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//===- 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 that, given a MachineInstr,
// returns the (currently, 32-bit unsigned) value of the instruction.
//
//===----------------------------------------------------------------------===//
#include "CodeGenHwModes.h"
#include "CodeGenInstruction.h"
#include "CodeGenTarget.h"
#include "InfoByHwMode.h"
#include "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>
using namespace llvm;
namespace {
class CodeEmitterGen {
RecordKeeper &Records;
public:
CodeEmitterGen(RecordKeeper &R) : Records(R) {}
void run(raw_ostream &o);
private:
int getVariableBit(const std::string &VarName, BitsInit *BI, int bit);
std::string getInstructionCase(Record *R, CodeGenTarget &Target);
std::string getInstructionCaseForEncoding(Record *R, Record *EncodingDef,
CodeGenTarget &Target);
bool addCodeToMergeInOperand(Record *R, BitsInit *BI,
const std::string &VarName,
std::string &Case, CodeGenTarget &Target);
void emitInstructionBaseValues(
raw_ostream &o, ArrayRef<const CodeGenInstruction *> NumberedInstructions,
CodeGenTarget &Target, int HwMode = -1);
unsigned BitWidth = 0u;
bool UseAPInt = false;
};
// 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,
BitsInit *BI, int bit) {
if (VarBitInit *VBI = dyn_cast<VarBitInit>(BI->getBit(bit))) {
if (VarInit *VI = dyn_cast<VarInit>(VBI->getBitVar()))
if (VI->getName() == VarName)
return VBI->getBitNum();
} else if (VarInit *VI = dyn_cast<VarInit>(BI->getBit(bit))) {
if (VI->getName() == VarName)
return 0;
}
return -1;
}
// Returns true if it succeeds, false if an error.
bool CodeEmitterGen::addCodeToMergeInOperand(Record *R, BitsInit *BI,
const std::string &VarName,
std::string &Case,
CodeGenTarget &Target) {
CodeGenInstruction &CGI = Target.getInstruction(R);
// Determine if VarName actually contributes to the Inst encoding.
int bit = BI->getNumBits()-1;
// Scan for a bit that this contributed to.
for (; bit >= 0; ) {
if (getVariableBit(VarName, BI, bit) != -1)
break;
--bit;
}
// If we found no bits, ignore this value, otherwise emit the call to get the
// operand encoding.
if (bit < 0)
return true;
// If the operand matches by name, reference according to that
// operand number. Non-matching operands are assumed to be in
// order.
unsigned OpIdx;
std::pair<unsigned, unsigned> SubOp;
if (CGI.Operands.hasSubOperandAlias(VarName, SubOp)) {
OpIdx = CGI.Operands[SubOp.first].MIOperandNo + SubOp.second;
} else if (CGI.Operands.hasOperandNamed(VarName, OpIdx)) {
// Get the machine operand number for the indicated operand.
OpIdx = CGI.Operands[OpIdx].MIOperandNo;
} else {
PrintError(R, Twine("No operand named ") + VarName + " in record " + R->getName());
return false;
}
if (CGI.Operands.isFlatOperandNotEmitted(OpIdx)) {
PrintError(R, "Operand " + VarName + " used but also marked as not emitted!");
return false;
}
std::pair<unsigned, unsigned> SO = CGI.Operands.getSubOperandNumber(OpIdx);
std::string &EncoderMethodName =
CGI.Operands[SO.first].EncoderMethodNames[SO.second];
if (UseAPInt)
Case += " op.clearAllBits();\n";
Case += " // op: " + VarName + "\n";
// If the source operand has a custom encoder, use it.
if (!EncoderMethodName.empty()) {
if (UseAPInt) {
Case += " " + EncoderMethodName + "(MI, " + utostr(OpIdx);
Case += ", op";
} else {
Case += " op = " + EncoderMethodName + "(MI, " + utostr(OpIdx);
}
Case += ", Fixups, STI);\n";
} else {
if (UseAPInt) {
Case += " getMachineOpValue(MI, MI.getOperand(" + utostr(OpIdx) + ")";
Case += ", op, Fixups, STI";
} else {
Case += " op = getMachineOpValue(MI, MI.getOperand(" + utostr(OpIdx) + ")";
Case += ", Fixups, STI";
}
Case += ");\n";
}
// Precalculate the number of lits this variable contributes to in the
// operand. If there is a single lit (consecutive range of bits) we can use a
// destructive sequence on APInt that reduces memory allocations.
