aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Target/Mips/Mips16HardFloat.cpp
blob: 9488e637a7e37010167acc91c0786b56bfc399fe (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
//===---- Mips16HardFloat.cpp for Mips16 Hard Float               --------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a pass needed for Mips16 Hard Float
//
//===----------------------------------------------------------------------===//

#include "Mips16HardFloat.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <string>

#define DEBUG_TYPE "mips16-hard-float"

static void inlineAsmOut
  (LLVMContext &C, StringRef AsmString, BasicBlock *BB ) {
  std::vector<llvm::Type *> AsmArgTypes;
  std::vector<llvm::Value*> AsmArgs;
  llvm::FunctionType *AsmFTy =
    llvm::FunctionType::get(Type::getVoidTy(C),
                            AsmArgTypes, false);
  llvm::InlineAsm *IA =
    llvm::InlineAsm::get(AsmFTy, AsmString, "", true,
                         /* IsAlignStack */ false,
                         llvm::InlineAsm::AD_ATT);
  CallInst::Create(IA, AsmArgs, "", BB);
}

namespace {

class InlineAsmHelper {
  LLVMContext &C;
  BasicBlock *BB;
public:
  InlineAsmHelper(LLVMContext &C_, BasicBlock *BB_) :
    C(C_), BB(BB_) {
  }

  void Out(StringRef AsmString) {
    inlineAsmOut(C, AsmString, BB);
  }

};
}
//
// Return types that matter for hard float are:
// float, double, complex float, and complex double
//
enum FPReturnVariant {
  FRet, DRet, CFRet, CDRet, NoFPRet
};

//
// Determine which FP return type this function has
//
static FPReturnVariant whichFPReturnVariant(Type *T) {
  switch (T->getTypeID()) {
  case Type::FloatTyID:
    return FRet;
  case Type::DoubleTyID:
    return DRet;
  case Type::StructTyID:
    if (T->getStructNumElements() != 2)
      break;
    if ((T->getContainedType(0)->isFloatTy()) &&
        (T->getContainedType(1)->isFloatTy()))
      return CFRet;
    if ((T->getContainedType(0)->isDoubleTy()) &&
        (T->getContainedType(1)->isDoubleTy()))
      return CDRet;
    break;
  default:
    break;
  }
  return NoFPRet;
}

//
// Parameter type that matter are float, (float, float), (float, double),
// double, (double, double), (double, float)
//
enum FPParamVariant {
  FSig, FFSig, FDSig,
  DSig, DDSig, DFSig, NoSig
};

// which floating point parameter signature variant we are dealing with
//
typedef Type::TypeID TypeID;
const Type::TypeID FloatTyID = Type::FloatTyID;
const Type::TypeID DoubleTyID = Type::DoubleTyID;

static FPParamVariant whichFPParamVariantNeeded(Function &F) {
  switch (F.arg_size()) {
  case 0:
    return NoSig;
  case 1:{
    TypeID ArgTypeID = F.getFunctionType()->getParamType(0)->getTypeID();
    switch (ArgTypeID) {
    case FloatTyID:
      return FSig;
    case DoubleTyID:
      return DSig;
    default:
      return NoSig;
    }
  }
  default: {
    TypeID ArgTypeID0 = F.getFunctionType()->getParamType(0)->getTypeID();
    TypeID ArgTypeID1 = F.getFunctionType()->getParamType(1)->getTypeID();
    switch(ArgTypeID0) {
    case FloatTyID: {
      switch (ArgTypeID1) {
      case FloatTyID:
        return FFSig;
      case DoubleTyID:
        return FDSig;
      default:
        return FSig;
      }
    }
    case DoubleTyID: {
      switch (ArgTypeID1) {
      case FloatTyID:
        return DFSig;
      case DoubleTyID:
        return DDSig;
      default:
        return DSig;
      }
    }
    default:
      return NoSig;
    }
  }
  }
  llvm_unreachable("can't get here");
}

// Figure out if we need float point based on the function parameters.
// We need to move variables in and/or out of floating point
// registers because of the ABI
//
static bool needsFPStubFromParams(Function &F) {
  if (F.arg_size() >=1) {
    Type *ArgType = F.getFunctionType()->getParamType(0);
    switch (ArgType->getTypeID()) {
      case Type::FloatTyID:
      case Type::DoubleTyID:
        return true;
      default:
        break;
    }
  }
  return false;
}

static bool needsFPReturnHelper(Function &F) {
  Type* RetType = F.getReturnType();
  return whichFPReturnVariant(RetType) != NoFPRet;
}

static bool needsFPReturnHelper(const FunctionType &FT) {
  Type* RetType = FT.getReturnType();
  return whichFPReturnVariant(RetType) != NoFPRet;
}

static bool needsFPHelperFromSig(Function &F) {
  return needsFPStubFromParams(F) || needsFPReturnHelper(F);
}

