LegalizeTypesGeneric.cpp revision 5275afbfb6ae643383456cf4293041d2c11c6158 
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, SDOperand &Lo,
32                                             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, SDOperand &Lo,
82                                            SDOperand &Hi) {
83  // Return the operands.
84  Lo = N->getOperand(0);
85  Hi = N->getOperand(1);
86}
87
88void DAGTypeLegalizer::ExpandRes_EXTRACT_ELEMENT(SDNode *N, SDOperand &Lo,
89                                                 SDOperand &Hi) {
90  GetExpandedOp(N->getOperand(0), Lo, Hi);
91  SDOperand Part = cast<ConstantSDNode>(N->getOperand(1))->getValue() ? Hi : Lo;
92
93  assert(Part.getValueType() == N->getValueType(0) &&
94         "Type twice as big as expanded type not itself expanded!");
95  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
96
97  Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, NVT, Part,
98                   DAG.getConstant(0, TLI.getPointerTy()));
99  Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, NVT, Part,
100                   DAG.getConstant(1, TLI.getPointerTy()));
101}
102
103void DAGTypeLegalizer::ExpandRes_EXTRACT_VECTOR_ELT(SDNode *N, SDOperand &Lo,
104                                                    SDOperand &Hi) {
105  SDOperand OldVec = N->getOperand(0);
106  unsigned OldElts = OldVec.getValueType().getVectorNumElements();
107
108  // Convert to a vector of the expanded element type, for example
109  // <3 x i64> -> <6 x i32>.
110  MVT OldVT = N->getValueType(0);
111  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
112
113  SDOperand NewVec = DAG.getNode(ISD::BIT_CONVERT,
114                                 MVT::getVectorVT(NewVT, 2*OldElts),
115                                 OldVec);
116
117  // Extract the elements at 2 * Idx and 2 * Idx + 1 from the new vector.
118  SDOperand Idx = N->getOperand(1);
119
120  // Make sure the type of Idx is big enough to hold the new values.
121  if (Idx.getValueType().bitsLT(TLI.getPointerTy()))
122    Idx = DAG.getNode(ISD::ZERO_EXTEND, TLI.getPointerTy(), Idx);
123
124  Idx = DAG.getNode(ISD::ADD, Idx.getValueType(), Idx, Idx);
125  Lo = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, NewVec, Idx);
126
127  Idx = DAG.getNode(ISD::ADD, Idx.getValueType(), Idx,
128                    DAG.getConstant(1, Idx.getValueType()));
129  Hi = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, NewVec, Idx);
130
131  if (TLI.isBigEndian())
132    std::swap(Lo, Hi);
133}
134
135void DAGTypeLegalizer::ExpandRes_NormalLoad(SDNode *N, SDOperand &Lo,
136                                            SDOperand &Hi) {
137  assert(ISD::isNormalLoad(N) && "This routine only for normal loads!");
138
139  LoadSDNode *LD = cast<LoadSDNode>(N);
140  MVT NVT = TLI.getTypeToTransformTo(LD->getValueType(0));
141  SDOperand Chain = LD->getChain();
142  SDOperand Ptr = LD->getBasePtr();
143  int SVOffset = LD->getSrcValueOffset();
144  unsigned Alignment = LD->getAlignment();
145  bool isVolatile = LD->isVolatile();
146
147  assert(NVT.isByteSized() && "Expanded type not byte sized!");
148
149  Lo = DAG.getLoad(NVT, Chain, Ptr, LD->getSrcValue(), SVOffset,
150                   isVolatile, Alignment);
151
152  // Increment the pointer to the other half.
153  unsigned IncrementSize = NVT.getSizeInBits() / 8;
154  Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
155                    DAG.getIntPtrConstant(IncrementSize));
156  Hi = DAG.getLoad(NVT, Chain, Ptr, LD->getSrcValue(), SVOffset+IncrementSize,
157                   isVolatile, MinAlign(Alignment, IncrementSize));
158
159  // Build a factor node to remember that this load is independent of the
160  // other one.
161  Chain = DAG.getNode(ISD::TokenFactor, MVT::Other, Lo.getValue(1),
162                      Hi.getValue(1));
163
164  // Handle endianness of the load.
