1 //===-- PerfectShuffle.cpp - Perfect Shuffle Generator --------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file computes an optimal sequence of instructions for doing all shuffles
11 // of two 4-element vectors. With a release build and when configured to emit
12 // an altivec instruction table, this takes about 30s to run on a 2.7Ghz
15 //===----------------------------------------------------------------------===//
24 // Masks are 4-nibble hex numbers. Values 0-7 in any nibble means that it takes
25 // an element from that value of the input vectors. A value of 8 means the
26 // entry is undefined.
28 // Mask manipulation functions.
29 static inline unsigned short MakeMask(unsigned V0, unsigned V1,
30 unsigned V2, unsigned V3) {
31 return (V0 << (3*4)) | (V1 << (2*4)) | (V2 << (1*4)) | (V3 << (0*4));
34 /// getMaskElt - Return element N of the specified mask.
35 static unsigned getMaskElt(unsigned Mask, unsigned Elt) {
36 return (Mask >> ((3-Elt)*4)) & 0xF;
39 static unsigned setMaskElt(unsigned Mask, unsigned Elt, unsigned NewVal) {
40 unsigned FieldShift = ((3-Elt)*4);
41 return (Mask & ~(0xF << FieldShift)) | (NewVal << FieldShift);
44 // Reject elements where the values are 9-15.
45 static bool isValidMask(unsigned short Mask) {
46 unsigned short UndefBits = Mask & 0x8888;
47 return (Mask & ((UndefBits >> 1)|(UndefBits>>2)|(UndefBits>>3))) == 0;
50 /// hasUndefElements - Return true if any of the elements in the mask are undefs
52 static bool hasUndefElements(unsigned short Mask) {
53 return (Mask & 0x8888) != 0;
56 /// isOnlyLHSMask - Return true if this mask only refers to its LHS, not
57 /// including undef values..
58 static bool isOnlyLHSMask(unsigned short Mask) {
59 return (Mask & 0x4444) == 0;
62 /// getLHSOnlyMask - Given a mask that refers to its LHS and RHS, modify it to
63 /// refer to the LHS only (for when one argument value is passed into the same
66 static unsigned short getLHSOnlyMask(unsigned short Mask) {
67 return Mask & 0xBBBB; // Keep only LHS and Undefs.
71 /// getCompressedMask - Turn a 16-bit uncompressed mask (where each elt uses 4
72 /// bits) into a compressed 13-bit mask, where each elt is multiplied by 9.
73 static unsigned getCompressedMask(unsigned short Mask) {
74 return getMaskElt(Mask, 0)*9*9*9 + getMaskElt(Mask, 1)*9*9 +
75 getMaskElt(Mask, 2)*9 + getMaskElt(Mask, 3);
78 static void PrintMask(unsigned i, std::ostream &OS) {
79 OS << "<" << (char)(getMaskElt(i, 0) == 8 ? 'u' : ('0'+getMaskElt(i, 0)))
80 << "," << (char)(getMaskElt(i, 1) == 8 ? 'u' : ('0'+getMaskElt(i, 1)))
81 << "," << (char)(getMaskElt(i, 2) == 8 ? 'u' : ('0'+getMaskElt(i, 2)))
82 << "," << (char)(getMaskElt(i, 3) == 8 ? 'u' : ('0'+getMaskElt(i, 3)))
86 /// ShuffleVal - This represents a shufflevector operation.
88 unsigned Cost; // Number of instrs used to generate this value.
89 Operator *Op; // The Operation used to generate this value.
90 unsigned short Arg0, Arg1; // Input operands for this value.
92 ShuffleVal() : Cost(1000000) {}
96 /// ShufTab - This is the actual shuffle table that we are trying to generate.
98 static ShuffleVal ShufTab[65536];
100 /// TheOperators - All of the operators that this target supports.
101 static std::vector<Operator*> TheOperators;
103 /// Operator - This is a vector operation that is available for use.