//
// We swap between FP and Integer registers to allow Mips16 and Mips32 to
// interoperate
//

static void swapFPIntParams
  (FPParamVariant PV, Module *M, InlineAsmHelper &IAH,
   bool LE, bool ToFP) {
  //LLVMContext &Context = M->getContext();
  std::string MI = ToFP? "mtc1 ": "mfc1 ";
  switch (PV) {
  case FSig:
    IAH.Out(MI + "$$4,$$f12");
    break;
  case FFSig:
    IAH.Out(MI +"$$4,$$f12");
    IAH.Out(MI + "$$5,$$f14");
    break;
  case FDSig:
    IAH.Out(MI + "$$4,$$f12");
    if (LE) {
      IAH.Out(MI + "$$6,$$f14");
      IAH.Out(MI + "$$7,$$f15");
    } else {
      IAH.Out(MI + "$$7,$$f14");
      IAH.Out(MI + "$$6,$$f15");
    }
    break;
  case DSig:
    if (LE) {
      IAH.Out(MI + "$$4,$$f12");
      IAH.Out(MI + "$$5,$$f13");
    } else {
      IAH.Out(MI + "$$5,$$f12");
      IAH.Out(MI + "$$4,$$f13");
    }
    break;
  case DDSig:
    if (LE) {
      IAH.Out(MI + "$$4,$$f12");
      IAH.Out(MI + "$$5,$$f13");
      IAH.Out(MI + "$$6,$$f14");
      IAH.Out(MI + "$$7,$$f15");
    } else {
      IAH.Out(MI + "$$5,$$f12");
      IAH.Out(MI + "$$4,$$f13");
      IAH.Out(MI + "$$7,$$f14");
      IAH.Out(MI + "$$6,$$f15");
    }
    break;
  case DFSig:
    if (LE) {
      IAH.Out(MI + "$$4,$$f12");
      IAH.Out(MI + "$$5,$$f13");
    } else {
      IAH.Out(MI + "$$5,$$f12");
      IAH.Out(MI + "$$4,$$f13");
    }
    IAH.Out(MI + "$$6,$$f14");
    break;
  case NoSig:
    return;
  }
}
//
// Make sure that we know we already need a stub for this function.
// Having called needsFPHelperFromSig
//
static void assureFPCallStub(Function &F, Module *M,
                             const MipsSubtarget &Subtarget) {
  // for now we only need them for static relocation
  if (Subtarget.getRelocationModel() == Reloc::PIC_)
    return;
  LLVMContext &Context = M->getContext();
  bool LE = Subtarget.isLittle();
  std::string Name = F.getName();
  std::string SectionName = ".mips16.call.fp." + Name;
  std::string StubName = "__call_stub_fp_" + Name;
  //
  // see if we already have the stub
  //
  Function *FStub = M->getFunction(StubName);
  if (FStub && !FStub->isDeclaration()) return;
  FStub = Function::Create(F.getFunctionType(),
                           Function::InternalLinkage, StubName, M);
  FStub->addFnAttr("mips16_fp_stub");
  FStub->addFnAttr(llvm::Attribute::Naked);
  FStub->addFnAttr(llvm::Attribute::NoInline);
  FStub->addFnAttr(llvm::Attribute::NoUnwind);
  FStub->addFnAttr("nomips16");
  FStub->setSection(SectionName);
  BasicBlock *BB = BasicBlock::Create(Context, "entry", FStub);
  InlineAsmHelper IAH(Context, BB);
  IAH.Out(".set reorder");
  FPReturnVariant RV = whichFPReturnVariant(FStub->getReturnType());
  FPParamVariant PV = whichFPParamVariantNeeded(F);
  swapFPIntParams(PV, M, IAH, LE, true);
  if (RV != NoFPRet) {
    IAH.Out("move $$18, $$31");
    IAH.Out("jal " + Name);
  } else {
    IAH.Out("lui  $$25,%hi(" + Name + ")");
    IAH.Out("addiu  $$25,$$25,%lo(" + Name + ")" );
  }
  switch (RV) {
  case FRet:
    IAH.Out("mfc1 $$2,$$f0");
    break;
  case DRet:
    if (LE) {
      IAH.Out("mfc1 $$2,$$f0");
      IAH.Out("mfc1 $$3,$$f1");
    } else {
      IAH.Out("mfc1 $$3,$$f0");
      IAH.Out("mfc1 $$2,$$f1");
    }
    break;
  case CFRet:
    if (LE) {
    IAH.Out("mfc1 $$2,$$f0");
    IAH.Out("mfc1 $$3,$$f2");
    } else {
      IAH.Out("mfc1 $$3,$$f0");
      IAH.Out("mfc1 $$3,$$f2");
    }
    break;
  case CDRet:
    if (LE) {
      IAH.Out("mfc1 $$4,$$f2");
      IAH.Out("mfc1 $$5,$$f3");
      IAH.Out("mfc1 $$2,$$f0");
      IAH.Out("mfc1 $$3,$$f1");

