LegalizeFloatTypes.cpp revision 4fc4fd657d4266059dac3849133a3a351b03d99d 
1//===-------- LegalizeFloatTypes.cpp - Legalization of float types --------===//
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 float type expansion and softening for LegalizeTypes.
11// Softening is the act of turning a computation in an illegal floating point
12// type into a computation in an integer type of the same size; also known as
13// "soft float".  For example, turning f32 arithmetic into operations using i32.
14// The resulting integer value is the same as what you would get by performing
15// the floating point operation and bitcasting the result to the integer type.
16// Expansion is the act of changing a computation in an illegal type to be a
17// computation in multiple registers of a smaller type.  For example,
18// implementing ppcf128 arithmetic in two f64 registers.
19//
20//===----------------------------------------------------------------------===//
21
22#include "LegalizeTypes.h"
23#include "llvm/CodeGen/PseudoSourceValue.h"
24#include "llvm/Constants.h"
25#include "llvm/DerivedTypes.h"
26using namespace llvm;
27
28/// GetFPLibCall - Return the right libcall for the given floating point type.
29static RTLIB::Libcall GetFPLibCall(MVT VT,
30                                   RTLIB::Libcall Call_F32,
31                                   RTLIB::Libcall Call_F64,
32                                   RTLIB::Libcall Call_F80,
33                                   RTLIB::Libcall Call_PPCF128) {
34  return
35    VT == MVT::f32 ? Call_F32 :
36    VT == MVT::f64 ? Call_F64 :
37    VT == MVT::f80 ? Call_F80 :
38    VT == MVT::ppcf128 ? Call_PPCF128 :
39    RTLIB::UNKNOWN_LIBCALL;
40}
41
42//===----------------------------------------------------------------------===//
43//  Result Float to Integer Conversion.
44//===----------------------------------------------------------------------===//
45
46void DAGTypeLegalizer::SoftenFloatResult(SDNode *N, unsigned ResNo) {
47  DEBUG(cerr << "Soften float result " << ResNo << ": "; N->dump(&DAG);
48        cerr << "\n");
49  SDOperand R = SDOperand();
50
51  // FIXME: Custom lowering for float-to-int?
52#if 0
53  // See if the target wants to custom convert this node to an integer.
54  if (TLI.getOperationAction(N->getOpcode(), N->getValueType(0)) ==
55      TargetLowering::Custom) {
56    // If the target wants to, allow it to lower this itself.
57    if (SDNode *P = TLI.FloatToIntOperationResult(N, DAG)) {
58      // Everything that once used N now uses P.  We are guaranteed that the
59      // result value types of N and the result value types of P match.
60      ReplaceNodeWith(N, P);
61      return;
62    }
63  }
64#endif
65
66  switch (N->getOpcode()) {
67  default:
68#ifndef NDEBUG
69    cerr << "SoftenFloatResult #" << ResNo << ": ";
70    N->dump(&DAG); cerr << "\n";
71#endif
72    assert(0 && "Do not know how to convert the result of this operator!");
73    abort();
74
75    case ISD::BIT_CONVERT: R = SoftenFloatRes_BIT_CONVERT(N); break;
76    case ISD::BUILD_PAIR:  R = SoftenFloatRes_BUILD_PAIR(N); break;
77    case ISD::ConstantFP:
78      R = SoftenFloatRes_ConstantFP(cast<ConstantFPSDNode>(N));
79      break;
80    case ISD::FCOPYSIGN:   R = SoftenFloatRes_FCOPYSIGN(N); break;
81    case ISD::LOAD:        R = SoftenFloatRes_LOAD(N); break;
82    case ISD::SINT_TO_FP:
83    case ISD::UINT_TO_FP:  R = SoftenFloatRes_XINT_TO_FP(N); break;
84
85    case ISD::FADD: R = SoftenFloatRes_FADD(N); break;
86    case ISD::FMUL: R = SoftenFloatRes_FMUL(N); break;
87    case ISD::FSUB: R = SoftenFloatRes_FSUB(N); break;
88  }
89
90  // If R is null, the sub-method took care of registering the result.
91  if (R.Val)
92    SetSoftenedFloat(SDOperand(N, ResNo), R);
93}
94
95SDOperand DAGTypeLegalizer::SoftenFloatRes_BIT_CONVERT(SDNode *N) {
96  return BitConvertToInteger(N->getOperand(0));
97}
98
99SDOperand DAGTypeLegalizer::SoftenFloatRes_BUILD_PAIR(SDNode *N) {
100  // Convert the inputs to integers, and build a new pair out of them.