105 unsigned short ShuffleMask;
106 unsigned short OpNum;
110 Operator(unsigned short shufflemask, const char *name, unsigned opnum,
112 : ShuffleMask(shufflemask), OpNum(opnum), Name(name), Cost(cost) {
113 TheOperators.push_back(this);
116 assert(TheOperators.back() == this);
117 TheOperators.pop_back();
120 bool isOnlyLHSOperator() const {
121 return isOnlyLHSMask(ShuffleMask);
124 const char *getName() const { return Name; }
125 unsigned getCost() const { return Cost; }
127 unsigned short getTransformedMask(unsigned short LHSMask, unsigned RHSMask) {
128 // Extract the elements from LHSMask and RHSMask, as appropriate.
130 for (unsigned i = 0; i != 4; ++i) {
131 unsigned SrcElt = (ShuffleMask >> (4*i)) & 0xF;
134 ResElt = getMaskElt(LHSMask, SrcElt);
136 ResElt = getMaskElt(RHSMask, SrcElt-4);
138 assert(SrcElt == 8 && "Bad src elt!");
141 Result |= ResElt << (4*i);
147 static const char *getZeroCostOpName(unsigned short Op) {
148 if (ShufTab[Op].Arg0 == 0x0123)
150 else if (ShufTab[Op].Arg0 == 0x4567)
153 assert(0 && "bad zero cost operation");
158 static void PrintOperation(unsigned ValNo, unsigned short Vals[]) {
159 unsigned short ThisOp = Vals[ValNo];
160 std::cerr << "t" << ValNo;
161 PrintMask(ThisOp, std::cerr);
162 std::cerr << " = " << ShufTab[ThisOp].Op->getName() << "(";
164 if (ShufTab[ShufTab[ThisOp].Arg0].Cost == 0) {
165 std::cerr << getZeroCostOpName(ShufTab[ThisOp].Arg0);
166 PrintMask(ShufTab[ThisOp].Arg0, std::cerr);
168 // Figure out what tmp # it is.
169 for (unsigned i = 0; ; ++i)
170 if (Vals[i] == ShufTab[ThisOp].Arg0) {
171 std::cerr << "t" << i;
176 if (!ShufTab[Vals[ValNo]].Op->isOnlyLHSOperator()) {
178 if (ShufTab[ShufTab[ThisOp].Arg1].Cost == 0) {
179 std::cerr << getZeroCostOpName(ShufTab[ThisOp].Arg1);
180 PrintMask(ShufTab[ThisOp].Arg1, std::cerr);
182 // Figure out what tmp # it is.
183 for (unsigned i = 0; ; ++i)
184 if (Vals[i] == ShufTab[ThisOp].Arg1) {
185 std::cerr << "t" << i;
193 static unsigned getNumEntered() {
195 for (unsigned i = 0; i != 65536; ++i)
196 Count += ShufTab[i].Cost < 100;
200 static void EvaluateOps(unsigned short Elt, unsigned short Vals[],
202 if (ShufTab[Elt].Cost == 0) return;
204 // If this value has already been evaluated, it is free. FIXME: match undefs.
205 for (unsigned i = 0, e = NumVals; i != e; ++i)
206 if (Vals[i] == Elt) return;
208 // Otherwise, get the operands of the value, then add it.
209 unsigned Arg0 = ShufTab[Elt].Arg0, Arg1 = ShufTab[Elt].Arg1;
210 if (ShufTab[Arg0].Cost)
211 EvaluateOps(Arg0, Vals, NumVals);
212 if (Arg0 != Arg1 && ShufTab[Arg1].Cost)
213 EvaluateOps(Arg1, Vals, NumVals);
215 Vals[NumVals++] = Elt;
220 // Seed the table with accesses to the LHS and RHS.
221 ShufTab[0x0123].Cost = 0;
222 ShufTab[0x0123].Op = nullptr;
223 ShufTab[0x0123].Arg0 = 0x0123;
224 ShufTab[0x4567].Cost = 0;
225 ShufTab[0x4567].Op = nullptr;
226 ShufTab[0x4567].Arg0 = 0x4567;
228 // Seed the first-level of shuffles, shuffles whose inputs are the input to
229 // the vectorshuffle operation.
