LegalizeTypesGeneric.cpp revision 907a2d20d36fb0bee4fb5e0cd1b37d4a94d6ec06 
1//===-------- LegalizeTypesGeneric.cpp - Generic type legalization --------===//
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 generic type expansion and splitting for LegalizeTypes.
11// The routines here perform legalization when the details of the type (such as
12// whether it is an integer or a float) do not matter.
13// Expansion is the act of changing a computation in an illegal type to be a
14// computation in two identical registers of a smaller type.
15// Splitting is the act of changing a computation in an illegal type to be a
16// computation in two not necessarily identical registers of a smaller type.
17//
18//===----------------------------------------------------------------------===//
19
20#include "LegalizeTypes.h"
21#include "llvm/Target/TargetData.h"
22#include "llvm/CodeGen/PseudoSourceValue.h"
23using namespace llvm;
24
25//===----------------------------------------------------------------------===//
26// Generic Result Expansion.
27//===----------------------------------------------------------------------===//
28
29// These routines assume that the Lo/Hi part is stored first in memory on
30// little/big-endian machines, followed by the Hi/Lo part.  This means that
31// they cannot be used as is on vectors, for which Lo is always stored first.
32
33void DAGTypeLegalizer::ExpandRes_BIT_CONVERT(SDNode *N, SDValue &Lo,
34                                             SDValue &Hi) {
35  MVT OutVT = N->getValueType(0);
36  MVT NOutVT = TLI.getTypeToTransformTo(OutVT);
37  SDValue InOp = N->getOperand(0);
38  MVT InVT = InOp.getValueType();
39  DebugLoc dl = N->getDebugLoc();
40
41  // Handle some special cases efficiently.
42  switch (getTypeAction(InVT)) {
43    default:
44      assert(false && "Unknown type action!");
45    case Legal:
46    case PromoteInteger:
47      break;
48    case SoftenFloat:
49      // Convert the integer operand instead.
50      SplitInteger(GetSoftenedFloat(InOp), Lo, Hi);
51      Lo = DAG.getNode(ISD::BIT_CONVERT, dl, NOutVT, Lo);
52      Hi = DAG.getNode(ISD::BIT_CONVERT, dl, NOutVT, Hi);
53      return;
54    case ExpandInteger:
55    case ExpandFloat:
56      // Convert the expanded pieces of the input.
57      GetExpandedOp(InOp, Lo, Hi);
58      Lo = DAG.getNode(ISD::BIT_CONVERT, dl, NOutVT, Lo);
59      Hi = DAG.getNode(ISD::BIT_CONVERT, dl, NOutVT, Hi);
60      return;
61    case SplitVector:
62      // Convert the split parts of the input if it was split in two.
63      GetSplitVector(InOp, Lo, Hi);
64      if (Lo.getValueType() == Hi.getValueType()) {
65        if (TLI.isBigEndian())
66          std::swap(Lo, Hi);
67        Lo = DAG.getNode(ISD::BIT_CONVERT, dl, NOutVT, Lo);
68        Hi = DAG.getNode(ISD::BIT_CONVERT, dl, NOutVT, Hi);
69        return;
70      }
71      break;
72    case ScalarizeVector:
73      // Convert the element instead.
74      SplitInteger(BitConvertToInteger(GetScalarizedVector(InOp)), Lo, Hi);
75      Lo = DAG.getNode(ISD::BIT_CONVERT, dl, NOutVT, Lo);
76      Hi = DAG.getNode(ISD::BIT_CONVERT, dl, NOutVT, Hi);
77      return;
78  }
79
80  // Lower the bit-convert to a store/load from the stack.
81  assert(NOutVT.isByteSized() && "Expanded type not byte sized!");
82
83  // Create the stack frame object.  Make sure it is aligned for both
84  // the source and expanded destination types.
85  unsigned Alignment =
86    TLI.getTargetData()->getPrefTypeAlignment(NOutVT.getTypeForMVT());
87  SDValue StackPtr = DAG.CreateStackTemporary(InVT, Alignment);
88  int SPFI = cast<FrameIndexSDNode>(StackPtr.getNode())->getIndex();
89  const Value *SV = PseudoSourceValue::getFixedStack(SPFI);
90
91  // Emit a store to the stack slot.
