LegalizeTypesGeneric.cpp revision f5aeb1a8e4cf272c7348376d185ef8d8267653e0 
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, SDValue &Lo,
32                                             SDValue &Hi) {
33  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
34  SDValue 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 SplitVector:
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 ScalarizeVector:
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  SDValue Op = CreateStackStoreLoad(InOp, N->getValueType(0));
78  ExpandRes_NormalLoad(Op.getNode(), Lo, Hi);
79}
80
81void DAGTypeLegalizer::ExpandRes_BUILD_PAIR(SDNode *N, SDValue &Lo,
82                                            SDValue &Hi) {
83  // Return the operands.
84  Lo = N->getOperand(0);
85  Hi = N->getOperand(1);
86}
87
88void DAGTypeLegalizer::ExpandRes_EXTRACT_ELEMENT(SDNode *N, SDValue &Lo,
89                                                 SDValue &Hi) {
90  GetExpandedOp(N->getOperand(0), Lo, Hi);
91  SDValue Part = cast<ConstantSDNode>(N->getOperand(1))->getZExtValue() ?
92                   Hi : Lo;
93
94  assert(Part.getValueType() == N->getValueType(0) &&
95         "Type twice as big as expanded type not itself expanded!");
96  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
97
98  Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, NVT, Part,
99                   DAG.getConstant(0, TLI.getPointerTy()));
100  Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, NVT, Part,
101                   DAG.getConstant(1, TLI.getPointerTy()));
102}
103
104void DAGTypeLegalizer::ExpandRes_EXTRACT_VECTOR_ELT(SDNode *N, SDValue &Lo,
105                                                    SDValue &Hi) {
106  SDValue OldVec = N->getOperand(0);
107  unsigned OldElts = OldVec.getValueType().getVectorNumElements();
108
109  // Convert to a vector of the expanded element type, for example
110  // <3 x i64> -> <6 x i32>.
111  MVT OldVT = N->getValueType(0);
112  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
113
114  SDValue NewVec = DAG.getNode(ISD::BIT_CONVERT,
115                                 MVT::getVectorVT(NewVT, 2*OldElts),
116                                 OldVec);
117
118  // Extract the elements at 2 * Idx and 2 * Idx + 1 from the new vector.
119  SDValue Idx = N->getOperand(1);
120
121  // Make sure the type of Idx is big enough to hold the new values.
122  if (Idx.getValueType().bitsLT(TLI.getPointerTy()))
123    Idx = DAG.getNode(ISD::ZERO_EXTEND, TLI.getPointerTy(), Idx);
124
125  Idx = DAG.getNode(ISD::ADD, Idx.getValueType(), Idx, Idx);
126  Lo = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, NewVec, Idx);
127
128  Idx = DAG.getNode(ISD::ADD, Idx.getValueType(), Idx,
129                    DAG.getConstant(1, Idx.getValueType()));
130  Hi = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, NewVec, Idx);
131
132  if (TLI.isBigEndian())
133    std::swap(Lo, Hi);
134}
135
136void DAGTypeLegalizer::ExpandRes_NormalLoad(SDNode *N, SDValue &Lo,
137                                            SDValue &Hi) {
138  assert(ISD::isNormalLoad(N) && "This routine only for normal loads!");
139
140  LoadSDNode *LD = cast<LoadSDNode>(N);
141  MVT NVT = TLI.getTypeToTransformTo(LD->getValueType(0));
142  SDValue Chain = LD->getChain();
143  SDValue Ptr = LD->getBasePtr();
144  int SVOffset = LD->getSrcValueOffset();
145  unsigned Alignment = LD->getAlignment();
146  bool isVolatile = LD->isVolatile();
147
148  assert(NVT.isByteSized() && "Expanded type not byte sized!");
149
150  Lo = DAG.getLoad(NVT, Chain, Ptr, LD->getSrcValue(), SVOffset,
151                   isVolatile, Alignment);
152
153  // Increment the pointer to the other half.
154  unsigned IncrementSize = NVT.getSizeInBits() / 8;
155  Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
156                    DAG.getIntPtrConstant(IncrementSize));
157  Hi = DAG.getLoad(NVT, Chain, Ptr, LD->getSrcValue(), SVOffset+IncrementSize,
158                   isVolatile, MinAlign(Alignment, IncrementSize));
159
160  // Build a factor node to remember that this load is independent of the
161  // other one.
