1 //===------------ FixedLenDecoderEmitter.cpp - Decoder 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 // It contains the tablegen backend that emits the decoder functions for
11 // targets with fixed length instruction set.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "decoder-emitter"
17 #include "FixedLenDecoderEmitter.h"
18 #include "CodeGenTarget.h"
20 #include "llvm/ADT/StringExtras.h"
21 #include "llvm/Support/Debug.h"
22 #include "llvm/Support/raw_ostream.h"
30 // The set (BIT_TRUE, BIT_FALSE, BIT_UNSET) represents a ternary logic system
33 // BIT_UNFILTERED is used as the init value for a filter position. It is used
34 // only for filter processings.
39 BIT_UNFILTERED // unfiltered
42 static bool ValueSet(bit_value_t V) {
43 return (V == BIT_TRUE || V == BIT_FALSE);
45 static bool ValueNotSet(bit_value_t V) {
46 return (V == BIT_UNSET);
48 static int Value(bit_value_t V) {
49 return ValueNotSet(V) ? -1 : (V == BIT_FALSE ? 0 : 1);
51 static bit_value_t bitFromBits(BitsInit &bits, unsigned index) {
52 if (BitInit *bit = dynamic_cast<BitInit*>(bits.getBit(index)))
53 return bit->getValue() ? BIT_TRUE : BIT_FALSE;
55 // The bit is uninitialized.
58 // Prints the bit value for each position.
59 static void dumpBits(raw_ostream &o, BitsInit &bits) {
62 for (index = bits.getNumBits(); index > 0; index--) {
63 switch (bitFromBits(bits, index - 1)) {
74 assert(0 && "unexpected return value from bitFromBits");
79 static BitsInit &getBitsField(const Record &def, const char *str) {
80 BitsInit *bits = def.getValueAsBitsInit(str);
84 // Forward declaration.
87 // Representation of the instruction to work on.
88 typedef std::vector<bit_value_t> insn_t;
90 /// Filter - Filter works with FilterChooser to produce the decoding tree for
93 /// It is useful to think of a Filter as governing the switch stmts of the
94 /// decoding tree in a certain level. Each case stmt delegates to an inferior
95 /// FilterChooser to decide what further decoding logic to employ, or in another
96 /// words, what other remaining bits to look at. The FilterChooser eventually
97 /// chooses a best Filter to do its job.
99 /// This recursive scheme ends when the number of Opcodes assigned to the
100 /// FilterChooser becomes 1 or if there is a conflict. A conflict happens when
101 /// the Filter/FilterChooser combo does not know how to distinguish among the
102 /// Opcodes assigned.
104 /// An example of a conflict is
107 /// 111101000.00........00010000....
108 /// 111101000.00........0001........
109 /// 1111010...00........0001........
110 /// 1111010...00....................
111 /// 1111010.........................
112 /// 1111............................
113 /// ................................
114 /// VST4q8a 111101000_00________00010000____
115 /// VST4q8b 111101000_00________00010000____
117 /// The Debug output shows the path that the decoding tree follows to reach the
118 /// the conclusion that there is a conflict. VST4q8a is a vst4 to double-spaced
119 /// even registers, while VST4q8b is a vst4 to double-spaced odd regsisters.
121 /// The encoding info in the .td files does not specify this meta information,
122 /// which could have been used by the decoder to resolve the conflict. The
123 /// decoder could try to decode the even/odd register numbering and assign to
124 /// VST4q8a or VST4q8b, but for the time being, the decoder chooses the "a"
125 /// version and return the Opcode since the two have the same Asm format string.
128 FilterChooser *Owner; // points to the FilterChooser who owns this filter
129 unsigned StartBit; // the starting bit position
130 unsigned NumBits; // number of bits to filter
131 bool Mixed; // a mixed region contains both set and unset bits
133 // Map of well-known segment value to the set of uid's with that value.
134 std::map<uint64_t, std::vector<unsigned> > FilteredInstructions;
136 // Set of uid's with non-constant segment values.
137 std::vector<unsigned> VariableInstructions;
139 // Map of well-known segment value to its delegate.
140 std::map<unsigned, FilterChooser*> FilterChooserMap;
142 // Number of instructions which fall under FilteredInstructions category.
143 unsigned NumFiltered;
145 // Keeps track of the last opcode in the filtered bucket.
146 unsigned LastOpcFiltered;
148 // Number of instructions which fall under VariableInstructions category.
149 unsigned NumVariable;
152 unsigned getNumFiltered() { return NumFiltered; }
153 unsigned getNumVariable() { return NumVariable; }
154 unsigned getSingletonOpc() {
155 assert(NumFiltered == 1);
156 return LastOpcFiltered;
158 // Return the filter chooser for the group of instructions without constant
160 FilterChooser &getVariableFC() {
161 assert(NumFiltered == 1);
162 assert(FilterChooserMap.size() == 1);
163 return *(FilterChooserMap.find((unsigned)-1)->second);
166 Filter(const Filter &f);
167 Filter(FilterChooser &owner, unsigned startBit, unsigned numBits, bool mixed);
171 // Divides the decoding task into sub tasks and delegates them to the
172 // inferior FilterChooser's.
174 // A special case arises when there's only one entry in the filtered
175 // instructions. In order to unambiguously decode the singleton, we need to
176 // match the remaining undecoded encoding bits against the singleton.
179 // Emit code to decode instructions given a segment or segments of bits.
180 void emit(raw_ostream &o, unsigned &Indentation);
182 // Returns the number of fanout produced by the filter. More fanout implies
183 // the filter distinguishes more categories of instructions.
184 unsigned usefulness() const;
185 }; // End of class Filter
187 // These are states of our finite state machines used in FilterChooser's
188 // filterProcessor() which produces the filter candidates to use.
197 /// FilterChooser - FilterChooser chooses the best filter among a set of Filters
198 /// in order to perform the decoding of instructions at the current level.