92  SDValue Store = DAG.getStore(DAG.getEntryNode(), dl, InOp, StackPtr, SV, 0);
93
94  // Load the first half from the stack slot.
95  Lo = DAG.getLoad(NOutVT, dl, Store, StackPtr, SV, 0);
96
97  // Increment the pointer to the other half.
98  unsigned IncrementSize = NOutVT.getSizeInBits() / 8;
99  StackPtr = DAG.getNode(ISD::ADD, dl, StackPtr.getValueType(), StackPtr,
100                         DAG.getIntPtrConstant(IncrementSize));
101
102  // Load the second half from the stack slot.
103  Hi = DAG.getLoad(NOutVT, dl, Store, StackPtr, SV, IncrementSize, false,
104                   MinAlign(Alignment, IncrementSize));
105
106  // Handle endianness of the load.
107  if (TLI.isBigEndian())
108    std::swap(Lo, Hi);
109}
110
111void DAGTypeLegalizer::ExpandRes_BUILD_PAIR(SDNode *N, SDValue &Lo,
112                                            SDValue &Hi) {
113  // Return the operands.
114  Lo = N->getOperand(0);
115  Hi = N->getOperand(1);
116}
117
118void DAGTypeLegalizer::ExpandRes_EXTRACT_ELEMENT(SDNode *N, SDValue &Lo,
119                                                 SDValue &Hi) {
120  GetExpandedOp(N->getOperand(0), Lo, Hi);
121  SDValue Part = cast<ConstantSDNode>(N->getOperand(1))->getZExtValue() ?
122                   Hi : Lo;
123  DebugLoc dl = N->getDebugLoc();
124
125  assert(Part.getValueType() == N->getValueType(0) &&
126         "Type twice as big as expanded type not itself expanded!");
127  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
128
129  Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, NVT, Part,
130                   DAG.getConstant(0, TLI.getPointerTy()));
131  Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, NVT, Part,
132                   DAG.getConstant(1, TLI.getPointerTy()));
133}
134
135void DAGTypeLegalizer::ExpandRes_EXTRACT_VECTOR_ELT(SDNode *N, SDValue &Lo,
136                                                    SDValue &Hi) {
137  SDValue OldVec = N->getOperand(0);
138  unsigned OldElts = OldVec.getValueType().getVectorNumElements();
139  DebugLoc dl = N->getDebugLoc();
140
141  // Convert to a vector of the expanded element type, for example
142  // <3 x i64> -> <6 x i32>.
143  MVT OldVT = N->getValueType(0);
144  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
145
146  SDValue NewVec = DAG.getNode(ISD::BIT_CONVERT, dl,
147                                 MVT::getVectorVT(NewVT, 2*OldElts),
148                                 OldVec);
149
150  // Extract the elements at 2 * Idx and 2 * Idx + 1 from the new vector.
151  SDValue Idx = N->getOperand(1);
152
153  // Make sure the type of Idx is big enough to hold the new values.
154  if (Idx.getValueType().bitsLT(TLI.getPointerTy()))
155    Idx = DAG.getNode(ISD::ZERO_EXTEND, dl, TLI.getPointerTy(), Idx);
156
157  Idx = DAG.getNode(ISD::ADD, dl, Idx.getValueType(), Idx, Idx);
158  Lo = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, NewVT, NewVec, Idx);
159
160  Idx = DAG.getNode(ISD::ADD, dl, Idx.getValueType(), Idx,
161                    DAG.getConstant(1, Idx.getValueType()));
162  Hi = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, NewVT, NewVec, Idx);
163
164  if (TLI.isBigEndian())
165    std::swap(Lo, Hi);
166}
167
168void DAGTypeLegalizer::ExpandRes_NormalLoad(SDNode *N, SDValue &Lo,
169                                            SDValue &Hi) {
170  assert(ISD::isNormalLoad(N) && "This routine only for normal loads!");
171  DebugLoc dl = N->getDebugLoc();
172
173  LoadSDNode *LD = cast<LoadSDNode>(N);
174  MVT NVT = TLI.getTypeToTransformTo(LD->getValueType(0));
175  SDValue Chain = LD->getChain();
176  SDValue Ptr = LD->getBasePtr();
177  int SVOffset = LD->getSrcValueOffset();
178  unsigned Alignment = LD->getAlignment();
179  bool isVolatile = LD->isVolatile();
180
181  assert(NVT.isByteSized() && "Expanded type not byte sized!");
182
183  Lo = DAG.getLoad(NVT, dl, Chain, Ptr, LD->getSrcValue(), SVOffset,
184                   isVolatile, Alignment);
185
186  // Increment the pointer to the other half.
