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 //
14 
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"
29 
30 using namespace llvm;
31 
32 // Prepare value for the target space for it
33 static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
34                                  MCContext *Ctx = nullptr) {
35 
36   unsigned Kind = Fixup.getKind();
37 
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     // The displacement is then divided by 4 to give us an 18 bit
63     // address range. Forcing a signed division because Value can be negative.
64     Value = (int64_t)Value / 4;
65     // We now check if Value can be encoded as a 16-bit signed immediate.
66     if (!isInt<16>(Value) && Ctx) {
67       Ctx->reportError(Fixup.getLoc(), "out of range PC16 fixup");
68       return 0;
69     }
70     break;
71   case Mips::fixup_MIPS_PC19_S2:
72   case Mips::fixup_MICROMIPS_PC19_S2:
73     // Forcing a signed division because Value can be negative.
74     Value = (int64_t)Value / 4;
75     // We now check if Value can be encoded as a 19-bit signed immediate.
76     if (!isInt<19>(Value) && Ctx) {
77       Ctx->reportError(Fixup.getLoc(), "out of range PC19 fixup");
78       return 0;
79     }
80     break;
81   case Mips::fixup_Mips_26:
82     // So far we are only using this type for jumps.
83     // The displacement is then divided by 4 to give us an 28 bit
84     // address range.
85     Value >>= 2;
86     break;
87   case Mips::fixup_Mips_HI16:
88   case Mips::fixup_Mips_GOT_Local:
89   case Mips::fixup_Mips_GOT_HI16:
90   case Mips::fixup_Mips_CALL_HI16:
91   case Mips::fixup_MICROMIPS_HI16:
92   case Mips::fixup_MIPS_PCHI16:
93     // Get the 2nd 16-bits. Also add 1 if bit 15 is 1.
94     Value = ((Value + 0x8000) >> 16) & 0xffff;
95     break;
96   case Mips::fixup_Mips_HIGHER:
97     // Get the 3rd 16-bits.
98     Value = ((Value + 0x80008000LL) >> 32) & 0xffff;
99     break;
100   case Mips::fixup_Mips_HIGHEST:
101     // Get the 4th 16-bits.
102     Value = ((Value + 0x800080008000LL) >> 48) & 0xffff;
103     break;
104   case Mips::fixup_MICROMIPS_26_S1:
105     Value >>= 1;
106     break;
107   case Mips::fixup_MICROMIPS_PC7_S1:
108     Value -= 4;
109     // Forcing a signed division because Value can be negative.
110     Value = (int64_t) Value / 2;
111     // We now check if Value can be encoded as a 7-bit signed immediate.
112     if (!isInt<7>(Value) && Ctx) {
113       Ctx->reportError(Fixup.getLoc(), "out of range PC7 fixup");
114       return 0;
115     }
116     break;
117   case Mips::fixup_MICROMIPS_PC10_S1:
118     Value -= 2;
119     // Forcing a signed division because Value can be negative.
120     Value = (int64_t) Value / 2;
121     // We now check if Value can be encoded as a 10-bit signed immediate.
122     if (!isInt<10>(Value) && Ctx) {
123       Ctx->reportError(Fixup.getLoc(), "out of range PC10 fixup");
124       return 0;
125     }
126     break;
127   case Mips::fixup_MICROMIPS_PC16_S1:
128     Value -= 4;
129     // Forcing a signed division because Value can be negative.
130     Value = (int64_t)Value / 2;
131     // We now check if Value can be encoded as a 16-bit signed immediate.
132     if (!isInt<16>(Value) && Ctx) {
133       Ctx->reportError(Fixup.getLoc(), "out of range PC16 fixup");
134       return 0;
135     }
136     break;
137   case Mips::fixup_MIPS_PC18_S3:
138     // Forcing a signed division because Value can be negative.
139     Value = (int64_t)Value / 8;
140     // We now check if Value can be encoded as a 18-bit signed immediate.
141     if (!isInt<18>(Value) && Ctx) {
142       Ctx->reportError(Fixup.getLoc(), "out of range PC18 fixup");
143       return 0;
144     }
145     break;
146   case Mips::fixup_MICROMIPS_PC18_S3:
147     // Check alignment.