101  return DAG.getNode(ISD::BUILD_PAIR,
102                     TLI.getTypeToTransformTo(N->getValueType(0)),
103                     BitConvertToInteger(N->getOperand(0)),
104                     BitConvertToInteger(N->getOperand(1)));
105}
106
107SDOperand DAGTypeLegalizer::SoftenFloatRes_ConstantFP(ConstantFPSDNode *N) {
108  return DAG.getConstant(N->getValueAPF().convertToAPInt(),
109                         TLI.getTypeToTransformTo(N->getValueType(0)));
110}
111
112SDOperand DAGTypeLegalizer::SoftenFloatRes_FADD(SDNode *N) {
113  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
114  SDOperand Ops[2] = { GetSoftenedFloat(N->getOperand(0)),
115                       GetSoftenedFloat(N->getOperand(1)) };
116  return MakeLibCall(GetFPLibCall(N->getValueType(0),
117                                  RTLIB::ADD_F32,
118                                  RTLIB::ADD_F64,
119                                  RTLIB::ADD_F80,
120                                  RTLIB::ADD_PPCF128),
121                     NVT, Ops, 2, false/*sign irrelevant*/);
122}
123
124SDOperand DAGTypeLegalizer::SoftenFloatRes_FCOPYSIGN(SDNode *N) {
125  SDOperand LHS = GetSoftenedFloat(N->getOperand(0));
126  SDOperand RHS = BitConvertToInteger(N->getOperand(1));
127
128  MVT LVT = LHS.getValueType();
129  MVT RVT = RHS.getValueType();
130
131  unsigned LSize = LVT.getSizeInBits();
132  unsigned RSize = RVT.getSizeInBits();
133
134  // First get the sign bit of second operand.
135  SDOperand SignBit = DAG.getNode(ISD::SHL, RVT, DAG.getConstant(1, RVT),
136                                  DAG.getConstant(RSize - 1,
137                                                  TLI.getShiftAmountTy()));
138  SignBit = DAG.getNode(ISD::AND, RVT, RHS, SignBit);
139
140  // Shift right or sign-extend it if the two operands have different types.
141  int SizeDiff = RVT.getSizeInBits() - LVT.getSizeInBits();
142  if (SizeDiff > 0) {
143    SignBit = DAG.getNode(ISD::SRL, RVT, SignBit,
144                          DAG.getConstant(SizeDiff, TLI.getShiftAmountTy()));
145    SignBit = DAG.getNode(ISD::TRUNCATE, LVT, SignBit);
146  } else if (SizeDiff < 0) {
147    SignBit = DAG.getNode(ISD::ANY_EXTEND, LVT, SignBit);
148    SignBit = DAG.getNode(ISD::SHL, LVT, SignBit,
149                          DAG.getConstant(-SizeDiff, TLI.getShiftAmountTy()));
150  }
151
152  // Clear the sign bit of the first operand.
153  SDOperand Mask = DAG.getNode(ISD::SHL, LVT, DAG.getConstant(1, LVT),
154                               DAG.getConstant(LSize - 1,
155                                               TLI.getShiftAmountTy()));
156  Mask = DAG.getNode(ISD::SUB, LVT, Mask, DAG.getConstant(1, LVT));
157  LHS = DAG.getNode(ISD::AND, LVT, LHS, Mask);
158
159  // Or the value with the sign bit.