int numOperandLits = 0;
for (int tmpBit = bit; tmpBit >= 0;) {
int varBit = getVariableBit(VarName, BI, tmpBit);
// If this bit isn't from a variable, skip it.
if (varBit == -1) {
--tmpBit;
continue;
}
// Figure out the consecutive range of bits covered by this operand, in
// order to generate better encoding code.
int beginVarBit = varBit;
int N = 1;
for (--tmpBit; tmpBit >= 0;) {
varBit = getVariableBit(VarName, BI, tmpBit);
if (varBit == -1 || varBit != (beginVarBit - N))
break;
++N;
--tmpBit;
}
++numOperandLits;
}
for (; bit >= 0; ) {
int varBit = getVariableBit(VarName, BI, bit);
// If this bit isn't from a variable, skip it.
if (varBit == -1) {
--bit;
continue;
}
// Figure out the consecutive range of bits covered by this operand, in
// order to generate better encoding code.
int beginInstBit = bit;
int beginVarBit = varBit;
int N = 1;
for (--bit; bit >= 0;) {
varBit = getVariableBit(VarName, BI, bit);
if (varBit == -1 || varBit != (beginVarBit - N)) break;
++N;
--bit;
}
std::string maskStr;
int opShift;
unsigned loBit = beginVarBit - N + 1;
unsigned hiBit = loBit + N;
unsigned loInstBit = beginInstBit - N + 1;
if (UseAPInt) {
std::string extractStr;
if (N >= 64) {
extractStr = "op.extractBits(" + itostr(hiBit - loBit) + ", " +
itostr(loBit) + ")";
Case += " Value.insertBits(" + extractStr + ", " +
itostr(loInstBit) + ");\n";
} else {
extractStr = "op.extractBitsAsZExtValue(" + itostr(hiBit - loBit) +
", " + itostr(loBit) + ")";
Case += " Value.insertBits(" + extractStr + ", " +
itostr(loInstBit) + ", " + itostr(hiBit - loBit) + ");\n";
}
} else {
uint64_t opMask = ~(uint64_t)0 >> (64 - N);
opShift = beginVarBit - N + 1;
opMask <<= opShift;
maskStr = "UINT64_C(" + utostr(opMask) + ")";
opShift = beginInstBit - beginVarBit;
if (numOperandLits == 1) {
Case += " op &= " + maskStr + ";\n";
if (opShift > 0) {
Case += " op <<= " + itostr(opShift) + ";\n";
} else if (opShift < 0) {
Case += " op >>= " + itostr(-opShift) + ";\n";
}
Case += " Value |= op;\n";
} else {
if (opShift > 0) {
Case += " Value |= (op & " + maskStr + ") << " +
itostr(opShift) + ";\n";
} else if (opShift < 0) {
Case += " Value |= (op & " + maskStr + ") >> " +
itostr(-opShift) + ";\n";
} else {
Case += " Value |= (op & " + maskStr + ");\n";
}
}
}
}
return true;
}
std::string CodeEmitterGen::getInstructionCase(Record *R,
CodeGenTarget &Target) {
std::string Case;
if (const RecordVal *RV = R->getValue("EncodingInfos")) {
if (auto *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
const CodeGenHwModes &HWM = Target.getHwModes();
EncodingInfoByHwMode EBM(DI->getDef(), HWM);
Case += " switch (HwMode) {\n";
Case += " default: llvm_unreachable(\"Unhandled HwMode\");\n";
for (auto &KV : EBM) {
Case += " case " + itostr(KV.first) + ": {\n";
Case += getInstructionCaseForEncoding(R, KV.second, Target);
Case += " break;\n";
Case += " }\n";
}
Case += " }\n";
return Case;
}
}
return getInstructionCaseForEncoding(R, R, Target);
}
std::string CodeEmitterGen::getInstructionCaseForEncoding(Record *R, Record *EncodingDef,
CodeGenTarget &Target) {
std::string Case;
BitsInit *BI = EncodingDef->getValueAsBitsInit("Inst");
// Loop over all of the fields in the instruction, determining which are the
// operands to the instruction.