    } else {
      IAH.Out("mfc1 $$5,$$f2");
      IAH.Out("mfc1 $$4,$$f3");
      IAH.Out("mfc1 $$3,$$f0");
      IAH.Out("mfc1 $$2,$$f1");
    }
    break;
  case NoFPRet:
    break;
  }
  if (RV != NoFPRet)
    IAH.Out("jr $$18");
  else
    IAH.Out("jr $$25");
  new UnreachableInst(Context, BB);
}

//
// Functions that are llvm intrinsics and don't need helpers.
//
static const char *IntrinsicInline[] =
  {"fabs",
   "fabsf",
   "llvm.ceil.f32", "llvm.ceil.f64",
   "llvm.copysign.f32", "llvm.copysign.f64",
   "llvm.cos.f32", "llvm.cos.f64",
   "llvm.exp.f32", "llvm.exp.f64",
   "llvm.exp2.f32", "llvm.exp2.f64",
   "llvm.fabs.f32", "llvm.fabs.f64",
   "llvm.floor.f32", "llvm.floor.f64",
   "llvm.fma.f32", "llvm.fma.f64",
   "llvm.log.f32", "llvm.log.f64",
   "llvm.log10.f32", "llvm.log10.f64",
   "llvm.nearbyint.f32", "llvm.nearbyint.f64",
   "llvm.pow.f32", "llvm.pow.f64",
   "llvm.powi.f32", "llvm.powi.f64",
   "llvm.rint.f32", "llvm.rint.f64",
   "llvm.round.f32", "llvm.round.f64",
   "llvm.sin.f32", "llvm.sin.f64",
   "llvm.sqrt.f32", "llvm.sqrt.f64",
   "llvm.trunc.f32", "llvm.trunc.f64",
  };

static bool isIntrinsicInline(Function *F) {
  return std::binary_search(std::begin(IntrinsicInline),
                            std::end(IntrinsicInline), F->getName());
}
//
// Returns of float, double and complex need to be handled with a helper
// function.
//
static bool fixupFPReturnAndCall
  (Function &F, Module *M,  const MipsSubtarget &Subtarget) {
  bool Modified = false;
  LLVMContext &C = M->getContext();
  Type *MyVoid = Type::getVoidTy(C);
  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
    for (BasicBlock::iterator I = BB->begin(), E = BB->end();
         I != E; ++I) {
      Instruction &Inst = *I;
      if (const ReturnInst *RI = dyn_cast<ReturnInst>(I)) {
        Value *RVal = RI->getReturnValue();
        if (!RVal) continue;
        //
        // If there is a return value and it needs a helper function,
        // figure out which one and add a call before the actual
        // return to this helper. The purpose of the helper is to move
        // floating point values from their soft float return mapping to
        // where they would have been mapped to in floating point registers.
        //
        Type *T = RVal->getType();
        FPReturnVariant RV = whichFPReturnVariant(T);
        if (RV == NoFPRet) continue;
        static const char* Helper[NoFPRet] =
          {"__mips16_ret_sf", "__mips16_ret_df", "__mips16_ret_sc",
           "__mips16_ret_dc"};
        const char *Name = Helper[RV];
        AttributeSet A;
        Value *Params[] = {RVal};
        Modified = true;
        //
        // These helper functions have a different calling ABI so
        // this __Mips16RetHelper indicates that so that later
        // during call setup, the proper call lowering to the helper
        // functions will take place.
        //
        A = A.addAttribute(C, AttributeSet::FunctionIndex,
                           "__Mips16RetHelper");
        A = A.addAttribute(C, AttributeSet::FunctionIndex,
                           Attribute::ReadNone);
        A = A.addAttribute(C, AttributeSet::FunctionIndex,
                           Attribute::NoInline);
        Value *F = (M->getOrInsertFunction(Name, A, MyVoid, T, nullptr));
        CallInst::Create(F, Params, "", &Inst );
      } else if (const CallInst *CI = dyn_cast<CallInst>(I)) {
          const Value* V = CI->getCalledValue();
          const Type* T = nullptr;
          if (V) T = V->getType();
          const PointerType *PFT=nullptr;
          if (T) PFT = dyn_cast<PointerType>(T);
          const FunctionType *FT=nullptr;
          if (PFT) FT = dyn_cast<FunctionType>(PFT->getElementType());
          Function *F_ =  CI->getCalledFunction();
          if (FT && needsFPReturnHelper(*FT) &&
              !(F_ && isIntrinsicInline(F_))) {
            Modified=true;
            F.addFnAttr("saveS2");
          }
          if (F_ && !isIntrinsicInline(F_)) {
          // pic mode calls are handled by already defined
          // helper functions
            if (needsFPReturnHelper(*F_)) {
              Modified=true;
              F.addFnAttr("saveS2");
            }
            if (Subtarget.getRelocationModel() != Reloc::PIC_ ) {
              if (needsFPHelperFromSig(*F_)) {
                assureFPCallStub(*F_, M, Subtarget);
                Modified=true;
              }
            }
          }
      }
    }
  return Modified;
}