230 bool MadeChange = true;
231 unsigned OpCount = 0;
235 std::cerr << "Starting iteration #" << OpCount << " with "
236 << getNumEntered() << " entries established.\n";
238 // Scan the table for two reasons: First, compute the maximum cost of any
239 // operation left in the table. Second, make sure that values with undefs
240 // have the cheapest alternative that they match.
241 unsigned MaxCost = ShufTab[0].Cost;
242 for (unsigned i = 1; i != 0x8889; ++i) {
243 if (!isValidMask(i)) continue;
244 if (ShufTab[i].Cost > MaxCost)
245 MaxCost = ShufTab[i].Cost;
247 // If this value has an undef, make it be computed the cheapest possible
248 // way of any of the things that it matches.
249 if (hasUndefElements(i)) {
250 // This code is a little bit tricky, so here's the idea: consider some
251 // permutation, like 7u4u. To compute the lowest cost for 7u4u, we
252 // need to take the minimum cost of all of 7[0-8]4[0-8], 81 entries. If
253 // there are 3 undefs, the number rises to 729 entries we have to scan,
254 // and for the 4 undef case, we have to scan the whole table.
256 // Instead of doing this huge amount of scanning, we process the table
257 // entries *in order*, and use the fact that 'u' is 8, larger than any
258 // valid index. Given an entry like 7u4u then, we only need to scan
259 // 7[0-7]4u - 8 entries. We can get away with this, because we already
260 // know that each of 704u, 714u, 724u, etc contain the minimum value of
261 // all of the 704[0-8], 714[0-8] and 724[0-8] entries respectively.
275 unsigned MinCost = ShufTab[i].Cost;
277 // Scan the 8 entries.
278 for (unsigned j = 0; j != 8; ++j) {
279 unsigned NewElt = setMaskElt(i, UndefIdx, j);
280 if (ShufTab[NewElt].Cost < MinCost) {
281 MinCost = ShufTab[NewElt].Cost;
286 // If we found something cheaper than what was here before, use it.
289 ShufTab[i] = ShufTab[MinVal];
294 for (unsigned LHS = 0; LHS != 0x8889; ++LHS) {
295 if (!isValidMask(LHS)) continue;
296 if (ShufTab[LHS].Cost > 1000) continue;
298 // If nothing involving this operand could possibly be cheaper than what
299 // we already have, don't consider it.
300 if (ShufTab[LHS].Cost + 1 >= MaxCost)
303 for (unsigned opnum = 0, e = TheOperators.size(); opnum != e; ++opnum) {
304 Operator *Op = TheOperators[opnum];
306 // Evaluate op(LHS,LHS)
307 unsigned ResultMask = Op->getTransformedMask(LHS, LHS);
309 unsigned Cost = ShufTab[LHS].Cost + Op->getCost();
310 if (Cost < ShufTab[ResultMask].Cost) {
311 ShufTab[ResultMask].Cost = Cost;
312 ShufTab[ResultMask].Op = Op;
313 ShufTab[ResultMask].Arg0 = LHS;
314 ShufTab[ResultMask].Arg1 = LHS;
318 // If this is a two input instruction, include the op(x,y) cases. If
319 // this is a one input instruction, skip this.
320 if (Op->isOnlyLHSOperator()) continue;
322 for (unsigned RHS = 0; RHS != 0x8889; ++RHS) {
323 if (!isValidMask(RHS)) continue;
324 if (ShufTab[RHS].Cost > 1000) continue;
326 // If nothing involving this operand could possibly be cheaper than
327 // what we already have, don't consider it.
328 if (ShufTab[RHS].Cost + 1 >= MaxCost)
332 // Evaluate op(LHS,RHS)
333 unsigned ResultMask = Op->getTransformedMask(LHS, RHS);
335 if (ShufTab[ResultMask].Cost <= OpCount ||
336 ShufTab[ResultMask].Cost <= ShufTab[LHS].Cost ||
337 ShufTab[ResultMask].Cost <= ShufTab[RHS].Cost)
340 // Figure out the cost to evaluate this, knowing that CSE's only need
341 // to be evaluated once.