bool Success = true;
for (const RecordVal &RV : EncodingDef->getValues()) {
// Ignore fixed fields in the record, we're looking for values like:
// bits<5> RST = { ?, ?, ?, ?, ? };
if (RV.isNonconcreteOK() || RV.getValue()->isComplete())
continue;
Success &=
addCodeToMergeInOperand(R, BI, std::string(RV.getName()),
Case, Target);
}
if (!Success) {
// Dump the record, so we can see what's going on...
std::string E;
raw_string_ostream S(E);
S << "Dumping record for previous error:\n";
S << *R;
PrintNote(E);
}
StringRef PostEmitter = R->getValueAsString("PostEncoderMethod");
if (!PostEmitter.empty()) {
Case += " Value = ";
Case += PostEmitter;
Case += "(MI, Value";
Case += ", STI";
Case += ");\n";
}
return Case;
}
static void emitInstBits(raw_ostream &OS, const APInt &Bits) {
for (unsigned I = 0; I < Bits.getNumWords(); ++I)
OS << ((I > 0) ? ", " : "") << "UINT64_C(" << utostr(Bits.getRawData()[I])
<< ")";
}
void CodeEmitterGen::emitInstructionBaseValues(
raw_ostream &o, ArrayRef<const CodeGenInstruction *> NumberedInstructions,
CodeGenTarget &Target, int HwMode) {
const CodeGenHwModes &HWM = Target.getHwModes();
if (HwMode == -1)
o << " static const uint64_t InstBits[] = {\n";
else
o << " static const uint64_t InstBits_" << HWM.getMode(HwMode).Name
<< "[] = {\n";
for (const CodeGenInstruction *CGI : NumberedInstructions) {
Record *R = CGI->TheDef;
if (R->getValueAsString("Namespace") == "TargetOpcode" ||
R->getValueAsBit("isPseudo")) {
o << " "; emitInstBits(o, APInt(BitWidth, 0)); o << ",\n";
continue;
}
Record *EncodingDef = R;
if (const RecordVal *RV = R->getValue("EncodingInfos")) {
if (auto *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
EncodingInfoByHwMode EBM(DI->getDef(), HWM);
if (EBM.hasMode(HwMode))
EncodingDef = EBM.get(HwMode);
}
}
BitsInit *BI = EncodingDef->getValueAsBitsInit("Inst");
// Start by filling in fixed values.
APInt Value(BitWidth, 0);
for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i) {
if (auto *B = dyn_cast<BitInit>(BI->getBit(i)); B && B->getValue())
Value.setBit(i);
}
o << " ";
emitInstBits(o, Value);
o << "," << '\t' << "// " << R->getName() << "\n";
}
o << " UINT64_C(0)\n };\n";
}
void CodeEmitterGen::run(raw_ostream &o) {
emitSourceFileHeader("Machine Code Emitter", o);
CodeGenTarget Target(Records);
std::vector<Record*> Insts = Records.getAllDerivedDefinitions("Instruction");
// For little-endian instruction bit encodings, reverse the bit order
Target.reverseBitsForLittleEndianEncoding();
ArrayRef<const CodeGenInstruction*> NumberedInstructions =
Target.getInstructionsByEnumValue();
if (any_of(NumberedInstructions, [](const CodeGenInstruction *CGI) {
Record *R = CGI->TheDef;
return R->getValue("Inst") && isa<DagInit>(R->getValueInit("Inst"));
})) {
emitVarLenCodeEmitter(Records, o);
} else {
const CodeGenHwModes &HWM = Target.getHwModes();
// The set of HwModes used by instruction encodings.