187  unsigned IncrementSize = NVT.getSizeInBits() / 8;
188  Ptr = DAG.getNode(ISD::ADD, dl, Ptr.getValueType(), Ptr,
189                    DAG.getIntPtrConstant(IncrementSize));
190  Hi = DAG.getLoad(NVT, dl, Chain, Ptr, LD->getSrcValue(),
191                   SVOffset+IncrementSize,
192                   isVolatile, MinAlign(Alignment, IncrementSize));
193
194  // Build a factor node to remember that this load is independent of the
195  // other one.
196  Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Lo.getValue(1),
197                      Hi.getValue(1));
198
199  // Handle endianness of the load.
200  if (TLI.isBigEndian())
201    std::swap(Lo, Hi);
202
203  // Modified the chain - switch anything that used the old chain to use
204  // the new one.
205  ReplaceValueWith(SDValue(N, 1), Chain);
206}
207
208void DAGTypeLegalizer::ExpandRes_VAARG(SDNode *N, SDValue &Lo, SDValue &Hi) {
209  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
210  SDValue Chain = N->getOperand(0);
211  SDValue Ptr = N->getOperand(1);
212  DebugLoc dl = N->getDebugLoc();
213
214  Lo = DAG.getVAArg(NVT, dl, Chain, Ptr, N->getOperand(2));
215  Hi = DAG.getVAArg(NVT, dl, Lo.getValue(1), Ptr, N->getOperand(2));
216
217  // Handle endianness of the load.
218  if (TLI.isBigEndian())
219    std::swap(Lo, Hi);
220
221  // Modified the chain - switch anything that used the old chain to use
222  // the new one.
223  ReplaceValueWith(SDValue(N, 1), Hi.getValue(1));
224}
225
226
227//===--------------------------------------------------------------------===//
228// Generic Operand Expansion.
229//===--------------------------------------------------------------------===//
230
231SDValue DAGTypeLegalizer::ExpandOp_BIT_CONVERT(SDNode *N) {
232  DebugLoc dl = N->getDebugLoc();
233  if (N->getValueType(0).isVector()) {
234    // An illegal expanding type is being converted to a legal vector type.
235    // Make a two element vector out of the expanded parts and convert that
236    // instead, but only if the new vector type is legal (otherwise there
237    // is no point, and it might create expansion loops).  For example, on
238    // x86 this turns v1i64 = BIT_CONVERT i64 into v1i64 = BIT_CONVERT v2i32.
239    MVT OVT = N->getOperand(0).getValueType();
240    MVT NVT = MVT::getVectorVT(TLI.getTypeToTransformTo(OVT), 2);
241
242    if (isTypeLegal(NVT)) {
243      SDValue Parts[2];
244      GetExpandedOp(N->getOperand(0), Parts[0], Parts[1]);
245
246      if (TLI.isBigEndian())
247        std::swap(Parts[0], Parts[1]);
248
249      SDValue Vec = DAG.getNode(ISD::BUILD_VECTOR, dl, NVT, Parts, 2);
250      return DAG.getNode(ISD::BIT_CONVERT, dl, N->getValueType(0), Vec);
251    }
252  }
253
254  // Otherwise, store to a temporary and load out again as the new type.
255  return CreateStackStoreLoad(N->getOperand(0), N->getValueType(0));
256}
257
258SDValue DAGTypeLegalizer::ExpandOp_BUILD_VECTOR(SDNode *N) {
259  // The vector type is legal but the element type needs expansion.
260  MVT VecVT = N->getValueType(0);
261  unsigned NumElts = VecVT.getVectorNumElements();
262  MVT OldVT = N->getOperand(0).getValueType();
263  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
264  DebugLoc dl = N->getDebugLoc();
265
266  // Build a vector of twice the length out of the expanded elements.
267  // For example <3 x i64> -> <6 x i32>.