148     if ((Value & 7) && Ctx) {
149       Ctx->reportError(Fixup.getLoc(), "out of range PC18 fixup");
150     }
151     // Forcing a signed division because Value can be negative.
152     Value = (int64_t)Value / 8;
153     // We now check if Value can be encoded as a 18-bit signed immediate.
154     if (!isInt<18>(Value) && Ctx) {
155       Ctx->reportError(Fixup.getLoc(), "out of range PC18 fixup");
156       return 0;
157     }
158     break;
159   case Mips::fixup_MIPS_PC21_S2:
160     // Forcing a signed division because Value can be negative.
161     Value = (int64_t) Value / 4;
162     // We now check if Value can be encoded as a 21-bit signed immediate.
163     if (!isInt<21>(Value) && Ctx) {
164       Ctx->reportError(Fixup.getLoc(), "out of range PC21 fixup");
165       return 0;
166     }
167     break;
168   case Mips::fixup_MIPS_PC26_S2:
169     // Forcing a signed division because Value can be negative.
170     Value = (int64_t) Value / 4;
171     // We now check if Value can be encoded as a 26-bit signed immediate.
172     if (!isInt<26>(Value) && Ctx) {
173       Ctx->reportError(Fixup.getLoc(), "out of range PC26 fixup");
174       return 0;
175     }
176     break;
177   case Mips::fixup_MICROMIPS_PC26_S1:
178     // Forcing a signed division because Value can be negative.
179     Value = (int64_t)Value / 2;
180     // We now check if Value can be encoded as a 26-bit signed immediate.
181     if (!isInt<26>(Value) && Ctx) {
182       Ctx->reportFatalError(Fixup.getLoc(), "out of range PC26 fixup");
183       return 0;
184     }
185     break;
186 
187   }
188 
189   return Value;
190 }
191 
192 MCObjectWriter *
193 MipsAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
194   return createMipsELFObjectWriter(OS,
195     MCELFObjectTargetWriter::getOSABI(OSType), IsLittle, Is64Bit);
196 }
197 
198 // Little-endian fixup data byte ordering:
199 //   mips32r2:   a | b | x | x
200 //   microMIPS:  x | x | a | b
201 
202 static bool needsMMLEByteOrder(unsigned Kind) {
203   return Kind != Mips::fixup_MICROMIPS_PC10_S1 &&
204          Kind >= Mips::fixup_MICROMIPS_26_S1 &&
205          Kind < Mips::LastTargetFixupKind;
206 }
207 
208 // Calculate index for microMIPS specific little endian byte order
209 static unsigned calculateMMLEIndex(unsigned i) {
210   assert(i <= 3 && "Index out of range!");
211 
212   return (1 - i / 2) * 2 + i % 2;
213 }
214 
215 /// ApplyFixup - Apply the \p Value for given \p Fixup into the provided
216 /// data fragment, at the offset specified by the fixup and following the
217 /// fixup kind as appropriate.
218 void MipsAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
219                                 unsigned DataSize, uint64_t Value,
220                                 bool IsPCRel) const {
221   MCFixupKind Kind = Fixup.getKind();
222   Value = adjustFixupValue(Fixup, Value);
223 
224   if (!Value)
225     return; // Doesn't change encoding.
226 
227   // Where do we start in the object
228   unsigned Offset = Fixup.getOffset();
229   // Number of bytes we need to fixup
230   unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8;
231   // Used to point to big endian bytes
232   unsigned FullSize;
233 
234   switch ((unsigned)Kind) {
235   case FK_Data_2:
236   case Mips::fixup_Mips_16:
237   case Mips::fixup_MICROMIPS_PC10_S1:
238     FullSize = 2;
239     break;
240   case FK_Data_8:
241   case Mips::fixup_Mips_64:
242     FullSize = 8;
243     break;
244   case FK_Data_4:
245   default:
246     FullSize = 4;
247     break;
248   }
249 
250   // Grab current value, if any, from bits.