160  return DAG.getNode(ISD::OR, LVT, LHS, SignBit);
161}
162
163SDOperand DAGTypeLegalizer::SoftenFloatRes_FMUL(SDNode *N) {
164  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
165  SDOperand Ops[2] = { GetSoftenedFloat(N->getOperand(0)),
166                       GetSoftenedFloat(N->getOperand(1)) };
167  return MakeLibCall(GetFPLibCall(N->getValueType(0),
168                                  RTLIB::MUL_F32,
169                                  RTLIB::MUL_F64,
170                                  RTLIB::MUL_F80,
171                                  RTLIB::MUL_PPCF128),
172                     NVT, Ops, 2, false/*sign irrelevant*/);
173}
174
175SDOperand DAGTypeLegalizer::SoftenFloatRes_FSUB(SDNode *N) {
176  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
177  SDOperand Ops[2] = { GetSoftenedFloat(N->getOperand(0)),
178                       GetSoftenedFloat(N->getOperand(1)) };
179  return MakeLibCall(GetFPLibCall(N->getValueType(0),
180                                  RTLIB::SUB_F32,
181                                  RTLIB::SUB_F64,
182                                  RTLIB::SUB_F80,
183                                  RTLIB::SUB_PPCF128),
184                     NVT, Ops, 2, false/*sign irrelevant*/);
185}
186
187SDOperand DAGTypeLegalizer::SoftenFloatRes_LOAD(SDNode *N) {
188  LoadSDNode *L = cast<LoadSDNode>(N);
189  MVT VT = N->getValueType(0);
190  MVT NVT = TLI.getTypeToTransformTo(VT);
191
192  if (L->getExtensionType() == ISD::NON_EXTLOAD)
193     return DAG.getLoad(L->getAddressingMode(), L->getExtensionType(),
194                        NVT, L->getChain(), L->getBasePtr(), L->getOffset(),
195                        L->getSrcValue(), L->getSrcValueOffset(), NVT,
196                        L->isVolatile(), L->getAlignment());
197
198  // Do a non-extending load followed by FP_EXTEND.
199  SDOperand NL = DAG.getLoad(L->getAddressingMode(), ISD::NON_EXTLOAD,
200                             L->getMemoryVT(), L->getChain(),
201                             L->getBasePtr(), L->getOffset(),
202                             L->getSrcValue(), L->getSrcValueOffset(),
203                             L->getMemoryVT(),
204                             L->isVolatile(), L->getAlignment());
205  return BitConvertToInteger(DAG.getNode(ISD::FP_EXTEND, VT, NL));
206}
207
208SDOperand DAGTypeLegalizer::SoftenFloatRes_XINT_TO_FP(SDNode *N) {
209  bool isSigned = N->getOpcode() == ISD::SINT_TO_FP;
210  MVT DestVT = N->getValueType(0);
211  SDOperand Op = N->getOperand(0);
212
213  if (Op.getValueType() == MVT::i32) {
214    // simple 32-bit [signed|unsigned] integer to float/double expansion
215
216    // Get the stack frame index of a 8 byte buffer.
217    SDOperand StackSlot = DAG.CreateStackTemporary(MVT::f64);
218
219    // word offset constant for Hi/Lo address computation
220    SDOperand Offset =
221      DAG.getConstant(MVT(MVT::i32).getSizeInBits() / 8,
222                      TLI.getPointerTy());
223    // set up Hi and Lo (into buffer) address based on endian
224    SDOperand Hi = StackSlot;
225    SDOperand Lo = DAG.getNode(ISD::ADD, TLI.getPointerTy(), StackSlot, Offset);
226    if (TLI.isLittleEndian())
227      std::swap(Hi, Lo);
228
229    // if signed map to unsigned space
230    SDOperand OpMapped;
231    if (isSigned) {
232      // constant used to invert sign bit (signed to unsigned mapping)