268  std::vector<SDValue> NewElts;
269  NewElts.reserve(NumElts*2);
270
271  for (unsigned i = 0; i < NumElts; ++i) {
272    SDValue Lo, Hi;
273    GetExpandedOp(N->getOperand(i), Lo, Hi);
274    if (TLI.isBigEndian())
275      std::swap(Lo, Hi);
276    NewElts.push_back(Lo);
277    NewElts.push_back(Hi);
278  }
279
280  SDValue NewVec = DAG.getNode(ISD::BUILD_VECTOR, dl,
281                                 MVT::getVectorVT(NewVT, NewElts.size()),
282                                 &NewElts[0], NewElts.size());
283
284  // Convert the new vector to the old vector type.
285  return DAG.getNode(ISD::BIT_CONVERT, dl, VecVT, NewVec);
286}
287
288SDValue DAGTypeLegalizer::ExpandOp_EXTRACT_ELEMENT(SDNode *N) {
289  SDValue Lo, Hi;
290  GetExpandedOp(N->getOperand(0), Lo, Hi);
291  return cast<ConstantSDNode>(N->getOperand(1))->getZExtValue() ? Hi : Lo;
292}
293
294SDValue DAGTypeLegalizer::ExpandOp_INSERT_VECTOR_ELT(SDNode *N) {
295  // The vector type is legal but the element type needs expansion.
296  MVT VecVT = N->getValueType(0);
297  unsigned NumElts = VecVT.getVectorNumElements();
298  DebugLoc dl = N->getDebugLoc();
299
300  SDValue Val = N->getOperand(1);
301  MVT OldEVT = Val.getValueType();
302  MVT NewEVT = TLI.getTypeToTransformTo(OldEVT);
303
304  assert(OldEVT == VecVT.getVectorElementType() &&
305         "Inserted element type doesn't match vector element type!");
306
307  // Bitconvert to a vector of twice the length with elements of the expanded
308  // type, insert the expanded vector elements, and then convert back.
309  MVT NewVecVT = MVT::getVectorVT(NewEVT, NumElts*2);
310  SDValue NewVec = DAG.getNode(ISD::BIT_CONVERT, dl,
311                               NewVecVT, N->getOperand(0));
312
313  SDValue Lo, Hi;
314  GetExpandedOp(Val, Lo, Hi);
315  if (TLI.isBigEndian())
316    std::swap(Lo, Hi);
317
318  SDValue Idx = N->getOperand(2);
319  Idx = DAG.getNode(ISD::ADD, dl, Idx.getValueType(), Idx, Idx);
320  NewVec = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, NewVecVT, NewVec, Lo, Idx);
321  Idx = DAG.getNode(ISD::ADD, dl,
322                    Idx.getValueType(), Idx, DAG.getIntPtrConstant(1));
323  NewVec =  DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, NewVecVT, NewVec, Hi, Idx);
324
325  // Convert the new vector to the old vector type.
326  return DAG.getNode(ISD::BIT_CONVERT, dl, VecVT, NewVec);
327}
328
329SDValue DAGTypeLegalizer::ExpandOp_SCALAR_TO_VECTOR(SDNode *N) {
330  DebugLoc dl = N->getDebugLoc();
331  MVT VT = N->getValueType(0);
332  unsigned NumElts = VT.getVectorNumElements();
333  SmallVector<SDValue, 16> Ops(NumElts);
334  Ops[0] = N->getOperand(0);
335  SDValue UndefVal = DAG.getUNDEF(Ops[0].getValueType());
336  for (unsigned i = 1; i < NumElts; ++i)
337    Ops[i] = UndefVal;
338  return DAG.getNode(ISD::BUILD_VECTOR, dl, VT, &Ops[0], NumElts);
339}
340
341SDValue DAGTypeLegalizer::ExpandOp_NormalStore(SDNode *N, unsigned OpNo) {
342  assert(ISD::isNormalStore(N) && "This routine only for normal stores!");
343  assert(OpNo == 1 && "Can only expand the stored value so far");
344  DebugLoc dl = N->getDebugLoc();
345
346  StoreSDNode *St = cast<StoreSDNode>(N);
347  MVT NVT = TLI.getTypeToTransformTo(St->getValue().getValueType());
348  SDValue Chain = St->getChain();
349  SDValue Ptr = St->getBasePtr();
350  int SVOffset = St->getSrcValueOffset();
351  unsigned Alignment = St->getAlignment();
352  bool isVolatile = St->isVolatile();
353
354  assert(NVT.isByteSized() && "Expanded type not byte sized!");
355  unsigned IncrementSize = NVT.getSizeInBits() / 8;
356
357  SDValue Lo, Hi;
358  GetExpandedOp(St->getValue(), Lo, Hi);
359
360  if (TLI.isBigEndian())
361    std::swap(Lo, Hi);
362
363  Lo = DAG.getStore(Chain, dl, Lo, Ptr, St->getSrcValue(), SVOffset,
364                    isVolatile, Alignment);
365
366  Ptr = DAG.getNode(ISD::ADD, dl, Ptr.getValueType(), Ptr,
367                    DAG.getIntPtrConstant(IncrementSize));
368  assert(isTypeLegal(Ptr.getValueType()) && "Pointers must be legal!");
369  Hi = DAG.getStore(Chain, dl, Hi, Ptr, St->getSrcValue(),
370                    SVOffset + IncrementSize,
371                    isVolatile, MinAlign(Alignment, IncrementSize));
372
373  return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Lo, Hi);
374}
375
376
377//===--------------------------------------------------------------------===//
378// Generic Result Splitting.
