1//===-- X86ShuffleDecode.cpp - X86 shuffle decode logic -------------------===//
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// Define several functions to decode x86 specific shuffle semantics into a
11// generic vector mask.
12//
13//===----------------------------------------------------------------------===//
14
15#include "X86ShuffleDecode.h"
16#include "llvm/CodeGen/MachineValueType.h"
17
18//===----------------------------------------------------------------------===//
19//  Vector Mask Decoding
20//===----------------------------------------------------------------------===//
21
22namespace llvm {
23
24void DecodeINSERTPSMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
25  // Defaults the copying the dest value.
26  ShuffleMask.push_back(0);
27  ShuffleMask.push_back(1);
28  ShuffleMask.push_back(2);
29  ShuffleMask.push_back(3);
30
31  // Decode the immediate.
32  unsigned ZMask = Imm & 15;
33  unsigned CountD = (Imm >> 4) & 3;
34  unsigned CountS = (Imm >> 6) & 3;
35
36  // CountS selects which input element to use.
37  unsigned InVal = 4+CountS;
38  // CountD specifies which element of destination to update.
39  ShuffleMask[CountD] = InVal;
40  // ZMask zaps values, potentially overriding the CountD elt.
41  if (ZMask & 1) ShuffleMask[0] = SM_SentinelZero;
42  if (ZMask & 2) ShuffleMask[1] = SM_SentinelZero;
43  if (ZMask & 4) ShuffleMask[2] = SM_SentinelZero;
44  if (ZMask & 8) ShuffleMask[3] = SM_SentinelZero;
45}
46
47// <3,1> or <6,7,2,3>
48void DecodeMOVHLPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask) {
49  for (unsigned i = NElts/2; i != NElts; ++i)
50    ShuffleMask.push_back(NElts+i);
51
52  for (unsigned i = NElts/2; i != NElts; ++i)
53    ShuffleMask.push_back(i);
54}
55
56// <0,2> or <0,1,4,5>
57void DecodeMOVLHPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask) {
58  for (unsigned i = 0; i != NElts/2; ++i)
59    ShuffleMask.push_back(i);
60
61  for (unsigned i = 0; i != NElts/2; ++i)
62    ShuffleMask.push_back(NElts+i);
63}
64
65void DecodePALIGNRMask(MVT VT, unsigned Imm,
66                       SmallVectorImpl<int> &ShuffleMask) {
67  unsigned NumElts = VT.getVectorNumElements();
68  unsigned Offset = Imm * (VT.getVectorElementType().getSizeInBits() / 8);
69
70  unsigned NumLanes = VT.getSizeInBits() / 128;
71  unsigned NumLaneElts = NumElts / NumLanes;
72
73  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
74    for (unsigned i = 0; i != NumLaneElts; ++i) {
75      unsigned Base = i + Offset;
76      // if i+offset is out of this lane then we actually need the other source
77      if (Base >= NumLaneElts) Base += NumElts - NumLaneElts;
78      ShuffleMask.push_back(Base + l);
79    }
80  }
81}
82
83/// DecodePSHUFMask - This decodes the shuffle masks for pshufd, and vpermilp*.
84/// VT indicates the type of the vector allowing it to handle different
85/// datatypes and vector widths.
86void DecodePSHUFMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
87  unsigned NumElts = VT.getVectorNumElements();
88
89  unsigned NumLanes = VT.getSizeInBits() / 128;
90  unsigned NumLaneElts = NumElts / NumLanes;
91
92  unsigned NewImm = Imm;
93  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
94    for (unsigned i = 0; i != NumLaneElts; ++i) {
95      ShuffleMask.push_back(NewImm % NumLaneElts + l);
96      NewImm /= NumLaneElts;
97    }
98    if (NumLaneElts == 4) NewImm = Imm; // reload imm
99  }
100}
101
102void DecodePSHUFHWMask(MVT VT, unsigned Imm,
103                       SmallVectorImpl<int> &ShuffleMask) {
104  unsigned NumElts = VT.getVectorNumElements();
105
106  for (unsigned l = 0; l != NumElts; l += 8) {
107    unsigned NewImm = Imm;
108    for (unsigned i = 0, e = 4; i != e; ++i) {
109      ShuffleMask.push_back(l + i);
110    }
111    for (unsigned i = 4, e = 8; i != e; ++i) {
112      ShuffleMask.push_back(l + 4 + (NewImm & 3));
113      NewImm >>= 2;
114    }
115  }
116}
117
118void DecodePSHUFLWMask(MVT VT, unsigned Imm,
119                       SmallVectorImpl<int> &ShuffleMask) {
120  unsigned NumElts = VT.getVectorNumElements();
121
122  for (unsigned l = 0; l != NumElts; l += 8) {
123    unsigned NewImm = Imm;
124    for (unsigned i = 0, e = 4; i != e; ++i) {
125      ShuffleMask.push_back(l + (NewImm & 3));
126      NewImm >>= 2;
127    }
128    for (unsigned i = 4, e = 8; i != e; ++i) {
129      ShuffleMask.push_back(l + i);
130    }
131  }
132}
133
134/// DecodeSHUFPMask - This decodes the shuffle masks for shufp*. VT indicates
135/// the type of the vector allowing it to handle different datatypes and vector
136/// widths.
