diff options
Diffstat (limited to 'llvm/utils/TableGen/FixedLenDecoderEmitter.cpp')
| -rw-r--r-- | llvm/utils/TableGen/FixedLenDecoderEmitter.cpp | 2529 |
1 files changed, 2529 insertions, 0 deletions
diff --git a/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp b/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp new file mode 100644 index 000000000000..ac69b431607d --- /dev/null +++ b/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp @@ -0,0 +1,2529 @@ +//===------------ FixedLenDecoderEmitter.cpp - Decoder Generator ----------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// It contains the tablegen backend that emits the decoder functions for +// targets with fixed length instruction set. +// +//===----------------------------------------------------------------------===// + +#include "CodeGenInstruction.h" +#include "CodeGenTarget.h" +#include "InfoByHwMode.h" +#include "llvm/ADT/APInt.h" +#include "llvm/ADT/ArrayRef.h" +#include "llvm/ADT/CachedHashString.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/ADT/StringExtras.h" +#include "llvm/ADT/StringRef.h" +#include "llvm/MC/MCFixedLenDisassembler.h" +#include "llvm/Support/Casting.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/FormattedStream.h" +#include "llvm/Support/LEB128.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/TableGen/Error.h" +#include "llvm/TableGen/Record.h" +#include <algorithm> +#include <cassert> +#include <cstddef> +#include <cstdint> +#include <map> +#include <memory> +#include <set> +#include <string> +#include <utility> +#include <vector> + +using namespace llvm; + +#define DEBUG_TYPE "decoder-emitter" + +namespace { + +STATISTIC(NumEncodings, "Number of encodings considered"); +STATISTIC(NumEncodingsLackingDisasm, "Number of encodings without disassembler info"); +STATISTIC(NumInstructions, "Number of instructions considered"); +STATISTIC(NumEncodingsSupported, "Number of encodings supported"); +STATISTIC(NumEncodingsOmitted, "Number of encodings omitted"); + +struct EncodingField { + unsigned Base, Width, Offset; + EncodingField(unsigned B, unsigned W, unsigned O) + : Base(B), Width(W), Offset(O) { } +}; + +struct OperandInfo { + std::vector<EncodingField> Fields; + std::string Decoder; + bool HasCompleteDecoder; + uint64_t InitValue; + + OperandInfo(std::string D, bool HCD) + : Decoder(std::move(D)), HasCompleteDecoder(HCD), InitValue(0) {} + + void addField(unsigned Base, unsigned Width, unsigned Offset) { + Fields.push_back(EncodingField(Base, Width, Offset)); + } + + unsigned numFields() const { return Fields.size(); } + + typedef std::vector<EncodingField>::const_iterator const_iterator; + + const_iterator begin() const { return Fields.begin(); } + const_iterator end() const { return Fields.end(); } +}; + +typedef std::vector<uint8_t> DecoderTable; +typedef uint32_t DecoderFixup; +typedef std::vector<DecoderFixup> FixupList; +typedef std::vector<FixupList> FixupScopeList; +typedef SmallSetVector<CachedHashString, 16> PredicateSet; +typedef SmallSetVector<CachedHashString, 16> DecoderSet; +struct DecoderTableInfo { + DecoderTable Table; + FixupScopeList FixupStack; + PredicateSet Predicates; + DecoderSet Decoders; +}; + +struct EncodingAndInst { + const Record *EncodingDef; + const CodeGenInstruction *Inst; + StringRef HwModeName; + + EncodingAndInst(const Record *EncodingDef, const CodeGenInstruction *Inst, + StringRef HwModeName = "") + : EncodingDef(EncodingDef), Inst(Inst), HwModeName(HwModeName) {} +}; + +struct EncodingIDAndOpcode { + unsigned EncodingID; + unsigned Opcode; + + EncodingIDAndOpcode() : EncodingID(0), Opcode(0) {} + EncodingIDAndOpcode(unsigned EncodingID, unsigned Opcode) + : EncodingID(EncodingID), Opcode(Opcode) {} +}; + +raw_ostream &operator<<(raw_ostream &OS, const EncodingAndInst &Value) { + if (Value.EncodingDef != Value.Inst->TheDef) + OS << Value.EncodingDef->getName() << ":"; + OS << Value.Inst->TheDef->getName(); + return OS; +} + +class FixedLenDecoderEmitter { + RecordKeeper &RK; + std::vector<EncodingAndInst> NumberedEncodings; + +public: + // Defaults preserved here for documentation, even though they aren't + // strictly necessary given the way that this is currently being called. + FixedLenDecoderEmitter(RecordKeeper &R, std::string PredicateNamespace, + std::string GPrefix = "if (", + std::string GPostfix = " == MCDisassembler::Fail)", + std::string ROK = "MCDisassembler::Success", + std::string RFail = "MCDisassembler::Fail", + std::string L = "") + : RK(R), Target(R), PredicateNamespace(std::move(PredicateNamespace)), + GuardPrefix(std::move(GPrefix)), GuardPostfix(std::move(GPostfix)), + ReturnOK(std::move(ROK)), ReturnFail(std::move(RFail)), + Locals(std::move(L)) {} + + // Emit the decoder state machine table. + void emitTable(formatted_raw_ostream &o, DecoderTable &Table, + unsigned Indentation, unsigned BitWidth, + StringRef Namespace) const; + void emitPredicateFunction(formatted_raw_ostream &OS, + PredicateSet &Predicates, + unsigned Indentation) const; + void emitDecoderFunction(formatted_raw_ostream &OS, + DecoderSet &Decoders, + unsigned Indentation) const; + + // run - Output the code emitter + void run(raw_ostream &o); + +private: + CodeGenTarget Target; + +public: + std::string PredicateNamespace; + std::string GuardPrefix, GuardPostfix; + std::string ReturnOK, ReturnFail; + std::string Locals; +}; + +} // end anonymous namespace + +// The set (BIT_TRUE, BIT_FALSE, BIT_UNSET) represents a ternary logic system +// for a bit value. +// +// BIT_UNFILTERED is used as the init value for a filter position. It is used +// only for filter processings. +typedef enum { + BIT_TRUE, // '1' + BIT_FALSE, // '0' + BIT_UNSET, // '?' + BIT_UNFILTERED // unfiltered +} bit_value_t; + +static bool ValueSet(bit_value_t V) { + return (V == BIT_TRUE || V == BIT_FALSE); +} + +static bool ValueNotSet(bit_value_t V) { + return (V == BIT_UNSET); +} + +static int Value(bit_value_t V) { + return ValueNotSet(V) ? -1 : (V == BIT_FALSE ? 0 : 1); +} + +static bit_value_t bitFromBits(const BitsInit &bits, unsigned index) { + if (BitInit *bit = dyn_cast<BitInit>(bits.getBit(index))) + return bit->getValue() ? BIT_TRUE : BIT_FALSE; + + // The bit is uninitialized. + return BIT_UNSET; +} + +// Prints the bit value for each position. +static void dumpBits(raw_ostream &o, const BitsInit &bits) { + for (unsigned index = bits.getNumBits(); index > 0; --index) { + switch (bitFromBits(bits, index - 1)) { + case BIT_TRUE: + o << "1"; + break; + case BIT_FALSE: + o << "0"; + break; + case BIT_UNSET: + o << "_"; + break; + default: + llvm_unreachable("unexpected return value from bitFromBits"); + } + } +} + +static BitsInit &getBitsField(const Record &def, StringRef str) { + BitsInit *bits = def.getValueAsBitsInit(str); + return *bits; +} + +// Representation of the instruction to work on. +typedef std::vector<bit_value_t> insn_t; + +namespace { + +class FilterChooser; + +/// Filter - Filter works with FilterChooser to produce the decoding tree for +/// the ISA. +/// +/// It is useful to think of a Filter as governing the switch stmts of the +/// decoding tree in a certain level. Each case stmt delegates to an inferior +/// FilterChooser to decide what further decoding logic to employ, or in another +/// words, what other remaining bits to look at. The FilterChooser eventually +/// chooses a best Filter to do its job. +/// +/// This recursive scheme ends when the number of Opcodes assigned to the +/// FilterChooser becomes 1 or if there is a conflict. A conflict happens when +/// the Filter/FilterChooser combo does not know how to distinguish among the +/// Opcodes assigned. +/// +/// An example of a conflict is +/// +/// Conflict: +/// 111101000.00........00010000.... +/// 111101000.00........0001........ +/// 1111010...00........0001........ +/// 1111010...00.................... +/// 1111010......................... +/// 1111............................ +/// ................................ +/// VST4q8a 111101000_00________00010000____ +/// VST4q8b 111101000_00________00010000____ +/// +/// The Debug output shows the path that the decoding tree follows to reach the +/// the conclusion that there is a conflict. VST4q8a is a vst4 to double-spaced +/// even registers, while VST4q8b is a vst4 to double-spaced odd registers. +/// +/// The encoding info in the .td files does not specify this meta information, +/// which could have been used by the decoder to resolve the conflict. The +/// decoder could try to decode the even/odd register numbering and assign to +/// VST4q8a or VST4q8b, but for the time being, the decoder chooses the "a" +/// version and return the Opcode since the two have the same Asm format string. +class Filter { +protected: + const FilterChooser *Owner;// points to the FilterChooser who owns this filter + unsigned StartBit; // the starting bit position + unsigned NumBits; // number of bits to filter + bool Mixed; // a mixed region contains both set and unset bits + + // Map of well-known segment value to the set of uid's with that value. + std::map<uint64_t, std::vector<EncodingIDAndOpcode>> + FilteredInstructions; + + // Set of uid's with non-constant segment values. + std::vector<EncodingIDAndOpcode> VariableInstructions; + + // Map of well-known segment value to its delegate. + std::map<unsigned, std::unique_ptr<const FilterChooser>> FilterChooserMap; + + // Number of instructions which fall under FilteredInstructions category. + unsigned NumFiltered; + + // Keeps track of the last opcode in the filtered bucket. + EncodingIDAndOpcode LastOpcFiltered; + +public: + Filter(Filter &&f); + Filter(FilterChooser &owner, unsigned startBit, unsigned numBits, bool mixed); + + ~Filter() = default; + + unsigned getNumFiltered() const { return NumFiltered; } + + EncodingIDAndOpcode getSingletonOpc() const { + assert(NumFiltered == 1); + return LastOpcFiltered; + } + + // Return the filter chooser for the group of instructions without constant + // segment values. + const FilterChooser &getVariableFC() const { + assert(NumFiltered == 1); + assert(FilterChooserMap.size() == 1); + return *(FilterChooserMap.find((unsigned)-1)->second); + } + + // Divides the decoding task into sub tasks and delegates them to the + // inferior FilterChooser's. + // + // A special case arises when there's only one entry in the filtered + // instructions. In order to unambiguously decode the singleton, we need to + // match the remaining undecoded