1 //===-- X86ShuffleDecodeConstantPool.cpp - X86 shuffle decode -------------===//
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.
main()7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Define several functions to decode x86 specific shuffle semantics using
11 // constants from the constant pool.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "Utils/X86ShuffleDecode.h"
16 #include "llvm/ADT/APInt.h"
17 #include "llvm/IR/Constants.h"
18
19 //===----------------------------------------------------------------------===//
20 // Vector Mask Decoding
21 //===----------------------------------------------------------------------===//
22
23 namespace llvm {
24
25 static bool extractConstantMask(const Constant *C, unsigned MaskEltSizeInBits,
26 APInt &UndefElts,
27 SmallVectorImpl<uint64_t> &RawMask) {
28 // It is not an error for shuffle masks to not be a vector of
29 // MaskEltSizeInBits because the constant pool uniques constants by their
30 // bit representation.
31 // e.g. the following take up the same space in the constant pool:
32 // i128 -170141183420855150465331762880109871104
33 //
34 // <2 x i64> <i64 -9223372034707292160, i64 -9223372034707292160>
35 //
36 // <4 x i32> <i32 -2147483648, i32 -2147483648,
37 // i32 -2147483648, i32 -2147483648>
38 Type *CstTy = C->getType();
39 if (!CstTy->isVectorTy())
40 return false;
41
42 Type *CstEltTy = CstTy->getVectorElementType();
43 if (!CstEltTy->isIntegerTy())
44 return false;
45
46 unsigned CstSizeInBits = CstTy->getPrimitiveSizeInBits();
47 unsigned CstEltSizeInBits = CstTy->getScalarSizeInBits();
48 unsigned NumCstElts = CstTy->getVectorNumElements();
49
50 assert((CstSizeInBits % MaskEltSizeInBits) == 0 &&
51 "Unaligned shuffle mask size");
52
53 unsigned NumMaskElts = CstSizeInBits / MaskEltSizeInBits;
54 UndefElts = APInt(NumMaskElts, 0);
55 RawMask.resize(NumMaskElts, 0);
56
57 // Fast path - if the constants match the mask size then copy direct.
58 if (MaskEltSizeInBits == CstEltSizeInBits) {
59 assert(NumCstElts == NumMaskElts && "Unaligned shuffle mask size");
60 for (unsigned i = 0; i != NumMaskElts; ++i) {
61 Constant *COp = C->getAggregateElement(i);
62 if (!COp || (!isa<UndefValue>(COp) && !isa<ConstantInt>(COp)))
63 return false;
64
65 if (isa<UndefValue>(COp)) {
66 UndefElts.setBit(i);
67 RawMask[i] = 0;
68 continue;
69 }
70
71 auto *Elt = cast<ConstantInt>(COp);
72 RawMask[i] = Elt->getValue().getZExtValue();
73 }
74 return true;
75 }
76
77 // Extract all the undef/constant element data and pack into single bitsets.
78 APInt UndefBits(CstSizeInBits, 0);
79 APInt MaskBits(CstSizeInBits, 0);
80 for (unsigned i = 0; i != NumCstElts; ++i) {
81 Constant *COp = C->getAggregateElement(i);
82 if (!COp || (!isa<UndefValue>(COp) && !isa<ConstantInt>(COp)))
83 return false;
84
85 unsigned BitOffset = i * CstEltSizeInBits;
86
87 if (isa<UndefValue>(COp)) {
88 UndefBits.setBits(BitOffset, BitOffset + CstEltSizeInBits);
89 continue;
90 }
91
92 MaskBits.insertBits(cast<ConstantInt>(COp)->getValue(), BitOffset);
93 }
94
95 // Now extract the undef/constant bit data into the raw shuffle masks.
96 for (unsigned i = 0; i != NumMaskElts; ++i) {
97 unsigned BitOffset = i * MaskEltSizeInBits;
98 APInt EltUndef = UndefBits.extractBits(MaskEltSizeInBits, BitOffset);
99
100 // Only treat the element as UNDEF if all bits are UNDEF, otherwise
101 // treat it as zero.
102 if (EltUndef.isAllOnesValue()) {
103 UndefElts.setBit(i);
104 RawMask[i] = 0;
105 continue;
106 }
107
108 APInt EltBits = MaskBits.extractBits(MaskEltSizeInBits, BitOffset);
109 RawMask[i] = EltBits.getZExtValue();
110 }
111
112 return true;
113 }
114
115 void DecodePSHUFBMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask) {
116 Type *MaskTy = C->getType();
117 unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
118 (void)MaskTySize;
119 assert((MaskTySize == 128 || MaskTySize == 256 || MaskTySize == 512) &&
120 "Unexpected vector size.");
121
122 // The shuffle mask requires a byte vector.