162  Chain = DAG.getNode(ISD::TokenFactor, MVT::Other, Lo.getValue(1),
163                      Hi.getValue(1));
164
165  // Handle endianness of the load.
166  if (TLI.isBigEndian())
167    std::swap(Lo, Hi);
168
169  // Modified the chain - switch anything that used the old chain to use
170  // the new one.
171  ReplaceValueWith(SDValue(N, 1), Chain);
172}
173
174
175//===--------------------------------------------------------------------===//
176// Generic Operand Expansion.
177//===--------------------------------------------------------------------===//
178
179SDValue DAGTypeLegalizer::ExpandOp_BIT_CONVERT(SDNode *N) {
180  if (N->getValueType(0).isVector()) {
181    // An illegal expanding type is being converted to a legal vector type.
182    // Make a two element vector out of the expanded parts and convert that
183    // instead, but only if the new vector type is legal (otherwise there
184    // is no point, and it might create expansion loops).  For example, on
185    // x86 this turns v1i64 = BIT_CONVERT i64 into v1i64 = BIT_CONVERT v2i32.
186    MVT OVT = N->getOperand(0).getValueType();
187    MVT NVT = MVT::getVectorVT(TLI.getTypeToTransformTo(OVT), 2);
188
189    if (isTypeLegal(NVT)) {
190      SDValue Parts[2];
191      GetExpandedOp(N->getOperand(0), Parts[0], Parts[1]);
192
193      if (TLI.isBigEndian())
194        std::swap(Parts[0], Parts[1]);
195
196      SDValue Vec = DAG.getNode(ISD::BUILD_VECTOR, NVT, Parts, 2);
197      return DAG.getNode(ISD::BIT_CONVERT, N->getValueType(0), Vec);
198    }
199  }
200
201  // Otherwise, store to a temporary and load out again as the new type.
202  return CreateStackStoreLoad(N->getOperand(0), N->getValueType(0));
203}
204
205SDValue DAGTypeLegalizer::ExpandOp_BUILD_VECTOR(SDNode *N) {
206  // The vector type is legal but the element type needs expansion.
207  MVT VecVT = N->getValueType(0);
208  unsigned NumElts = VecVT.getVectorNumElements();
209  MVT OldVT = N->getOperand(0).getValueType();
210  MVT NewVT = TLI.getTypeToTransformTo(OldVT);
211
212  // Build a vector of twice the length out of the expanded elements.
213  // For example <3 x i64> -> <6 x i32>.
214  std::vector<SDValue> NewElts;
215  NewElts.reserve(NumElts*2);
216
217  for (unsigned i = 0; i < NumElts; ++i) {
218    SDValue Lo, Hi;
219    GetExpandedOp(N->getOperand(i), Lo, Hi);
220    if (TLI.isBigEndian())
221      std::swap(Lo, Hi);
222    NewElts.push_back(Lo);
223    NewElts.push_back(Hi);
224  }
225
226  SDValue NewVec = DAG.getNode(ISD::BUILD_VECTOR,
227                                 MVT::getVectorVT(NewVT, NewElts.size()),
228                                 &NewElts[0], NewElts.size());
229
230  // Convert the new vector to the old vector type.