encoding bits against the singleton. + void recurse(); + + // Emit table entries to decode instructions given a segment or segments of + // bits. + void emitTableEntry(DecoderTableInfo &TableInfo) const; + + // Returns the number of fanout produced by the filter. More fanout implies + // the filter distinguishes more categories of instructions. + unsigned usefulness() const; +}; // end class Filter + +} // end anonymous namespace + +// These are states of our finite state machines used in FilterChooser's +// filterProcessor() which produces the filter candidates to use. +typedef enum { + ATTR_NONE, + ATTR_FILTERED, + ATTR_ALL_SET, + ATTR_ALL_UNSET, + ATTR_MIXED +} bitAttr_t; + +/// FilterChooser - FilterChooser chooses the best filter among a set of Filters +/// in order to perform the decoding of instructions at the current level. +/// +/// Decoding proceeds from the top down. Based on the well-known encoding bits +/// of instructions available, FilterChooser builds up the possible Filters that +/// can further the task of decoding by distinguishing among the remaining +/// candidate instructions. +/// +/// Once a filter has been chosen, it is called upon to divide the decoding task +/// into sub-tasks and delegates them to its inferior FilterChoosers for further +/// processings. +/// +/// It is useful to think of a Filter as governing the switch stmts of the +/// decoding tree. And each case is delegated to an inferior FilterChooser to +/// decide what further remaining bits to look at. +namespace { + +class FilterChooser { +protected: + friend class Filter; + + // Vector of codegen instructions to choose our filter. + ArrayRef<EncodingAndInst> AllInstructions; + + // Vector of uid's for this filter chooser to work on. + // The first member of the pair is the opcode id being decoded, the second is + // the opcode id that should be emitted. + const std::vector<EncodingIDAndOpcode> &Opcodes; + + // Lookup table for the operand decoding of instructions. + const std::map<unsigned, std::vector<OperandInfo>> &Operands; + + // Vector of candidate filters. + std::vector<Filter> Filters; + + // Array of bit values passed down from our parent. + // Set to all BIT_UNFILTERED's for Parent == NULL. + std::vector<bit_value_t> FilterBitValues; + + // Links to the FilterChooser above us in the decoding tree. + const FilterChooser *Parent; + + // Index of the best filter from Filters. + int BestIndex; + + // Width of instructions + unsigned BitWidth; + + // Parent emitter + const FixedLenDecoderEmitter *Emitter; + +public: + FilterChooser(ArrayRef<EncodingAndInst> Insts, + const std::vector<EncodingIDAndOpcode> &IDs, + const std::map<unsigned, std::vector<OperandInfo>> &Ops, + unsigned BW, const FixedLenDecoderEmitter *E) + : AllInstructions(Insts), Opcodes(IDs), Operands(Ops), + FilterBitValues(BW, BIT_UNFILTERED), Parent(nullptr), BestIndex(-1), + BitWidth(BW), Emitter(E) { + doFilter(); + } + + FilterChooser(ArrayRef<EncodingAndInst> Insts, + const std::vector<EncodingIDAndOpcode> &IDs, + const std::map<unsigned, std::vector<OperandInfo>> &Ops, + const std::vector<bit_value_t> &ParentFilterBitValues, + const FilterChooser &parent) + : AllInstructions(Insts), Opcodes(IDs), Operands(Ops), + FilterBitValues(ParentFilterBitValues), Parent(&parent), BestIndex(-1), + BitWidth(parent.BitWidth), Emitter(parent.Emitter) { + doFilter(); + } + + FilterChooser(const FilterChooser &) = delete; + void operator=(const FilterChooser &) = delete; + + unsigned getBitWidth() const { return BitWidth; } + +protected: + // Populates the insn given the uid. + void insnWithID(insn_t &Insn, unsigned Opcode) const { + BitsInit &Bits = getBitsField(*AllInstructions[Opcode].EncodingDef, "Inst"); + + // We may have a SoftFail bitmask, which specifies a mask where an encoding + // may differ from the value in "Inst" and yet still be valid, but the + // disassembler should return SoftFail instead of Success. + // + // This is used for marking UNPREDICTABLE instructions in the ARM world. + BitsInit *SFBits = + AllInstructions[Opcode].EncodingDef->getValueAsBitsInit("SoftFail"); + + for (unsigned i = 0; i < BitWidth; ++i) { + if (SFBits && bitFromBits(*SFBits, i) == BIT_TRUE) + Insn.push_back(BIT_UNSET); + else + Insn.push_back(bitFromBits(Bits, i)); + } + } + + // Emit the name of the encoding/instruction pair. + void emitNameWithID(raw_ostream &OS, unsigned Opcode) const { + const Record *EncodingDef = AllInstructions[Opcode].EncodingDef; + const Record *InstDef = AllInstructions[Opcode].Inst->TheDef; + if (EncodingDef != InstDef) + OS << EncodingDef->getName() << ":"; + OS << InstDef->getName(); + } + + // Populates the field of the insn given the start position and the number of + // consecutive bits to scan for. + // + // Returns false if there exists any uninitialized bit value in the range. + // Returns true, otherwise. + bool fieldFromInsn(uint64_t &Field, insn_t &Insn, unsigned StartBit, + unsigned NumBits) const; + + /// dumpFilterArray - dumpFilterArray prints out debugging info for the given + /// filter array as a series of chars. + void dumpFilterArray(raw_ostream &o, + const std::vector<bit_value_t> & filter) const; + + /// dumpStack - dumpStack traverses the filter chooser chain and calls + /// dumpFilterArray on each filter chooser up to the top level one. + void dumpStack(raw_ostream &o, const char *prefix) const; + + Filter &bestFilter() { + assert(BestIndex != -1 && "BestIndex not set"); + return Filters[BestIndex]; + } + + bool PositionFiltered(unsigned i) const { + return ValueSet(FilterBitValues[i]); + } + + // Calculates the island(s) needed to decode the instruction. + // This returns a lit of undecoded bits of an instructions, for example, + // Inst{20} = 1 && Inst{3-0} == 0b1111 represents two islands of yet-to-be + // decoded bits in order to verify that the instruction matches the Opcode. + unsigned getIslands(std::vector<unsigned> &StartBits, + std::vector<unsigned> &EndBits, + std::vector<uint64_t> &FieldVals, + const insn_t &Insn) const; + + // Emits code to check the Predicates member of an instruction are true. + // Returns true if predicate matches were emitted, false otherwise. + bool emitPredicateMatch(raw_ostream &o, unsigned &Indentation, + unsigned Opc) const; + + bool doesOpcodeNeedPredicate(unsigned Opc) const; + unsigned getPredicateIndex(DecoderTableInfo &TableInfo, StringRef P) const; + void emitPredicateTableEntry(DecoderTableInfo &TableInfo, + unsigned Opc) const; + + void emitSoftFailTableEntry(DecoderTableInfo &TableInfo, + unsigned Opc) const; + + // Emits table entries to decode the singleton. + void emitSingletonTableEntry(DecoderTableInfo &TableInfo, + EncodingIDAndOpcode Opc) const; + + // Emits code to decode the singleton, and then to decode the rest. + void emitSingletonTableEntry(DecoderTableInfo &TableInfo, + const Filter &Best) const; + + void emitBinaryParser(raw_ostream &o, unsigned &Indentation, + const OperandInfo &OpInfo, + bool &OpHasCompleteDecoder) const; + + void emitDecoder(raw_ostream &OS, unsigned Indentation, unsigned Opc, + bool &HasCompleteDecoder) const; + unsigned getDecoderIndex(DecoderSet &Decoders, unsigned Opc, + bool &HasCompleteDecoder) const; + + // Assign a single filter and run with it. + void runSingleFilter(unsigned startBit, unsigned numBit, bool mixed); + + // reportRegion is a helper function for filterProcessor to mark a region as + // eligible for use as a filter region. + void reportRegion(bitAttr_t RA, unsigned StartBit, unsigned BitIndex, + bool AllowMixed); + + // FilterProcessor scans the well-known encoding bits of the instructions and + // builds up a list of candidate filters. It chooses the best filter and + // recursively descends down the decoding tree. + bool filterProcessor(bool AllowMixed, bool Greedy = true); + + // Decides on the best configuration of filter(s) to use in order to decode + // the instructions. A conflict of instructions may occur, in which case we + // dump the conflict set to the standard error. + void doFilter(); + +public: + // emitTableEntries - Emit state machine entries to decode our share of + // instructions. + void emitTableEntries(DecoderTableInfo &TableInfo) const; +}; + +} // end anonymous namespace + +/////////////////////////// +// // +// Filter Implementation // +// // +/////////////////////////// + +Filter::Filter(Filter &&f) + : Owner(f.Owner), StartBit(f.StartBit), NumBits(f.NumBits), Mixed(f.Mixed), + FilteredInstructions(std::move(f.FilteredInstructions)), + VariableInstructions(std::move(f.VariableInstructions)), + FilterChooserMap(std::move(f.FilterChooserMap)), NumFiltered(f.NumFiltered), + LastOpcFiltered(f.LastOpcFiltered) { +} + +Filter::Filter(FilterChooser &owner, unsigned startBit, unsigned numBits, + bool mixed) + : Owner(&owner), StartBit(startBit), NumBits(numBits), Mixed(mixed) { + assert(StartBit + NumBits - 1 < Owner->BitWidth); + + NumFiltered = 0; + LastOpcFiltered = {0, 0}; + + for (unsigned i = 0, e = Owner->Opcodes.size(); i != e; ++i) { + insn_t Insn; + + // Populates the insn given the uid. + Owner->insnWithID(Insn, Owner->Opcodes[i].EncodingID); + + uint64_t Field; + // Scans the segment for possibly well-specified encoding bits. + bool ok = Owner->fieldFromInsn(Field, Insn, StartBit, NumBits); + + if (ok) { + // The encoding bits are well-known. Lets add the uid of the + // instruction into the bucket keyed off the constant field value. + LastOpcFiltered = Owner->Opcodes[i]; + FilteredInstructions[Field].push_back(LastOpcFiltered); + ++NumFiltered; + } else { + // Some of the encoding bit(s) are unspecified. This contributes to + // one additional member of "Variable" instructions. + VariableInstructions.push_back(Owner->Opcodes[i]); + } + } + + assert((FilteredInstructions.size() + VariableInstructions.size() > 0) + && "Filter returns no instruction categories"); +} + +// Divides the decoding task into sub tasks and delegates them to the +// inferior FilterChooser's. +// +// A special case arises when there's only one entry in the filtered +// instructions. In order to unambiguously decode the singleton, we need to +// match the remaining undecoded encoding bits against the singleton. +void Filter::recurse() { + // Starts by inheriting our parent filter chooser's filter bit values. + std::vector<bit_value_t> BitValueArray(Owner->FilterBitValues); + + if (!VariableInstructions.empty()) { + // Conservatively marks each segment position as