LegalizeTypesGeneric.cpp revision 47d9dcc584cdb7fd645ca1d5c2a0ce363570aeb7 
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"
22using namespace llvm;
23
24//===----------------------------------------------------------------------===//
25// Generic Result Expansion.
26//===----------------------------------------------------------------------===//
27
28// These routines assume that the Lo/Hi part is stored first in memory on
29// little/big-endian machines, followed by the Hi/Lo part.  This means that
30// they cannot be used as is on vectors, for which Lo is always stored first.
31
32void DAGTypeLegalizer::ExpandRes_BIT_CONVERT(SDNode *N, SDValue &Lo,
33                                             SDValue &Hi) {
34  MVT OutVT = N->getValueType(0);
35  MVT NOutVT = TLI.getTypeToTransformTo(OutVT);
36  SDValue InOp = N->getOperand(0);
37  MVT InVT = InOp.getValueType();
38
39  // Handle some special cases efficiently.
40  switch (getTypeAction(InVT)) {
41    default:
42      assert(false && "Unknown type action!");
43    case Legal:
44    case PromoteInteger:
45      break;
46    case SoftenFloat:
47      // Convert the integer operand instead.
48      SplitInteger(GetSoftenedFloat(InOp), Lo, Hi);
49      Lo = DAG.getNode(ISD::BIT_CONVERT, NOutVT, Lo);
50      Hi = DAG.getNode(ISD::BIT_CONVERT, NOutVT, Hi);
51      return;
52    case ExpandInteger:
53    case ExpandFloat:
54      // Convert the expanded pieces of the input.
55      GetExpandedOp(InOp, Lo, Hi);
56      Lo = DAG.getNode(ISD::BIT_CONVERT, NOutVT, Lo);
57      Hi = DAG.getNode(ISD::BIT_CONVERT, NOutVT, Hi);
58      return;
59    case SplitVector:
60      // Convert the split parts of the input if it was split in two.
61      GetSplitVector(InOp, Lo, Hi);
62      if (Lo.getValueType() == Hi.getValueType()) {
63        if (TLI.isBigEndian())
64          std::swap(Lo, Hi);
65        Lo = DAG.getNode(ISD::BIT_CONVERT, NOutVT, Lo);
66        Hi = DAG.getNode(ISD::BIT_CONVERT, NOutVT, Hi);
67        return;
68      }
69      break;
70    case ScalarizeVector:
71      // Convert the element instead.
72      SplitInteger(BitConvertToInteger(GetScalarizedVector(InOp)), Lo, Hi);
73      Lo = DAG.getNode(ISD::BIT_CONVERT, NOutVT, Lo);
74      Hi = DAG.getNode(ISD::BIT_CONVERT, NOutVT, Hi);
75      return;
76  }
77
78  // Lower the bit-convert to a store/load from the stack.
79  assert(NOutVT.isByteSized() && "Expanded type not byte sized!");
80
81  // Create the stack frame object.  Make sure it is aligned for both
82  // the source and expanded destination types.
83  unsigned Alignment =
84    TLI.getTargetData()->getPrefTypeAlignment(NOutVT.getTypeForMVT());
85  SDValue StackPtr = DAG.CreateStackTemporary(InVT, Alignment);
86
87  // Emit a store to the stack slot.
88  SDValue Store = DAG.getStore(DAG.getEntryNode(), InOp, StackPtr, NULL, 0);
89
90  // Load the first half from the stack slot.
91  Lo = DAG.getLoad(NOutVT, Store, StackPtr, NULL, 0);
92
93  // Increment the pointer to the other half.
94  unsigned IncrementSize = NOutVT.getSizeInBits() / 8;
95  StackPtr = DAG.getNode(ISD::ADD, StackPtr.getValueType(), StackPtr,
96                         DAG.getIntPtrConstant(IncrementSize));
97
98  // Load the second half from the stack slot.
99  Hi = DAG.getLoad(NOutVT, Store, StackPtr, NULL, 0, false,
100                   MinAlign(Alignment, IncrementSize));
101
102  // Handle endianness of the load.
103  if (TLI.isBigEndian())
104    std::swap(Lo, Hi);
105}
106
107void DAGTypeLegalizer::ExpandRes_BUILD_PAIR(SDNode *N, SDValue &Lo,
108                                            SDValue &Hi) {
109  // Return the operands.