200 /// Decoding proceeds from the top down. Based on the well-known encoding bits
201 /// of instructions available, FilterChooser builds up the possible Filters that
202 /// can further the task of decoding by distinguishing among the remaining
203 /// candidate instructions.
205 /// Once a filter has been chosen, it is called upon to divide the decoding task
206 /// into sub-tasks and delegates them to its inferior FilterChoosers for further
209 /// It is useful to think of a Filter as governing the switch stmts of the
210 /// decoding tree. And each case is delegated to an inferior FilterChooser to
211 /// decide what further remaining bits to look at.
212 class FilterChooser {
216 // Vector of codegen instructions to choose our filter.
217 const std::vector<const CodeGenInstruction*> &AllInstructions;
219 // Vector of uid's for this filter chooser to work on.
220 const std::vector<unsigned> Opcodes;
222 // Lookup table for the operand decoding of instructions.
223 std::map<unsigned, std::vector<OperandInfo> > &Operands;
225 // Vector of candidate filters.
226 std::vector<Filter> Filters;
228 // Array of bit values passed down from our parent.
229 // Set to all BIT_UNFILTERED's for Parent == NULL.
230 std::vector<bit_value_t> FilterBitValues;
232 // Links to the FilterChooser above us in the decoding tree.
233 FilterChooser *Parent;
235 // Index of the best filter from Filters.
238 // Width of instructions
242 FilterChooser(const FilterChooser &FC) :
243 AllInstructions(FC.AllInstructions), Opcodes(FC.Opcodes),
244 Operands(FC.Operands), Filters(FC.Filters),
245 FilterBitValues(FC.FilterBitValues), Parent(FC.Parent),
246 BestIndex(FC.BestIndex), BitWidth(FC.BitWidth) { }
248 FilterChooser(const std::vector<const CodeGenInstruction*> &Insts,
249 const std::vector<unsigned> &IDs,
250 std::map<unsigned, std::vector<OperandInfo> > &Ops,
252 AllInstructions(Insts), Opcodes(IDs), Operands(Ops), Filters(),
253 Parent(NULL), BestIndex(-1), BitWidth(BW) {
254 for (unsigned i = 0; i < BitWidth; ++i)
255 FilterBitValues.push_back(BIT_UNFILTERED);
260 FilterChooser(const std::vector<const CodeGenInstruction*> &Insts,
261 const std::vector<unsigned> &IDs,
262 std::map<unsigned, std::vector<OperandInfo> > &Ops,
263 std::vector<bit_value_t> &ParentFilterBitValues,
264 FilterChooser &parent) :
265 AllInstructions(Insts), Opcodes(IDs), Operands(Ops),
266 Filters(), FilterBitValues(ParentFilterBitValues),
267 Parent(&parent), BestIndex(-1), BitWidth(parent.BitWidth) {
271 // The top level filter chooser has NULL as its parent.
272 bool isTopLevel() { return Parent == NULL; }
274 // Emit the top level typedef and decodeInstruction() function.
275 void emitTop(raw_ostream &o, unsigned Indentation, std::string Namespace);
278 // Populates the insn given the uid.
279 void insnWithID(insn_t &Insn, unsigned Opcode) const {
280 BitsInit &Bits = getBitsField(*AllInstructions[Opcode]->TheDef, "Inst");
282 for (unsigned i = 0; i < BitWidth; ++i)
283 Insn.push_back(bitFromBits(Bits, i));
286 // Returns the record name.
287 const std::string &nameWithID(unsigned Opcode) const {
288 return AllInstructions[Opcode]->TheDef->getName();
291 // Populates the field of the insn given the start position and the number of
292 // consecutive bits to scan for.
294 // Returns false if there exists any uninitialized bit value in the range.
295 // Returns true, otherwise.
296 bool fieldFromInsn(uint64_t &Field, insn_t &Insn, unsigned StartBit,
297 unsigned NumBits) const;
299 /// dumpFilterArray - dumpFilterArray prints out debugging info for the given
300 /// filter array as a series of chars.
301 void dumpFilterArray(raw_ostream &o, std::vector<bit_value_t> & filter);
303 /// dumpStack - dumpStack traverses the filter chooser chain and calls
304 /// dumpFilterArray on each filter chooser up to the top level one.
305 void dumpStack(raw_ostream &o, const char *prefix);
307 Filter &bestFilter() {
308 assert(BestIndex != -1 && "BestIndex not set");
309 return Filters[BestIndex];
312 // Called from Filter::recurse() when singleton exists. For debug purpose.
313 void SingletonExists(unsigned Opc);
315 bool PositionFiltered(unsigned i) {
316 return ValueSet(FilterBitValues[i]);
319 // Calculates the island(s) needed to decode the instruction.
320 // This returns a lit of undecoded bits of an instructions, for example,
321 // Inst{20} = 1 && Inst{3-0} == 0b1111 represents two islands of yet-to-be
322 // decoded bits in order to verify that the instruction matches the Opcode.
323 unsigned getIslands(std::vector<unsigned> &StartBits,
324 std::vector<unsigned> &EndBits, std::vector<uint64_t> &FieldVals,
327 // Emits code to decode the singleton. Return true if we have matched all the
329 bool emitSingletonDecoder(raw_ostream &o, unsigned &Indentation,unsigned Opc);
331 // Emits code to decode the singleton, and then to decode the rest.
332 void emitSingletonDecoder(raw_ostream &o, unsigned &Indentation,Filter &Best);
334 void emitBinaryParser(raw_ostream &o , unsigned &Indentation,
335 OperandInfo &OpInfo);
337 // Assign a single filter and run with it.
338 void runSingleFilter(FilterChooser &owner, unsigned startBit, unsigned numBit,
341 // reportRegion is a helper function for filterProcessor to mark a region as
342 // eligible for use as a filter region.
343 void reportRegion(bitAttr_t RA, unsigned StartBit, unsigned BitIndex,
346 // FilterProcessor scans the well-known encoding bits of the instructions and
347 // builds up a list of candidate filters. It chooses the best filter and
348 // recursively descends down the decoding tree.
