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Diffstat (limited to 'contrib/llvm/utils/TableGen/CodeEmitterGen.cpp')
| -rw-r--r-- | contrib/llvm/utils/TableGen/CodeEmitterGen.cpp | 295 |
1 files changed, 295 insertions, 0 deletions
diff --git a/contrib/llvm/utils/TableGen/CodeEmitterGen.cpp b/contrib/llvm/utils/TableGen/CodeEmitterGen.cpp new file mode 100644 index 0000000..957dd19 --- /dev/null +++ b/contrib/llvm/utils/TableGen/CodeEmitterGen.cpp @@ -0,0 +1,295 @@ +//===- CodeEmitterGen.cpp - Code Emitter Generator ------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// 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 "CodeEmitterGen.h" +#include "CodeGenTarget.h" +#include "Record.h" +#include "llvm/ADT/StringExtras.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include <map> +using namespace llvm; + +// FIXME: Somewhat hackish to use a command line option for this. There should +// be a CodeEmitter class in the Target.td that controls this sort of thing +// instead. +static cl::opt<bool> +MCEmitter("mc-emitter", + cl::desc("Generate CodeEmitter for use with the MC library."), + cl::init(false)); + +void CodeEmitterGen::reverseBits(std::vector<Record*> &Insts) { + for (std::vector<Record*>::iterator I = Insts.begin(), E = Insts.end(); + I != E; ++I) { + Record *R = *I; + if (R->getValueAsString("Namespace") == "TargetOpcode") + continue; + + BitsInit *BI = R->getValueAsBitsInit("Inst"); + + unsigned numBits = BI->getNumBits(); + BitsInit *NewBI = new BitsInit(numBits); + for (unsigned bit = 0, end = numBits / 2; bit != end; ++bit) { + unsigned bitSwapIdx = numBits - bit - 1; + Init *OrigBit = BI->getBit(bit); + Init *BitSwap = BI->getBit(bitSwapIdx); + NewBI->setBit(bit, BitSwap); + NewBI->setBit(bitSwapIdx, OrigBit); + } + if (numBits % 2) { + unsigned middle = (numBits + 1) / 2; + NewBI->setBit(middle, BI->getBit(middle)); + } + + // Update the bits in reversed order so that emitInstrOpBits will get the + // correct endianness. + R->getValue("Inst")->setValue(NewBI); + } +} + +// 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 = dynamic_cast<VarBitInit*>(BI->getBit(bit))) + if (VarInit *VI = dynamic_cast<VarInit*>(VBI->getVariable())) + if (VI->getName() == VarName) + return VBI->getBitNum(); + + return -1; +} + +void CodeEmitterGen:: +AddCodeToMergeInOperand(Record *R, BitsInit *BI, const std::string &VarName, + unsigned &NumberedOp, + 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; + + // If the operand matches by name, reference according to that + // operand number. Non-matching operands are assumed to be in + // order. + unsigned OpIdx; + if (CGI.Operands.hasOperandNamed(VarName, OpIdx)) { + // Get the machine operand number for the indicated operand. + OpIdx = CGI.Operands[OpIdx].MIOperandNo; + assert(!CGI.Operands.isFlatOperandNotEmitted(OpIdx) && + "Explicitly used operand also marked as not emitted!"); + } else { + /// If this operand is not supposed to be emitted by the + /// generated emitter, skip it. + while (CGI.Operands.isFlatOperandNotEmitted(NumberedOp)) + ++NumberedOp; + OpIdx = NumberedOp++; + } + + std::pair<unsigned, unsigned> SO = CGI.Operands.getSubOperandNumber(OpIdx); + std::string &EncoderMethodName = CGI.Operands[SO.first].EncoderMethodName; + + // If the source operand has a custom encoder, use it. This will + // get the encoding for all of the suboperands. + if (!EncoderMethodName.empty()) { + // A custom encoder has all of the information for the + // sub-operands, if there are more than one, so only + // query the encoder once per source operand. + if (SO.second == 0) { + Case += " // op: " + VarName + "\n" + + " op = " + EncoderMethodName + "(MI, " + utostr(OpIdx); + if (MCEmitter) + Case += ", Fixups"; + Case += ");\n"; + } + } else { + Case += " // op: " + VarName + "\n" + + " op = getMachineOpValue(MI, MI.getOperand(" + utostr(OpIdx) + ")"; + if (MCEmitter) + Case += ", Fixups"; + Case += ");\n"; + } + + 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; + } + + unsigned opMask = ~0U >> (32-N); + int opShift = beginVarBit - N + 1; + opMask <<= opShift; + opShift = beginInstBit - beginVarBit; + + if (opShift > 0) { + Case += " Value |= (op & " + utostr(opMask) + "U) << " + + itostr(opShift) + ";\n"; + } else if (opShift < 0) { + Case += " Value |= (op & " + utostr(opMask) + "U) >> " + + itostr(-opShift) + ";\n"; + } else { + Case += " Value |= op & " + utostr(opMask) + "U;\n"; + } + } +} + + +std::string CodeEmitterGen::getInstructionCase(Record *R, + CodeGenTarget &Target) { + std::string Case; + + BitsInit *BI = R->getValueAsBitsInit("Inst"); + const std::vector<RecordVal> &Vals = R->getValues(); + unsigned NumberedOp = 0; + + // Loop over all of the fields in the instruction, determining which are the + // operands to the instruction. + 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; + + AddCodeToMergeInOperand(R, BI, Vals[i].getName(), NumberedOp, Case, Target); + } + + std::string PostEmitter = R->getValueAsString("PostEncoderMethod"); + if (!PostEmitter.empty()) + Case += " Value = " + PostEmitter + "(MI, Value);\n"; + + return Case; +} + +void CodeEmitterGen::run(raw_ostream &o) { + CodeGenTarget Target(Records); + std::vector<Record*> Insts = Records.getAllDerivedDefinitions("Instruction"); + + // For little-endian instruction bit encodings, reverse the bit order + if (Target.isLittleEndianEncoding()) reverseBits(Insts); + + EmitSourceFileHeader("Machine Code Emitter", o); + + const std::vector<const CodeGenInstruction*> &NumberedInstructions = + Target.getInstructionsByEnumValue(); + + // Emit function declaration + o << "unsigned " << Target.getName(); + if (MCEmitter) + o << "MCCodeEmitter::getBinaryCodeForInstr(const MCInst &MI,\n" + << " SmallVectorImpl<MCFixup> &Fixups) const {\n"; + else + o << "CodeEmitter::getBinaryCodeForInstr(const MachineInstr &MI) const {\n"; + + // Emit instruction base values + o << " static const unsigned InstBits[] = {\n"; + for (std::vector<const CodeGenInstruction*>::const_iterator + IN = NumberedInstructions.begin(), + EN = NumberedInstructions.end(); + IN != EN; ++IN) { + const CodeGenInstruction *CGI = *IN; + Record *R = CGI->TheDef; + + if (R->getValueAsString("Namespace") == "TargetOpcode") { + o << " 0U,\n"; + continue; + } + + BitsInit *BI = R->getValueAsBitsInit("Inst"); + + // Start by filling in fixed values. + unsigned Value = 0; + for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i) { + if (BitInit *B = dynamic_cast<BitInit*>(BI->getBit(e-i-1))) + Value |= B->getValue() << (e-i-1); + } + o << " " << Value << "U," << '\t' << "// " << R->getName() << "\n"; + } + o << " 0U\n };\n"; + + // Map to accumulate all the cases. + std::map<std::string, std::vector<std::string> > CaseMap; + + // Construct all cases statement for each opcode + for (std::vector<Record*>::iterator IC = Insts.begin(), EC = Insts.end(); + IC != EC; ++IC) { + Record *R = *IC; + if (R->getValueAsString("Namespace") == "TargetOpcode") + continue; + const std::string &InstName = R->getValueAsString("Namespace") + "::" + + R->getName(); + std::string Case = getInstructionCase(R, Target); + + CaseMap[Case].push_back(InstName); + } + + // Emit initial function code + o << " const unsigned opcode = MI.getOpcode();\n" + << " unsigned Value = InstBits[opcode];\n" + << " unsigned 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());\n" + << " }\n" + << " return Value;\n" + << "}\n\n"; +} |