379//===--------------------------------------------------------------------===//
380
381// Be careful to make no assumptions about which of Lo/Hi is stored first in
382// memory (for vectors it is always Lo first followed by Hi in the following
383// bytes; for integers and floats it is Lo first if and only if the machine is
384// little-endian).
385
386void DAGTypeLegalizer::SplitRes_MERGE_VALUES(SDNode *N,
387                                             SDValue &Lo, SDValue &Hi) {
388  // A MERGE_VALUES node can produce any number of values.  We know that the
389  // first illegal one needs to be expanded into Lo/Hi.
390  unsigned i;
391
392  // The string of legal results gets turned into input operands, which have
393  // the same type.
394  for (i = 0; isTypeLegal(N->getValueType(i)); ++i)
395    ReplaceValueWith(SDValue(N, i), SDValue(N->getOperand(i)));
396
397  // The first illegal result must be the one that needs to be expanded.
398  GetSplitOp(N->getOperand(i), Lo, Hi);
399
400  // Legalize the rest of the results into the input operands whether they are
401  // legal or not.
402  unsigned e = N->getNumValues();
403  for (++i; i != e; ++i)
404    ReplaceValueWith(SDValue(N, i), SDValue(N->getOperand(i)));
405}
406
407void DAGTypeLegalizer::SplitRes_SELECT(SDNode *N, SDValue &Lo,
408                                       SDValue &Hi) {
409  SDValue LL, LH, RL, RH;
410  DebugLoc dl = N->getDebugLoc();
411  GetSplitOp(N->getOperand(1), LL, LH);
412  GetSplitOp(N->getOperand(2), RL, RH);
413
414  SDValue Cond = N->getOperand(0);
415  Lo = DAG.getNode(ISD::SELECT, dl, LL.getValueType(), Cond, LL, RL);
416  Hi = DAG.getNode(ISD::SELECT, dl, LH.getValueType(), Cond, LH, RH);
417}
418
419void DAGTypeLegalizer::SplitRes_SELECT_CC(SDNode *N, SDValue &Lo,
420                                          SDValue &Hi) {
421  SDValue LL, LH, RL, RH;
422  DebugLoc dl = N->getDebugLoc();
423  GetSplitOp(N->getOperand(2), LL, LH);
424  GetSplitOp(N->getOperand(3), RL, RH);
425
426  Lo = DAG.getNode(ISD::SELECT_CC, dl, LL.getValueType(), N->getOperand(0),
427                   N->getOperand(1), LL, RL, N->getOperand(4));
428  Hi = DAG.getNode(ISD::SELECT_CC, dl, LH.getValueType(), N->getOperand(0),
429                   N->getOperand(1), LH, RH, N->getOperand(4));
430}
431
432void DAGTypeLegalizer::SplitRes_UNDEF(SDNode *N, SDValue &Lo, SDValue &Hi) {
433  MVT LoVT, HiVT;
434  DebugLoc dl = N->getDebugLoc();
435  GetSplitDestVTs(N->getValueType(0), LoVT, HiVT);
436  Lo = DAG.getUNDEF(LoVT);
437  Hi = DAG.getUNDEF(HiVT);
438}
439