349 bool filterProcessor(bool AllowMixed, bool Greedy = true);
351 // Decides on the best configuration of filter(s) to use in order to decode
352 // the instructions. A conflict of instructions may occur, in which case we
353 // dump the conflict set to the standard error.
356 // Emits code to decode our share of instructions. Returns true if the
357 // emitted code causes a return, which occurs if we know how to decode
358 // the instruction at this level or the instruction is not decodeable.
359 bool emit(raw_ostream &o, unsigned &Indentation);
362 ///////////////////////////
364 // Filter Implmenetation //
366 ///////////////////////////
368 Filter::Filter(const Filter &f) :
369 Owner(f.Owner), StartBit(f.StartBit), NumBits(f.NumBits), Mixed(f.Mixed),
370 FilteredInstructions(f.FilteredInstructions),
371 VariableInstructions(f.VariableInstructions),
372 FilterChooserMap(f.FilterChooserMap), NumFiltered(f.NumFiltered),
373 LastOpcFiltered(f.LastOpcFiltered), NumVariable(f.NumVariable) {
376 Filter::Filter(FilterChooser &owner, unsigned startBit, unsigned numBits,
377 bool mixed) : Owner(&owner), StartBit(startBit), NumBits(numBits),
379 assert(StartBit + NumBits - 1 < Owner->BitWidth);
385 for (unsigned i = 0, e = Owner->Opcodes.size(); i != e; ++i) {
388 // Populates the insn given the uid.
389 Owner->insnWithID(Insn, Owner->Opcodes[i]);
392 // Scans the segment for possibly well-specified encoding bits.
393 bool ok = Owner->fieldFromInsn(Field, Insn, StartBit, NumBits);
396 // The encoding bits are well-known. Lets add the uid of the
397 // instruction into the bucket keyed off the constant field value.
398 LastOpcFiltered = Owner->Opcodes[i];
399 FilteredInstructions[Field].push_back(LastOpcFiltered);
402 // Some of the encoding bit(s) are unspecfied. This contributes to
403 // one additional member of "Variable" instructions.
404 VariableInstructions.push_back(Owner->Opcodes[i]);
409 assert((FilteredInstructions.size() + VariableInstructions.size() > 0)
410 && "Filter returns no instruction categories");
414 std::map<unsigned, FilterChooser*>::iterator filterIterator;
415 for (filterIterator = FilterChooserMap.begin();
416 filterIterator != FilterChooserMap.end();
418 delete filterIterator->second;
422 // Divides the decoding task into sub tasks and delegates them to the
423 // inferior FilterChooser's.
425 // A special case arises when there's only one entry in the filtered
426 // instructions. In order to unambiguously decode the singleton, we need to
427 // match the remaining undecoded encoding bits against the singleton.
428 void Filter::recurse() {
429 std::map<uint64_t, std::vector<unsigned> >::const_iterator mapIterator;
431 // Starts by inheriting our parent filter chooser's filter bit values.
432 std::vector<bit_value_t> BitValueArray(Owner->FilterBitValues);
436 if (VariableInstructions.size()) {
437 // Conservatively marks each segment position as BIT_UNSET.
438 for (bitIndex = 0; bitIndex < NumBits; bitIndex++)
439 BitValueArray[StartBit + bitIndex] = BIT_UNSET;
441 // Delegates to an inferior filter chooser for further processing on this
442 // group of instructions whose segment values are variable.
443 FilterChooserMap.insert(std::pair<unsigned, FilterChooser*>(
445 new FilterChooser(Owner->AllInstructions,
446 VariableInstructions,
453 // No need to recurse for a singleton filtered instruction.
454 // See also Filter::emit().
455 if (getNumFiltered() == 1) {
456 //Owner->SingletonExists(LastOpcFiltered);
457 assert(FilterChooserMap.size() == 1);
461 // Otherwise, create sub choosers.
462 for (mapIterator = FilteredInstructions.begin();
463 mapIterator != FilteredInstructions.end();
466 // Marks all the segment positions with either BIT_TRUE or BIT_FALSE.
467 for (bitIndex = 0; bitIndex < NumBits; bitIndex++) {
468 if (mapIterator->first & (1ULL << bitIndex))
469 BitValueArray[StartBit + bitIndex] = BIT_TRUE;
471 BitValueArray[StartBit + bitIndex] = BIT_FALSE;
474 // Delegates to an inferior filter chooser for further processing on this
475 // category of instructions.
476 FilterChooserMap.insert(std::pair<unsigned, FilterChooser*>(
478 new FilterChooser(Owner->AllInstructions,
487 // Emit code to decode instructions given a segment or segments of bits.
488 void Filter::emit(raw_ostream &o, unsigned &Indentation) {
489 o.indent(Indentation) << "// Check Inst{";
492 o << (StartBit + NumBits - 1) << '-';
494 o << StartBit << "} ...\n";
496 o.indent(Indentation) << "switch (fieldFromInstruction" << Owner->BitWidth
497 << "(insn, " << StartBit << ", "
498 << NumBits << ")) {\n";
500 std::map<unsigned, FilterChooser*>::iterator filterIterator;
502 bool DefaultCase = false;
503 for (filterIterator = FilterChooserMap.begin();
504 filterIterator != FilterChooserMap.end();
507 // Field value -1 implies a non-empty set of variable instructions.
508 // See also recurse().
509 if (filterIterator->first == (unsigned)-1) {
512 o.indent(Indentation) << "default:\n";
513 o.indent(Indentation) << " break; // fallthrough\n";
515 // Closing curly brace for the switch statement.
516 // This is unconventional because we want the default processing to be
517 // performed for the fallthrough cases as well, i.e., when the "cases"
518 // did not prove a decoded instruction.
519 o.indent(Indentation) << "}\n";
522 o.indent(Indentation) << "case " << filterIterator->first << ":\n";
524 // We arrive at a category of instructions with the same segment value.