251   uint64_t CurVal = 0;
252 
253   bool microMipsLEByteOrder = needsMMLEByteOrder((unsigned) Kind);
254 
255   for (unsigned i = 0; i != NumBytes; ++i) {
256     unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i)
257                                                     : i)
258                             : (FullSize - 1 - i);
259     CurVal |= (uint64_t)((uint8_t)Data[Offset + Idx]) << (i*8);
260   }
261 
262   uint64_t Mask = ((uint64_t)(-1) >>
263                     (64 - getFixupKindInfo(Kind).TargetSize));
264   CurVal |= Value & Mask;
265 
266   // Write out the fixed up bytes back to the code/data bits.
267   for (unsigned i = 0; i != NumBytes; ++i) {
268     unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i)
269                                                     : i)
270                             : (FullSize - 1 - i);
271     Data[Offset + Idx] = (uint8_t)((CurVal >> (i*8)) & 0xff);
272   }
273 }
274 
275 Optional<MCFixupKind> MipsAsmBackend::getFixupKind(StringRef Name) const {
276   return StringSwitch<Optional<MCFixupKind>>(Name)
277       .Case("R_MIPS_NONE", (MCFixupKind)Mips::fixup_Mips_NONE)
278       .Case("R_MIPS_32", FK_Data_4)
279       .Default(MCAsmBackend::getFixupKind(Name));
280 }
281 
282 const MCFixupKindInfo &MipsAsmBackend::
283 getFixupKindInfo(MCFixupKind Kind) const {
284   const static MCFixupKindInfo LittleEndianInfos[Mips::NumTargetFixupKinds] = {
285     // This table *must* be in same the order of fixup_* kinds in
286     // MipsFixupKinds.h.
287     //
288     // name                    offset  bits  flags
289     { "fixup_Mips_NONE",         0,      0,   0 },
290     { "fixup_Mips_16",           0,     16,   0 },
291     { "fixup_Mips_32",           0,     32,   0 },
292     { "fixup_Mips_REL32",        0,     32,   0 },
293     { "fixup_Mips_26",           0,     26,   0 },
294     { "fixup_Mips_HI16",         0,     16,   0 },
295     { "fixup_Mips_LO16",         0,     16,   0 },
296     { "fixup_Mips_GPREL16",      0,     16,   0 },
297     { "fixup_Mips_LITERAL",      0,     16,   0 },
298     { "fixup_Mips_GOT_Global",   0,     16,   0 },
299     { "fixup_Mips_GOT_Local",    0,     16,   0 },
300     { "fixup_Mips_PC16",         0,     16,  MCFixupKindInfo::FKF_IsPCRel },
301     { "fixup_Mips_CALL16",       0,     16,   0 },
302     { "fixup_Mips_GPREL32",      0,     32,   0 },
303     { "fixup_Mips_SHIFT5",       6,      5,   0 },
304     { "fixup_Mips_SHIFT6",       6,      5,   0 },
305     { "fixup_Mips_64",           0,     64,   0 },
306     { "fixup_Mips_TLSGD",        0,     16,   0 },
307     { "fixup_Mips_GOTTPREL",     0,     16,   0 },
308     { "fixup_Mips_TPREL_HI",     0,     16,   0 },
309     { "fixup_Mips_TPREL_LO",     0,     16,   0 },
310     { "fixup_Mips_TLSLDM",       0,     16,   0 },
