llvm/llvm/utils/TableGen/CodeEmitterGen.cpp

//===- CodeEmitterGen.cpp - Code Emitter 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
//
//===----------------------------------------------------------------------===//
//
// CodeEmitterGen uses the descriptions of instructions and their fields to
// construct an automated code emitter: a function called
// getBinaryCodeForInstr() that, given a MCInst, returns the value of the
// instruction - either as an uint64_t or as an APInt, depending on the
// maximum bit width of all Inst definitions.
//
// In addition, it generates another function called getOperandBitOffset()
// that, given a MCInst and an operand index, returns the minimum of indices of
// all bits that carry some portion of the respective operand. When the target's
// encodeInstruction() stores the instruction in a little-endian byte order, the
// returned value is the offset of the start of the operand in the encoded
// instruction. Other targets might need to adjust the returned value according
// to their encodeInstruction() implementation.
//
//===----------------------------------------------------------------------===//

#include "Common/CodeGenHwModes.h"
#include "Common/CodeGenInstruction.h"
#include "Common/CodeGenTarget.h"
#include "Common/InfoByHwMode.h"
#include "Common/VarLenCodeEmitterGen.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/TableGen/Error.h"
#include "llvm/TableGen/Record.h"
#include "llvm/TableGen/TableGenBackend.h"
#include <cstdint>
#include <map>
#include <set>
#include <string>
#include <utility>
#include <vector>

usingnamespacellvm;

namespace {

class CodeEmitterGen { … };

// If the VarBitInit at position 'bit' matches the specified variable then
// return the variable bit position.  Otherwise return -1.
int CodeEmitterGen::getVariableBit(const std::string &VarName,
                                   const BitsInit *BI, int bit) { … }

// Returns true if it succeeds, false if an error.
bool CodeEmitterGen::addCodeToMergeInOperand(const Record *R,
                                             const BitsInit *BI,
                                             const std::string &VarName,
                                             std::string &Case,
                                             std::string &BitOffsetCase,
                                             const CodeGenTarget &Target) { … }

std::pair<std::string, std::string>
CodeEmitterGen::getInstructionCases(const Record *R,
                                    const CodeGenTarget &Target) { … }

void CodeEmitterGen::addInstructionCasesForEncoding(
    const Record *R, const Record *EncodingDef, const CodeGenTarget &Target,
    std::string &Case, std::string &BitOffsetCase) { … }

static void emitInstBits(raw_ostream &OS, const APInt &Bits) { … }

void CodeEmitterGen::emitInstructionBaseValues(
    raw_ostream &o, ArrayRef<const CodeGenInstruction *> NumberedInstructions,
    const CodeGenTarget &Target, unsigned HwMode) { … }

void CodeEmitterGen::emitCaseMap(
    raw_ostream &o,
    const std::map<std::string, std::vector<std::string>> &CaseMap) { … }

void CodeEmitterGen::run(raw_ostream &o) { … }

} // end anonymous namespace

static TableGen::Emitter::OptClass<CodeEmitterGen>
    X("gen-emitter", "Generate machine code emitter");