525 // Now delegate to the sub filter chooser for further decodings.
526 // The case may fallthrough, which happens if the remaining well-known
527 // encoding bits do not match exactly.
528 if (!DefaultCase) { ++Indentation; ++Indentation; }
530 bool finished = filterIterator->second->emit(o, Indentation);
531 // For top level default case, there's no need for a break statement.
532 if (Owner->isTopLevel() && DefaultCase)
535 o.indent(Indentation) << "break;\n";
537 if (!DefaultCase) { --Indentation; --Indentation; }
540 // If there is no default case, we still need to supply a closing brace.
542 // Closing curly brace for the switch statement.
543 o.indent(Indentation) << "}\n";
547 // Returns the number of fanout produced by the filter. More fanout implies
548 // the filter distinguishes more categories of instructions.
549 unsigned Filter::usefulness() const {
550 if (VariableInstructions.size())
551 return FilteredInstructions.size();
553 return FilteredInstructions.size() + 1;
556 //////////////////////////////////
558 // Filterchooser Implementation //
560 //////////////////////////////////
562 // Emit the top level typedef and decodeInstruction() function.
563 void FilterChooser::emitTop(raw_ostream &o, unsigned Indentation,
564 std::string Namespace) {
565 o.indent(Indentation) <<
566 "static bool decode" << Namespace << "Instruction" << BitWidth
567 << "(MCInst &MI, uint" << BitWidth << "_t insn, uint64_t Address, "
568 << "const void *Decoder) {\n";
569 o.indent(Indentation) << " unsigned tmp = 0;\n (void)tmp;\n";
571 ++Indentation; ++Indentation;
572 // Emits code to decode the instructions.
573 emit(o, Indentation);
576 o.indent(Indentation) << "return false;\n";
577 --Indentation; --Indentation;
579 o.indent(Indentation) << "}\n";
584 // Populates the field of the insn given the start position and the number of
585 // consecutive bits to scan for.
587 // Returns false if and on the first uninitialized bit value encountered.
588 // Returns true, otherwise.
589 bool FilterChooser::fieldFromInsn(uint64_t &Field, insn_t &Insn,
590 unsigned StartBit, unsigned NumBits) const {
593 for (unsigned i = 0; i < NumBits; ++i) {
594 if (Insn[StartBit + i] == BIT_UNSET)
597 if (Insn[StartBit + i] == BIT_TRUE)
598 Field = Field | (1ULL << i);
604 /// dumpFilterArray - dumpFilterArray prints out debugging info for the given
605 /// filter array as a series of chars.
606 void FilterChooser::dumpFilterArray(raw_ostream &o,
607 std::vector<bit_value_t> &filter) {
610 for (bitIndex = BitWidth; bitIndex > 0; bitIndex--) {
611 switch (filter[bitIndex - 1]) {
628 /// dumpStack - dumpStack traverses the filter chooser chain and calls
629 /// dumpFilterArray on each filter chooser up to the top level one.
630 void FilterChooser::dumpStack(raw_ostream &o, const char *prefix) {
631 FilterChooser *current = this;
635 dumpFilterArray(o, current->FilterBitValues);
637 current = current->Parent;
641 // Called from Filter::recurse() when singleton exists. For debug purpose.
642 void FilterChooser::SingletonExists(unsigned Opc) {
644 insnWithID(Insn0, Opc);
646 errs() << "Singleton exists: " << nameWithID(Opc)
647 << " with its decoding dominating ";
648 for (unsigned i = 0; i < Opcodes.size(); ++i) {
649 if (Opcodes[i] == Opc) continue;
650 errs() << nameWithID(Opcodes[i]) << ' ';
654 dumpStack(errs(), "\t\t");
655 for (unsigned i = 0; i < Opcodes.size(); i++) {
656 const std::string &Name = nameWithID(Opcodes[i]);
658 errs() << '\t' << Name << " ";
660 getBitsField(*AllInstructions[Opcodes[i]]->TheDef, "Inst"));
665 // Calculates the island(s) needed to decode the instruction.
666 // This returns a list of undecoded bits of an instructions, for example,
667 // Inst{20} = 1 && Inst{3-0} == 0b1111 represents two islands of yet-to-be
668 // decoded bits in order to verify that the instruction matches the Opcode.
669 unsigned FilterChooser::getIslands(std::vector<unsigned> &StartBits,
670 std::vector<unsigned> &EndBits, std::vector<uint64_t> &FieldVals,
675 uint64_t FieldVal = 0;
678 // 1: Water (the bit value does not affect decoding)
679 // 2: Island (well-known bit value needed for decoding)
683 for (unsigned i = 0; i < BitWidth; ++i) {
684 Val = Value(Insn[i]);
685 bool Filtered = PositionFiltered(i);
688 assert(0 && "Unreachable code!");
692 if (Filtered || Val == -1)
693 State = 1; // Still in Water
695 State = 2; // Into the Island
697 StartBits.push_back(i);
702 if (Filtered || Val == -1) {
703 State = 1; // Into the Water
704 EndBits.push_back(i - 1);
705 FieldVals.push_back(FieldVal);
708 State = 2; // Still in Island
710 FieldVal = FieldVal | Val << BitNo;
715 // If we are still in Island after the loop, do some housekeeping.