311     { "fixup_Mips_DTPREL_HI",    0,     16,   0 },
312     { "fixup_Mips_DTPREL_LO",    0,     16,   0 },
313     { "fixup_Mips_Branch_PCRel", 0,     16,  MCFixupKindInfo::FKF_IsPCRel },
314     { "fixup_Mips_GPOFF_HI",     0,     16,   0 },
315     { "fixup_Mips_GPOFF_LO",     0,     16,   0 },
316     { "fixup_Mips_GOT_PAGE",     0,     16,   0 },
317     { "fixup_Mips_GOT_OFST",     0,     16,   0 },
318     { "fixup_Mips_GOT_DISP",     0,     16,   0 },
319     { "fixup_Mips_HIGHER",       0,     16,   0 },
320     { "fixup_Mips_HIGHEST",      0,     16,   0 },
321     { "fixup_Mips_GOT_HI16",     0,     16,   0 },
322     { "fixup_Mips_GOT_LO16",     0,     16,   0 },
323     { "fixup_Mips_CALL_HI16",    0,     16,   0 },
324     { "fixup_Mips_CALL_LO16",    0,     16,   0 },
325     { "fixup_Mips_PC18_S3",      0,     18,  MCFixupKindInfo::FKF_IsPCRel },
326     { "fixup_MIPS_PC19_S2",      0,     19,  MCFixupKindInfo::FKF_IsPCRel },
327     { "fixup_MIPS_PC21_S2",      0,     21,  MCFixupKindInfo::FKF_IsPCRel },
328     { "fixup_MIPS_PC26_S2",      0,     26,  MCFixupKindInfo::FKF_IsPCRel },
329     { "fixup_MIPS_PCHI16",       0,     16,  MCFixupKindInfo::FKF_IsPCRel },
330     { "fixup_MIPS_PCLO16",       0,     16,  MCFixupKindInfo::FKF_IsPCRel },
331     { "fixup_MICROMIPS_26_S1",   0,     26,   0 },
332     { "fixup_MICROMIPS_HI16",    0,     16,   0 },
333     { "fixup_MICROMIPS_LO16",    0,     16,   0 },
334     { "fixup_MICROMIPS_GOT16",   0,     16,   0 },
335     { "fixup_MICROMIPS_PC7_S1",  0,      7,   MCFixupKindInfo::FKF_IsPCRel },
336     { "fixup_MICROMIPS_PC10_S1", 0,     10,   MCFixupKindInfo::FKF_IsPCRel },
337     { "fixup_MICROMIPS_PC16_S1", 0,     16,   MCFixupKindInfo::FKF_IsPCRel },
338     { "fixup_MICROMIPS_PC26_S1", 0,     26,   MCFixupKindInfo::FKF_IsPCRel },
339     { "fixup_MICROMIPS_PC19_S2", 0,     19,   MCFixupKindInfo::FKF_IsPCRel },
340     { "fixup_MICROMIPS_PC18_S3", 0,     18,   MCFixupKindInfo::FKF_IsPCRel },
341     { "fixup_MICROMIPS_CALL16",  0,     16,   0 },
342     { "fixup_MICROMIPS_GOT_DISP",        0,     16,   0 },
343     { "fixup_MICROMIPS_GOT_PAGE",        0,     16,   0 },
344     { "fixup_MICROMIPS_GOT_OFST",        0,     16,   0 },
345     { "fixup_MICROMIPS_TLS_GD",          0,     16,   0 },
346     { "fixup_MICROMIPS_TLS_LDM",         0,     16,   0 },
347     { "fixup_MICROMIPS_TLS_DTPREL_HI16", 0,     16,   0 },
348     { "fixup_MICROMIPS_TLS_DTPREL_LO16", 0,     16,   0 },
349     { "fixup_MICROMIPS_TLS_TPREL_HI16",  0,     16,   0 },
350     { "fixup_MICROMIPS_TLS_TPREL_LO16",  0,     16,   0 }
351   };
352 
353   const static MCFixupKindInfo BigEndianInfos[Mips::NumTargetFixupKinds] = {
354     // This table *must* be in same the order of fixup_* kinds in
355     // MipsFixupKinds.h.