165  if (TLI.isBigEndian())
166    std::swap(Lo, Hi);
167
168  // Modified the chain - switch anything that used the old chain to use
169  // the new one.
170  ReplaceValueWith(SDOperand(N, 1), Chain);
171}
172
173//===--------------------------------------------------------------------===//
174// Generic Operand Expansion.
175//===--------------------------------------------------------------------===//
176
177SDOperand DAGTypeLegalizer::ExpandOp_BIT_CONVERT(SDNode *N) {
178  if (N->getValueType(0).isVector()) {
179    // An illegal expanding type is being converted to a legal vector type.
180    // Make a two element vector out of the expanded parts and convert that
181    // instead, but only if the new vector type is legal (otherwise there
182    // is no point, and it might create expansion loops).  For example, on
183    // x86 this turns v1i64 = BIT_CONVERT i64 into v1i64 = BIT_CONVERT v2i32.
184    MVT OVT = N->getOperand(0).getValueType();
185    MVT NVT = MVT::getVectorVT(TLI.getTypeToTransformTo(OVT), 2);
186
187    if (isTypeLegal(NVT)) {
188      SDOperand Parts[2];
189      GetExpandedOp(N->getOperand(0), Parts[0], Parts[1]);
190
191      if (TLI.isBigEndian())
192        std::swap(Parts[0], Parts[1]);
193
194      SDOperand Vec = DAG.getNode(ISD::BUILD_VECTOR, NVT, Parts, 2);
195      return DAG.getNode(ISD::BIT_CONVERT, N->getValueType(0), Vec);
196    }
197  }
198
199  // Otherwise, store to a temporary and load out again as the new type.
200  return CreateStackStoreLoad(N->getOperand(0), N->getValueType(0));
201}
202
203SDOperand DAGTypeLegalizer::ExpandOp_BUILD_VECTOR(SDNode *N) {
204  // The vector type is legal but the element type needs expansion.
205  MVT VecVT = N->getValueType(0);
206  unsigned NumElts = VecVT.getVectorNumElements();
207  MVT OldVT = N->getOperand(0).getValueType();
208  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
209
210  // Build a vector of twice the length out of the expanded elements.
211  // For example <3 x i64> -> <6 x i32>.
212  std::vector<SDOperand> NewElts;
213  NewElts.reserve(NumElts*2);
214
215  for (unsigned i = 0; i < NumElts; ++i) {
216    SDOperand Lo, Hi;
217    GetExpandedOp(N->getOperand(i), Lo, Hi);
218    if (TLI.isBigEndian())
219      std::swap(Lo, Hi);
220    NewElts.push_back(Lo);
221    NewElts.push_back(Hi);
222  }
223
224  SDOperand NewVec = DAG.getNode(ISD::BUILD_VECTOR,
225                                 MVT::getVectorVT(NewVT, NewElts.size()),
226                                 &NewElts[0], NewElts.size());
227
228  // Convert the new vector to the old vector type.
229  return DAG.getNode(ISD::BIT_CONVERT, VecVT, NewVec);
230}
231
232SDOperand DAGTypeLegalizer::ExpandOp_EXTRACT_ELEMENT(SDNode *N) {
233  SDOperand Lo, Hi;
234  GetExpandedOp(N->getOperand(0), Lo, Hi);
235  return cast<ConstantSDNode>(N->getOperand(1))->getValue() ? Hi : Lo;
236}
237
238SDOperand DAGTypeLegalizer::ExpandOp_NormalStore(SDNode *N, unsigned OpNo) {
239  assert(ISD::isNormalStore(N) && "This routine only for normal stores!");
240  assert(OpNo == 1 && "Can only expand the stored value so far");
241
242  StoreSDNode *St = cast<StoreSDNode>(N);
243  MVT NVT = TLI.getTypeToTransformTo(St->getValue().getValueType());
244  SDOperand Chain = St->getChain();
245  SDOperand Ptr = St->getBasePtr();
246  int SVOffset = St->getSrcValueOffset();
247  unsigned Alignment = St->getAlignment();
248  bool isVolatile = St->isVolatile();
249
250  assert(NVT.isByteSized() && "Expanded type not byte sized!");
251  unsigned IncrementSize = NVT.getSizeInBits() / 8;
252
253  SDOperand Lo, Hi;
254  GetExpandedOp(St->getValue(), Lo, Hi);
255
256  if (TLI.isBigEndian())
257    std::swap(Lo, Hi);
258
259  Lo = DAG.getStore(Chain, Lo, Ptr, St->getSrcValue(), SVOffset,
260                    isVolatile, Alignment);
261
262  Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
263                    DAG.getIntPtrConstant(IncrementSize));
264  assert(isTypeLegal(Ptr.getValueType()) && "Pointers must be legal!");
265  Hi = DAG.getStore(Chain, Hi, Ptr, St->getSrcValue(), SVOffset + IncrementSize,
266                    isVolatile, MinAlign(Alignment, IncrementSize));
267
268  return DAG.getNode(ISD::TokenFactor, MVT::Other, Lo, Hi);
269}
270
271
272//===--------------------------------------------------------------------===//
273// Generic Result Splitting.
