X86ShuffleDecode.cpp revision 239462 
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
64/// DecodePSHUFMask - This decodes the shuffle masks for pshufd, and vpermilp*.
65/// VT indicates the type of the vector allowing it to handle different
66/// datatypes and vector widths.
67void DecodePSHUFMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
68  unsigned NumElts = VT.getVectorNumElements();
69
70  unsigned NumLanes = VT.getSizeInBits() / 128;
71  unsigned NumLaneElts = NumElts / NumLanes;
72
73  unsigned NewImm = Imm;
74  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
75    for (unsigned i = 0; i != NumLaneElts; ++i) {
76      ShuffleMask.push_back(NewImm % NumLaneElts + l);
77      NewImm /= NumLaneElts;
78    }
79    if (NumLaneElts == 4) NewImm = Imm; // reload imm
80  }
81}
82
83void DecodePSHUFHWMask(MVT VT, unsigned Imm,
84                       SmallVectorImpl<int> &ShuffleMask) {
85  unsigned NumElts = VT.getVectorNumElements();
86
87  for (unsigned l = 0; l != NumElts; l += 8) {
88    unsigned NewImm = Imm;
89    for (unsigned i = 0, e = 4; i != e; ++i) {
90      ShuffleMask.push_back(l + i);
91    }
92    for (unsigned i = 4, e = 8; i != e; ++i) {
93      ShuffleMask.push_back(l + 4 + (NewImm & 3));
94      NewImm >>= 2;
95    }
96  }
97}
98
99void DecodePSHUFLWMask(MVT VT, unsigned Imm,
100                       SmallVectorImpl<int> &ShuffleMask) {
101  unsigned NumElts = VT.getVectorNumElements();
102
103  for (unsigned l = 0; l != NumElts; l += 8) {
104    unsigned NewImm = Imm;
105    for (unsigned i = 0, e = 4; i != e; ++i) {
106      ShuffleMask.push_back(l + (NewImm & 3));
107      NewImm >>= 2;
108    }
109    for (unsigned i = 4, e = 8; i != e; ++i) {
110      ShuffleMask.push_back(l + i);
111    }
112  }
113}
114
115/// DecodeSHUFPMask - This decodes the shuffle masks for shufp*. VT indicates
116/// the type of the vector allowing it to handle different datatypes and vector
117/// widths.
118void DecodeSHUFPMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
119  unsigned NumElts = VT.getVectorNumElements();
120
121  unsigned NumLanes = VT.getSizeInBits() / 128;
122  unsigned NumLaneElts = NumElts / NumLanes;
123
124  unsigned NewImm = Imm;
125  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
126    // each half of a lane comes from different source
127    for (unsigned s = 0; s != NumElts*2; s += NumElts) {
128      for (unsigned i = 0; i != NumLaneElts/2; ++i) {
129        ShuffleMask.push_back(NewImm % NumLaneElts + s + l);
130        NewImm /= NumLaneElts;
131      }
132    }
133    if (NumLaneElts == 4) NewImm = Imm; // reload imm
134  }
135}
136
137/// DecodeUNPCKHMask - This decodes the shuffle masks for unpckhps/unpckhpd
138/// and punpckh*. VT indicates the type of the vector allowing it to handle
139/// different datatypes and vector widths.
140void DecodeUNPCKHMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
141  unsigned NumElts = VT.getVectorNumElements();
142
143  // Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
144  // independently on 128-bit lanes.
145  unsigned NumLanes = VT.getSizeInBits() / 128;
146  if (NumLanes == 0 ) NumLanes = 1;  // Handle MMX
147  unsigned NumLaneElts = NumElts / NumLanes;
148
149  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
150    for (unsigned i = l + NumLaneElts/2, e = l + NumLaneElts; i != e; ++i) {
151      ShuffleMask.push_back(i);          // Reads from dest/src1
152      ShuffleMask.push_back(i+NumElts);  // Reads from src/src2
153    }
154  }
155}
156
157/// DecodeUNPCKLMask - This decodes the shuffle masks for unpcklps/unpcklpd
158/// and punpckl*. VT indicates the type of the vector allowing it to handle
159/// different datatypes and vector widths.
160void DecodeUNPCKLMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
161  unsigned NumElts = VT.getVectorNumElements();
162
163  // Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
164  // independently on 128-bit lanes.
165  unsigned NumLanes = VT.getSizeInBits() / 128;
166  if (NumLanes == 0 ) NumLanes = 1;  // Handle MMX
167  unsigned NumLaneElts = NumElts / NumLanes;
168
169  for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
170    for (unsigned i = l, e = l + NumLaneElts/2; i != e; ++i) {
171      ShuffleMask.push_back(i);          // Reads from dest/src1
172      ShuffleMask.push_back(i+NumElts);  // Reads from src/src2
173    }
174  }
175}
176
177void DecodeVPERM2X128Mask(MVT VT, unsigned Imm,
178                          SmallVectorImpl<int> &ShuffleMask) {
179  if (Imm & 0x88)
180    return; // Not a shuffle
181
182  unsigned HalfSize = VT.getVectorNumElements()/2;
183
184  for (unsigned l = 0; l != 2; ++l) {
185    unsigned HalfBegin = ((Imm >> (l*4)) & 0x3) * HalfSize;
186    for (unsigned i = HalfBegin, e = HalfBegin+HalfSize; i != e; ++i)
187      ShuffleMask.push_back(i);
188  }
189}
190
191/// DecodeVPERMMask - this decodes the shuffle masks for VPERMQ/VPERMPD.
192/// No VT provided since it only works on 256-bit, 4 element vectors.
193void DecodeVPERMMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
194  for (unsigned i = 0; i != 4; ++i) {
195    ShuffleMask.push_back((Imm >> (2*i)) & 3);
196  }
197}
198
199} // llvm namespace
200