because Value can be negative.
132 Value = (int64_t) Value / 4;
133 // We now check if Value can be encoded as a 21-bit signed immediate.
134 if (!isIntN(21, Value) && Ctx)
135 Ctx->FatalError(Fixup.getLoc(), "out of range PC21 fixup");
136 break;
137 case Mips::fixup_MIPS_PC26_S2:
138 Value -= 4;
139 // Forcing a signed division because Value can be negative.
140 Value = (int64_t) Value / 4;
141 // We now check if Value can be encoded as a 26-bit signed immediate.
142 if (!isIntN(26, Value) && Ctx)
143 Ctx->FatalError(Fixup.getLoc(), "out of range PC26 fixup");
144 break;
145 }
147 return Value;
148 }
150 MCObjectWriter *MipsAsmBackend::createObjectWriter(raw_ostream &OS) const {
151 return createMipsELFObjectWriter(OS,
152 MCELFObjectTargetWriter::getOSABI(OSType), IsLittle, Is64Bit);
153 }
155 // Little-endian fixup data byte ordering:
156 // mips32r2: a | b | x | x
157 // microMIPS: x | x | a | b
159 static bool needsMMLEByteOrder(unsigned Kind) {
160 return Kind >= Mips::fixup_MICROMIPS_26_S1 &&
161 Kind < Mips::LastTargetFixupKind;
162 }
164 // Calculate index for microMIPS specific little endian byte order
165 static unsigned calculateMMLEIndex(unsigned i) {
166 assert(i <= 3 && "Index out of range!");
168 return (1 - i / 2) * 2 + i % 2;
169 }
171 /// ApplyFixup - Apply the \p Value for given \p Fixup into the provided
172 /// data fragment, at the offset specified by the fixup and following the
173 /// fixup kind as appropriate.
174 void MipsAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
175 unsigned DataSize, uint64_t Value,
176 bool IsPCRel) const {
177 MCFixupKind Kind = Fixup.getKind();
178 Value = adjustFixupValue(Fixup, Value);
180 if (!Value)
181 return; // Doesn't change encoding.
183 // Where do we start in the object
184 unsigned Offset = Fixup.getOffset();
185 // Number of bytes we need to fixup
186 unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8;
187 // Used to point to big endian bytes
188 unsigned FullSize;
190 switch ((unsigned)Kind) {
191 case FK_Data_2:
192 case Mips::fixup_Mips_16:
193 FullSize = 2;
194 break;
195 case FK_Data_8:
196 case Mips::fixup_Mips_64:
197 FullSize = 8;
198 break;
199 case FK_Data_4:
200 default:
201 FullSize = 4;
202 break;
203 }
205 // Grab current value, if any, from bits.
206 uint64_t CurVal = 0;
208 bool microMipsLEByteOrder = needsMMLEByteOrder((unsigned) Kind);
210 for (unsigned i = 0; i != NumBytes; ++i) {
211 unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i)
212 : i)
213 : (FullSize - 1 - i);
214 CurVal |= (uint64_t)((uint8_t)Data[Offset + Idx]) << (i*8);
215 }
217 uint64_t Mask = ((uint64_t)(-1) >>
218 (64 - getFixupKindInfo(Kind).TargetSize));
219 CurVal |= Value & Mask;
221 // Write out the fixed up bytes back to the code/data bits.
222 for (unsigned i = 0; i != NumBytes; ++i) {
223 unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i)
224 : i)
225 : (FullSize - 1 - i);
226 Data[Offset + Idx] = (uint8_t)((CurVal >> (i*8)) & 0xff);
227 }
228 }
230 const MCFixupKindInfo &MipsAsmBackend::
231 getFixupKindInfo(MCFixupKind Kind) const {
232 const static MCFixupKindInfo LittleEndianInfos[Mips::NumTargetFixupKinds] = {
233 // This table *must* be in same the order of fixup_* kinds in
234 // MipsFixupKinds.h.