356     //
357     // name                    offset  bits  flags
358     { "fixup_Mips_NONE",         0,      0,   0 },
359     { "fixup_Mips_16",          16,     16,   0 },
360     { "fixup_Mips_32",           0,     32,   0 },
361     { "fixup_Mips_REL32",        0,     32,   0 },
362     { "fixup_Mips_26",           6,     26,   0 },
363     { "fixup_Mips_HI16",        16,     16,   0 },
364     { "fixup_Mips_LO16",        16,     16,   0 },
365     { "fixup_Mips_GPREL16",     16,     16,   0 },
366     { "fixup_Mips_LITERAL",     16,     16,   0 },
367     { "fixup_Mips_GOT_Global",  16,     16,   0 },
368     { "fixup_Mips_GOT_Local",   16,     16,   0 },
369     { "fixup_Mips_PC16",        16,     16,  MCFixupKindInfo::FKF_IsPCRel },
370     { "fixup_Mips_CALL16",      16,     16,   0 },
371     { "fixup_Mips_GPREL32",      0,     32,   0 },
372     { "fixup_Mips_SHIFT5",      21,      5,   0 },
373     { "fixup_Mips_SHIFT6",      21,      5,   0 },
374     { "fixup_Mips_64",           0,     64,   0 },
375     { "fixup_Mips_TLSGD",       16,     16,   0 },
376     { "fixup_Mips_GOTTPREL",    16,     16,   0 },
377     { "fixup_Mips_TPREL_HI",    16,     16,   0 },
378     { "fixup_Mips_TPREL_LO",    16,     16,   0 },
379     { "fixup_Mips_TLSLDM",      16,     16,   0 },
380     { "fixup_Mips_DTPREL_HI",   16,     16,   0 },
381     { "fixup_Mips_DTPREL_LO",   16,     16,   0 },
382     { "fixup_Mips_Branch_PCRel",16,     16,  MCFixupKindInfo::FKF_IsPCRel },
383     { "fixup_Mips_GPOFF_HI",    16,     16,   0 },
384     { "fixup_Mips_GPOFF_LO",    16,     16,   0 },
385     { "fixup_Mips_GOT_PAGE",    16,     16,   0 },
386     { "fixup_Mips_GOT_OFST",    16,     16,   0 },
387     { "fixup_Mips_GOT_DISP",    16,     16,   0 },
388     { "fixup_Mips_HIGHER",      16,     16,   0 },
389     { "fixup_Mips_HIGHEST",     16,     16,   0 },
390     { "fixup_Mips_GOT_HI16",    16,     16,   0 },
391     { "fixup_Mips_GOT_LO16",    16,     16,   0 },
392     { "fixup_Mips_CALL_HI16",   16,     16,   0 },
393     { "fixup_Mips_CALL_LO16",   16,     16,   0 },
394     { "fixup_Mips_PC18_S3",     14,     18,  MCFixupKindInfo::FKF_IsPCRel },
395     { "fixup_MIPS_PC19_S2",     13,     19,  MCFixupKindInfo::FKF_IsPCRel },
396     { "fixup_MIPS_PC21_S2",     11,     21,  MCFixupKindInfo::FKF_IsPCRel },
397     { "fixup_MIPS_PC26_S2",      6,     26,  MCFixupKindInfo::FKF_IsPCRel },
398     { "fixup_MIPS_PCHI16",      16,     16,  MCFixupKindInfo::FKF_IsPCRel },
399     { "fixup_MIPS_PCLO16",      16,     16,  MCFixupKindInfo::FKF_IsPCRel },
400     { "fixup_MICROMIPS_26_S1",   6,     26,   0 },
401     { "fixup_MICROMIPS_HI16",   16,     16,   0 },
402     { "fixup_MICROMIPS_LO16",   16,     16,   0 },
403     { "fixup_MICROMIPS_GOT16",  16,     16,   0 },
404     { "fixup_MICROMIPS_PC7_S1",  9,      7,   MCFixupKindInfo::FKF_IsPCRel },
405     { "fixup_MICROMIPS_PC10_S1", 6,     10,   MCFixupKindInfo::FKF_IsPCRel },
406     { "fixup_MICROMIPS_PC16_S1",16,     16,   MCFixupKindInfo::FKF_IsPCRel },
407     { "fixup_MICROMIPS_PC26_S1", 6,     26,   MCFixupKindInfo::FKF_IsPCRel },
408     { "fixup_MICROMIPS_PC19_S2",13,     19,   MCFixupKindInfo::FKF_IsPCRel },
409     { "fixup_MICROMIPS_PC18_S3",14,     18,   MCFixupKindInfo::FKF_IsPCRel },
410     { "fixup_MICROMIPS_CALL16", 16,     16,   0 },
411     { "fixup_MICROMIPS_GOT_DISP",        16,     16,   0 },
412     { "fixup_MICROMIPS_GOT_PAGE",        16,     16,   0 },
413     { "fixup_MICROMIPS_GOT_OFST",        16,     16,   0 },
414     { "fixup_MICROMIPS_TLS_GD",          16,     16,   0 },
415     { "fixup_MICROMIPS_TLS_LDM",         16,     16,   0 },