123 APInt UndefElts;
124 SmallVector<uint64_t, 64> RawMask;
125 if (!extractConstantMask(C, 8, UndefElts, RawMask))
126 return;
127
128 unsigned NumElts = RawMask.size();
129 assert((NumElts == 16 || NumElts == 32 || NumElts == 64) &&
130 "Unexpected number of vector elements.");
131
132 for (unsigned i = 0; i != NumElts; ++i) {
133 if (UndefElts[i]) {
134 ShuffleMask.push_back(SM_SentinelUndef);
135 continue;
136 }
137
138 uint64_t Element = RawMask[i];
139 // If the high bit (7) of the byte is set, the element is zeroed.
140 if (Element & (1 << 7))
141 ShuffleMask.push_back(SM_SentinelZero);
142 else {
143 // For AVX vectors with 32 bytes the base of the shuffle is the 16-byte
144 // lane of the vector we're inside.
145 unsigned Base = i & ~0xf;
146
147 // Only the least significant 4 bits of the byte are used.
148 int Index = Base + (Element & 0xf);
149 ShuffleMask.push_back(Index);
150 }
151 }
152 }
153
154 void DecodeVPERMILPMask(const Constant *C, unsigned ElSize,
155 SmallVectorImpl<int> &ShuffleMask) {
156 Type *MaskTy = C->getType();
157 unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
158 (void)MaskTySize;
159 assert((MaskTySize == 128 || MaskTySize == 256 || MaskTySize == 512) &&
160 "Unexpected vector size.");
161 assert((ElSize == 32 || ElSize == 64) && "Unexpected vector element size.");
162
163 // The shuffle mask requires elements the same size as the target.
164 APInt UndefElts;
165 SmallVector<uint64_t, 16> RawMask;
166 if (!extractConstantMask(C, ElSize, UndefElts, RawMask))
167 return;
168
169 unsigned NumElts = RawMask.size();
170 unsigned NumEltsPerLane = 128 / ElSize;
171 assert((NumElts == 2 || NumElts == 4 || NumElts == 8 || NumElts == 16) &&
172 "Unexpected number of vector elements.");
173
174 for (unsigned i = 0; i != NumElts; ++i) {
175 if (UndefElts[i]) {
176 ShuffleMask.push_back(SM_SentinelUndef);
177 continue;
178 }
179
180 int Index = i & ~(NumEltsPerLane - 1);
181 uint64_t Element = RawMask[i];
182 if (ElSize == 64)
183 Index += (Element >> 1) & 0x1;
184 else
185 Index += Element & 0x3;
186
187 ShuffleMask.push_back(Index);
188 }
189 }
190
191 void DecodeVPERMIL2PMask(const Constant *C, unsigned M2Z, unsigned ElSize,
192 SmallVectorImpl<int> &ShuffleMask) {
193 Type *MaskTy = C->getType();
194 unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
195 (void)MaskTySize;
196 assert((MaskTySize == 128 || MaskTySize == 256) && "Unexpected vector size.");
197
198 // The shuffle mask requires elements the same size as the target.
199 APInt UndefElts;
200 SmallVector<uint64_t, 8> RawMask;
201 if (!extractConstantMask(C, ElSize, UndefElts, RawMask))
202 return;
203
204 unsigned NumElts = RawMask.size();
205 unsigned NumEltsPerLane = 128 / ElSize;
206 assert((NumElts == 2 || NumElts == 4 || NumElts == 8) &&
207 "Unexpected number of vector elements.");
208
209 for (unsigned i = 0; i != NumElts; ++i) {
210 if (UndefElts[i]) {
211 ShuffleMask.push_back(SM_SentinelUndef);
212 continue;
213 }
214
215 // VPERMIL2 Operation.
216 // Bits[3] - Match Bit.
217 // Bits[2:1] - (Per Lane) PD Shuffle Mask.
218 // Bits[2:0] - (Per Lane) PS Shuffle Mask.
219 uint64_t Selector = RawMask[i];
220 unsigned MatchBit = (Selector >> 3) & 0x1;
221
222 // M2Z[0:1] MatchBit
223 // 0Xb X Source selected by Selector index.
224 // 10b 0 Source selected by Selector index.
225 // 10b 1 Zero.
226 // 11b 0 Zero.
227 // 11b 1 Source selected by Selector index.