137void DecodeSHUFPMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
138  unsigned NumElts = VT.getVectorNumElements();
139
140  unsigned NumLanes = VT.getSizeInBits() / 128;
141  unsigned NumLaneElts = NumElts / NumLanes;
142
143  unsigned NewImm = Imm;
144  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
145    // each half of a lane comes from different source
146    for (unsigned s = 0; s != NumElts*2; s += NumElts) {
147      for (unsigned i = 0; i != NumLaneElts/2; ++i) {
148        ShuffleMask.push_back(NewImm % NumLaneElts + s + l);
149        NewImm /= NumLaneElts;
150      }
151    }
152    if (NumLaneElts == 4) NewImm = Imm; // reload imm
153  }
154}
155
156/// DecodeUNPCKHMask - This decodes the shuffle masks for unpckhps/unpckhpd
157/// and punpckh*. VT indicates the type of the vector allowing it to handle
158/// different datatypes and vector widths.
159void DecodeUNPCKHMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
160  unsigned NumElts = VT.getVectorNumElements();
161
162  // Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
163  // independently on 128-bit lanes.
164  unsigned NumLanes = VT.getSizeInBits() / 128;
165  if (NumLanes == 0 ) NumLanes = 1;  // Handle MMX
166  unsigned NumLaneElts = NumElts / NumLanes;
167
168  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
169    for (unsigned i = l + NumLaneElts/2, e = l + NumLaneElts; i != e; ++i) {
170      ShuffleMask.push_back(i);          // Reads from dest/src1
171      ShuffleMask.push_back(i+NumElts);  // Reads from src/src2
172    }
173  }
174}
175
176/// DecodeUNPCKLMask - This decodes the shuffle masks for unpcklps/unpcklpd
177/// and punpckl*. VT indicates the type of the vector allowing it to handle
178/// different datatypes and vector widths.
179void DecodeUNPCKLMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
180  unsigned NumElts = VT.getVectorNumElements();
181
182  // Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
183  // independently on 128-bit lanes.
184  unsigned NumLanes = VT.getSizeInBits() / 128;
185  if (NumLanes == 0 ) NumLanes = 1;  // Handle MMX
186  unsigned NumLaneElts = NumElts / NumLanes;
187
188  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
189    for (unsigned i = l, e = l + NumLaneElts/2; i != e; ++i) {
190      ShuffleMask.push_back(i);          // Reads from dest/src1
191      ShuffleMask.push_back(i+NumElts);  // Reads from src/src2
192    }
193  }
194}
195
196void DecodeVPERM2X128Mask(MVT VT, unsigned Imm,
197                          SmallVectorImpl<int> &ShuffleMask) {
198  if (Imm & 0x88)
199    return; // Not a shuffle
200
201  unsigned HalfSize = VT.getVectorNumElements()/2;
202
203  for (unsigned l = 0; l != 2; ++l) {
204    unsigned HalfBegin = ((Imm >> (l*4)) & 0x3) * HalfSize;
205    for (unsigned i = HalfBegin, e = HalfBegin+HalfSize; i != e; ++i)
206      ShuffleMask.push_back(i);
207  }
208}
209
210/// DecodeVPERMMask - this decodes the shuffle masks for VPERMQ/VPERMPD.
211/// No VT provided since it only works on 256-bit, 4 element vectors.
212void DecodeVPERMMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
213  for (unsigned i = 0; i != 4; ++i) {
214    ShuffleMask.push_back((Imm >> (2*i)) & 3);
215  }
216}
217
218} // llvm namespace
219