110  Lo = N->getOperand(0);
111  Hi = N->getOperand(1);
112}
113
114void DAGTypeLegalizer::ExpandRes_EXTRACT_ELEMENT(SDNode *N, SDValue &Lo,
115                                                 SDValue &Hi) {
116  GetExpandedOp(N->getOperand(0), Lo, Hi);
117  SDValue Part = cast<ConstantSDNode>(N->getOperand(1))->getZExtValue() ?
118                   Hi : Lo;
119
120  assert(Part.getValueType() == N->getValueType(0) &&
121         "Type twice as big as expanded type not itself expanded!");
122  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
123
124  Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, NVT, Part,
125                   DAG.getConstant(0, TLI.getPointerTy()));
126  Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, NVT, Part,
127                   DAG.getConstant(1, TLI.getPointerTy()));
128}
129
130void DAGTypeLegalizer::ExpandRes_EXTRACT_VECTOR_ELT(SDNode *N, SDValue &Lo,
131                                                    SDValue &Hi) {
132  SDValue OldVec = N->getOperand(0);
133  unsigned OldElts = OldVec.getValueType().getVectorNumElements();
134
135  // Convert to a vector of the expanded element type, for example
136  // <3 x i64> -> <6 x i32>.
137  MVT OldVT = N->getValueType(0);
138  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
139
140  SDValue NewVec = DAG.getNode(ISD::BIT_CONVERT,
141                                 MVT::getVectorVT(NewVT, 2*OldElts),
142                                 OldVec);
143
144  // Extract the elements at 2 * Idx and 2 * Idx + 1 from the new vector.
145  SDValue Idx = N->getOperand(1);
146
147  // Make sure the type of Idx is big enough to hold the new values.
148  if (Idx.getValueType().bitsLT(TLI.getPointerTy()))
149    Idx = DAG.getNode(ISD::ZERO_EXTEND, TLI.getPointerTy(), Idx);
150
151  Idx = DAG.getNode(ISD::ADD, Idx.getValueType(), Idx, Idx);
152  Lo = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, NewVec, Idx);
153
154  Idx = DAG.getNode(ISD::ADD, Idx.getValueType(), Idx,
155                    DAG.getConstant(1, Idx.getValueType()));
156  Hi = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, NewVec, Idx);
157
158  if (TLI.isBigEndian())
159    std::swap(Lo, Hi);
160}
161
162void DAGTypeLegalizer::ExpandRes_NormalLoad(SDNode *N, SDValue &Lo,
163                                            SDValue &Hi) {
164  assert(ISD::isNormalLoad(N) && "This routine only for normal loads!");
165
166  LoadSDNode *LD = cast<LoadSDNode>(N);
167  MVT NVT = TLI.getTypeToTransformTo(LD->getValueType(0));
168  SDValue Chain = LD->getChain();
169  SDValue Ptr = LD->getBasePtr();
170  int SVOffset = LD->getSrcValueOffset();
171  unsigned Alignment = LD->getAlignment();
172  bool isVolatile = LD->isVolatile();
173
174  assert(NVT.isByteSized() && "Expanded type not byte sized!");
175
176  Lo = DAG.getLoad(NVT, Chain, Ptr, LD->getSrcValue(), SVOffset,
177                   isVolatile, Alignment);
178
179  // Increment the pointer to the other half.
180  unsigned IncrementSize = NVT.getSizeInBits() / 8;
181  Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
182                    DAG.getIntPtrConstant(IncrementSize));
183  Hi = DAG.getLoad(NVT, Chain, Ptr, LD->getSrcValue(), SVOffset+IncrementSize,
184                   isVolatile, MinAlign(Alignment, IncrementSize));
185
186  // Build a factor node to remember that this load is independent of the
187  // other one.
188  Chain = DAG.getNode(ISD::TokenFactor, MVT::Other, Lo.getValue(1),
189                      Hi.getValue(1));
190
191  // Handle endianness of the load.
192  if (TLI.isBigEndian())
193    std::swap(Lo, Hi);
194
195  // Modified the chain - switch anything that used the old chain to use
196  // the new one.