717 EndBits.push_back(BitWidth - 1);
718 FieldVals.push_back(FieldVal);
722 assert(StartBits.size() == Num && EndBits.size() == Num &&
723 FieldVals.size() == Num);
727 void FilterChooser::emitBinaryParser(raw_ostream &o, unsigned &Indentation,
728 OperandInfo &OpInfo) {
729 std::string &Decoder = OpInfo.Decoder;
731 if (OpInfo.numFields() == 1) {
732 OperandInfo::iterator OI = OpInfo.begin();
733 o.indent(Indentation) << " tmp = fieldFromInstruction" << BitWidth
734 << "(insn, " << OI->Base << ", " << OI->Width
737 o.indent(Indentation) << " tmp = 0;\n";
738 for (OperandInfo::iterator OI = OpInfo.begin(), OE = OpInfo.end();
740 o.indent(Indentation) << " tmp |= (fieldFromInstruction" << BitWidth
741 << "(insn, " << OI->Base << ", " << OI->Width
742 << ") << " << OI->Offset << ");\n";
747 o.indent(Indentation) << " if (!" << Decoder
748 << "(MI, tmp, Address, Decoder)) return false;\n";
750 o.indent(Indentation) << " MI.addOperand(MCOperand::CreateImm(tmp));\n";
754 // Emits code to decode the singleton. Return true if we have matched all the
756 bool FilterChooser::emitSingletonDecoder(raw_ostream &o, unsigned &Indentation,
758 std::vector<unsigned> StartBits;
759 std::vector<unsigned> EndBits;
760 std::vector<uint64_t> FieldVals;
762 insnWithID(Insn, Opc);
764 // Look for islands of undecoded bits of the singleton.
765 getIslands(StartBits, EndBits, FieldVals, Insn);
767 unsigned Size = StartBits.size();
770 // If we have matched all the well-known bits, just issue a return.
772 o.indent(Indentation) << "{\n";
773 o.indent(Indentation) << " MI.setOpcode(" << Opc << ");\n";
774 std::vector<OperandInfo>& InsnOperands = Operands[Opc];
775 for (std::vector<OperandInfo>::iterator
776 I = InsnOperands.begin(), E = InsnOperands.end(); I != E; ++I) {
777 // If a custom instruction decoder was specified, use that.
778 if (I->numFields() == 0 && I->Decoder.size()) {
779 o.indent(Indentation) << " if (!" << I->Decoder
780 << "(MI, insn, Address, Decoder)) return false;\n";
784 emitBinaryParser(o, Indentation, *I);
787 o.indent(Indentation) << " return true; // " << nameWithID(Opc)
789 o.indent(Indentation) << "}\n";
793 // Otherwise, there are more decodings to be done!
795 // Emit code to match the island(s) for the singleton.
796 o.indent(Indentation) << "// Check ";
798 for (I = Size; I != 0; --I) {
799 o << "Inst{" << EndBits[I-1] << '-' << StartBits[I-1] << "} ";
803 o << "for singleton decoding...\n";
806 o.indent(Indentation) << "if (";
808 for (I = Size; I != 0; --I) {
809 NumBits = EndBits[I-1] - StartBits[I-1] + 1;
810 o << "fieldFromInstruction" << BitWidth << "(insn, "
811 << StartBits[I-1] << ", " << NumBits
812 << ") == " << FieldVals[I-1];
818 o.indent(Indentation) << " MI.setOpcode(" << Opc << ");\n";
819 std::vector<OperandInfo>& InsnOperands = Operands[Opc];
820 for (std::vector<OperandInfo>::iterator
821 I = InsnOperands.begin(), E = InsnOperands.end(); I != E; ++I) {
822 // If a custom instruction decoder was specified, use that.
823 if (I->numFields() == 0 && I->Decoder.size()) {
824 o.indent(Indentation) << " if (!" << I->Decoder
825 << "(MI, insn, Address, Decoder)) return false;\n";
829 emitBinaryParser(o, Indentation, *I);
831 o.indent(Indentation) << " return true; // " << nameWithID(Opc)
833 o.indent(Indentation) << "}\n";
838 // Emits code to decode the singleton, and then to decode the rest.
839 void FilterChooser::emitSingletonDecoder(raw_ostream &o, unsigned &Indentation,
842 unsigned Opc = Best.getSingletonOpc();
844 emitSingletonDecoder(o, Indentation, Opc);
846 // Emit code for the rest.
847 o.indent(Indentation) << "else\n";
850 Best.getVariableFC().emit(o, Indentation);
854 // Assign a single filter and run with it. Top level API client can initialize
855 // with a single filter to start the filtering process.
856 void FilterChooser::runSingleFilter(FilterChooser &owner, unsigned startBit,
857 unsigned numBit, bool mixed) {
859 Filter F(*this, startBit, numBit, true);
860 Filters.push_back(F);
861 BestIndex = 0; // Sole Filter instance to choose from.
862 bestFilter().recurse();
865 // reportRegion is a helper function for filterProcessor to mark a region as
866 // eligible for use as a filter region.
867 void FilterChooser::reportRegion(bitAttr_t RA, unsigned StartBit,
868 unsigned BitIndex, bool AllowMixed) {
869 if (RA == ATTR_MIXED && AllowMixed)
870 Filters.push_back(Filter(*this, StartBit, BitIndex - StartBit, true));
871 else if (RA == ATTR_ALL_SET && !AllowMixed)
872 Filters.push_back(Filter(*this, StartBit, BitIndex - StartBit, false));
875 // FilterProcessor scans the well-known encoding bits of the instructions and
876 // builds up a list of candidate filters. It chooses the best filter and
877 // recursively descends down the decoding tree.
878 bool FilterChooser::filterProcessor(bool AllowMixed, bool Greedy) {
881 unsigned numInstructions = Opcodes.size();
883 assert(numInstructions && "Filter created with no instructions");
885 // No further filtering is necessary.
886 if (numInstructions == 1)
889 // Heuristics. See also doFilter()'s "Heuristics" comment when num of
890 // instructions is 3.
891 if (AllowMixed && !Greedy) {
892 assert(numInstructions == 3);
894 for (unsigned i = 0; i < Opcodes.size(); ++i) {
895 std::vector<unsigned> StartBits;
896 std::vector<unsigned> EndBits;
897 std::vector<uint64_t> FieldVals;
900 insnWithID(Insn, Opcodes[i]);
902 // Look for islands of undecoded bits of any instruction.
903 if (getIslands(StartBits, EndBits, FieldVals, Insn) > 0) {
904 // Found an instruction with island(s). Now just assign a filter.
