LegalizeTypesGeneric.cpp revision f6a721c7a51d15f54d103e3f0d9ac2df4cf255c7
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"
21using namespace llvm;
22
23//===----------------------------------------------------------------------===//
24// Generic Result Expansion.
25//===----------------------------------------------------------------------===//
26
27// These routines assume that the Lo/Hi part is stored first in memory on
28// little/big-endian machines, followed by the Hi/Lo part.  This means that
29// they cannot be used as is on vectors, for which Lo is always stored first.
30
31void DAGTypeLegalizer::ExpandRes_BIT_CONVERT(SDNode *N,
32                                             SDOperand &Lo, SDOperand &Hi) {
33  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
34  SDOperand InOp = N->getOperand(0);
35  MVT InVT = InOp.getValueType();
36
37  // Handle some special cases efficiently.
38  switch (getTypeAction(InVT)) {
39    default:
40      assert(false && "Unknown type action!");
41    case Legal:
42    case PromoteInteger:
43      break;
44    case SoftenFloat:
45      // Convert the integer operand instead.
46      SplitInteger(GetSoftenedFloat(InOp), Lo, Hi);
47      Lo = DAG.getNode(ISD::BIT_CONVERT, NVT, Lo);
48      Hi = DAG.getNode(ISD::BIT_CONVERT, NVT, Hi);
49      return;
50    case ExpandInteger:
51    case ExpandFloat:
52      // Convert the expanded pieces of the input.
53      GetExpandedOp(InOp, Lo, Hi);
54      Lo = DAG.getNode(ISD::BIT_CONVERT, NVT, Lo);
55      Hi = DAG.getNode(ISD::BIT_CONVERT, NVT, Hi);
56      return;
57    case Split:
58      // Convert the split parts of the input if it was split in two.
59      GetSplitVector(InOp, Lo, Hi);
60      if (Lo.getValueType() == Hi.getValueType()) {
61        if (TLI.isBigEndian())
62          std::swap(Lo, Hi);
63        Lo = DAG.getNode(ISD::BIT_CONVERT, NVT, Lo);
64        Hi = DAG.getNode(ISD::BIT_CONVERT, NVT, Hi);
65        return;
66      }
67      break;
68    case Scalarize:
69      // Convert the element instead.
70      SplitInteger(BitConvertToInteger(GetScalarizedVector(InOp)), Lo, Hi);
71      Lo = DAG.getNode(ISD::BIT_CONVERT, NVT, Lo);
72      Hi = DAG.getNode(ISD::BIT_CONVERT, NVT, Hi);
73      return;
74  }
75
76  // Lower the bit-convert to a store/load from the stack, then expand the load.
77  SDOperand Op = CreateStackStoreLoad(InOp, N->getValueType(0));
78  ExpandRes_NormalLoad(Op.Val, Lo, Hi);
79}
80
81void DAGTypeLegalizer::ExpandRes_BUILD_PAIR(SDNode *N,
82                                            SDOperand &Lo, SDOperand &Hi) {
83  // Return the operands.
84  Lo = N->getOperand(0);
85  Hi = N->getOperand(1);
86}
87
88void DAGTypeLegalizer::ExpandRes_EXTRACT_VECTOR_ELT(SDNode *N,
89                                                    SDOperand &Lo,
90                                                    SDOperand &Hi) {
91  SDOperand OldVec = N->getOperand(0);
92  unsigned OldElts = OldVec.getValueType().getVectorNumElements();
93
94  // Convert to a vector of the expanded element type, for example
95  // <3 x i64> -> <6 x i32>.
96  MVT OldVT = N->getValueType(0);
97  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
98
99  SDOperand NewVec = DAG.getNode(ISD::BIT_CONVERT,
100                                 MVT::getVectorVT(NewVT, 2*OldElts),
101                                 OldVec);
102
103  // Extract the elements at 2 * Idx and 2 * Idx + 1 from the new vector.
104  SDOperand Idx = N->getOperand(1);
105
106  // Make sure the type of Idx is big enough to hold the new values.