197  ReplaceValueWith(SDValue(N, 1), Chain);
198}
199
200void DAGTypeLegalizer::ExpandRes_VAARG(SDNode *N, SDValue &Lo, SDValue &Hi) {
201  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
202  SDValue Chain = N->getOperand(0);
203  SDValue Ptr = N->getOperand(1);
204
205  Lo = DAG.getVAArg(NVT, Chain, Ptr, N->getOperand(2));
206  Hi = DAG.getVAArg(NVT, Lo.getValue(1), Ptr, N->getOperand(2));
207
208  // Handle endianness of the load.
209  if (TLI.isBigEndian())
210    std::swap(Lo, Hi);
211
212  // Modified the chain - switch anything that used the old chain to use
213  // the new one.
214  ReplaceValueWith(SDValue(N, 1), Hi.getValue(1));
215}
216
217
218//===--------------------------------------------------------------------===//
219// Generic Operand Expansion.
220//===--------------------------------------------------------------------===//
221
222SDValue DAGTypeLegalizer::ExpandOp_BIT_CONVERT(SDNode *N) {
223  if (N->getValueType(0).isVector()) {
224    // An illegal expanding type is being converted to a legal vector type.
225    // Make a two element vector out of the expanded parts and convert that
226    // instead, but only if the new vector type is legal (otherwise there
227    // is no point, and it might create expansion loops).  For example, on
228    // x86 this turns v1i64 = BIT_CONVERT i64 into v1i64 = BIT_CONVERT v2i32.
229    MVT OVT = N->getOperand(0).getValueType();
230    MVT NVT = MVT::getVectorVT(TLI.getTypeToTransformTo(OVT), 2);
231
232    if (isTypeLegal(NVT)) {
233      SDValue Parts[2];
234      GetExpandedOp(N->getOperand(0), Parts[0], Parts[1]);
235
236      if (TLI.isBigEndian())
237        std::swap(Parts[0], Parts[1]);
238
239      SDValue Vec = DAG.getNode(ISD::BUILD_VECTOR, NVT, Parts, 2);
240      return DAG.getNode(ISD::BIT_CONVERT, N->getValueType(0), Vec);
241    }
242  }
243
244  // Otherwise, store to a temporary and load out again as the new type.
245  return CreateStackStoreLoad(N->getOperand(0), N->getValueType(0));
246}
247
248SDValue DAGTypeLegalizer::ExpandOp_BUILD_VECTOR(SDNode *N) {
249  // The vector type is legal but the element type needs expansion.
250  MVT VecVT = N->getValueType(0);
251  unsigned NumElts = VecVT.getVectorNumElements();
252  MVT OldVT = N->getOperand(0).getValueType();
253  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
254
255  // Build a vector of twice the length out of the expanded elements.
256  // For example <3 x i64> -> <6 x i32>.
257  std::vector<SDValue> NewElts;
258  NewElts.reserve(NumElts*2);
259
260  for (unsigned i = 0; i < NumElts; ++i) {
261    SDValue Lo, Hi;
262    GetExpandedOp(N->getOperand(i), Lo, Hi);
263    if (TLI.isBigEndian())
264      std::swap(Lo, Hi);
265    NewElts.push_back(Lo);
266    NewElts.push_back(Hi);
267  }
268
269  SDValue NewVec = DAG.getNode(ISD::BUILD_VECTOR,
270                                 MVT::getVectorVT(NewVT, NewElts.size()),
271                                 &NewElts[0], NewElts.size());
272
273  // Convert the new vector to the old vector type.