BIT_UNSET. + for (unsigned bitIndex = 0; bitIndex < NumBits; ++bitIndex) + BitValueArray[StartBit + bitIndex] = BIT_UNSET; + + // Delegates to an inferior filter chooser for further processing on this + // group of instructions whose segment values are variable. + FilterChooserMap.insert( + std::make_pair(-1U, std::make_unique<FilterChooser>( + Owner->AllInstructions, VariableInstructions, + Owner->Operands, BitValueArray, *Owner))); + } + + // No need to recurse for a singleton filtered instruction. + // See also Filter::emit*(). + if (getNumFiltered() == 1) { + assert(FilterChooserMap.size() == 1); + return; + } + + // Otherwise, create sub choosers. + for (const auto &Inst : FilteredInstructions) { + + // Marks all the segment positions with either BIT_TRUE or BIT_FALSE. + for (unsigned bitIndex = 0; bitIndex < NumBits; ++bitIndex) { + if (Inst.first & (1ULL << bitIndex)) + BitValueArray[StartBit + bitIndex] = BIT_TRUE; + else + BitValueArray[StartBit + bitIndex] = BIT_FALSE; + } + + // Delegates to an inferior filter chooser for further processing on this + // category of instructions. + FilterChooserMap.insert(std::make_pair( + Inst.first, std::make_unique<FilterChooser>( + Owner->AllInstructions, Inst.second, + Owner->Operands, BitValueArray, *Owner))); + } +} + +static void resolveTableFixups(DecoderTable &Table, const FixupList &Fixups, + uint32_t DestIdx) { + // Any NumToSkip fixups in the current scope can resolve to the + // current location. + for (FixupList::const_reverse_iterator I = Fixups.rbegin(), + E = Fixups.rend(); + I != E; ++I) { + // Calculate the distance from the byte following the fixup entry byte + // to the destination. The Target is calculated from after the 16-bit + // NumToSkip entry itself, so subtract two from the displacement here + // to account for that. + uint32_t FixupIdx = *I; + uint32_t Delta = DestIdx - FixupIdx - 3; + // Our NumToSkip entries are 24-bits. Make sure our table isn't too + // big. + assert(Delta < (1u << 24)); + Table[FixupIdx] = (uint8_t)Delta; + Table[FixupIdx + 1] = (uint8_t)(Delta >> 8); + Table[FixupIdx + 2] = (uint8_t)(Delta >> 16); + } +} + +// Emit table entries to decode instructions given a segment or segments +// of bits. +void Filter::emitTableEntry(DecoderTableInfo &TableInfo) const { + TableInfo.Table.push_back(MCD::OPC_ExtractField); + TableInfo.Table.push_back(StartBit); + TableInfo.Table.push_back(NumBits); + + // A new filter entry begins a new scope for fixup resolution. + TableInfo.FixupStack.emplace_back(); + + DecoderTable &Table = TableInfo.Table; + + size_t PrevFilter = 0; + bool HasFallthrough = false; + for (auto &Filter : FilterChooserMap) { + // Field value -1 implies a non-empty set of variable instructions. + // See also recurse(). + if (Filter.first == (unsigned)-1) { + HasFallthrough = true; + + // Each scope should always have at least one filter value to check + // for. + assert(PrevFilter != 0 && "empty filter set!"); + FixupList &CurScope = TableInfo.FixupStack.back(); + // Resolve any NumToSkip fixups in the current scope. + resolveTableFixups(Table, CurScope, Table.size()); + CurScope.clear(); + PrevFilter = 0; // Don't re-process the filter's fallthrough. + } else { + Table.push_back(MCD::OPC_FilterValue); + // Encode and emit the value to filter against. + uint8_t Buffer[16]; + unsigned Len = encodeULEB128(Filter.first, Buffer); + Table.insert(Table.end(), Buffer, Buffer + Len); + // Reserve space for the NumToSkip entry. We'll backpatch the value + // later. + PrevFilter = Table.size(); + Table.push_back(0); + Table.push_back(0); + Table.push_back(0); + } + + // We arrive at a category of instructions with the same segment value. + // Now delegate to the sub filter chooser for further decodings. + // The case may fallthrough, which happens if the remaining well-known + // encoding bits do not match exactly. + Filter.second->emitTableEntries(TableInfo); + + // Now that we've emitted the body of the handler, update the NumToSkip + // of the filter itself to be able to skip forward when false. Subtract + // two as to account for the width of the NumToSkip field itself. + if (PrevFilter) { + uint32_t NumToSkip = Table.size() - PrevFilter - 3; + assert(NumToSkip < (1u << 24) && "disassembler decoding table too large!"); + Table[PrevFilter] = (uint8_t)NumToSkip; + Table[PrevFilter + 1] = (uint8_t)(NumToSkip >> 8); + Table[PrevFilter + 2] = (uint8_t)(NumToSkip >> 16); + } + } + + // Any remaining unresolved fixups bubble up to the parent fixup scope. + assert(TableInfo.FixupStack.size() > 1 && "fixup stack underflow!"); + FixupScopeList::iterator Source = TableInfo.FixupStack.end() - 1; + FixupScopeList::iterator Dest = Source - 1; + Dest->insert(Dest->end(), Source->begin(), Source->end()); + TableInfo.FixupStack.pop_back(); + + // If there is no fallthrough, then the final filter should get fixed + // up according to the enclosing scope rather than the current position. + if (!HasFallthrough) + TableInfo.FixupStack.back().push_back(PrevFilter); +} + +// Returns the number of fanout produced by the filter. More fanout implies +// the filter distinguishes more categories of instructions. +unsigned Filter::usefulness() const { + if (!VariableInstructions.empty()) + return FilteredInstructions.size(); + else + return FilteredInstructions.size() + 1; +} + +////////////////////////////////// +// // +// Filterchooser Implementation // +// // +////////////////////////////////// + +// Emit the decoder state machine table. +void FixedLenDecoderEmitter::emitTable(formatted_raw_ostream &OS, + DecoderTable &Table, + unsigned Indentation, + unsigned BitWidth, + StringRef Namespace) const { + OS.indent(Indentation) << "static const uint8_t DecoderTable" << Namespace + << BitWidth << "[] = {\n"; + + Indentation += 2; + + // FIXME: We may be able to use the NumToSkip values to recover + // appropriate indentation levels. + DecoderTable::const_iterator I = Table.begin(); + DecoderTable::const_iterator E = Table.end(); + while (I != E) { + assert (I < E && "incomplete decode table entry!"); + + uint64_t Pos = I - Table.begin(); + OS << "/* " << Pos << " */"; + OS.PadToColumn(12); + + switch (*I) { + default: + PrintFatalError("invalid decode table opcode"); + case MCD::OPC_ExtractField: { + ++I; + unsigned Start = *I++; + unsigned Len = *I++; + OS.indent(Indentation) << "MCD::OPC_ExtractField, " << Start << ", " + << Len << ", // Inst{"; + if (Len > 1) + OS << (Start + Len - 1) << "-"; + OS << Start << "} ...\n"; + break; + } + case MCD::OPC_FilterValue: { + ++I; + OS.indent(Indentation) << "MCD::OPC_FilterValue, "; + // The filter value is ULEB128 encoded. + while (*I >= 128) + OS << (unsigned)*I++ << ", "; + OS << (unsigned)*I++ << ", "; + + // 24-bit numtoskip value. + uint8_t Byte = *I++; + uint32_t NumToSkip = Byte; + OS << (unsigned)Byte << ", "; + Byte = *I++; + OS << (unsigned)Byte << ", "; + NumToSkip |= Byte << 8; + Byte = *I++; + OS << utostr(Byte) << ", "; + NumToSkip |= Byte << 16; + OS << "// Skip to: " << ((I - Table.begin()) + NumToSkip) << "\n"; + break; + } + case MCD::OPC_CheckField: { + ++I; + unsigned Start = *I++; + unsigned Len = *I++; + OS.indent(Indentation) << "MCD::OPC_CheckField, " << Start << ", " + << Len << ", ";// << Val << ", " << NumToSkip << ",\n"; + // ULEB128 encoded field value. + for (; *I >= 128; ++I) + OS << (unsigned)*I << ", "; + OS << (unsigned)*I++ << ", "; + // 24-bit numtoskip value. + uint8_t Byte = *I++; + uint32_t NumToSkip = Byte; + OS << (unsigned)Byte << ", "; + Byte = *I++; + OS << (unsigned)Byte << ", "; + NumToSkip |= Byte << 8; + Byte = *I++; + OS << utostr(Byte) << ", "; + NumToSkip |= Byte << 16; + OS << "// Skip to: " << ((I - Table.begin()) + NumToSkip) << "\n"; + break; + } + case MCD::OPC_CheckPredicate: { + ++I; + OS.indent(Indentation) << "MCD::OPC_CheckPredicate, "; + for (; *I >= 128; ++I) + OS << (unsigned)*I << ", "; + OS << (unsigned)*I++ << ", "; + + // 24-bit numtoskip value. + uint8_t Byte = *I++; + uint32_t NumToSkip = Byte; + OS << (unsigned)Byte << ", "; + Byte = *I++; + OS << (unsigned)Byte << ", "; + NumToSkip |= Byte << 8; + Byte = *I++; + OS << utostr(Byte) << ", "; + NumToSkip |= Byte << 16; + OS << "// Skip to: " << ((I - Table.begin()) + NumToSkip) << "\n"; + break; + } + case MCD::OPC_Decode: + case MCD::OPC_TryDecode: { + bool IsTry = *I == MCD::OPC_TryDecode; + ++I; + // Extract the ULEB128 encoded Opcode to a buffer. + uint8_t Buffer[16], *p = Buffer; + while ((*p++ = *I++) >= 128) + assert((p - Buffer) <= (ptrdiff_t)sizeof(Buffer) + && "ULEB128 value too large!"); + // Decode the Opcode value. + unsigned Opc = decodeULEB128(Buffer); + OS.indent(Indentation) << "MCD::OPC_" << (IsTry ? "Try" : "") + << "Decode, "; + for (p = Buffer; *p >= 128; ++p) + OS << (unsigned)*p << ", "; + OS << (unsigned)*p << ", "; + + // Decoder index. + for (; *I >= 128; ++I) + OS << (unsigned)*I << ", "; + OS << (unsigned)*I++ << ", "; + + if (!IsTry) { + OS << "// Opcode: " << NumberedEncodings[Opc] << "\n"; + break; + } + + // Fallthrough for OPC_TryDecode. + + // 24-bit numtoskip value. + uint8_t Byte = *I++; + uint32_t NumToSkip = Byte; + OS << (unsigned)Byte << ", "; + Byte = *I++; + OS << (unsigned)Byte << ", "; + NumToSkip |= Byte << 8; + Byte = *I++; + OS << utostr(Byte) << ", "; + NumToSkip |= Byte << 16; + + OS << "// Opcode: " << NumberedEncodings[Opc] + << ", skip to: " << ((I - Table.begin()) + NumToSkip) << "\n"; + break; + } + case MCD::OPC_SoftFail: { + ++I; + OS.indent(Indentation) << "MCD::OPC_SoftFail"; + // Positive mask + uint64_t Value = 0; + unsigned Shift = 0; + do { + OS << ", " << (unsigned)*I; + Value += (*I & 0x7f) << Shift; + Shift += 7; + } while (*I++ >= 128); + if (Value > 127) { + OS << " /* 0x"; + OS.write_hex(Value); + OS << " */"; + } + // Negative mask + Value = 0; + Shift = 0; + do { + OS << ", " << (unsigned)*I; + Value += (*I & 0x7f) << Shift; + Shift += 7; + } while (*I++ >= 128); + if (Value > 127) { + OS << " /* 0x"; + OS.write_hex(Value); + OS << " */"; + } + OS << ",\n"; + break; + } + case MCD::OPC_Fail: { + ++I; + OS.indent(Indentation) << "MCD::OPC_Fail,\n"; + break; + } + } + } + OS.indent(Indentation) << "0\n"; + + Indentation -= 2; + + OS.indent(Indentation) << "};\n\n"; +} + +void FixedLenDecoderEmitter:: +emitPredicateFunction(formatted_raw_ostream &OS, PredicateSet &Predicates, + unsigned Indentation) const { + // The predicate function is just a big switch statement based on the + // input predicate index. + OS.indent(Indentation) << "static bool checkDecoderPredicate(unsigned Idx, " + << "const FeatureBitset& Bits) {\n"; + Indentation += 2; + if (!Predicates.empty()) { + OS.indent(Indentation) << "switch (Idx) {\n"; + OS.indent(Indentation) << "default: llvm_unreachable(\"Invalid index!