235 //
236 // name offset bits flags
237 { "fixup_Mips_16", 0, 16, 0 },
238 { "fixup_Mips_32", 0, 32, 0 },
239 { "fixup_Mips_REL32", 0, 32, 0 },
240 { "fixup_Mips_26", 0, 26, 0 },
241 { "fixup_Mips_HI16", 0, 16, 0 },
242 { "fixup_Mips_LO16", 0, 16, 0 },
243 { "fixup_Mips_GPREL16", 0, 16, 0 },
244 { "fixup_Mips_LITERAL", 0, 16, 0 },
245 { "fixup_Mips_GOT_Global", 0, 16, 0 },
246 { "fixup_Mips_GOT_Local", 0, 16, 0 },
247 { "fixup_Mips_PC16", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
248 { "fixup_Mips_CALL16", 0, 16, 0 },
249 { "fixup_Mips_GPREL32", 0, 32, 0 },
250 { "fixup_Mips_SHIFT5", 6, 5, 0 },
251 { "fixup_Mips_SHIFT6", 6, 5, 0 },
252 { "fixup_Mips_64", 0, 64, 0 },
253 { "fixup_Mips_TLSGD", 0, 16, 0 },
254 { "fixup_Mips_GOTTPREL", 0, 16, 0 },
255 { "fixup_Mips_TPREL_HI", 0, 16, 0 },
256 { "fixup_Mips_TPREL_LO", 0, 16, 0 },
257 { "fixup_Mips_TLSLDM", 0, 16, 0 },
258 { "fixup_Mips_DTPREL_HI", 0, 16, 0 },
259 { "fixup_Mips_DTPREL_LO", 0, 16, 0 },
260 { "fixup_Mips_Branch_PCRel", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
261 { "fixup_Mips_GPOFF_HI", 0, 16, 0 },
262 { "fixup_Mips_GPOFF_LO", 0, 16, 0 },
263 { "fixup_Mips_GOT_PAGE", 0, 16, 0 },
264 { "fixup_Mips_GOT_OFST", 0, 16, 0 },
265 { "fixup_Mips_GOT_DISP", 0, 16, 0 },
266 { "fixup_Mips_HIGHER", 0, 16, 0 },
267 { "fixup_Mips_HIGHEST", 0, 16, 0 },
268 { "fixup_Mips_GOT_HI16", 0, 16, 0 },
269 { "fixup_Mips_GOT_LO16", 0, 16, 0 },
270 { "fixup_Mips_CALL_HI16", 0, 16, 0 },
271 { "fixup_Mips_CALL_LO16", 0, 16, 0 },
272 { "fixup_Mips_PC18_S3", 0, 18, MCFixupKindInfo::FKF_IsPCRel },
273 { "fixup_MIPS_PC19_S2", 0, 19, MCFixupKindInfo::FKF_IsPCRel },
274 { "fixup_MIPS_PC21_S2", 0, 21, MCFixupKindInfo::FKF_IsPCRel },
275 { "fixup_MIPS_PC26_S2", 0, 26, MCFixupKindInfo::FKF_IsPCRel },
276 { "fixup_MIPS_PCHI16", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
277 { "fixup_MIPS_PCLO16", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
278 { "fixup_MICROMIPS_26_S1", 0, 26, 0 },
279 { "fixup_MICROMIPS_HI16", 0, 16, 0 },
280 { "fixup_MICROMIPS_LO16", 0, 16, 0 },
281 { "fixup_MICROMIPS_GOT16", 0, 16, 0 },
282 { "fixup_MICROMIPS_PC7_S1", 0, 7, MCFixupKindInfo::FKF_IsPCRel },
283 { "fixup_MICROMIPS_PC16_S1", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
284 { "fixup_MICROMIPS_CALL16", 0, 16, 0 },
285 { "fixup_MICROMIPS_GOT_DISP", 0, 16, 0 },
286 { "fixup_MICROMIPS_GOT_PAGE", 0, 16, 0 },
287 { "fixup_MICROMIPS_GOT_OFST", 0, 16, 0 },
288 { "fixup_MICROMIPS_TLS_GD", 0, 16, 0 },
289 { "fixup_MICROMIPS_TLS_LDM", 0, 16, 0 },
290 { "fixup_MICROMIPS_TLS_DTPREL_HI16", 0, 16, 0 },
291 { "fixup_MICROMIPS_TLS_DTPREL_LO16", 0, 16, 0 },
292 { "fixup_MICROMIPS_TLS_TPREL_HI16", 0, 16, 0 },
293 { "fixup_MICROMIPS_TLS_TPREL_LO16", 0, 16, 0 }
294 };
296 const static MCFixupKindInfo BigEndianInfos[Mips::NumTargetFixupKinds] = {
297 // This table *must* be in same the order of fixup_* kinds in
298 // MipsFixupKinds.h.