905 runSingleFilter(*this, StartBits[0], EndBits[0] - StartBits[0] + 1,
912 unsigned BitIndex, InsnIndex;
914 // We maintain BIT_WIDTH copies of the bitAttrs automaton.
915 // The automaton consumes the corresponding bit from each
918 // Input symbols: 0, 1, and _ (unset).
919 // States: NONE, FILTERED, ALL_SET, ALL_UNSET, and MIXED.
920 // Initial state: NONE.
922 // (NONE) ------- [01] -> (ALL_SET)
923 // (NONE) ------- _ ----> (ALL_UNSET)
924 // (ALL_SET) ---- [01] -> (ALL_SET)
925 // (ALL_SET) ---- _ ----> (MIXED)
926 // (ALL_UNSET) -- [01] -> (MIXED)
927 // (ALL_UNSET) -- _ ----> (ALL_UNSET)
928 // (MIXED) ------ . ----> (MIXED)
929 // (FILTERED)---- . ----> (FILTERED)
931 std::vector<bitAttr_t> bitAttrs;
933 // FILTERED bit positions provide no entropy and are not worthy of pursuing.
934 // Filter::recurse() set either BIT_TRUE or BIT_FALSE for each position.
935 for (BitIndex = 0; BitIndex < BitWidth; ++BitIndex)
936 if (FilterBitValues[BitIndex] == BIT_TRUE ||
937 FilterBitValues[BitIndex] == BIT_FALSE)
938 bitAttrs.push_back(ATTR_FILTERED);
940 bitAttrs.push_back(ATTR_NONE);
942 for (InsnIndex = 0; InsnIndex < numInstructions; ++InsnIndex) {
945 insnWithID(insn, Opcodes[InsnIndex]);
947 for (BitIndex = 0; BitIndex < BitWidth; ++BitIndex) {
948 switch (bitAttrs[BitIndex]) {
950 if (insn[BitIndex] == BIT_UNSET)
951 bitAttrs[BitIndex] = ATTR_ALL_UNSET;
953 bitAttrs[BitIndex] = ATTR_ALL_SET;
956 if (insn[BitIndex] == BIT_UNSET)
957 bitAttrs[BitIndex] = ATTR_MIXED;
960 if (insn[BitIndex] != BIT_UNSET)
961 bitAttrs[BitIndex] = ATTR_MIXED;
970 // The regionAttr automaton consumes the bitAttrs automatons' state,
971 // lowest-to-highest.
973 // Input symbols: F(iltered), (all_)S(et), (all_)U(nset), M(ixed)
974 // States: NONE, ALL_SET, MIXED
975 // Initial state: NONE
977 // (NONE) ----- F --> (NONE)
978 // (NONE) ----- S --> (ALL_SET) ; and set region start
979 // (NONE) ----- U --> (NONE)
980 // (NONE) ----- M --> (MIXED) ; and set region start
981 // (ALL_SET) -- F --> (NONE) ; and report an ALL_SET region
982 // (ALL_SET) -- S --> (ALL_SET)
983 // (ALL_SET) -- U --> (NONE) ; and report an ALL_SET region
984 // (ALL_SET) -- M --> (MIXED) ; and report an ALL_SET region
985 // (MIXED) ---- F --> (NONE) ; and report a MIXED region
986 // (MIXED) ---- S --> (ALL_SET) ; and report a MIXED region
987 // (MIXED) ---- U --> (NONE) ; and report a MIXED region
988 // (MIXED) ---- M --> (MIXED)
990 bitAttr_t RA = ATTR_NONE;
991 unsigned StartBit = 0;
993 for (BitIndex = 0; BitIndex < BitWidth; BitIndex++) {
994 bitAttr_t bitAttr = bitAttrs[BitIndex];
996 assert(bitAttr != ATTR_NONE && "Bit without attributes");
1004 StartBit = BitIndex;
1007 case ATTR_ALL_UNSET:
1010 StartBit = BitIndex;
1014 assert(0 && "Unexpected bitAttr!");
1020 reportRegion(RA, StartBit, BitIndex, AllowMixed);
1025 case ATTR_ALL_UNSET:
1026 reportRegion(RA, StartBit, BitIndex, AllowMixed);
1030 reportRegion(RA, StartBit, BitIndex, AllowMixed);
1031 StartBit = BitIndex;
1035 assert(0 && "Unexpected bitAttr!");
1041 reportRegion(RA, StartBit, BitIndex, AllowMixed);
1042 StartBit = BitIndex;
1046 reportRegion(RA, StartBit, BitIndex, AllowMixed);
1047 StartBit = BitIndex;
1050 case ATTR_ALL_UNSET:
1051 reportRegion(RA, StartBit, BitIndex, AllowMixed);
1057 assert(0 && "Unexpected bitAttr!");
1060 case ATTR_ALL_UNSET:
1061 assert(0 && "regionAttr state machine has no ATTR_UNSET state");
1063 assert(0 && "regionAttr state machine has no ATTR_FILTERED state");
1067 // At the end, if we're still in ALL_SET or MIXED states, report a region
1074 reportRegion(RA, StartBit, BitIndex, AllowMixed);
1076 case ATTR_ALL_UNSET:
1079 reportRegion(RA, StartBit, BitIndex, AllowMixed);
1083 // We have finished with the filter processings. Now it's time to choose
1084 // the best performing filter.
1086 bool AllUseless = true;
1087 unsigned BestScore = 0;
1089 for (unsigned i = 0, e = Filters.size(); i != e; ++i) {
1090 unsigned Usefulness = Filters[i].usefulness();
1095 if (Usefulness > BestScore) {
1097 BestScore = Usefulness;
1102 bestFilter().recurse();
1105 } // end of FilterChooser::filterProcessor(bool)
1107 // Decides on the best configuration of filter(s) to use in order to decode
1108 // the instructions. A conflict of instructions may occur, in which case we
1109 // dump the conflict set to the standard error.