\");\n"; + unsigned Index = 0; + for (const auto &Predicate : Predicates) { + OS.indent(Indentation) << "case " << Index++ << ":\n"; + OS.indent(Indentation+2) << "return (" << Predicate << ");\n"; + } + OS.indent(Indentation) << "}\n"; + } else { + // No case statement to emit + OS.indent(Indentation) << "llvm_unreachable(\"Invalid index!\");\n"; + } + Indentation -= 2; + OS.indent(Indentation) << "}\n\n"; +} + +void FixedLenDecoderEmitter:: +emitDecoderFunction(formatted_raw_ostream &OS, DecoderSet &Decoders, + unsigned Indentation) const { + // The decoder function is just a big switch statement based on the + // input decoder index. + OS.indent(Indentation) << "template<typename InsnType>\n"; + OS.indent(Indentation) << "static DecodeStatus decodeToMCInst(DecodeStatus S," + << " unsigned Idx, InsnType insn, MCInst &MI,\n"; + OS.indent(Indentation) << " uint64_t " + << "Address, const void *Decoder, bool &DecodeComplete) {\n"; + Indentation += 2; + OS.indent(Indentation) << "DecodeComplete = true;\n"; + OS.indent(Indentation) << "InsnType tmp;\n"; + OS.indent(Indentation) << "switch (Idx) {\n"; + OS.indent(Indentation) << "default: llvm_unreachable(\"Invalid index!\");\n"; + unsigned Index = 0; + for (const auto &Decoder : Decoders) { + OS.indent(Indentation) << "case " << Index++ << ":\n"; + OS << Decoder; + OS.indent(Indentation+2) << "return S;\n"; + } + OS.indent(Indentation) << "}\n"; + Indentation -= 2; + OS.indent(Indentation) << "}\n\n"; +} + +// Populates the field of the insn given the start position and the number of +// consecutive bits to scan for. +// +// Returns false if and on the first uninitialized bit value encountered. +// Returns true, otherwise. +bool FilterChooser::fieldFromInsn(uint64_t &Field, insn_t &Insn, + unsigned StartBit, unsigned NumBits) const { + Field = 0; + + for (unsigned i = 0; i < NumBits; ++i) { + if (Insn[StartBit + i] == BIT_UNSET) + return false; + + if (Insn[StartBit + i] == BIT_TRUE) + Field = Field | (1ULL << i); + } + + return true; +} + +/// dumpFilterArray - dumpFilterArray prints out debugging info for the given +/// filter array as a series of chars. +void FilterChooser::dumpFilterArray(raw_ostream &o, + const std::vector<bit_value_t> &filter) const { + for (unsigned bitIndex = BitWidth; bitIndex > 0; bitIndex--) { + switch (filter[bitIndex - 1]) { + case BIT_UNFILTERED: + o << "."; + break; + case BIT_UNSET: + o << "_"; + break; + case BIT_TRUE: + o << "1"; + break; + case BIT_FALSE: + o << "0"; + break; + } + } +} + +/// dumpStack - dumpStack traverses the filter chooser chain and calls +/// dumpFilterArray on each filter chooser up to the top level one. +void FilterChooser::dumpStack(raw_ostream &o, const char *prefix) const { + const FilterChooser *current = this; + + while (current) { + o << prefix; + dumpFilterArray(o, current->FilterBitValues); + o << '\n'; + current = current->Parent; + } +} + +// Calculates the island(s) needed to decode the instruction. +// This returns a list of undecoded bits of an instructions, for example, +// Inst{20} = 1 && Inst{3-0} == 0b1111 represents two islands of yet-to-be +// decoded bits in order to verify that the instruction matches the Opcode. +unsigned FilterChooser::getIslands(std::vector<unsigned> &StartBits, + std::vector<unsigned> &EndBits, + std::vector<uint64_t> &FieldVals, + const insn_t &Insn) const { + unsigned Num, BitNo; + Num = BitNo = 0; + + uint64_t FieldVal = 0; + + // 0: Init + // 1: Water (the bit value does not affect decoding) + // 2: Island (well-known bit value needed for decoding) + int State = 0; + int64_t Val = -1; + + for (unsigned i = 0; i < BitWidth; ++i) { + Val = Value(Insn[i]); + bool Filtered = PositionFiltered(i); + switch (State) { + default: llvm_unreachable("Unreachable code!"); + case 0: + case 1: + if (Filtered || Val == -1) + State = 1; // Still in Water + else { + State = 2; // Into the Island + BitNo = 0; + StartBits.push_back(i); + FieldVal = Val; + } + break; + case 2: + if (Filtered || Val == -1) { + State = 1; // Into the Water + EndBits.push_back(i - 1); + FieldVals.push_back(FieldVal); + ++Num; + } else { + State = 2; // Still in Island + ++BitNo; + FieldVal = FieldVal | Val << BitNo; + } + break; + } + } + // If we are still in Island after the loop, do some housekeeping. + if (State == 2) { + EndBits.push_back(BitWidth - 1); + FieldVals.push_back(FieldVal); + ++Num; + } + + assert(StartBits.size() == Num && EndBits.size() == Num && + FieldVals.size() == Num); + return Num; +} + +void FilterChooser::emitBinaryParser(raw_ostream &o, unsigned &Indentation, + const OperandInfo &OpInfo, + bool &OpHasCompleteDecoder) const { + const std::string &Decoder = OpInfo.Decoder; + + if (OpInfo.numFields() != 1 || OpInfo.InitValue != 0) { + o.indent(Indentation) << "tmp = 0x"; + o.write_hex(OpInfo.InitValue); + o << ";\n"; + } + + for (const EncodingField &EF : OpInfo) { + o.indent(Indentation) << "tmp "; + if (OpInfo.numFields() != 1 || OpInfo.InitValue != 0) o << '|'; + o << "= fieldFromInstruction" + << "(insn, " << EF.Base << ", " << EF.Width << ')'; + if (OpInfo.numFields() != 1 || EF.Offset != 0) + o << " << " << EF.Offset; + o << ";\n"; + } + + if (Decoder != "") { + OpHasCompleteDecoder = OpInfo.HasCompleteDecoder; + o.indent(Indentation) << Emitter->GuardPrefix << Decoder + << "(MI, tmp, Address, Decoder)" + << Emitter->GuardPostfix + << " { " << (OpHasCompleteDecoder ? "" : "DecodeComplete = false; ") + << "return MCDisassembler::Fail; }\n"; + } else { + OpHasCompleteDecoder = true; + o.indent(Indentation) << "MI.addOperand(MCOperand::createImm(tmp));\n"; + } +} + +void FilterChooser::emitDecoder(raw_ostream &OS, unsigned Indentation, + unsigned Opc, bool &HasCompleteDecoder) const { + HasCompleteDecoder = true; + + for (const auto &Op : Operands.find(Opc)->second) { + // If a custom instruction decoder was specified, use that. + if (Op.numFields() == 0 && !Op.Decoder.empty()) { + HasCompleteDecoder = Op.HasCompleteDecoder; + OS.indent(Indentation) << Emitter->GuardPrefix << Op.Decoder + << "(MI, insn, Address, Decoder)" + << Emitter->GuardPostfix + << " { " << (HasCompleteDecoder ? "" : "DecodeComplete = false; ") + << "return MCDisassembler::Fail; }\n"; + break; + } + + bool OpHasCompleteDecoder; + emitBinaryParser(OS, Indentation, Op, OpHasCompleteDecoder); + if (!OpHasCompleteDecoder) + HasCompleteDecoder = false; + } +} + +unsigned FilterChooser::getDecoderIndex(DecoderSet &Decoders, + unsigned Opc, + bool &HasCompleteDecoder) const { + // Build up the predicate string. + SmallString<256> Decoder; + // FIXME: emitDecoder() function can take a buffer directly rather than + // a stream. + raw_svector_ostream S(Decoder); + unsigned I = 4; + emitDecoder(S, I, Opc, HasCompleteDecoder); + + // Using the full decoder string as the key value here is a bit + // heavyweight, but is effective. If the string comparisons become a + // performance concern, we can implement a mangling of the predicate + // data easily enough with a map back to the actual string. That's + // overkill for now, though. + + // Make sure the predicate is in the table. + Decoders.insert(CachedHashString(Decoder)); + // Now figure out the index for when we write out the table. + DecoderSet::const_iterator P = find(Decoders, Decoder.str()); + return (unsigned)(P - Decoders.begin()); +} + +static void emitSinglePredicateMatch(raw_ostream &o, StringRef str, + const std::string &PredicateNamespace) { + if (str[0] == '!') + o << "!Bits[" << PredicateNamespace << "::" + << str.slice(1,str.size()) << "]"; + else + o << "Bits[" << PredicateNamespace << "::" << str << "]"; +} + +bool FilterChooser::emitPredicateMatch(raw_ostream &o, unsigned &Indentation, + unsigned Opc) const { + ListInit *Predicates = + AllInstructions[Opc].EncodingDef->getValueAsListInit("Predicates"); + bool IsFirstEmission = true; + for (unsigned i = 0; i < Predicates->size(); ++i) { + Record *Pred = Predicates->getElementAsRecord(i); + if (!Pred->getValue("AssemblerMatcherPredicate")) + continue; + + StringRef P = Pred->getValueAsString("AssemblerCondString"); + + if (P.empty()) + continue; + + if (!IsFirstEmission) + o << " && "; + + std::pair<StringRef, StringRef> pairs = P.split(','); + while (!pairs.second.empty()) { + emitSinglePredicateMatch(o, pairs.first, Emitter->PredicateNamespace); + o << " && "; + pairs = pairs.second.split(','); + } + emitSinglePredicateMatch(o, pairs.first, Emitter->PredicateNamespace); + IsFirstEmission = false; + } + return !Predicates->empty(); +} + +bool FilterChooser::doesOpcodeNeedPredicate(unsigned Opc) const { + ListInit *Predicates = + AllInstructions[Opc].EncodingDef->getValueAsListInit("Predicates"); + for (unsigned i = 0; i < Predicates->size(); ++i) { + Record *Pred = Predicates->getElementAsRecord(i); + if (!Pred->getValue("AssemblerMatcherPredicate")) + continue; + + StringRef P = Pred->getValueAsString("AssemblerCondString"); + + if (P.empty()) + continue; + + return true; + } + return false; +} + +unsigned FilterChooser::getPredicateIndex(DecoderTableInfo &TableInfo, + StringRef Predicate) const { + // Using the full predicate string as the key value here is a bit + // heavyweight, but is effective. If the string comparisons become a + // performance concern, we can implement a mangling of the predicate + // data easily enough with a map back to the actual string. That's + // overkill for now, though. + + // Make sure the predicate is in the table. + TableInfo.Predicates.insert(CachedHashString(Predicate)); + // Now figure out the index for when we write out the table. + PredicateSet::const_iterator P = find(TableInfo.Predicates, Predicate); + return (unsigned)(P - TableInfo.Predicates.begin()); +} + +void FilterChooser::emitPredicateTableEntry(DecoderTableInfo &TableInfo, + unsigned Opc) const { + if (!doesOpcodeNeedPredicate(Opc)) + return; + + // Build up the predicate string. + SmallString<256> Predicate; + // FIXME: emitPredicateMatch() functions can take a buffer directly rather + // than a stream. + raw_svector_ostream PS(Predicate); + unsigned I = 0; + emitPredicateMatch(PS, I, Opc); + + // Figure out the index into the predicate table for the predicate just + // computed. + unsigned PIdx = getPredicateIndex(TableInfo, PS.str()); + SmallString<16> PBytes; + raw_svector_ostream S(PBytes); + encodeULEB128(PIdx, S); + + TableInfo.Table.push_back(MCD::OPC_CheckPredicate); + // Predicate index + for (unsigned i = 0, e = PBytes.size(); i != e; ++i) + TableInfo.Table.push_back(PBytes[i]); + // Push location for NumToSkip backpatching. + TableInfo.FixupStack.back().push_back(TableInfo.Table.size()); + TableInfo.Table.push_back(0); + TableInfo.Table.push_back(0); + TableInfo.Table.push_back(0); +} + +void FilterChooser::emitSoftFailTableEntry(DecoderTableInfo &TableInfo, + unsigned Opc) const { + BitsInit *SFBits = + AllInstructions[Opc].EncodingDef->getValueAsBitsInit("SoftFail"); + if (!SFBits) return; + BitsInit *InstBits = + AllInstructions[Opc].EncodingDef->getValueAsBitsInit("Inst"); + + APInt PositiveMask(BitWidth, 0ULL); + APInt NegativeMask(BitWidth, 0ULL); + for (unsigned i = 0; i < BitWidth; ++i) { + bit_value_t B = bitFromBits(*SFBits, i); + bit_value_t IB = bitFromBits(*InstBits, i); + + if (B != BIT_TRUE) continue; + + switch (IB) { + case BIT_FALSE: + // The bit is meant to be false, so emit a check to see if it is true. + PositiveMask.setBit(i); + break; + case BIT_TRUE: + // The bit is meant to be true, so emit a check to see if it is false. + NegativeMask.setBit(i); + break; + default: + // The bit is not set; this must be an error! + errs() << "SoftFail Conflict: bit SoftFail{" << i << "} in " + << AllInstructions[Opc] << " is set but Inst{" << i + << "} is unset!