342 unsigned short Vals[30];
343 unsigned NumVals = 0;
344 EvaluateOps(LHS, Vals, NumVals);
345 EvaluateOps(RHS, Vals, NumVals);
347 unsigned Cost = NumVals + Op->getCost();
348 if (Cost < ShufTab[ResultMask].Cost) {
349 ShufTab[ResultMask].Cost = Cost;
350 ShufTab[ResultMask].Op = Op;
351 ShufTab[ResultMask].Arg0 = LHS;
352 ShufTab[ResultMask].Arg1 = RHS;
360 std::cerr << "Finished Table has " << getNumEntered()
361 << " entries established.\n";
363 unsigned CostArray[10] = { 0 };
365 // Compute a cost histogram.
366 for (unsigned i = 0; i != 65536; ++i) {
367 if (!isValidMask(i)) continue;
368 if (ShufTab[i].Cost > 9)
371 ++CostArray[ShufTab[i].Cost];
374 for (unsigned i = 0; i != 9; ++i)
376 std::cout << "// " << CostArray[i] << " entries have cost " << i << "\n";
378 std::cout << "// " << CostArray[9] << " entries have higher cost!\n";
381 // Build up the table to emit.
382 std::cout << "\n// This table is 6561*4 = 26244 bytes in size.\n";
383 std::cout << "static const unsigned PerfectShuffleTable[6561+1] = {\n";
385 for (unsigned i = 0; i != 0x8889; ++i) {
386 if (!isValidMask(i)) continue;
388 // CostSat - The cost of this operation saturated to two bits.
389 unsigned CostSat = ShufTab[i].Cost;
390 if (CostSat > 4) CostSat = 4;
391 if (CostSat == 0) CostSat = 1;
392 --CostSat; // Cost is now between 0-3.
394 unsigned OpNum = ShufTab[i].Op ? ShufTab[i].Op->OpNum : 0;
395 assert(OpNum < 16 && "Too few bits to encode operation!");
397 unsigned LHS = getCompressedMask(ShufTab[i].Arg0);
398 unsigned RHS = getCompressedMask(ShufTab[i].Arg1);
400 // Encode this as 2 bits of saturated cost, 4 bits of opcodes, 13 bits of
401 // LHS, and 13 bits of RHS = 32 bits.
402 unsigned Val = (CostSat << 30) | (OpNum << 26) | (LHS << 13) | RHS;
404 std::cout << " " << std::setw(10) << Val << "U, // ";
405 PrintMask(i, std::cout);
406 std::cout << ": Cost " << ShufTab[i].Cost;
407 std::cout << " " << (ShufTab[i].Op ? ShufTab[i].Op->getName() : "copy");
409 if (ShufTab[ShufTab[i].Arg0].Cost == 0) {
410 std::cout << getZeroCostOpName(ShufTab[i].Arg0);
412 PrintMask(ShufTab[i].Arg0, std::cout);
415 if (ShufTab[i].Op && !ShufTab[i].Op->isOnlyLHSOperator()) {
417 if (ShufTab[ShufTab[i].Arg1].Cost == 0) {
418 std::cout << getZeroCostOpName(ShufTab[i].Arg1);
420 PrintMask(ShufTab[i].Arg1, std::cout);
425 std::cout << " 0\n};\n";
428 // Print out the table.
429 for (unsigned i = 0; i != 0x8889; ++i) {
430 if (!isValidMask(i)) continue;
431 if (ShufTab[i].Cost < 1000) {
432 PrintMask(i, std::cerr);
433 std::cerr << " - Cost " << ShufTab[i].Cost << " - ";
435 unsigned short Vals[30];
436 unsigned NumVals = 0;
437 EvaluateOps(i, Vals, NumVals);
439 for (unsigned j = 0, e = NumVals; j != e; ++j)
440 PrintOperation(j, Vals);
448 #ifdef GENERATE_ALTIVEC
450 ///===---------------------------------------------------------------------===//
451 /// The altivec instruction definitions. This is the altivec-specific part of
453 ///===---------------------------------------------------------------------===//
455 // Note that the opcode numbers here must match those in the PPC backend.
