X86ShuffleDecode.cpp revision 218893 
1//===-- X86ShuffleDecode.h - 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<unsigned> &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,
48                       SmallVectorImpl<unsigned> &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,
58                       SmallVectorImpl<unsigned> &ShuffleMask) {
59  for (unsigned i = 0; i != NElts/2; ++i)
60    ShuffleMask.push_back(i);
61
62  for (unsigned i = 0; i != NElts/2; ++i)
63    ShuffleMask.push_back(NElts+i);
64}
65
66void DecodePSHUFMask(unsigned NElts, unsigned Imm,
67                     SmallVectorImpl<unsigned> &ShuffleMask) {
68  for (unsigned i = 0; i != NElts; ++i) {
69    ShuffleMask.push_back(Imm % NElts);
70    Imm /= NElts;
71  }
72}
73
74void DecodePSHUFHWMask(unsigned Imm,
75                       SmallVectorImpl<unsigned> &ShuffleMask) {
76  ShuffleMask.push_back(0);
77  ShuffleMask.push_back(1);
78  ShuffleMask.push_back(2);
79  ShuffleMask.push_back(3);
80  for (unsigned i = 0; i != 4; ++i) {
81    ShuffleMask.push_back(4+(Imm & 3));
82    Imm >>= 2;
83  }
84}
85
86void DecodePSHUFLWMask(unsigned Imm,
87                       SmallVectorImpl<unsigned> &ShuffleMask) {
88  for (unsigned i = 0; i != 4; ++i) {
89    ShuffleMask.push_back((Imm & 3));
90    Imm >>= 2;
91  }
92  ShuffleMask.push_back(4);
93  ShuffleMask.push_back(5);
94  ShuffleMask.push_back(6);
95  ShuffleMask.push_back(7);
96}
97
98void DecodePUNPCKLMask(unsigned NElts,
99                       SmallVectorImpl<unsigned> &ShuffleMask) {
100  for (unsigned i = 0; i != NElts/2; ++i) {
101    ShuffleMask.push_back(i);
102    ShuffleMask.push_back(i+NElts);
103  }
104}
105
106void DecodePUNPCKHMask(unsigned NElts,
107                       SmallVectorImpl<unsigned> &ShuffleMask) {
108  for (unsigned i = 0; i != NElts/2; ++i) {
109    ShuffleMask.push_back(i+NElts/2);
110    ShuffleMask.push_back(i+NElts+NElts/2);
111  }
112}
113
114void DecodeSHUFPSMask(unsigned NElts, unsigned Imm,
115                      SmallVectorImpl<unsigned> &ShuffleMask) {
116  // Part that reads from dest.
117  for (unsigned i = 0; i != NElts/2; ++i) {
118    ShuffleMask.push_back(Imm % NElts);
119    Imm /= NElts;
120  }
121  // Part that reads from src.
122  for (unsigned i = 0; i != NElts/2; ++i) {
123    ShuffleMask.push_back(Imm % NElts + NElts);
124    Imm /= NElts;
125  }
126}
127
128void DecodeUNPCKHPMask(unsigned NElts,
129                       SmallVectorImpl<unsigned> &ShuffleMask) {
130  for (unsigned i = 0; i != NElts/2; ++i) {
131    ShuffleMask.push_back(i+NElts/2);        // Reads from dest
132    ShuffleMask.push_back(i+NElts+NElts/2);  // Reads from src
133  }
134}
135
136
137/// DecodeUNPCKLPMask - This decodes the shuffle masks for unpcklps/unpcklpd
138/// etc.  NElts indicates the number of elements in the vector allowing it to
139/// handle different datatypes and vector widths.
140void DecodeUNPCKLPMask(unsigned NElts,
141                       SmallVectorImpl<unsigned> &ShuffleMask) {
142  for (unsigned i = 0; i != NElts/2; ++i) {
143    ShuffleMask.push_back(i);        // Reads from dest
144    ShuffleMask.push_back(i+NElts);  // Reads from src
145  }
146}
147
148} // llvm namespace
149