299 //
300 // name offset bits flags
301 { "fixup_Mips_16", 16, 16, 0 },
302 { "fixup_Mips_32", 0, 32, 0 },
303 { "fixup_Mips_REL32", 0, 32, 0 },
304 { "fixup_Mips_26", 6, 26, 0 },
305 { "fixup_Mips_HI16", 16, 16, 0 },
306 { "fixup_Mips_LO16", 16, 16, 0 },
307 { "fixup_Mips_GPREL16", 16, 16, 0 },
308 { "fixup_Mips_LITERAL", 16, 16, 0 },
309 { "fixup_Mips_GOT_Global", 16, 16, 0 },
310 { "fixup_Mips_GOT_Local", 16, 16, 0 },
311 { "fixup_Mips_PC16", 16, 16, MCFixupKindInfo::FKF_IsPCRel },
312 { "fixup_Mips_CALL16", 16, 16, 0 },
313 { "fixup_Mips_GPREL32", 0, 32, 0 },
314 { "fixup_Mips_SHIFT5", 21, 5, 0 },
315 { "fixup_Mips_SHIFT6", 21, 5, 0 },
316 { "fixup_Mips_64", 0, 64, 0 },
317 { "fixup_Mips_TLSGD", 16, 16, 0 },
318 { "fixup_Mips_GOTTPREL", 16, 16, 0 },
319 { "fixup_Mips_TPREL_HI", 16, 16, 0 },
320 { "fixup_Mips_TPREL_LO", 16, 16, 0 },
321 { "fixup_Mips_TLSLDM", 16, 16, 0 },
322 { "fixup_Mips_DTPREL_HI", 16, 16, 0 },
323 { "fixup_Mips_DTPREL_LO", 16, 16, 0 },
324 { "fixup_Mips_Branch_PCRel",16, 16, MCFixupKindInfo::FKF_IsPCRel },
325 { "fixup_Mips_GPOFF_HI", 16, 16, 0 },
326 { "fixup_Mips_GPOFF_LO", 16, 16, 0 },
327 { "fixup_Mips_GOT_PAGE", 16, 16, 0 },
328 { "fixup_Mips_GOT_OFST", 16, 16, 0 },
329 { "fixup_Mips_GOT_DISP", 16, 16, 0 },
330 { "fixup_Mips_HIGHER", 16, 16, 0 },
331 { "fixup_Mips_HIGHEST", 16, 16, 0 },
332 { "fixup_Mips_GOT_HI16", 16, 16, 0 },
333 { "fixup_Mips_GOT_LO16", 16, 16, 0 },
334 { "fixup_Mips_CALL_HI16", 16, 16, 0 },
335 { "fixup_Mips_CALL_LO16", 16, 16, 0 },
336 { "fixup_Mips_PC18_S3", 14, 18, MCFixupKindInfo::FKF_IsPCRel },
337 { "fixup_MIPS_PC19_S2", 13, 19, MCFixupKindInfo::FKF_IsPCRel },
338 { "fixup_MIPS_PC21_S2", 11, 21, MCFixupKindInfo::FKF_IsPCRel },
339 { "fixup_MIPS_PC26_S2", 6, 26, MCFixupKindInfo::FKF_IsPCRel },
340 { "fixup_MIPS_PCHI16", 16, 16, MCFixupKindInfo::FKF_IsPCRel },
341 { "fixup_MIPS_PCLO16", 16, 16, MCFixupKindInfo::FKF_IsPCRel },
342 { "fixup_MICROMIPS_26_S1", 6, 26, 0 },
343 { "fixup_MICROMIPS_HI16", 16, 16, 0 },
344 { "fixup_MICROMIPS_LO16", 16, 16, 0 },
345 { "fixup_MICROMIPS_GOT16", 16, 16, 0 },
346 { "fixup_MICROMIPS_PC7_S1", 9, 7, MCFixupKindInfo::FKF_IsPCRel },
347 { "fixup_MICROMIPS_PC16_S1",16, 16, MCFixupKindInfo::FKF_IsPCRel },
348 { "fixup_MICROMIPS_CALL16", 16, 16, 0 },
349 { "fixup_MICROMIPS_GOT_DISP", 16, 16, 0 },
350 { "fixup_MICROMIPS_GOT_PAGE", 16, 16, 0 },
351 { "fixup_MICROMIPS_GOT_OFST", 16, 16, 0 },
352 { "fixup_MICROMIPS_TLS_GD", 16, 16, 0 },
353 { "fixup_MICROMIPS_TLS_LDM", 16, 16, 0 },
354 { "fixup_MICROMIPS_TLS_DTPREL_HI16", 16, 16, 0 },
355 { "fixup_MICROMIPS_TLS_DTPREL_LO16", 16, 16, 0 },
356 { "fixup_MICROMIPS_TLS_TPREL_HI16", 16, 16, 0 },
357 { "fixup_MICROMIPS_TLS_TPREL_LO16", 16, 16, 0 }
358 };
360 if (Kind < FirstTargetFixupKind)