457 OP_COPY = 0, // Copy, used for things like <u,u,u,3> to say it is <0,1,2,3>
469 struct vmrghw : public Operator {
470 vmrghw() : Operator(0x0415, "vmrghw", OP_VMRGHW) {}
473 struct vmrglw : public Operator {
474 vmrglw() : Operator(0x2637, "vmrglw", OP_VMRGLW) {}
477 template<unsigned Elt>
478 struct vspltisw : public Operator {
479 vspltisw(const char *N, unsigned Opc)
480 : Operator(MakeMask(Elt, Elt, Elt, Elt), N, Opc) {}
483 vspltisw<0> the_vspltisw0("vspltisw0", OP_VSPLTISW0);
484 vspltisw<1> the_vspltisw1("vspltisw1", OP_VSPLTISW1);
485 vspltisw<2> the_vspltisw2("vspltisw2", OP_VSPLTISW2);
486 vspltisw<3> the_vspltisw3("vspltisw3", OP_VSPLTISW3);
489 struct vsldoi : public Operator {
490 vsldoi(const char *Name, unsigned Opc)
491 : Operator(MakeMask(N&7, (N+1)&7, (N+2)&7, (N+3)&7), Name, Opc) {
495 vsldoi<1> the_vsldoi1("vsldoi4" , OP_VSLDOI4);
496 vsldoi<2> the_vsldoi2("vsldoi8" , OP_VSLDOI8);
497 vsldoi<3> the_vsldoi3("vsldoi12", OP_VSLDOI12);
501 #define GENERATE_NEON
505 OP_COPY = 0, // Copy, used for things like <u,u,u,3> to say it is <0,1,2,3>
514 OP_VUZPL, // VUZP, left result
515 OP_VUZPR, // VUZP, right result
516 OP_VZIPL, // VZIP, left result
517 OP_VZIPR, // VZIP, right result
518 OP_VTRNL, // VTRN, left result
519 OP_VTRNR // VTRN, right result
522 struct vrev : public Operator {
523 vrev() : Operator(0x1032, "vrev", OP_VREV) {}
526 template<unsigned Elt>
527 struct vdup : public Operator {
528 vdup(const char *N, unsigned Opc)
529 : Operator(MakeMask(Elt, Elt, Elt, Elt), N, Opc) {}
532 vdup<0> the_vdup0("vdup0", OP_VDUP0);
533 vdup<1> the_vdup1("vdup1", OP_VDUP1);
534 vdup<2> the_vdup2("vdup2", OP_VDUP2);
535 vdup<3> the_vdup3("vdup3", OP_VDUP3);
538 struct vext : public Operator {
539 vext(const char *Name, unsigned Opc)
540 : Operator(MakeMask(N&7, (N+1)&7, (N+2)&7, (N+3)&7), Name, Opc) {
544 vext<1> the_vext1("vext1", OP_VEXT1);
545 vext<2> the_vext2("vext2", OP_VEXT2);
546 vext<3> the_vext3("vext3", OP_VEXT3);
548 struct vuzpl : public Operator {
549 vuzpl() : Operator(0x0246, "vuzpl", OP_VUZPL, 2) {}
552 struct vuzpr : public Operator {
553 vuzpr() : Operator(0x1357, "vuzpr", OP_VUZPR, 2) {}
556 struct vzipl : public Operator {
557 vzipl() : Operator(0x0415, "vzipl", OP_VZIPL, 2) {}
560 struct vzipr : public Operator {
561 vzipr() : Operator(0x2637, "vzipr", OP_VZIPR, 2) {}
564 struct vtrnl : public Operator {
565 vtrnl() : Operator(0x0426, "vtrnl", OP_VTRNL, 2) {}
568 struct vtrnr : public Operator {
569 vtrnr() : Operator(0x1537, "vtrnr", OP_VTRNR, 2) {}