416     { "fixup_MICROMIPS_TLS_DTPREL_HI16", 16,     16,   0 },
417     { "fixup_MICROMIPS_TLS_DTPREL_LO16", 16,     16,   0 },
418     { "fixup_MICROMIPS_TLS_TPREL_HI16",  16,     16,   0 },
419     { "fixup_MICROMIPS_TLS_TPREL_LO16",  16,     16,   0 }
420   };
421 
422   if (Kind < FirstTargetFixupKind)
423     return MCAsmBackend::getFixupKindInfo(Kind);
424 
425   assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
426           "Invalid kind!");
427 
428   if (IsLittle)
429     return LittleEndianInfos[Kind - FirstTargetFixupKind];
430   return BigEndianInfos[Kind - FirstTargetFixupKind];
431 }
432 
433 /// WriteNopData - Write an (optimal) nop sequence of Count bytes
434 /// to the given output. If the target cannot generate such a sequence,
435 /// it should return an error.
436 ///
437 /// \return - True on success.
438 bool MipsAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
439   // Check for a less than instruction size number of bytes
440   // FIXME: 16 bit instructions are not handled yet here.
441   // We shouldn't be using a hard coded number for instruction size.
442 
443   // If the count is not 4-byte aligned, we must be writing data into the text
444   // section (otherwise we have unaligned instructions, and thus have far
445   // bigger problems), so just write zeros instead.
446   OW->WriteZeros(Count);
447   return true;
448 }
449 
450 /// processFixupValue - Target hook to process the literal value of a fixup
451 /// if necessary.
452 void MipsAsmBackend::processFixupValue(const MCAssembler &Asm,
453                                        const MCAsmLayout &Layout,
454                                        const MCFixup &Fixup,
455                                        const MCFragment *DF,
456                                        const MCValue &Target,
457                                        uint64_t &Value,
458                                        bool &IsResolved) {
459   // At this point we'll ignore the value returned by adjustFixupValue as
460   // we are only checking if the fixup can be applied correctly. We have
461   // access to MCContext from here which allows us to report a fatal error
462   // with *possibly* a source code location.
463   (void)adjustFixupValue(Fixup, Value, &Asm.getContext());
464 }
465 
466 // MCAsmBackend
467 MCAsmBackend *llvm::createMipsAsmBackendEL32(const Target &T,
468                                              const MCRegisterInfo &MRI,
469                                              const Triple &TT, StringRef CPU) {
470   return new MipsAsmBackend(T, TT.getOS(), /*IsLittle*/ true,
471                             /*Is64Bit*/ false);
472 }
473 
474 MCAsmBackend *llvm::createMipsAsmBackendEB32(const Target &T,
475                                              const MCRegisterInfo &MRI,
476                                              const Triple &TT, StringRef CPU) {
477   return new MipsAsmBackend(T, TT.getOS(), /*IsLittle*/ false,
478                             /*Is64Bit*/ false);
479 }
480 
481 MCAsmBackend *llvm::createMipsAsmBackendEL64(const Target &T,
482                                              const MCRegisterInfo &MRI,
483                                              const Triple &TT, StringRef CPU) {
484   return new MipsAsmBackend(T, TT.getOS(), /*IsLittle*/ true, /*Is64Bit*/ true);
485 }
486 
487 MCAsmBackend *llvm::createMipsAsmBackendEB64(const Target &T,
488                                              const MCRegisterInfo &MRI,
489                                              const Triple &TT, StringRef CPU) {
490   return new MipsAsmBackend(T, TT.getOS(), /*IsLittle*/ false,
491                             /*Is64Bit*/ true);
492 }
493