1110 void FilterChooser::doFilter() {
1111 unsigned Num = Opcodes.size();
1112 assert(Num && "FilterChooser created with no instructions");
1114 // Try regions of consecutive known bit values first.
1115 if (filterProcessor(false))
1118 // Then regions of mixed bits (both known and unitialized bit values allowed).
1119 if (filterProcessor(true))
1122 // Heuristics to cope with conflict set {t2CMPrs, t2SUBSrr, t2SUBSrs} where
1123 // no single instruction for the maximum ATTR_MIXED region Inst{14-4} has a
1124 // well-known encoding pattern. In such case, we backtrack and scan for the
1125 // the very first consecutive ATTR_ALL_SET region and assign a filter to it.
1126 if (Num == 3 && filterProcessor(true, false))
1129 // If we come to here, the instruction decoding has failed.
1130 // Set the BestIndex to -1 to indicate so.
1134 // Emits code to decode our share of instructions. Returns true if the
1135 // emitted code causes a return, which occurs if we know how to decode
1136 // the instruction at this level or the instruction is not decodeable.
1137 bool FilterChooser::emit(raw_ostream &o, unsigned &Indentation) {
1138 if (Opcodes.size() == 1)
1139 // There is only one instruction in the set, which is great!
1140 // Call emitSingletonDecoder() to see whether there are any remaining
1142 return emitSingletonDecoder(o, Indentation, Opcodes[0]);
1144 // Choose the best filter to do the decodings!
1145 if (BestIndex != -1) {
1146 Filter &Best = bestFilter();
1147 if (Best.getNumFiltered() == 1)
1148 emitSingletonDecoder(o, Indentation, Best);
1150 bestFilter().emit(o, Indentation);
1154 // We don't know how to decode these instructions! Return 0 and dump the
1156 o.indent(Indentation) << "return 0;" << " // Conflict set: ";
1157 for (int i = 0, N = Opcodes.size(); i < N; ++i) {
1158 o << nameWithID(Opcodes[i]);
1165 // Print out useful conflict information for postmortem analysis.
1166 errs() << "Decoding Conflict:\n";
1168 dumpStack(errs(), "\t\t");
1170 for (unsigned i = 0; i < Opcodes.size(); i++) {
1171 const std::string &Name = nameWithID(Opcodes[i]);
1173 errs() << '\t' << Name << " ";
1175 getBitsField(*AllInstructions[Opcodes[i]]->TheDef, "Inst"));
1182 static bool populateInstruction(const CodeGenInstruction &CGI,
1184 std::map<unsigned, std::vector<OperandInfo> >& Operands){
1185 const Record &Def = *CGI.TheDef;
1186 // If all the bit positions are not specified; do not decode this instruction.
1187 // We are bound to fail! For proper disassembly, the well-known encoding bits
1188 // of the instruction must be fully specified.
1190 // This also removes pseudo instructions from considerations of disassembly,
1191 // which is a better design and less fragile than the name matchings.
1192 // Ignore "asm parser only" instructions.
1193 if (Def.getValueAsBit("isAsmParserOnly") ||
1194 Def.getValueAsBit("isCodeGenOnly"))
1197 BitsInit &Bits = getBitsField(Def, "Inst");
1198 if (Bits.allInComplete()) return false;
1200 std::vector<OperandInfo> InsnOperands;
1202 // If the instruction has specified a custom decoding hook, use that instead
1203 // of trying to auto-generate the decoder.
1204 std::string InstDecoder = Def.getValueAsString("DecoderMethod");
1205 if (InstDecoder != "") {
1206 InsnOperands.push_back(OperandInfo(InstDecoder));
1207 Operands[Opc] = InsnOperands;
1211 // Generate a description of the operand of the instruction that we know
1212 // how to decode automatically.
1213 // FIXME: We'll need to have a way to manually override this as needed.
1215 // Gather the outputs/inputs of the instruction, so we can find their
1216 // positions in the encoding. This assumes for now that they appear in the
1217 // MCInst in the order that they're listed.
1218 std::vector<std::pair<Init*, std::string> > InOutOperands;
1219 DagInit *Out = Def.getValueAsDag("OutOperandList");
1220 DagInit *In = Def.getValueAsDag("InOperandList");
1221 for (unsigned i = 0; i < Out->getNumArgs(); ++i)
1222 InOutOperands.push_back(std::make_pair(Out->getArg(i), Out->getArgName(i)));
1223 for (unsigned i = 0; i < In->getNumArgs(); ++i)
1224 InOutOperands.push_back(std::make_pair(In->getArg(i), In->getArgName(i)));
1226 // Search for tied operands, so that we can correctly instantiate
1227 // operands that are not explicitly represented in the encoding.
1228 std::map<std::string, std::string> TiedNames;
1229 for (unsigned i = 0; i < CGI.Operands.size(); ++i) {
1230 int tiedTo = CGI.Operands[i].getTiedRegister();
1232 TiedNames[InOutOperands[i].second] = InOutOperands[tiedTo].second;
1233 TiedNames[InOutOperands[tiedTo].second] = InOutOperands[i].second;
1237 // For each operand, see if we can figure out where it is encoded.
1238 for (std::vector<std::pair<Init*, std::string> >::iterator
1239 NI = InOutOperands.begin(), NE = InOutOperands.end(); NI != NE; ++NI) {
1240 std::string Decoder = "";
1242 // At this point, we can locate the field, but we need to know how to
1243 // interpret it. As a first step, require the target to provide callbacks
1244 // for decoding register classes.
1245 // FIXME: This need to be extended to handle instructions with custom
1246 // decoder methods, and operands with (simple) MIOperandInfo's.