107  if (Idx.getValueType().bitsLT(TLI.getPointerTy()))
108    Idx = DAG.getNode(ISD::ZERO_EXTEND, TLI.getPointerTy(), Idx);
109
110  Idx = DAG.getNode(ISD::ADD, Idx.getValueType(), Idx, Idx);
111  Lo = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, NewVec, Idx);
112
113  Idx = DAG.getNode(ISD::ADD, Idx.getValueType(), Idx,
114                    DAG.getConstant(1, Idx.getValueType()));
115  Hi = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, NewVec, Idx);
116
117  if (TLI.isBigEndian())
118    std::swap(Lo, Hi);
119}
120
121void DAGTypeLegalizer::ExpandRes_NormalLoad(SDNode *N, SDOperand &Lo,
122                                            SDOperand &Hi) {
123  assert(ISD::isNormalLoad(N) && "This routine only for normal loads!");
124
125  LoadSDNode *LD = cast<LoadSDNode>(N);
126  MVT NVT = TLI.getTypeToTransformTo(LD->getValueType(0));
127  SDOperand Chain = LD->getChain();
128  SDOperand Ptr = LD->getBasePtr();
129  int SVOffset = LD->getSrcValueOffset();
130  unsigned Alignment = LD->getAlignment();
131  bool isVolatile = LD->isVolatile();
132
133  assert(NVT.isByteSized() && "Expanded type not byte sized!");
134
135  Lo = DAG.getLoad(NVT, Chain, Ptr, LD->getSrcValue(), SVOffset,
136                   isVolatile, Alignment);
137
138  // Increment the pointer to the other half.
139  unsigned IncrementSize = NVT.getSizeInBits() / 8;
140  Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
141                    DAG.getIntPtrConstant(IncrementSize));
142  Hi = DAG.getLoad(NVT, Chain, Ptr, LD->getSrcValue(), SVOffset+IncrementSize,
143                   isVolatile, MinAlign(Alignment, IncrementSize));
144
145  // Build a factor node to remember that this load is independent of the
146  // other one.
147  Chain = DAG.getNode(ISD::TokenFactor, MVT::Other, Lo.getValue(1),
148                      Hi.getValue(1));
149
150  // Handle endianness of the load.
151  if (TLI.isBigEndian())
152    std::swap(Lo, Hi);
153
154  // Modified the chain - switch anything that used the old chain to use
155  // the new one.
156  ReplaceValueWith(SDOperand(N, 1), Chain);
157}
158
159//===--------------------------------------------------------------------===//
160// Generic Operand Expansion.
161//===--------------------------------------------------------------------===//
162
163SDOperand DAGTypeLegalizer::ExpandOp_BIT_CONVERT(SDNode *N) {
164  if (N->getValueType(0).isVector()) {
165    // An illegal expanding type is being converted to a legal vector type.
166    // Make a two element vector out of the expanded parts and convert that
167    // instead, but only if the new vector type is legal (otherwise there
168    // is no point, and it might create expansion loops).  For example, on
169    // x86 this turns v1i64 = BIT_CONVERT i64 into v1i64 = BIT_CONVERT v2i32.
170    MVT OVT = N->getOperand(0).getValueType();
171    MVT NVT = MVT::getVectorVT(TLI.getTypeToTransformTo(OVT), 2);
172
173    if (isTypeLegal(NVT)) {
174      SDOperand Parts[2];
175      GetExpandedOp(N->getOperand(0), Parts[0], Parts[1]);
176
177      if (TLI.isBigEndian())
178        std::swap(Parts[0], Parts[1]);
179
180      SDOperand Vec = DAG.getNode(ISD::BUILD_VECTOR, NVT, Parts, 2);
181      return DAG.getNode(ISD::BIT_CONVERT, N->getValueType(0), Vec);
182    }
183  }
184
185  // Otherwise, store to a temporary and load out again as the new type.
186  return CreateStackStoreLoad(N->getOperand(0), N->getValueType(0));
187}
188
189SDOperand DAGTypeLegalizer::ExpandOp_BUILD_VECTOR(SDNode *N) {
190  // The vector type is legal but the element type needs expansion.
191  MVT VecVT = N->getValueType(0);
192  unsigned NumElts = VecVT.getVectorNumElements();
193  MVT OldVT = N->getOperand(0).getValueType();
194  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
195
196  // Build a vector of twice the length out of the expanded elements.
197  // For example <3 x i64> -> <6 x i32>.
198  std::vector<SDOperand> NewElts;
199  NewElts.reserve(NumElts*2);
200
201  for (unsigned i = 0; i < NumElts; ++i) {
202    SDOperand Lo, Hi;
203    GetExpandedOp(N->getOperand(i), Lo, Hi);
204    if (TLI.isBigEndian())
205      std::swap(Lo, Hi);
206    NewElts.push_back(Lo);
207    NewElts.push_back(Hi);
208  }
209
210  SDOperand NewVec = DAG.getNode(ISD::BUILD_VECTOR,
211                                 MVT::getVectorVT(NewVT, NewElts.size()),
212                                 &NewElts[0], NewElts.size());
213
214  // Convert the new vector to the old vector type.