361 return MCAsmBackend::getFixupKindInfo(Kind);
363 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
364 "Invalid kind!");
366 if (IsLittle)
367 return LittleEndianInfos[Kind - FirstTargetFixupKind];
368 return BigEndianInfos[Kind - FirstTargetFixupKind];
369 }
371 /// WriteNopData - Write an (optimal) nop sequence of Count bytes
372 /// to the given output. If the target cannot generate such a sequence,
373 /// it should return an error.
374 ///
375 /// \return - True on success.
376 bool MipsAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
377 // Check for a less than instruction size number of bytes
378 // FIXME: 16 bit instructions are not handled yet here.
379 // We shouldn't be using a hard coded number for instruction size.
381 // If the count is not 4-byte aligned, we must be writing data into the text
382 // section (otherwise we have unaligned instructions, and thus have far
383 // bigger problems), so just write zeros instead.
384 for (uint64_t i = 0, e = Count % 4; i != e; ++i)
385 OW->Write8(0);
387 uint64_t NumNops = Count / 4;
388 for (uint64_t i = 0; i != NumNops; ++i)
389 OW->Write32(0);
390 return true;
391 }
393 /// processFixupValue - Target hook to process the literal value of a fixup
394 /// if necessary.
395 void MipsAsmBackend::processFixupValue(const MCAssembler &Asm,
396 const MCAsmLayout &Layout,
397 const MCFixup &Fixup,
398 const MCFragment *DF,
399 const MCValue &Target,
400 uint64_t &Value,
401 bool &IsResolved) {
402 // At this point we'll ignore the value returned by adjustFixupValue as
403 // we are only checking if the fixup can be applied correctly. We have
404 // access to MCContext from here which allows us to report a fatal error
405 // with *possibly* a source code location.
406 (void)adjustFixupValue(Fixup, Value, &Asm.getContext());
407 }
409 // MCAsmBackend
410 MCAsmBackend *llvm::createMipsAsmBackendEL32(const Target &T,
411 const MCRegisterInfo &MRI,
412 StringRef TT,
413 StringRef CPU) {
414 return new MipsAsmBackend(T, Triple(TT).getOS(),
415 /*IsLittle*/true, /*Is64Bit*/false);
416 }
418 MCAsmBackend *llvm::createMipsAsmBackendEB32(const Target &T,
419 const MCRegisterInfo &MRI,
420 StringRef TT,
421 StringRef CPU) {
422 return new MipsAsmBackend(T, Triple(TT).getOS(),
423 /*IsLittle*/false, /*Is64Bit*/false);
424 }
426 MCAsmBackend *llvm::createMipsAsmBackendEL64(const Target &T,
427 const MCRegisterInfo &MRI,
428 StringRef TT,
429 StringRef CPU) {
430 return new MipsAsmBackend(T, Triple(TT).getOS(),
431 /*IsLittle*/true, /*Is64Bit*/true);
432 }
434 MCAsmBackend *llvm::createMipsAsmBackendEB64(const Target &T,
435 const MCRegisterInfo &MRI,
436 StringRef TT,
437 StringRef CPU) {
438 return new MipsAsmBackend(T, Triple(TT).getOS(),
439 /*IsLittle*/false, /*Is64Bit*/true);
440 }