1247 TypedInit *TI = dynamic_cast<TypedInit*>(NI->first);
1248 RecordRecTy *Type = dynamic_cast<RecordRecTy*>(TI->getType());
1249 Record *TypeRecord = Type->getRecord();
1251 if (TypeRecord->isSubClassOf("RegisterOperand"))
1252 TypeRecord = TypeRecord->getValueAsDef("RegClass");
1253 if (TypeRecord->isSubClassOf("RegisterClass")) {
1254 Decoder = "Decode" + TypeRecord->getName() + "RegisterClass";
1258 RecordVal *DecoderString = TypeRecord->getValue("DecoderMethod");
1259 StringInit *String = DecoderString ?
1260 dynamic_cast<StringInit*>(DecoderString->getValue()) : 0;
1261 if (!isReg && String && String->getValue() != "")
1262 Decoder = String->getValue();
1264 OperandInfo OpInfo(Decoder);
1265 unsigned Base = ~0U;
1267 unsigned Offset = 0;
1269 for (unsigned bi = 0; bi < Bits.getNumBits(); ++bi) {
1271 VarBitInit *BI = dynamic_cast<VarBitInit*>(Bits.getBit(bi));
1273 Var = dynamic_cast<VarInit*>(BI->getVariable());
1275 Var = dynamic_cast<VarInit*>(Bits.getBit(bi));
1279 OpInfo.addField(Base, Width, Offset);
1287 if (Var->getName() != NI->second &&
1288 Var->getName() != TiedNames[NI->second]) {
1290 OpInfo.addField(Base, Width, Offset);
1301 Offset = BI ? BI->getBitNum() : 0;
1302 } else if (BI && BI->getBitNum() != Offset + Width) {
1303 OpInfo.addField(Base, Width, Offset);
1306 Offset = BI->getBitNum();
1313 OpInfo.addField(Base, Width, Offset);
1315 if (OpInfo.numFields() > 0)
1316 InsnOperands.push_back(OpInfo);
1319 Operands[Opc] = InsnOperands;
1324 // Dumps the instruction encoding bits.
1325 dumpBits(errs(), Bits);
1329 // Dumps the list of operand info.
1330 for (unsigned i = 0, e = CGI.Operands.size(); i != e; ++i) {
1331 const CGIOperandList::OperandInfo &Info = CGI.Operands[i];
1332 const std::string &OperandName = Info.Name;
1333 const Record &OperandDef = *Info.Rec;
1335 errs() << "\t" << OperandName << " (" << OperandDef.getName() << ")\n";
1343 static void emitHelper(llvm::raw_ostream &o, unsigned BitWidth) {
1344 unsigned Indentation = 0;
1345 std::string WidthStr = "uint" + utostr(BitWidth) + "_t";
1349 o.indent(Indentation) << "static " << WidthStr <<
1350 " fieldFromInstruction" << BitWidth <<
1351 "(" << WidthStr <<" insn, unsigned startBit, unsigned numBits)\n";
1353 o.indent(Indentation) << "{\n";
1355 ++Indentation; ++Indentation;
1356 o.indent(Indentation) << "assert(startBit + numBits <= " << BitWidth
1357 << " && \"Instruction field out of bounds!\");\n";
1359 o.indent(Indentation) << WidthStr << " fieldMask;\n";
1361 o.indent(Indentation) << "if (numBits == " << BitWidth << ")\n";
1363 ++Indentation; ++Indentation;
1364 o.indent(Indentation) << "fieldMask = (" << WidthStr << ")-1;\n";
1365 --Indentation; --Indentation;
1367 o.indent(Indentation) << "else\n";
1369 ++Indentation; ++Indentation;
1370 o.indent(Indentation) << "fieldMask = ((1 << numBits) - 1) << startBit;\n";
1371 --Indentation; --Indentation;
1374 o.indent(Indentation) << "return (insn & fieldMask) >> startBit;\n";
1375 --Indentation; --Indentation;
1377 o.indent(Indentation) << "}\n";
1382 // Emits disassembler code for instruction decoding.
1383 void FixedLenDecoderEmitter::run(raw_ostream &o)
1385 o << "#include \"llvm/MC/MCInst.h\"\n";
1386 o << "#include \"llvm/Support/DataTypes.h\"\n";
1387 o << "#include <assert.h>\n";
1389 o << "namespace llvm {\n\n";
1391 // Parameterize the decoders based on namespace and instruction width.
1392 NumberedInstructions = Target.getInstructionsByEnumValue();
1393 std::map<std::pair<std::string, unsigned>,
1394 std::vector<unsigned> > OpcMap;
1395 std::map<unsigned, std::vector<OperandInfo> > Operands;
1397 for (unsigned i = 0; i < NumberedInstructions.size(); ++i) {
1398 const CodeGenInstruction *Inst = NumberedInstructions[i];
1399 Record *Def = Inst->TheDef;
1400 unsigned Size = Def->getValueAsInt("Size");
1401 if (Def->getValueAsString("Namespace") == "TargetOpcode" ||
1402 Def->getValueAsBit("isPseudo") ||
1403 Def->getValueAsBit("isAsmParserOnly") ||
1404 Def->getValueAsBit("isCodeGenOnly"))
1407 std::string DecoderNamespace = Def->getValueAsString("DecoderNamespace");
1410 if (populateInstruction(*Inst, i, Operands)) {
1411 OpcMap[std::make_pair(DecoderNamespace, Size)].push_back(i);
1416 std::set<unsigned> Sizes;
1417 for (std::map<std::pair<std::string, unsigned>,
1418 std::vector<unsigned> >::iterator
1419 I = OpcMap.begin(), E = OpcMap.end(); I != E; ++I) {
1420 // If we haven't visited this instruction width before, emit the
1421 // helper method to extract fields.
1422 if (!Sizes.count(I->first.second)) {
1423 emitHelper(o, 8*I->first.second);
1424 Sizes.insert(I->first.second);
1427 // Emit the decoder for this namespace+width combination.
1428 FilterChooser FC(NumberedInstructions, I->second, Operands,
1430 FC.emitTop(o, 0, I->first.first);
1433 o << "\n} // End llvm namespace \n";