215  return DAG.getNode(ISD::BIT_CONVERT, VecVT, NewVec);
216}
217
218SDOperand DAGTypeLegalizer::ExpandOp_EXTRACT_ELEMENT(SDNode *N) {
219  SDOperand Lo, Hi;
220  GetExpandedOp(N->getOperand(0), Lo, Hi);
221  return cast<ConstantSDNode>(N->getOperand(1))->getValue() ? Hi : Lo;
222}
223
224SDOperand DAGTypeLegalizer::ExpandOp_NormalStore(SDNode *N, unsigned OpNo) {
225  assert(ISD::isNormalStore(N) && "This routine only for normal stores!");
226  assert(OpNo == 1 && "Can only expand the stored value so far");
227
228  StoreSDNode *St = cast<StoreSDNode>(N);
229  MVT NVT = TLI.getTypeToTransformTo(St->getValue().getValueType());
230  SDOperand Chain = St->getChain();
231  SDOperand Ptr = St->getBasePtr();
232  int SVOffset = St->getSrcValueOffset();
233  unsigned Alignment = St->getAlignment();
234  bool isVolatile = St->isVolatile();
235
236  assert(NVT.isByteSized() && "Expanded type not byte sized!");
237  unsigned IncrementSize = NVT.getSizeInBits() / 8;
238
239  SDOperand Lo, Hi;
240  GetExpandedOp(St->getValue(), Lo, Hi);
241
242  if (TLI.isBigEndian())
243    std::swap(Lo, Hi);
244
245  Lo = DAG.getStore(Chain, Lo, Ptr, St->getSrcValue(), SVOffset,
246                    isVolatile, Alignment);
247
248  Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
249                    DAG.getIntPtrConstant(IncrementSize));
250  assert(isTypeLegal(Ptr.getValueType()) && "Pointers must be legal!");
251  Hi = DAG.getStore(Chain, Hi, Ptr, St->getSrcValue(), SVOffset + IncrementSize,
252                    isVolatile, MinAlign(Alignment, IncrementSize));
253
254  return DAG.getNode(ISD::TokenFactor, MVT::Other, Lo, Hi);
255}
256
257
258//===--------------------------------------------------------------------===//
259// Generic Result Splitting.
260//===--------------------------------------------------------------------===//
261
262// Be careful to make no assumptions about which of Lo/Hi is stored first in
263// memory (for vectors it is always Lo first followed by Hi in the following
264// bytes; for integers and floats it is Lo first if and only if the machine is
265// little-endian).
266
267void DAGTypeLegalizer::SplitRes_MERGE_VALUES(SDNode *N,
268                                             SDOperand &Lo, SDOperand &Hi) {
269  // A MERGE_VALUES node can produce any number of values.  We know that the
270  // first illegal one needs to be expanded into Lo/Hi.
271  unsigned i;
272
273  // The string of legal results gets turns into the input operands, which have
274  // the same type.
275  for (i = 0; isTypeLegal(N->getValueType(i)); ++i)
276    ReplaceValueWith(SDOperand(N, i), SDOperand(N->getOperand(i)));
277
278  // The first illegal result must be the one that needs to be expanded.
279  GetSplitOp(N->getOperand(i), Lo, Hi);
280
281  // Legalize the rest of the results into the input operands whether they are
282  // legal or not.
283  unsigned e = N->getNumValues();
284  for (++i; i != e; ++i)
285    ReplaceValueWith(SDOperand(N, i), SDOperand(N->getOperand(i)));
286}
287
288void DAGTypeLegalizer::SplitRes_SELECT(SDNode *N, SDOperand &Lo,
289                                       SDOperand &Hi) {
290  SDOperand LL, LH, RL, RH;
291  GetSplitOp(N->getOperand(1), LL, LH);
292  GetSplitOp(N->getOperand(2), RL, RH);
293
294  SDOperand Cond = N->getOperand(0);
295  Lo = DAG.getNode(ISD::SELECT, LL.getValueType(), Cond, LL, RL);
296  Hi = DAG.getNode(ISD::SELECT, LH.getValueType(), Cond, LH, RH);
297}
298
299void DAGTypeLegalizer::SplitRes_SELECT_CC(SDNode *N, SDOperand &Lo,
300                                          SDOperand &Hi) {
301  SDOperand LL, LH, RL, RH;
302  GetSplitOp(N->getOperand(2), LL, LH);
303  GetSplitOp(N->getOperand(3), RL, RH);
304
305  Lo = DAG.getNode(ISD::SELECT_CC, LL.getValueType(), N->getOperand(0),
306                   N->getOperand(1), LL, RL, N->getOperand(4));
307  Hi = DAG.getNode(ISD::SELECT_CC, LH.getValueType(), N->getOperand(0),
308                   N->getOperand(1), LH, RH, N->getOperand(4));
309}
310
311void DAGTypeLegalizer::SplitRes_UNDEF(SDNode *N, SDOperand &Lo, SDOperand &Hi) {
312  MVT LoVT, HiVT;
313  GetSplitDestVTs(N->getValueType(0), LoVT, HiVT);
314  Lo = DAG.getNode(ISD::UNDEF, LoVT);
315  Hi = DAG.getNode(ISD::UNDEF, HiVT);
316}
317