228 if ((M2Z & 0x2) != 0u && MatchBit != (M2Z & 0x1)) {
229 ShuffleMask.push_back(SM_SentinelZero);
230 continue;
231 }
232
233 int Index = i & ~(NumEltsPerLane - 1);
234 if (ElSize == 64)
235 Index += (Selector >> 1) & 0x1;
236 else
237 Index += Selector & 0x3;
238
239 int Src = (Selector >> 2) & 0x1;
240 Index += Src * NumElts;
241 ShuffleMask.push_back(Index);
242 }
243 }
244
245 void DecodeVPPERMMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask) {
246 assert(C->getType()->getPrimitiveSizeInBits() == 128 &&
247 "Unexpected vector size.");
248
249 // The shuffle mask requires a byte vector.
250 APInt UndefElts;
251 SmallVector<uint64_t, 16> RawMask;
252 if (!extractConstantMask(C, 8, UndefElts, RawMask))
253 return;
254
255 unsigned NumElts = RawMask.size();
256 assert(NumElts == 16 && "Unexpected number of vector elements.");
257
258 for (unsigned i = 0; i != NumElts; ++i) {
259 if (UndefElts[i]) {
260 ShuffleMask.push_back(SM_SentinelUndef);
261 continue;
262 }
263
264 // VPPERM Operation
265 // Bits[4:0] - Byte Index (0 - 31)
266 // Bits[7:5] - Permute Operation
267 //
268 // Permute Operation:
269 // 0 - Source byte (no logical operation).
270 // 1 - Invert source byte.
271 // 2 - Bit reverse of source byte.
272 // 3 - Bit reverse of inverted source byte.
273 // 4 - 00h (zero - fill).
274 // 5 - FFh (ones - fill).
275 // 6 - Most significant bit of source byte replicated in all bit positions.
276 // 7 - Invert most significant bit of source byte and replicate in all bit
277 // positions.
278 uint64_t Element = RawMask[i];
279 uint64_t Index = Element & 0x1F;
280 uint64_t PermuteOp = (Element >> 5) & 0x7;
281
282 if (PermuteOp == 4) {
283 ShuffleMask.push_back(SM_SentinelZero);
284 continue;
285 }
286 if (PermuteOp != 0) {
287 ShuffleMask.clear();
288 return;
289 }
290 ShuffleMask.push_back((int)Index);
291 }
292 }
293
294 void DecodeVPERMVMask(const Constant *C, unsigned ElSize,
295 SmallVectorImpl<int> &ShuffleMask) {
296 Type *MaskTy = C->getType();
297 unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
298 (void)MaskTySize;
299 assert((MaskTySize == 128 || MaskTySize == 256 || MaskTySize == 512) &&
300 "Unexpected vector size.");
301 assert((ElSize == 8 || ElSize == 16 || ElSize == 32 || ElSize == 64) &&
302 "Unexpected vector element size.");
303
304 // The shuffle mask requires elements the same size as the target.
305 APInt UndefElts;
306 SmallVector<uint64_t, 64> RawMask;
307 if (!extractConstantMask(C, ElSize, UndefElts, RawMask))
308 return;
309
310 unsigned NumElts = RawMask.size();
311
312 for (unsigned i = 0; i != NumElts; ++i) {
313 if (UndefElts[i]) {
314 ShuffleMask.push_back(SM_SentinelUndef);
315 continue;
316 }
317 int Index = RawMask[i] & (NumElts - 1);
318 ShuffleMask.push_back(Index);
319 }
320 }
321
322 void DecodeVPERMV3Mask(const Constant *C, unsigned ElSize,
323 SmallVectorImpl<int> &ShuffleMask) {
324 Type *MaskTy = C->getType();
325 unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
326 (void)MaskTySize;
327 assert((MaskTySize == 128 || MaskTySize == 256 || MaskTySize == 512) &&
328 "Unexpected vector size.");
329 assert((ElSize == 8 || ElSize == 16 || ElSize == 32 || ElSize == 64) &&
330 "Unexpected vector element size.");
331
332 // The shuffle mask requires elements the same size as the target.
333 APInt UndefElts;
334 SmallVector<uint64_t, 64> RawMask;
335 if (!extractConstantMask(C, ElSize, UndefElts, RawMask))
336 return;
337
338 unsigned NumElts = RawMask.size();
339
340 for (unsigned i = 0; i != NumElts; ++i) {
341 if (UndefElts[i]) {
342 ShuffleMask.push_back(SM_SentinelUndef);
343 continue;
344 }
345 int Index = RawMask[i] & (NumElts*2 - 1);
346 ShuffleMask.push_back(Index);
347 }
348 }
349 } // llvm namespace
350