233      SDOperand SignBit = DAG.getConstant(0x80000000u, MVT::i32);
234      OpMapped = DAG.getNode(ISD::XOR, MVT::i32, Op, SignBit);
235    } else {
236      OpMapped = Op;
237    }
238    // store the lo of the constructed double - based on integer input
239    SDOperand Store1 = DAG.getStore(DAG.getEntryNode(),
240                                    OpMapped, Lo, NULL, 0);
241    // initial hi portion of constructed double
242    SDOperand InitialHi = DAG.getConstant(0x43300000u, MVT::i32);
243    // store the hi of the constructed double - biased exponent
244    SDOperand Store2=DAG.getStore(Store1, InitialHi, Hi, NULL, 0);
245    // load the constructed double
246    SDOperand Load = DAG.getLoad(MVT::f64, Store2, StackSlot, NULL, 0);
247    // FP constant to bias correct the final result
248    SDOperand Bias = DAG.getConstantFP(isSigned ?
249                                            BitsToDouble(0x4330000080000000ULL)
250                                          : BitsToDouble(0x4330000000000000ULL),
251                                     MVT::f64);
252    // subtract the bias
253    SDOperand Sub = DAG.getNode(ISD::FSUB, MVT::f64, Load, Bias);
254    // final result
255    SDOperand Result;
256    // handle final rounding
257    if (DestVT == MVT::f64) {
258      // do nothing
259      Result = Sub;
260    } else if (DestVT.bitsLT(MVT::f64)) {
261      Result = DAG.getNode(ISD::FP_ROUND, DestVT, Sub,
262                           DAG.getIntPtrConstant(0));
263    } else if (DestVT.bitsGT(MVT::f64)) {
264      Result = DAG.getNode(ISD::FP_EXTEND, DestVT, Sub);
265    }
266    return BitConvertToInteger(Result);
267  }
268  assert(!isSigned && "Legalize cannot Expand SINT_TO_FP for i64 yet");
269  SDOperand Tmp1 = DAG.getNode(ISD::SINT_TO_FP, DestVT, Op);
270
271  SDOperand SignSet = DAG.getSetCC(TLI.getSetCCResultType(Op), Op,
272                                   DAG.getConstant(0, Op.getValueType()),
273                                   ISD::SETLT);
274  SDOperand Zero = DAG.getIntPtrConstant(0), Four = DAG.getIntPtrConstant(4);
275  SDOperand CstOffset = DAG.getNode(ISD::SELECT, Zero.getValueType(),
276                                    SignSet, Four, Zero);
277
278  // If the sign bit of the integer is set, the large number will be treated
279  // as a negative number.  To counteract this, the dynamic code adds an
280  // offset depending on the data type.
281  uint64_t FF;
282  switch (Op.getValueType().getSimpleVT()) {
283  default: assert(0 && "Unsupported integer type!");
284  case MVT::i8 : FF = 0x43800000ULL; break;  // 2^8  (as a float)
285  case MVT::i16: FF = 0x47800000ULL; break;  // 2^16 (as a float)
286  case MVT::i32: FF = 0x4F800000ULL; break;  // 2^32 (as a float)
287  case MVT::i64: FF = 0x5F800000ULL; break;  // 2^64 (as a float)
288  }
289  if (TLI.isLittleEndian()) FF <<= 32;
290  static Constant *FudgeFactor = ConstantInt::get(Type::Int64Ty, FF);
291
292  SDOperand CPIdx = DAG.getConstantPool(FudgeFactor, TLI.getPointerTy());
293  CPIdx = DAG.getNode(ISD::ADD, TLI.getPointerTy(), CPIdx, CstOffset);
294  SDOperand FudgeInReg;
295  if (DestVT == MVT::f32)
296    FudgeInReg = DAG.getLoad(MVT::f32, DAG.getEntryNode(), CPIdx,
297                             PseudoSourceValue::getConstantPool(), 0);
298  else {
299    FudgeInReg = DAG.getExtLoad(ISD::EXTLOAD, DestVT,
300                                DAG.getEntryNode(), CPIdx,
301                                PseudoSourceValue::getConstantPool(), 0,
302                                MVT::f32);
303  }
304
305  return BitConvertToInteger(DAG.getNode(ISD::FADD, DestVT, Tmp1, FudgeInReg));
306}
307
308
309//===----------------------------------------------------------------------===//
310//  Operand Float to Integer Conversion..
311//===----------------------------------------------------------------------===//
312
313bool DAGTypeLegalizer::SoftenFloatOperand(SDNode *N, unsigned OpNo) {
314  DEBUG(cerr << "Soften float operand " << OpNo << ": "; N->dump(&DAG);
315        cerr << "\n");
316  SDOperand Res(0, 0);
317
318  // FIXME: Custom lowering for float-to-int?
319#if 0
320  if (TLI.getOperationAction(N->getOpcode(), N->getOperand(OpNo).getValueType())
321      == TargetLowering::Custom)
322    Res = TLI.LowerOperation(SDOperand(N, 0), DAG);
323#endif
324
325  if (Res.Val == 0) {
326    switch (N->getOpcode()) {
327    default:
328#ifndef NDEBUG
329      cerr << "SoftenFloatOperand Op #" << OpNo << ": ";
330      N->dump(&DAG); cerr << "\n";
331#endif
332      assert(0 && "Do not know how to convert this operator's operand!");
333      abort();
334
335      case ISD::BIT_CONVERT: Res = SoftenFloatOp_BIT_CONVERT(N); break;
336    }
337  }
338
339  // If the result is null, the sub-method took care of registering results etc.
340  if (!Res.Val) return false;
341
342  // If the result is N, the sub-method updated N in place.  Check to see if any
343  // operands are new, and if so, mark them.
