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