static void createFPFnStub(Function *F, Module *M, FPParamVariant PV,
                  const MipsSubtarget &Subtarget ) {
  bool PicMode = Subtarget.getRelocationModel() == Reloc::PIC_;
  bool LE = Subtarget.isLittle();
  LLVMContext &Context = M->getContext();
  std::string Name = F->getName();
  std::string SectionName = ".mips16.fn." + Name;
  std::string StubName = "__fn_stub_" + Name;
  std::string LocalName = "$$__fn_local_" + Name;
  Function *FStub = Function::Create
    (F->getFunctionType(),
     Function::InternalLinkage, StubName, M);
  FStub->addFnAttr("mips16_fp_stub");
  FStub->addFnAttr(llvm::Attribute::Naked);
  FStub->addFnAttr(llvm::Attribute::NoUnwind);
  FStub->addFnAttr(llvm::Attribute::NoInline);
  FStub->addFnAttr("nomips16");
  FStub->setSection(SectionName);
  BasicBlock *BB = BasicBlock::Create(Context, "entry", FStub);
  InlineAsmHelper IAH(Context, BB);
  IAH.Out(" .set  macro");
  if (PicMode) {
    IAH.Out(".set noreorder");
    IAH.Out(".cpload  $$25");
    IAH.Out(".set reorder");
    IAH.Out(".reloc 0,R_MIPS_NONE," + Name);
    IAH.Out("la $$25," + LocalName);
  }
  else {
    IAH.Out(".set reorder");
    IAH.Out("la $$25," + Name);
  }
  swapFPIntParams(PV, M, IAH, LE, false);
  IAH.Out("jr $$25");
  IAH.Out(LocalName + " = " + Name);
  new UnreachableInst(FStub->getContext(), BB);
}

//
// remove the use-soft-float attribute
//
static void removeUseSoftFloat(Function &F) {
  AttributeSet A;
  DEBUG(errs() << "removing -use-soft-float\n");
  A = A.addAttribute(F.getContext(), AttributeSet::FunctionIndex,
                     "use-soft-float", "false");
  F.removeAttributes(AttributeSet::FunctionIndex, A);
  if (F.hasFnAttribute("use-soft-float")) {
    DEBUG(errs() << "still has -use-soft-float\n");
  }
  F.addAttributes(AttributeSet::FunctionIndex, A);
}

namespace llvm {

//
// This pass only makes sense when the underlying chip has floating point but
// we are compiling as mips16.
// For all mips16 functions (that are not stubs we have already generated), or
// declared via attributes as nomips16, we must:
//    1) fixup all returns of float, double, single and double complex
//       by calling a helper function before the actual return.
//    2) generate helper functions (stubs) that can be called by mips32
//       functions that will move parameters passed normally passed in
//       floating point
//       registers the soft float equivalents.
//    3) in the case of static relocation, generate helper functions so that
//       mips16 functions can call extern functions of unknown type (mips16 or
//       mips32).
//    4) TBD. For pic, calls to extern functions of unknown type are handled by
//       predefined helper functions in libc but this work is currently done
//       during call lowering but it should be moved here in the future.
//
bool Mips16HardFloat::runOnModule(Module &M) {
  DEBUG(errs() << "Run on Module Mips16HardFloat\n");
  bool Modified = false;
  for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
    if (F->hasFnAttribute("nomips16") &&
        F->hasFnAttribute("use-soft-float")) {
      removeUseSoftFloat(*F);
      continue;
    }
    if (F->isDeclaration() || F->hasFnAttribute("mips16_fp_stub") ||
        F->hasFnAttribute("nomips16")) continue;
    Modified |= fixupFPReturnAndCall(*F, &M, Subtarget);
    FPParamVariant V = whichFPParamVariantNeeded(*F);
    if (V != NoSig) {
      Modified = true;
      createFPFnStub(F, &M, V, Subtarget);
    }
  }
  return Modified;
}

char Mips16HardFloat::ID = 0;

}

ModulePass *llvm::createMips16HardFloat(MipsTargetMachine &TM) {
  return new Mips16HardFloat(TM);
}