\n" + << " - You can only mark a bit as SoftFail if it is fully defined" + << " (1/0 - not '?') in Inst\n"; + return; + } + } + + bool NeedPositiveMask = PositiveMask.getBoolValue(); + bool NeedNegativeMask = NegativeMask.getBoolValue(); + + if (!NeedPositiveMask && !NeedNegativeMask) + return; + + TableInfo.Table.push_back(MCD::OPC_SoftFail); + + SmallString<16> MaskBytes; + raw_svector_ostream S(MaskBytes); + if (NeedPositiveMask) { + encodeULEB128(PositiveMask.getZExtValue(), S); + for (unsigned i = 0, e = MaskBytes.size(); i != e; ++i) + TableInfo.Table.push_back(MaskBytes[i]); + } else + TableInfo.Table.push_back(0); + if (NeedNegativeMask) { + MaskBytes.clear(); + encodeULEB128(NegativeMask.getZExtValue(), S); + for (unsigned i = 0, e = MaskBytes.size(); i != e; ++i) + TableInfo.Table.push_back(MaskBytes[i]); + } else + TableInfo.Table.push_back(0); +} + +// Emits table entries to decode the singleton. +void FilterChooser::emitSingletonTableEntry(DecoderTableInfo &TableInfo, + EncodingIDAndOpcode Opc) const { + std::vector<unsigned> StartBits; + std::vector<unsigned> EndBits; + std::vector<uint64_t> FieldVals; + insn_t Insn; + insnWithID(Insn, Opc.EncodingID); + + // Look for islands of undecoded bits of the singleton. + getIslands(StartBits, EndBits, FieldVals, Insn); + + unsigned Size = StartBits.size(); + + // Emit the predicate table entry if one is needed. + emitPredicateTableEntry(TableInfo, Opc.EncodingID); + + // Check any additional encoding fields needed. + for (unsigned I = Size; I != 0; --I) { + unsigned NumBits = EndBits[I-1] - StartBits[I-1] + 1; + TableInfo.Table.push_back(MCD::OPC_CheckField); + TableInfo.Table.push_back(StartBits[I-1]); + TableInfo.Table.push_back(NumBits); + uint8_t Buffer[16], *p; + encodeULEB128(FieldVals[I-1], Buffer); + for (p = Buffer; *p >= 128 ; ++p) + TableInfo.Table.push_back(*p); + TableInfo.Table.push_back(*p); + // Push location for NumToSkip backpatching. + TableInfo.FixupStack.back().push_back(TableInfo.Table.size()); + // The fixup is always 24-bits, so go ahead and allocate the space + // in the table so all our relative position calculations work OK even + // before we fully resolve the real value here. + TableInfo.Table.push_back(0); + TableInfo.Table.push_back(0); + TableInfo.Table.push_back(0); + } + + // Check for soft failure of the match. + emitSoftFailTableEntry(TableInfo, Opc.EncodingID); + + bool HasCompleteDecoder; + unsigned DIdx = + getDecoderIndex(TableInfo.Decoders, Opc.EncodingID, HasCompleteDecoder); + + // Produce OPC_Decode or OPC_TryDecode opcode based on the information + // whether the instruction decoder is complete or not. If it is complete + // then it handles all possible values of remaining variable/unfiltered bits + // and for any value can determine if the bitpattern is a valid instruction + // or not. This means OPC_Decode will be the final step in the decoding + // process. If it is not complete, then the Fail return code from the + // decoder method indicates that additional processing should be done to see + // if there is any other instruction that also matches the bitpattern and + // can decode it. + TableInfo.Table.push_back(HasCompleteDecoder ? MCD::OPC_Decode : + MCD::OPC_TryDecode); + NumEncodingsSupported++; + uint8_t Buffer[16], *p; + encodeULEB128(Opc.Opcode, Buffer); + for (p = Buffer; *p >= 128 ; ++p) + TableInfo.Table.push_back(*p); + TableInfo.Table.push_back(*p); + + SmallString<16> Bytes; + raw_svector_ostream S(Bytes); + encodeULEB128(DIdx, S); + + // Decoder index + for (unsigned i = 0, e = Bytes.size(); i != e; ++i) + TableInfo.Table.push_back(Bytes[i]); + + if (!HasCompleteDecoder) { + // Push location for NumToSkip backpatching. + TableInfo.FixupStack.back().push_back(TableInfo.Table.size()); + // Allocate the space for the fixup. + TableInfo.Table.push_back(0); + TableInfo.Table.push_back(0); + TableInfo.Table.push_back(0); + } +} + +// Emits table entries to decode the singleton, and then to decode the rest. +void FilterChooser::emitSingletonTableEntry(DecoderTableInfo &TableInfo, + const Filter &Best) const { + EncodingIDAndOpcode Opc = Best.getSingletonOpc(); + + // complex singletons need predicate checks from the first singleton + // to refer forward to the variable filterchooser that follows. + TableInfo.FixupStack.emplace_back(); + + emitSingletonTableEntry(TableInfo, Opc); + + resolveTableFixups(TableInfo.Table, TableInfo.FixupStack.back(), + TableInfo.Table.size()); + TableInfo.FixupStack.pop_back(); + + Best.getVariableFC().emitTableEntries(TableInfo); +} + +// Assign a single filter and run with it. Top level API client can initialize +// with a single filter to start the filtering process. +void FilterChooser::runSingleFilter(unsigned startBit, unsigned numBit, + bool mixed) { + Filters.clear(); + Filters.emplace_back(*this, startBit, numBit, true); + BestIndex = 0; // Sole Filter instance to choose from. + bestFilter().recurse(); +} + +// reportRegion is a helper function for filterProcessor to mark a region as +// eligible for use as a filter region. +void FilterChooser::reportRegion(bitAttr_t RA, unsigned StartBit, + unsigned BitIndex, bool AllowMixed) { + if (RA == ATTR_MIXED && AllowMixed) + Filters.emplace_back(*this, StartBit, BitIndex - StartBit, true); + else if (RA == ATTR_ALL_SET && !AllowMixed) + Filters.emplace_back(*this, StartBit, BitIndex - StartBit, false); +} + +// FilterProcessor scans the well-known encoding bits of the instructions and +// builds up a list of candidate filters. It chooses the best filter and +// recursively descends down the decoding tree. +bool FilterChooser::filterProcessor(bool AllowMixed, bool Greedy) { + Filters.clear(); + BestIndex = -1; + unsigned numInstructions = Opcodes.size(); + + assert(numInstructions && "Filter created with no instructions"); + + // No further filtering is necessary. + if (numInstructions == 1) + return true; + + // Heuristics. See also doFilter()'s "Heuristics" comment when num of + // instructions is 3. + if (AllowMixed && !Greedy) { + assert(numInstructions == 3); + + for (unsigned i = 0; i < Opcodes.size(); ++i) { + std::vector<unsigned> StartBits; + std::vector<unsigned> EndBits; + std::vector<uint64_t> FieldVals; + insn_t Insn; + + insnWithID(Insn, Opcodes[i].EncodingID); + + // Look for islands of undecoded bits of any instruction. + if (getIslands(StartBits, EndBits, FieldVals, Insn) > 0) { + // Found an instruction with island(s). Now just assign a filter. + runSingleFilter(StartBits[0], EndBits[0] - StartBits[0] + 1, true); + return true; + } + } + } + + unsigned BitIndex; + + // We maintain BIT_WIDTH copies of the bitAttrs automaton. + // The automaton consumes the corresponding bit from each + // instruction. + // + // Input symbols: 0, 1, and _ (unset). + // States: NONE, FILTERED, ALL_SET, ALL_UNSET, and MIXED. + // Initial state: NONE. + // + // (NONE) ------- [01] -> (ALL_SET) + // (NONE) ------- _ ----> (ALL_UNSET) + // (ALL_SET) ---- [01] -> (ALL_SET) + // (ALL_SET) ---- _ ----> (MIXED) + // (ALL_UNSET) -- [01] -> (MIXED) + // (ALL_UNSET) -- _ ----> (ALL_UNSET) + // (MIXED) ------ . ----> (MIXED) + // (FILTERED)---- . ----> (FILTERED) + + std::vector<bitAttr_t> bitAttrs; + + // FILTERED bit positions provide no entropy and are not worthy of pursuing. + // Filter::recurse() set either BIT_TRUE or BIT_FALSE for each position. + for (BitIndex = 0; BitIndex < BitWidth; ++BitIndex) + if (FilterBitValues[BitIndex] == BIT_TRUE || + FilterBitValues[BitIndex] == BIT_FALSE) + bitAttrs.push_back(ATTR_FILTERED); + else + bitAttrs.push_back(ATTR_NONE); + + for (unsigned InsnIndex = 0; InsnIndex < numInstructions; ++InsnIndex) { + insn_t insn; + + insnWithID(insn, Opcodes[InsnIndex].EncodingID); + + for (BitIndex = 0; BitIndex < BitWidth; ++BitIndex) { + switch (bitAttrs[BitIndex]) { + case ATTR_NONE: + if (insn[BitIndex] == BIT_UNSET) + bitAttrs[BitIndex] = ATTR_ALL_UNSET; + else + bitAttrs[BitIndex] = ATTR_ALL_SET; + break; + case ATTR_ALL_SET: + if (insn[BitIndex] == BIT_UNSET) + bitAttrs[BitIndex] = ATTR_MIXED; + break; + case ATTR_ALL_UNSET: + if (insn[BitIndex] != BIT_UNSET) + bitAttrs[BitIndex] = ATTR_MIXED; + break; + case ATTR_MIXED: + case ATTR_FILTERED: + break; + } + } + } + + // The regionAttr automaton consumes the bitAttrs automatons' state, + // lowest-to-highest. + // + // Input symbols: F(iltered), (all_)S(et), (all_)U(nset), M(ixed) + // States: NONE, ALL_SET, MIXED + // Initial state: NONE + // + // (NONE) ----- F --> (NONE) + // (NONE) ----- S --> (ALL_SET) ; and set region start + // (NONE) ----- U --> (NONE) + // (NONE) ----- M --> (MIXED) ; and set region start + // (ALL_SET) -- F --> (NONE) ; and report an ALL_SET region + // (ALL_SET) -- S --> (ALL_SET) + // (ALL_SET) -- U --> (NONE) ; and report an ALL_SET region + // (ALL_SET) -- M --> (MIXED) ; and report an ALL_SET region + // (MIXED) ---- F --> (NONE) ; and