231  return DAG.getNode(ISD::BIT_CONVERT, VecVT, NewVec);
232}
233
234SDValue DAGTypeLegalizer::ExpandOp_EXTRACT_ELEMENT(SDNode *N) {
235  SDValue Lo, Hi;
236  GetExpandedOp(N->getOperand(0), Lo, Hi);
237  return cast<ConstantSDNode>(N->getOperand(1))->getZExtValue() ? Hi : Lo;
238}
239
240SDValue DAGTypeLegalizer::ExpandOp_NormalStore(SDNode *N, unsigned OpNo) {
241  assert(ISD::isNormalStore(N) && "This routine only for normal stores!");
242  assert(OpNo == 1 && "Can only expand the stored value so far");
243
244  StoreSDNode *St = cast<StoreSDNode>(N);
245  MVT NVT = TLI.getTypeToTransformTo(St->getValue().getValueType());
246  SDValue Chain = St->getChain();
247  SDValue Ptr = St->getBasePtr();
248  int SVOffset = St->getSrcValueOffset();
249  unsigned Alignment = St->getAlignment();
250  bool isVolatile = St->isVolatile();
251
252  assert(NVT.isByteSized() && "Expanded type not byte sized!");
253  unsigned IncrementSize = NVT.getSizeInBits() / 8;
254
255  SDValue Lo, Hi;
256  GetExpandedOp(St->getValue(), Lo, Hi);
257
258  if (TLI.isBigEndian())
259    std::swap(Lo, Hi);
260
261  Lo = DAG.getStore(Chain, Lo, Ptr, St->getSrcValue(), SVOffset,
262                    isVolatile, Alignment);
263
264  Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
265                    DAG.getIntPtrConstant(IncrementSize));
266  assert(isTypeLegal(Ptr.getValueType()) && "Pointers must be legal!");
267  Hi = DAG.getStore(Chain, Hi, Ptr, St->getSrcValue(), SVOffset + IncrementSize,
268                    isVolatile, MinAlign(Alignment, IncrementSize));
269
270  return DAG.getNode(ISD::TokenFactor, MVT::Other, Lo, Hi);
271}
272
273
274//===--------------------------------------------------------------------===//
275// Generic Result Splitting.
276//===--------------------------------------------------------------------===//
277
278// Be careful to make no assumptions about which of Lo/Hi is stored first in
279// memory (for vectors it is always Lo first followed by Hi in the following
280// bytes; for integers and floats it is Lo first if and only if the machine is
281// little-endian).
282
283void DAGTypeLegalizer::SplitRes_MERGE_VALUES(SDNode *N,
284                                             SDValue &Lo, SDValue &Hi) {
285  // A MERGE_VALUES node can produce any number of values.  We know that the
286  // first illegal one needs to be expanded into Lo/Hi.
287  unsigned i;
288
289  // The string of legal results gets turns into the input operands, which have
290  // the same type.
291  for (i = 0; isTypeLegal(N->getValueType(i)); ++i)
292    ReplaceValueWith(SDValue(N, i), SDValue(N->getOperand(i)));
293
294  // The first illegal result must be the one that needs to be expanded.
295  GetSplitOp(N->getOperand(i), Lo, Hi);
296
297  // Legalize the rest of the results into the input operands whether they are
298  // legal or not.
299  unsigned e = N->getNumValues();
300  for (++i; i != e; ++i)
301    ReplaceValueWith(SDValue(N, i), SDValue(N->getOperand(i)));
302}
303
304void DAGTypeLegalizer::SplitRes_SELECT(SDNode *N, SDValue &Lo,
305                                       SDValue &Hi) {
306  SDValue LL, LH, RL, RH;
307  GetSplitOp(N->getOperand(1), LL, LH);
308  GetSplitOp(N->getOperand(2), RL, RH);
309
310  SDValue Cond = N->getOperand(0);
311  Lo = DAG.getNode(ISD::SELECT, LL.getValueType(), Cond, LL, RL);
312  Hi = DAG.getNode(ISD::SELECT, LH.getValueType(), Cond, LH, RH);
313}
314
315void DAGTypeLegalizer::SplitRes_SELECT_CC(SDNode *N, SDValue &Lo,
316                                          SDValue &Hi) {
317  SDValue LL, LH, RL, RH;
318  GetSplitOp(N->getOperand(2), LL, LH);
319  GetSplitOp(N->getOperand(3), RL, RH);
320
321  Lo = DAG.getNode(ISD::SELECT_CC, LL.getValueType(), N->getOperand(0),
322                   N->getOperand(1), LL, RL, N->getOperand(4));
323  Hi = DAG.getNode(ISD::SELECT_CC, LH.getValueType(), N->getOperand(0),
324                   N->getOperand(1), LH, RH, N->getOperand(4));
325}
326
327void DAGTypeLegalizer::SplitRes_UNDEF(SDNode *N, SDValue &Lo, SDValue &Hi) {
328  MVT LoVT, HiVT;
329  GetSplitDestVTs(N->getValueType(0), LoVT, HiVT);
330  Lo = DAG.getNode(ISD::UNDEF, LoVT);
331  Hi = DAG.getNode(ISD::UNDEF, HiVT);
332}
333