std::set<unsigned> HwModes;
BitWidth = 0;
for (const CodeGenInstruction *CGI : NumberedInstructions) {
Record *R = CGI->TheDef;
if (R->getValueAsString("Namespace") == "TargetOpcode" ||
R->getValueAsBit("isPseudo"))
continue;
if (const RecordVal *RV = R->getValue("EncodingInfos")) {
if (DefInit *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
EncodingInfoByHwMode EBM(DI->getDef(), HWM);
for (auto &KV : EBM) {
BitsInit *BI = KV.second->getValueAsBitsInit("Inst");
BitWidth = std::max(BitWidth, BI->getNumBits());
HwModes.insert(KV.first);
}
continue;
}
}
BitsInit *BI = R->getValueAsBitsInit("Inst");
BitWidth = std::max(BitWidth, BI->getNumBits());
}
UseAPInt = BitWidth > 64;
// Emit function declaration
if (UseAPInt) {
o << "void " << Target.getName()
<< "MCCodeEmitter::getBinaryCodeForInstr(const MCInst &MI,\n"
<< " SmallVectorImpl<MCFixup> &Fixups,\n"
<< " APInt &Inst,\n"
<< " APInt &Scratch,\n"
<< " const MCSubtargetInfo &STI) const {\n";
} else {
o << "uint64_t " << Target.getName();
o << "MCCodeEmitter::getBinaryCodeForInstr(const MCInst &MI,\n"
<< " SmallVectorImpl<MCFixup> &Fixups,\n"
<< " const MCSubtargetInfo &STI) const {\n";
}
// Emit instruction base values
if (HwModes.empty()) {
emitInstructionBaseValues(o, NumberedInstructions, Target, -1);
} else {
for (unsigned HwMode : HwModes)
emitInstructionBaseValues(o, NumberedInstructions, Target, (int)HwMode);
}
if (!HwModes.empty()) {
o << " const uint64_t *InstBits;\n";
o << " unsigned HwMode = STI.getHwMode();\n";
o << " switch (HwMode) {\n";
o << " default: llvm_unreachable(\"Unknown hardware mode!\"); break;\n";
for (unsigned I : HwModes) {
o << " case " << I << ": InstBits = InstBits_" << HWM.getMode(I).Name
<< "; break;\n";
}
o << " };\n";
}
// Map to accumulate all the cases.
std::map<std::string, std::vector<std::string>> CaseMap;
// Construct all cases statement for each opcode
for (Record *R : Insts) {
if (R->getValueAsString("Namespace") == "TargetOpcode" ||
R->getValueAsBit("isPseudo"))
continue;
std::string InstName =
(R->getValueAsString("Namespace") + "::" + R->getName()).str();
std::string Case = getInstructionCase(R, Target);
CaseMap[Case].push_back(std::move(InstName));
}
// Emit initial function code
if (UseAPInt) {
int NumWords = APInt::getNumWords(BitWidth);
o << " const unsigned opcode = MI.getOpcode();\n"
<< " if (Scratch.getBitWidth() != " << BitWidth << ")\n"
<< " Scratch = Scratch.zext(" << BitWidth << ");\n"
<< " Inst = APInt(" << BitWidth << ", ArrayRef(InstBits + opcode * "
<< NumWords << ", " << NumWords << "));\n"
<< " APInt &Value = Inst;\n"
<< " APInt &op = Scratch;\n"
<< " switch (opcode) {\n";
} else {
o << " const unsigned opcode = MI.getOpcode();\n"
<< " uint64_t Value = InstBits[opcode];\n"
<< " uint64_t op = 0;\n"
<< " (void)op; // suppress warning\n"
<< " switch (opcode) {\n";
}
// Emit each case statement
std::map<std::string, std::vector<std::string>>::iterator IE, EE;
for (IE = CaseMap.begin(), EE = CaseMap.end(); IE != EE; ++IE) {
const std::string &Case = IE->first;
std::vector<std::string> &InstList = IE->second;
for (int i = 0, N = InstList.size(); i < N; i++) {
if (i)
o << "\n";
o << " case " << InstList[i] << ":";
}
o << " {\n";
o << Case;
o << " break;\n"
<< " }\n";
}
// Default case: unhandled opcode
o << " default:\n"
<< " std::string msg;\n"
<< " raw_string_ostream Msg(msg);\n"
<< " Msg << \"Not supported instr: \" << MI;\n"
<< " report_fatal_error(Msg.str().c_str());\n"
<< " }\n";
if (UseAPInt)
o << " Inst = Value;\n";
else
o << " return Value;\n";
o << "}\n\n";
}
}
} // end anonymous namespace
static TableGen::Emitter::OptClass<CodeEmitterGen>
X("gen-emitter", "Generate machine code emitter");