report a MIXED region + // (MIXED) ---- S --> (ALL_SET) ; and report a MIXED region + // (MIXED) ---- U --> (NONE) ; and report a MIXED region + // (MIXED) ---- M --> (MIXED) + + bitAttr_t RA = ATTR_NONE; + unsigned StartBit = 0; + + for (BitIndex = 0; BitIndex < BitWidth; ++BitIndex) { + bitAttr_t bitAttr = bitAttrs[BitIndex]; + + assert(bitAttr != ATTR_NONE && "Bit without attributes"); + + switch (RA) { + case ATTR_NONE: + switch (bitAttr) { + case ATTR_FILTERED: + break; + case ATTR_ALL_SET: + StartBit = BitIndex; + RA = ATTR_ALL_SET; + break; + case ATTR_ALL_UNSET: + break; + case ATTR_MIXED: + StartBit = BitIndex; + RA = ATTR_MIXED; + break; + default: + llvm_unreachable("Unexpected bitAttr!"); + } + break; + case ATTR_ALL_SET: + switch (bitAttr) { + case ATTR_FILTERED: + reportRegion(RA, StartBit, BitIndex, AllowMixed); + RA = ATTR_NONE; + break; + case ATTR_ALL_SET: + break; + case ATTR_ALL_UNSET: + reportRegion(RA, StartBit, BitIndex, AllowMixed); + RA = ATTR_NONE; + break; + case ATTR_MIXED: + reportRegion(RA, StartBit, BitIndex, AllowMixed); + StartBit = BitIndex; + RA = ATTR_MIXED; + break; + default: + llvm_unreachable("Unexpected bitAttr!"); + } + break; + case ATTR_MIXED: + switch (bitAttr) { + case ATTR_FILTERED: + reportRegion(RA, StartBit, BitIndex, AllowMixed); + StartBit = BitIndex; + RA = ATTR_NONE; + break; + case ATTR_ALL_SET: + reportRegion(RA, StartBit, BitIndex, AllowMixed); + StartBit = BitIndex; + RA = ATTR_ALL_SET; + break; + case ATTR_ALL_UNSET: + reportRegion(RA, StartBit, BitIndex, AllowMixed); + RA = ATTR_NONE; + break; + case ATTR_MIXED: + break; + default: + llvm_unreachable("Unexpected bitAttr!"); + } + break; + case ATTR_ALL_UNSET: + llvm_unreachable("regionAttr state machine has no ATTR_UNSET state"); + case ATTR_FILTERED: + llvm_unreachable("regionAttr state machine has no ATTR_FILTERED state"); + } + } + + // At the end, if we're still in ALL_SET or MIXED states, report a region + switch (RA) { + case ATTR_NONE: + break; + case ATTR_FILTERED: + break; + case ATTR_ALL_SET: + reportRegion(RA, StartBit, BitIndex, AllowMixed); + break; + case ATTR_ALL_UNSET: + break; + case ATTR_MIXED: + reportRegion(RA, StartBit, BitIndex, AllowMixed); + break; + } + + // We have finished with the filter processings. Now it's time to choose + // the best performing filter. + BestIndex = 0; + bool AllUseless = true; + unsigned BestScore = 0; + + for (unsigned i = 0, e = Filters.size(); i != e; ++i) { + unsigned Usefulness = Filters[i].usefulness(); + + if (Usefulness) + AllUseless = false; + + if (Usefulness > BestScore) { + BestIndex = i; + BestScore = Usefulness; + } + } + + if (!AllUseless) + bestFilter().recurse(); + + return !AllUseless; +} // end of FilterChooser::filterProcessor(bool) + +// Decides on the best configuration of filter(s) to use in order to decode +// the instructions. A conflict of instructions may occur, in which case we +// dump the conflict set to the standard error. +void FilterChooser::doFilter() { + unsigned Num = Opcodes.size(); + assert(Num && "FilterChooser created with no instructions"); + + // Try regions of consecutive known bit values first. + if (filterProcessor(false)) + return; + + // Then regions of mixed bits (both known and unitialized bit values allowed). + if (filterProcessor(true)) + return; + + // Heuristics to cope with conflict set {t2CMPrs, t2SUBSrr, t2SUBSrs} where + // no single instruction for the maximum ATTR_MIXED region Inst{14-4} has a + // well-known encoding pattern. In such case, we backtrack and scan for the + // the very first consecutive ATTR_ALL_SET region and assign a filter to it. + if (Num == 3 && filterProcessor(true, false)) + return; + + // If we come to here, the instruction decoding has failed. + // Set the BestIndex to -1 to indicate so. + BestIndex = -1; +} + +// emitTableEntries - Emit state machine entries to decode our share of +// instructions. +void FilterChooser::emitTableEntries(DecoderTableInfo &TableInfo) const { + if (Opcodes.size() == 1) { + // There is only one instruction in the set, which is great! + // Call emitSingletonDecoder() to see whether there are any remaining + // encodings bits. + emitSingletonTableEntry(TableInfo, Opcodes[0]); + return; + } + + // Choose the best filter to do the decodings! + if (BestIndex != -1) { + const Filter &Best = Filters[BestIndex]; + if (Best.getNumFiltered() == 1) + emitSingletonTableEntry(TableInfo, Best); + else + Best.emitTableEntry(TableInfo); + return; + } + + // We don't know how to decode these instructions! Dump the + // conflict set and bail. + + // Print out useful conflict information for postmortem analysis. + errs() << "Decoding Conflict:\n"; + + dumpStack(errs(), "\t\t"); + + for (unsigned i = 0; i < Opcodes.size(); ++i) { + errs() << '\t'; + emitNameWithID(errs(), Opcodes[i].EncodingID); + errs() << " "; + dumpBits( + errs(), + getBitsField(*AllInstructions[Opcodes[i].EncodingID].EncodingDef, "Inst")); + errs() << '\n'; + } +} + +static std::string findOperandDecoderMethod(TypedInit *TI) { + std::string Decoder; + + Record *Record = cast<DefInit>(TI)->getDef(); + + RecordVal *DecoderString = Record->getValue("DecoderMethod"); + StringInit *String = DecoderString ? + dyn_cast<StringInit>(DecoderString->getValue()) : nullptr; + if (String) { + Decoder = String->getValue(); + if (!Decoder.empty()) + return Decoder; + } + + if (Record->isSubClassOf("RegisterOperand")) + Record = Record->getValueAsDef("RegClass"); + + if (Record->isSubClassOf("RegisterClass")) { + Decoder = "Decode" + Record->getName().str() + "RegisterClass"; + } else if (Record->isSubClassOf("PointerLikeRegClass")) { + Decoder = "DecodePointerLikeRegClass" + + utostr(Record->getValueAsInt("RegClassKind")); + } + + return Decoder; +} + +static bool +populateInstruction(CodeGenTarget &Target, const Record &EncodingDef, + const CodeGenInstruction &CGI, unsigned Opc, + std::map<unsigned, std::vector<OperandInfo>> &Operands) { + const Record &Def = *CGI.TheDef; + // If all the bit positions are not specified; do not decode this instruction. + // We are bound to fail! For proper disassembly, the well-known encoding bits + // of the instruction must be fully specified. + + BitsInit &Bits = getBitsField(EncodingDef, "Inst"); + if (Bits.allInComplete()) return false; + + std::vector<OperandInfo> InsnOperands; + + // If the instruction has specified a custom decoding hook, use that instead + // of trying to auto-generate the decoder. + StringRef InstDecoder = EncodingDef.getValueAsString("DecoderMethod"); + if (InstDecoder != "") { + bool HasCompleteInstDecoder = EncodingDef.getValueAsBit("hasCompleteDecoder"); + InsnOperands.push_back(OperandInfo(InstDecoder, HasCompleteInstDecoder)); + Operands[Opc] = InsnOperands; + return true; + } + + // Generate a description of the operand of the instruction that we know + // how to decode automatically. + // FIXME: We'll need to have a way to manually override this as needed. + + // Gather the outputs/inputs of the instruction, so we can find their + // positions in the encoding. This assumes for now that they appear in the + // MCInst in the order that they're listed. + std::vector<std::pair<Init*, StringRef>> InOutOperands; + DagInit *Out = Def.getValueAsDag("OutOperandList"); + DagInit *In = Def.getValueAsDag("InOperandList"); + for (unsigned i = 0; i < Out->getNumArgs(); ++i) + InOutOperands.push_back(std::make_pair(Out->getArg(i), + Out->getArgNameStr(i))); + for (unsigned i = 0; i < In->getNumArgs(); ++i) + InOutOperands.push_back(std::make_pair(In->getArg(i), + In->getArgNameStr(i))); + + // Search for tied operands, so that we can correctly instantiate + // operands that are not explicitly represented in the encoding. + std::map<std::string, std::string> TiedNames; + for (unsigned i = 0; i < CGI.Operands.size(); ++i) { + int tiedTo = CGI.Operands[i].getTiedRegister(); + if (tiedTo != -1) { + std::pair<unsigned, unsigned> SO = + CGI.Operands.getSubOperandNumber(tiedTo); + TiedNames[InOutOperands[i].second] = InOutOperands[SO.first].second; + TiedNames[InOutOperands[SO.first].second] = InOutOperands[i].second; + } + } + + std::map<std::string, std::vector<OperandInfo>> NumberedInsnOperands; + std::set<std::string> NumberedInsnOperandsNoTie; + if (Target.getInstructionSet()-> + getValueAsBit("decodePositionallyEncodedOperands")) { + const std::vector<RecordVal> &Vals = Def.getValues(); + unsigned NumberedOp = 0; + + std::set<unsigned> NamedOpIndices; + if (Target.getInstructionSet()-> + getValueAsBit("noNamedPositionallyEncodedOperands")) + // Collect the set of operand indices that might correspond to named + // operand, and skip these when assigning operands based on position. + for (unsigned i = 0, e = Vals.size(); i != e; ++i) { + unsigned OpIdx; + if (!CGI.Operands.hasOperandNamed(Vals[i].getName(), OpIdx)) + continue; + + NamedOpIndices.insert(OpIdx); + } + + for (unsigned i = 0, e = Vals.size(); i != e; ++i) { + // Ignore fixed fields in the record, we're looking for values like: + // bits<5> RST = { ?, ?, ?, ?, ? }; + if (Vals[i].getPrefix() || Vals[i].getValue()->isComplete()) + continue; + + // Determine if Vals[i] actually contributes to the Inst encoding. + unsigned bi = 0; + for (; bi < Bits.getNumBits(); ++bi) { + VarInit *Var = nullptr; + VarBitInit *BI = dyn_cast<VarBitInit>(Bits.getBit(bi)); + if (BI) + Var = dyn_cast<VarInit>(BI->getBitVar()); + else + Var = dyn_cast<VarInit>(Bits.getBit(bi)); + + if (Var && Var->getName() == Vals[i].getName()) + break; + } + + if (bi == Bits.getNumBits()) + continue; + + // Skip variables that correspond to explicitly-named operands. + unsigned OpIdx; + if (CGI.Operands.hasOperandNamed(Vals[i].getName(), OpIdx)) + continue; + + // Get the bit range for this operand: + unsigned bitStart = bi++, bitWidth = 1; + for (; bi < Bits.getNumBits(); ++bi) { + VarInit *Var = nullptr; + VarBitInit *BI = dyn_cast<VarBitInit>(Bits.getBit(bi)); + if (BI) + Var = dyn_cast<VarInit>(BI->getBitVar()); + else + Var = dyn_cast<VarInit>(Bits.getBit(bi)); + + if (!Var) + break; + + if (Var->getName() != Vals[i].getName()) + break; + + ++bitWidth; + } + + unsigned NumberOps = CGI.Operands.size(); + while (NumberedOp < NumberOps && + (CGI.Operands.isFlatOperandNotEmitted(NumberedOp) || + (!NamedOpIndices.empty() && NamedOpIndices.count( + CGI.Operands.getSubOperandNumber(NumberedOp).first)))) + ++NumberedOp; + + OpIdx = NumberedOp++; + + // OpIdx now holds the ordered operand number