274//===--------------------------------------------------------------------===//
275
276// Be careful to make no assumptions about which of Lo/Hi is stored first in
277// memory (for vectors it is always Lo first followed by Hi in the following
278// bytes; for integers and floats it is Lo first if and only if the machine is
279// little-endian).
280
281void DAGTypeLegalizer::SplitRes_MERGE_VALUES(SDNode *N,
282                                             SDOperand &Lo, SDOperand &Hi) {
283  // A MERGE_VALUES node can produce any number of values.  We know that the
284  // first illegal one needs to be expanded into Lo/Hi.
285  unsigned i;
286
287  // The string of legal results gets turns into the input operands, which have
288  // the same type.
289  for (i = 0; isTypeLegal(N->getValueType(i)); ++i)
290    ReplaceValueWith(SDOperand(N, i), SDOperand(N->getOperand(i)));
291
292  // The first illegal result must be the one that needs to be expanded.
293  GetSplitOp(N->getOperand(i), Lo, Hi);
294
295  // Legalize the rest of the results into the input operands whether they are
296  // legal or not.
297  unsigned e = N->getNumValues();
298  for (++i; i != e; ++i)
299    ReplaceValueWith(SDOperand(N, i), SDOperand(N->getOperand(i)));
300}
301
302void DAGTypeLegalizer::SplitRes_SELECT(SDNode *N, SDOperand &Lo,
303                                       SDOperand &Hi) {
304  SDOperand LL, LH, RL, RH;
305  GetSplitOp(N->getOperand(1), LL, LH);
306  GetSplitOp(N->getOperand(2), RL, RH);
307
308  SDOperand Cond = N->getOperand(0);
309  Lo = DAG.getNode(ISD::SELECT, LL.getValueType(), Cond, LL, RL);
310  Hi = DAG.getNode(ISD::SELECT, LH.getValueType(), Cond, LH, RH);
311}
312
313void DAGTypeLegalizer::SplitRes_SELECT_CC(SDNode *N, SDOperand &Lo,
314                                          SDOperand &Hi) {
315  SDOperand LL, LH, RL, RH;
316  GetSplitOp(N->getOperand(2), LL, LH);
317  GetSplitOp(N->getOperand(3), RL, RH);
318
319  Lo = DAG.getNode(ISD::SELECT_CC, LL.getValueType(), N->getOperand(0),
320                   N->getOperand(1), LL, RL, N->getOperand(4));
321  Hi = DAG.getNode(ISD::SELECT_CC, LH.getValueType(), N->getOperand(0),
322                   N->getOperand(1), LH, RH, N->getOperand(4));
323}
324
325void DAGTypeLegalizer::SplitRes_UNDEF(SDNode *N, SDOperand &Lo, SDOperand &Hi) {
326  MVT LoVT, HiVT;
327  GetSplitDestVTs(N->getValueType(0), LoVT, HiVT);
328  Lo = DAG.getNode(ISD::UNDEF, LoVT);
329  Hi = DAG.getNode(ISD::UNDEF, HiVT);
330}
331