344  if (Res.Val == N) {
345    // Mark N as new and remark N and its operands.  This allows us to correctly
346    // revisit N if it needs another step of promotion and allows us to visit
347    // any new operands to N.
348    ReanalyzeNode(N);
349    return true;
350  }
351
352  assert(Res.getValueType() == N->getValueType(0) && N->getNumValues() == 1 &&
353         "Invalid operand expansion");
354
355  ReplaceValueWith(SDOperand(N, 0), Res);
356  return false;
357}
358
359SDOperand DAGTypeLegalizer::SoftenFloatOp_BIT_CONVERT(SDNode *N) {
360  return DAG.getNode(ISD::BIT_CONVERT, N->getValueType(0),
361                     GetSoftenedFloat(N->getOperand(0)));
362}
363
364
365//===----------------------------------------------------------------------===//
366//  Float Result Expansion
367//===----------------------------------------------------------------------===//
368
369/// ExpandFloatResult - This method is called when the specified result of the
370/// specified node is found to need expansion.  At this point, the node may also
371/// have invalid operands or may have other results that need promotion, we just
372/// know that (at least) one result needs expansion.
373void DAGTypeLegalizer::ExpandFloatResult(SDNode *N, unsigned ResNo) {
374  DEBUG(cerr << "Expand float result: "; N->dump(&DAG); cerr << "\n");
375  SDOperand Lo, Hi;
376  Lo = Hi = SDOperand();
377
378  // See if the target wants to custom expand this node.
379  if (TLI.getOperationAction(N->getOpcode(), N->getValueType(0)) ==
380          TargetLowering::Custom) {
381    // If the target wants to, allow it to lower this itself.
382    if (SDNode *P = TLI.ExpandOperationResult(N, DAG)) {
383      // Everything that once used N now uses P.  We are guaranteed that the
384      // result value types of N and the result value types of P match.
385      ReplaceNodeWith(N, P);
386      return;
387    }
388  }
389
390  switch (N->getOpcode()) {
391  default:
392#ifndef NDEBUG
393    cerr << "ExpandFloatResult #" << ResNo << ": ";
394    N->dump(&DAG); cerr << "\n";
395#endif
396    assert(0 && "Do not know how to expand the result of this operator!");
397    abort();
398  }
399
400  // If Lo/Hi is null, the sub-method took care of registering results etc.
401  if (Lo.Val)
402    SetExpandedFloat(SDOperand(N, ResNo), Lo, Hi);
403}
404
405
406//===----------------------------------------------------------------------===//
407//  Float Operand Expansion
408//===----------------------------------------------------------------------===//
409
410/// ExpandFloatOperand - This method is called when the specified operand of the
411/// specified node is found to need expansion.  At this point, all of the result
412/// types of the node are known to be legal, but other operands of the node may
413/// need promotion or expansion as well as the specified one.
414bool DAGTypeLegalizer::ExpandFloatOperand(SDNode *N, unsigned OpNo) {
415  DEBUG(cerr << "Expand float operand: "; N->dump(&DAG); cerr << "\n");
416  SDOperand Res(0, 0);
417
418  if (TLI.getOperationAction(N->getOpcode(), N->getOperand(OpNo).getValueType())
419      == TargetLowering::Custom)
420    Res = TLI.LowerOperation(SDOperand(N, 0), DAG);
421
422  if (Res.Val == 0) {
423    switch (N->getOpcode()) {
424    default:
425  #ifndef NDEBUG
426      cerr << "ExpandFloatOperand Op #" << OpNo << ": ";
427      N->dump(&DAG); cerr << "\n";
428  #endif
429      assert(0 && "Do not know how to expand this operator's operand!");
430      abort();
431    }
432  }
433
434  // If the result is null, the sub-method took care of registering results etc.
435  if (!Res.Val) return false;
436  // If the result is N, the sub-method updated N in place.  Check to see if any
437  // operands are new, and if so, mark them.
438  if (Res.Val == N) {
439    // Mark N as new and remark N and its operands.  This allows us to correctly
440    // revisit N if it needs another step of expansion and allows us to visit
441    // any new operands to N.
442    ReanalyzeNode(N);
443    return true;
444  }
445
446  assert(Res.getValueType() == N->getValueType(0) && N->getNumValues() == 1 &&
447         "Invalid operand expansion");
448
449  ReplaceValueWith(SDOperand(N, 0), Res);
450  return false;
451}
452