of Vals[i]. + std::pair<unsigned, unsigned> SO = + CGI.Operands.getSubOperandNumber(OpIdx); + const std::string &Name = CGI.Operands[SO.first].Name; + + LLVM_DEBUG(dbgs() << "Numbered operand mapping for " << Def.getName() + << ": " << Name << "(" << SO.first << ", " << SO.second + << ") => " << Vals[i].getName() << "\n"); + + std::string Decoder; + Record *TypeRecord = CGI.Operands[SO.first].Rec; + + RecordVal *DecoderString = TypeRecord->getValue("DecoderMethod"); + StringInit *String = DecoderString ? + dyn_cast<StringInit>(DecoderString->getValue()) : nullptr; + if (String && String->getValue() != "") + Decoder = String->getValue(); + + if (Decoder == "" && + CGI.Operands[SO.first].MIOperandInfo && + CGI.Operands[SO.first].MIOperandInfo->getNumArgs()) { + Init *Arg = CGI.Operands[SO.first].MIOperandInfo-> + getArg(SO.second); + if (DefInit *DI = cast<DefInit>(Arg)) + TypeRecord = DI->getDef(); + } + + bool isReg = false; + if (TypeRecord->isSubClassOf("RegisterOperand")) + TypeRecord = TypeRecord->getValueAsDef("RegClass"); + if (TypeRecord->isSubClassOf("RegisterClass")) { + Decoder = "Decode" + TypeRecord->getName().str() + "RegisterClass"; + isReg = true; + } else if (TypeRecord->isSubClassOf("PointerLikeRegClass")) { + Decoder = "DecodePointerLikeRegClass" + + utostr(TypeRecord->getValueAsInt("RegClassKind")); + isReg = true; + } + + DecoderString = TypeRecord->getValue("DecoderMethod"); + String = DecoderString ? + dyn_cast<StringInit>(DecoderString->getValue()) : nullptr; + if (!isReg && String && String->getValue() != "") + Decoder = String->getValue(); + + RecordVal *HasCompleteDecoderVal = + TypeRecord->getValue("hasCompleteDecoder"); + BitInit *HasCompleteDecoderBit = HasCompleteDecoderVal ? + dyn_cast<BitInit>(HasCompleteDecoderVal->getValue()) : nullptr; + bool HasCompleteDecoder = HasCompleteDecoderBit ? + HasCompleteDecoderBit->getValue() : true; + + OperandInfo OpInfo(Decoder, HasCompleteDecoder); + OpInfo.addField(bitStart, bitWidth, 0); + + NumberedInsnOperands[Name].push_back(OpInfo); + + // FIXME: For complex operands with custom decoders we can't handle tied + // sub-operands automatically. Skip those here and assume that this is + // fixed up elsewhere. + if (CGI.Operands[SO.first].MIOperandInfo && + CGI.Operands[SO.first].MIOperandInfo->getNumArgs() > 1 && + String && String->getValue() != "") + NumberedInsnOperandsNoTie.insert(Name); + } + } + + // For each operand, see if we can figure out where it is encoded. + for (const auto &Op : InOutOperands) { + if (!NumberedInsnOperands[Op.second].empty()) { + InsnOperands.insert(InsnOperands.end(), + NumberedInsnOperands[Op.second].begin(), + NumberedInsnOperands[Op.second].end()); + continue; + } + if (!NumberedInsnOperands[TiedNames[Op.second]].empty()) { + if (!NumberedInsnOperandsNoTie.count(TiedNames[Op.second])) { + // Figure out to which (sub)operand we're tied. + unsigned i = CGI.Operands.getOperandNamed(TiedNames[Op.second]); + int tiedTo = CGI.Operands[i].getTiedRegister(); + if (tiedTo == -1) { + i = CGI.Operands.getOperandNamed(Op.second); + tiedTo = CGI.Operands[i].getTiedRegister(); + } + + if (tiedTo != -1) { + std::pair<unsigned, unsigned> SO = + CGI.Operands.getSubOperandNumber(tiedTo); + + InsnOperands.push_back(NumberedInsnOperands[TiedNames[Op.second]] + [SO.second]); + } + } + continue; + } + + TypedInit *TI = cast<TypedInit>(Op.first); + + // At this point, we can locate the decoder field, but we need to know how + // to interpret it. As a first step, require the target to provide + // callbacks for decoding register classes. + std::string Decoder = findOperandDecoderMethod(TI); + Record *TypeRecord = cast<DefInit>(TI)->getDef(); + + RecordVal *HasCompleteDecoderVal = + TypeRecord->getValue("hasCompleteDecoder"); + BitInit *HasCompleteDecoderBit = HasCompleteDecoderVal ? + dyn_cast<BitInit>(HasCompleteDecoderVal->getValue()) : nullptr; + bool HasCompleteDecoder = HasCompleteDecoderBit ? + HasCompleteDecoderBit->getValue() : true; + + OperandInfo OpInfo(Decoder, HasCompleteDecoder); + + // Some bits of the operand may be required to be 1 depending on the + // instruction's encoding. Collect those bits. + if (const RecordVal *EncodedValue = EncodingDef.getValue(Op.second)) + if (const BitsInit *OpBits = dyn_cast<BitsInit>(EncodedValue->getValue())) + for (unsigned I = 0; I < OpBits->getNumBits(); ++I) + if (const BitInit *OpBit = dyn_cast<BitInit>(OpBits->getBit(I))) + if (OpBit->getValue()) + OpInfo.InitValue |= 1ULL << I; + + unsigned Base = ~0U; + unsigned Width = 0; + unsigned Offset = 0; + + for (unsigned bi = 0; bi < Bits.getNumBits(); ++bi) { + VarInit *Var = nullptr; + VarBitInit *BI = dyn_cast<VarBitInit>(Bits.getBit(bi)); + if (BI) + Var = dyn_cast<VarInit>(BI->getBitVar()); + else + Var = dyn_cast<VarInit>(Bits.getBit(bi)); + + if (!Var) { + if (Base != ~0U) { + OpInfo.addField(Base, Width, Offset); + Base = ~0U; + Width = 0; + Offset = 0; + } + continue; + } + + if (Var->getName() != Op.second && + Var->getName() != TiedNames[Op.second]) { + if (Base != ~0U) { + OpInfo.addField(Base, Width, Offset); + Base = ~0U; + Width = 0; + Offset = 0; + } + continue; + } + + if (Base == ~0U) { + Base = bi; + Width = 1; + Offset = BI ? BI->getBitNum() : 0; + } else if (BI && BI->getBitNum() != Offset + Width) { + OpInfo.addField(Base, Width, Offset); + Base = bi; + Width = 1; + Offset = BI->getBitNum(); + } else { + ++Width; + } + } + + if (Base != ~0U) + OpInfo.addField(Base, Width, Offset); + + if (OpInfo.numFields() > 0) + InsnOperands.push_back(OpInfo); + } + + Operands[Opc] = InsnOperands; + +#if 0 + LLVM_DEBUG({ + // Dumps the instruction encoding bits. + dumpBits(errs(), Bits); + + errs() << '\n'; + + // Dumps the list of operand info. + for (unsigned i = 0, e = CGI.Operands.size(); i != e; ++i) { + const CGIOperandList::OperandInfo &Info = CGI.Operands[i]; + const std::string &OperandName = Info.Name; + const Record &OperandDef = *Info.Rec; + + errs() << "\t" << OperandName << " (" << OperandDef.getName() << ")\n"; + } + }); +#endif + + return true; +} + +// emitFieldFromInstruction - Emit the templated helper function +// fieldFromInstruction(). +// On Windows we make sure that this function is not inlined when +// using the VS compiler. It has a bug which causes the function +// to be optimized out in some circustances. See llvm.org/pr38292 +static void emitFieldFromInstruction(formatted_raw_ostream &OS) { + OS << "// Helper functions for extracting fields from encoded instructions.\n" + << "// InsnType must either be integral or an APInt-like object that " + "must:\n" + << "// * Have a static const max_size_in_bits equal to the number of bits " + "in the\n" + << "// encoding.\n" + << "// * be default-constructible and copy-constructible\n" + << "// * be constructible from a uint64_t\n" + << "// * be constructible from an APInt (this can be private)\n" + << "// * Support getBitsSet(loBit, hiBit)\n" + << "// * be convertible to uint64_t\n" + << "// * Support the ~, &, ==, !=, and |= operators with other objects of " + "the same type\n" + << "// * Support shift (<<, >>) with signed and unsigned integers on the " + "RHS\n" + << "// * Support put (<<) to raw_ostream&\n" + << "template<typename InsnType>\n" + << "#if defined(_MSC_VER) && !defined(__clang__)\n" + << "__declspec(noinline)\n" + << "#endif\n" + << "static InsnType fieldFromInstruction(InsnType insn, unsigned " + "startBit,\n" + << " unsigned numBits, " + "std::true_type) {\n" + << " assert(startBit + numBits <= 64 && \"Cannot support >64-bit " + "extractions!\");\n" + << " assert(startBit + numBits <= (sizeof(InsnType) * 8) &&\n" + << " \"Instruction field out of bounds!\");\n" + << " InsnType fieldMask;\n" + << " if (numBits == sizeof(InsnType) * 8)\n" + << " fieldMask = (InsnType)(-1LL);\n" + << " else\n" + << " fieldMask = (((InsnType)1 << numBits) - 1) << startBit;\n" + << " return (insn & fieldMask) >> startBit;\n" + << "}\n" + << "\n" + << "template<typename InsnType>\n" + << "static InsnType fieldFromInstruction(InsnType insn, unsigned " + "startBit,\n" + << " unsigned numBits, " + "std::false_type) {\n" + << " assert(startBit + numBits <= InsnType::max_size_in_bits && " + "\"Instruction field out of bounds!\");\n" + << " InsnType fieldMask = InsnType::getBitsSet(0, numBits);\n" + << " return (insn >> startBit) & fieldMask;\n" + << "}\n" + << "\n" + << "template<typename InsnType>\n" + << "static InsnType fieldFromInstruction(InsnType insn, unsigned " + "startBit,\n" + << " unsigned numBits) {\n" + << " return fieldFromInstruction(insn, startBit, numBits, " + "std::is_integral<InsnType>());\n" + << "}\n\n"; +} + +// emitDecodeInstruction - Emit the templated helper function +// decodeInstruction(). +static void emitDecodeInstruction(formatted_raw_ostream &OS) { + OS << "template<typename InsnType>\n" + << "static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], " + "MCInst &MI,\n" + << " InsnType insn, uint64_t " + "Address,\n" + << " const void *DisAsm,\n" + << " const MCSubtargetInfo &STI) {\n" + << " const FeatureBitset& Bits = STI.getFeatureBits();\n" + << "\n" + << " const uint8_t *Ptr = DecodeTable;\n" + << " InsnType CurFieldValue = 0;\n" + << " DecodeStatus S = MCDisassembler::Success;\n" + << " while (true) {\n" + << " ptrdiff_t Loc = Ptr - DecodeTable;\n" + << " switch (*Ptr) {\n" + << " default:\n" + << " errs() << Loc << \": Unexpected decode table opcode!\\n\";\n" + << " return MCDisassembler::Fail;\n" + << " case MCD::OPC_ExtractField: {\n" + << " unsigned Start = *++Ptr;\n" + << " unsigned Len = *++Ptr;\n" + << " ++Ptr;\n" + << " CurFieldValue = fieldFromInstruction(insn, Start, Len);\n" + << " LLVM_DEBUG(dbgs() << Loc << \": OPC_ExtractField(\" << Start << " + "\", \"\n" + << " << Len << \"): \" << CurFieldValue << \"\\n\");\n" + << " break;\n" + << " }\n" + << " case MCD::OPC_FilterValue: {\n" + << " // Decode the field value.\n" + << " unsigned Len;\n" + << " InsnType Val = decodeULEB128(++Ptr, &Len);\n" + << " Ptr += Len;\n" + << " // NumToSkip is a plain 24-bit integer.\n" + << " unsigned NumToSkip = *Ptr++;\n" + << " NumToSkip |= (*Ptr++) << 8;\n" + << " NumToSkip |= (*Ptr++) << 16;\n" + << "\n" + << " // Perform the filter operation.