274  return DAG.getNode(ISD::BIT_CONVERT, VecVT, NewVec);
275}
276
277SDValue DAGTypeLegalizer::ExpandOp_EXTRACT_ELEMENT(SDNode *N) {
278  SDValue Lo, Hi;
279  GetExpandedOp(N->getOperand(0), Lo, Hi);
280  return cast<ConstantSDNode>(N->getOperand(1))->getZExtValue() ? Hi : Lo;
281}
282
283SDValue DAGTypeLegalizer::ExpandOp_NormalStore(SDNode *N, unsigned OpNo) {
284  assert(ISD::isNormalStore(N) && "This routine only for normal stores!");
285  assert(OpNo == 1 && "Can only expand the stored value so far");
286
287  StoreSDNode *St = cast<StoreSDNode>(N);
288  MVT NVT = TLI.getTypeToTransformTo(St->getValue().getValueType());
289  SDValue Chain = St->getChain();
290  SDValue Ptr = St->getBasePtr();
291  int SVOffset = St->getSrcValueOffset();
292  unsigned Alignment = St->getAlignment();
293  bool isVolatile = St->isVolatile();
294
295  assert(NVT.isByteSized() && "Expanded type not byte sized!");
296  unsigned IncrementSize = NVT.getSizeInBits() / 8;
297
298  SDValue Lo, Hi;
299  GetExpandedOp(St->getValue(), Lo, Hi);
300
301  if (TLI.isBigEndian())
302    std::swap(Lo, Hi);
303
304  Lo = DAG.getStore(Chain, Lo, Ptr, St->getSrcValue(), SVOffset,
305                    isVolatile, Alignment);
306
307  Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
308                    DAG.getIntPtrConstant(IncrementSize));
309  assert(isTypeLegal(Ptr.getValueType()) && "Pointers must be legal!");
310  Hi = DAG.getStore(Chain, Hi, Ptr, St->getSrcValue(), SVOffset + IncrementSize,
311                    isVolatile, MinAlign(Alignment, IncrementSize));
312
313  return DAG.getNode(ISD::TokenFactor, MVT::Other, Lo, Hi);
314}
315
316
317//===--------------------------------------------------------------------===//
318// Generic Result Splitting.
319//===--------------------------------------------------------------------===//
320
321// Be careful to make no assumptions about which of Lo/Hi is stored first in
322// memory (for vectors it is always Lo first followed by Hi in the following
323// bytes; for integers and floats it is Lo first if and only if the machine is
324// little-endian).
325
326void DAGTypeLegalizer::SplitRes_MERGE_VALUES(SDNode *N,
327                                             SDValue &Lo, SDValue &Hi) {
328  // A MERGE_VALUES node can produce any number of values.  We know that the
329  // first illegal one needs to be expanded into Lo/Hi.
330  unsigned i;
331
332  // The string of legal results gets turned into input operands, which have
333  // the same type.
334  for (i = 0; isTypeLegal(N->getValueType(i)); ++i)
335    ReplaceValueWith(SDValue(N, i), SDValue(N->getOperand(i)));
336
337  // The first illegal result must be the one that needs to be expanded.
338  GetSplitOp(N->getOperand(i), Lo, Hi);
339
340  // Legalize the rest of the results into the input operands whether they are
341  // legal or not.
342  unsigned e = N->getNumValues();
343  for (++i; i != e; ++i)
344    ReplaceValueWith(SDValue(N, i), SDValue(N->getOperand(i)));
345}
346
347void DAGTypeLegalizer::SplitRes_SELECT(SDNode *N, SDValue &Lo,
348                                       SDValue &Hi) {
349  SDValue LL, LH, RL, RH;
350  GetSplitOp(N->getOperand(1), LL, LH);
351  GetSplitOp(N->getOperand(2), RL, RH);
352
353  SDValue Cond = N->getOperand(0);
354  Lo = DAG.getNode(ISD::SELECT, LL.getValueType(), Cond, LL, RL);
355  Hi = DAG.getNode(ISD::SELECT, LH.getValueType(), Cond, LH, RH);
356}
357
358void DAGTypeLegalizer::SplitRes_SELECT_CC(SDNode *N, SDValue &Lo,
359                                          SDValue &Hi) {
360  SDValue LL, LH, RL, RH;
361  GetSplitOp(N->getOperand(2), LL, LH);
362  GetSplitOp(N->getOperand(3), RL, RH);
363
364  Lo = DAG.getNode(ISD::SELECT_CC, LL.getValueType(), N->getOperand(0),
365                   N->getOperand(1), LL, RL, N->getOperand(4));
366  Hi = DAG.getNode(ISD::SELECT_CC, LH.getValueType(), N->getOperand(0),
367                   N->getOperand(1), LH, RH, N->getOperand(4));
368}
369
370void DAGTypeLegalizer::SplitRes_UNDEF(SDNode *N, SDValue &Lo, SDValue &Hi) {
371  MVT LoVT, HiVT;
372  GetSplitDestVTs(N->getValueType(0), LoVT, HiVT);
373  Lo = DAG.getNode(ISD::UNDEF, LoVT);
374  Hi = DAG.getNode(ISD::UNDEF, HiVT);
375}
376