\n" + << " if (Val != CurFieldValue)\n" + << " Ptr += NumToSkip;\n" + << " LLVM_DEBUG(dbgs() << Loc << \": OPC_FilterValue(\" << Val << " + "\", \" << NumToSkip\n" + << " << \"): \" << ((Val != CurFieldValue) ? \"FAIL:\" " + ": \"PASS:\")\n" + << " << \" continuing at \" << (Ptr - DecodeTable) << " + "\"\\n\");\n" + << "\n" + << " break;\n" + << " }\n" + << " case MCD::OPC_CheckField: {\n" + << " unsigned Start = *++Ptr;\n" + << " unsigned Len = *++Ptr;\n" + << " InsnType FieldValue = fieldFromInstruction(insn, Start, Len);\n" + << " // Decode the field value.\n" + << " InsnType ExpectedValue = decodeULEB128(++Ptr, &Len);\n" + << " Ptr += Len;\n" + << " // NumToSkip is a plain 24-bit integer.\n" + << " unsigned NumToSkip = *Ptr++;\n" + << " NumToSkip |= (*Ptr++) << 8;\n" + << " NumToSkip |= (*Ptr++) << 16;\n" + << "\n" + << " // If the actual and expected values don't match, skip.\n" + << " if (ExpectedValue != FieldValue)\n" + << " Ptr += NumToSkip;\n" + << " LLVM_DEBUG(dbgs() << Loc << \": OPC_CheckField(\" << Start << " + "\", \"\n" + << " << Len << \", \" << ExpectedValue << \", \" << " + "NumToSkip\n" + << " << \"): FieldValue = \" << FieldValue << \", " + "ExpectedValue = \"\n" + << " << ExpectedValue << \": \"\n" + << " << ((ExpectedValue == FieldValue) ? \"PASS\\n\" : " + "\"FAIL\\n\"));\n" + << " break;\n" + << " }\n" + << " case MCD::OPC_CheckPredicate: {\n" + << " unsigned Len;\n" + << " // Decode the Predicate Index value.\n" + << " unsigned PIdx = decodeULEB128(++Ptr, &Len);\n" + << " Ptr += Len;\n" + << " // NumToSkip is a plain 24-bit integer.\n" + << " unsigned NumToSkip = *Ptr++;\n" + << " NumToSkip |= (*Ptr++) << 8;\n" + << " NumToSkip |= (*Ptr++) << 16;\n" + << " // Check the predicate.\n" + << " bool Pred;\n" + << " if (!(Pred = checkDecoderPredicate(PIdx, Bits)))\n" + << " Ptr += NumToSkip;\n" + << " (void)Pred;\n" + << " LLVM_DEBUG(dbgs() << Loc << \": OPC_CheckPredicate(\" << PIdx " + "<< \"): \"\n" + << " << (Pred ? \"PASS\\n\" : \"FAIL\\n\"));\n" + << "\n" + << " break;\n" + << " }\n" + << " case MCD::OPC_Decode: {\n" + << " unsigned Len;\n" + << " // Decode the Opcode value.\n" + << " unsigned Opc = decodeULEB128(++Ptr, &Len);\n" + << " Ptr += Len;\n" + << " unsigned DecodeIdx = decodeULEB128(Ptr, &Len);\n" + << " Ptr += Len;\n" + << "\n" + << " MI.clear();\n" + << " MI.setOpcode(Opc);\n" + << " bool DecodeComplete;\n" + << " S = decodeToMCInst(S, DecodeIdx, insn, MI, Address, DisAsm, " + "DecodeComplete);\n" + << " assert(DecodeComplete);\n" + << "\n" + << " LLVM_DEBUG(dbgs() << Loc << \": OPC_Decode: opcode \" << Opc\n" + << " << \", using decoder \" << DecodeIdx << \": \"\n" + << " << (S != MCDisassembler::Fail ? \"PASS\" : " + "\"FAIL\") << \"\\n\");\n" + << " return S;\n" + << " }\n" + << " case MCD::OPC_TryDecode: {\n" + << " unsigned Len;\n" + << " // Decode the Opcode value.\n" + << " unsigned Opc = decodeULEB128(++Ptr, &Len);\n" + << " Ptr += Len;\n" + << " unsigned DecodeIdx = decodeULEB128(Ptr, &Len);\n" + << " Ptr += Len;\n" + << " // NumToSkip is a plain 24-bit integer.\n" + << " unsigned NumToSkip = *Ptr++;\n" + << " NumToSkip |= (*Ptr++) << 8;\n" + << " NumToSkip |= (*Ptr++) << 16;\n" + << "\n" + << " // Perform the decode operation.\n" + << " MCInst TmpMI;\n" + << " TmpMI.setOpcode(Opc);\n" + << " bool DecodeComplete;\n" + << " S = decodeToMCInst(S, DecodeIdx, insn, TmpMI, Address, DisAsm, " + "DecodeComplete);\n" + << " LLVM_DEBUG(dbgs() << Loc << \": OPC_TryDecode: opcode \" << " + "Opc\n" + << " << \", using decoder \" << DecodeIdx << \": \");\n" + << "\n" + << " if (DecodeComplete) {\n" + << " // Decoding complete.\n" + << " LLVM_DEBUG(dbgs() << (S != MCDisassembler::Fail ? \"PASS\" : " + "\"FAIL\") << \"\\n\");\n" + << " MI = TmpMI;\n" + << " return S;\n" + << " } else {\n" + << " assert(S == MCDisassembler::Fail);\n" + << " // If the decoding was incomplete, skip.\n" + << " Ptr += NumToSkip;\n" + << " LLVM_DEBUG(dbgs() << \"FAIL: continuing at \" << (Ptr - " + "DecodeTable) << \"\\n\");\n" + << " // Reset decode status. This also drops a SoftFail status " + "that could be\n" + << " // set before the decode attempt.\n" + << " S = MCDisassembler::Success;\n" + << " }\n" + << " break;\n" + << " }\n" + << " case MCD::OPC_SoftFail: {\n" + << " // Decode the mask values.\n" + << " unsigned Len;\n" + << " InsnType PositiveMask = decodeULEB128(++Ptr, &Len);\n" + << " Ptr += Len;\n" + << " InsnType NegativeMask = decodeULEB128(Ptr, &Len);\n" + << " Ptr += Len;\n" + << " bool Fail = (insn & PositiveMask) || (~insn & NegativeMask);\n" + << " if (Fail)\n" + << " S = MCDisassembler::SoftFail;\n" + << " LLVM_DEBUG(dbgs() << Loc << \": OPC_SoftFail: \" << (Fail ? " + "\"FAIL\\n\":\"PASS\\n\"));\n" + << " break;\n" + << " }\n" + << " case MCD::OPC_Fail: {\n" + << " LLVM_DEBUG(dbgs() << Loc << \": OPC_Fail\\n\");\n" + << " return MCDisassembler::Fail;\n" + << " }\n" + << " }\n" + << " }\n" + << " llvm_unreachable(\"bogosity detected in disassembler state " + "machine!\");\n" + << "}\n\n"; +} + +// Emits disassembler code for instruction decoding. +void FixedLenDecoderEmitter::run(raw_ostream &o) { + formatted_raw_ostream OS(o); + OS << "#include \"llvm/MC/MCInst.h\"\n"; + OS << "#include \"llvm/Support/Debug.h\"\n"; + OS << "#include \"llvm/Support/DataTypes.h\"\n"; + OS << "#include \"llvm/Support/LEB128.h\"\n"; + OS << "#include \"llvm/Support/raw_ostream.h\"\n"; + OS << "#include <assert.h>\n"; + OS << '\n'; + OS << "namespace llvm {\n\n"; + + emitFieldFromInstruction(OS); + + Target.reverseBitsForLittleEndianEncoding(); + + // Parameterize the decoders based on namespace and instruction width. + std::set<StringRef> HwModeNames; + const auto &NumberedInstructions = Target.getInstructionsByEnumValue(); + NumberedEncodings.reserve(NumberedInstructions.size()); + DenseMap<Record *, unsigned> IndexOfInstruction; + // First, collect all HwModes referenced by the target. + for (const auto &NumberedInstruction : NumberedInstructions) { + IndexOfInstruction[NumberedInstruction->TheDef] = NumberedEncodings.size(); + + if (const RecordVal *RV = + NumberedInstruction->TheDef->getValue("EncodingInfos")) { + if (auto *DI = dyn_cast_or_null<DefInit>(RV->getValue())) { + const CodeGenHwModes &HWM = Target.getHwModes(); + EncodingInfoByHwMode EBM(DI->getDef(), HWM); + for (auto &KV : EBM.Map) + HwModeNames.insert(HWM.getMode(KV.first).Name); + } + } + } + + // If HwModeNames is empty, add the empty string so we always have one HwMode. + if (HwModeNames.empty()) + HwModeNames.insert(""); + + for (const auto &NumberedInstruction : NumberedInstructions) { + IndexOfInstruction[NumberedInstruction->TheDef] = NumberedEncodings.size(); + + if (const RecordVal *RV = + NumberedInstruction->TheDef->getValue("EncodingInfos")) { + if (DefInit *DI = dyn_cast_or_null<DefInit>(RV->getValue())) { + const CodeGenHwModes &HWM = Target.getHwModes(); + EncodingInfoByHwMode EBM(DI->getDef(), HWM); + for (auto &KV : EBM.Map) { + NumberedEncodings.emplace_back(KV.second, NumberedInstruction, + HWM.getMode(KV.first).Name); + HwModeNames.insert(HWM.getMode(KV.first).Name); + } + continue; + } + } + // This instruction is encoded the same on all HwModes. Emit it for all + // HwModes. + for (StringRef HwModeName : HwModeNames) + NumberedEncodings.emplace_back(NumberedInstruction->TheDef, + NumberedInstruction, HwModeName); + } + for (const auto &NumberedAlias : RK.getAllDerivedDefinitions("AdditionalEncoding")) + NumberedEncodings.emplace_back( + NumberedAlias, + &Target.getInstruction(NumberedAlias->getValueAsDef("AliasOf"))); + + std::map<std::pair<std::string, unsigned>, std::vector<EncodingIDAndOpcode>> + OpcMap; + std::map<unsigned, std::vector<OperandInfo>> Operands; + + for (unsigned i = 0; i < NumberedEncodings.size(); ++i) { + const Record *EncodingDef = NumberedEncodings[i].EncodingDef; + const CodeGenInstruction *Inst = NumberedEncodings[i].Inst; + const Record *Def = Inst->TheDef; + unsigned Size = EncodingDef->getValueAsInt("Size"); + if (Def->getValueAsString("Namespace") == "TargetOpcode" || + Def->getValueAsBit("isPseudo") || + Def->getValueAsBit("isAsmParserOnly") || + Def->getValueAsBit("isCodeGenOnly")) { + NumEncodingsLackingDisasm++; + continue; + } + + if (i < NumberedInstructions.size()) + NumInstructions++; + NumEncodings++; + + if (!Size) + continue; + + if (populateInstruction(Target, *EncodingDef, *Inst, i, Operands)) { + std::string DecoderNamespace = + EncodingDef->getValueAsString("DecoderNamespace"); + if (!NumberedEncodings[i].HwModeName.empty()) + DecoderNamespace += + std::string("_") + NumberedEncodings[i].HwModeName.str(); + OpcMap[std::make_pair(DecoderNamespace, Size)].emplace_back( + i, IndexOfInstruction.find(Def)->second); + } else { + NumEncodingsOmitted++; + } + } + + DecoderTableInfo TableInfo; + for (const auto &Opc : OpcMap) { + // Emit the decoder for this namespace+width combination. + ArrayRef<EncodingAndInst> NumberedEncodingsRef( + NumberedEncodings.data(), NumberedEncodings.size()); + FilterChooser FC(NumberedEncodingsRef, Opc.second, Operands, + 8 * Opc.first.second, this); + + // The decode table is cleared for each top level decoder function. The + // predicates and decoders themselves, however, are shared across all + // decoders to give more opportunities for uniqueing. + TableInfo.Table.clear(); + TableInfo.FixupStack.clear(); + TableInfo.Table.reserve(16384); + TableInfo.FixupStack.emplace_back(); + FC.emitTableEntries(TableInfo); + // Any NumToSkip fixups in the top level scope can resolve to the + // OPC_Fail at the end of the table. + assert(TableInfo.FixupStack.size() == 1 && "fixup stack phasing error!"); + // Resolve any NumToSkip fixups in the current scope. + resolveTableFixups(TableInfo.Table, TableInfo.FixupStack.back(), + TableInfo.Table.size()); + TableInfo.FixupStack.clear(); + + TableInfo.Table.push_back(MCD::OPC_Fail); + + // Print the table to the output stream. + emitTable(OS, TableInfo.Table, 0, FC.getBitWidth(), Opc.first.first); + OS.flush(); + } + + // Emit the predicate function. + emitPredicateFunction(OS, TableInfo.Predicates, 0); + + // Emit the decoder function. + emitDecoderFunction(OS, TableInfo.Decoders, 0); + + // Emit the main entry point for the decoder, decodeInstruction(). + emitDecodeInstruction(OS); + + OS << "\n} // end namespace llvm\n"; +} + +namespace llvm { + +void EmitFixedLenDecoder(RecordKeeper &RK, raw_ostream &OS, + const std::string &PredicateNamespace, + const std::string &GPrefix, + const std::string &GPostfix, const std::string &ROK, + const std::string &RFail, const std::string &L) { + FixedLenDecoderEmitter(RK, PredicateNamespace, GPrefix, GPostfix, + ROK, RFail, L).run(OS); +} + +} // end namespace llvm |