third_party/LLVM/utils/TableGen/CodeEmitterGen.cpp - SwiftShader - Git at Google

 //===- 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 "llvm/TableGen/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" ||
         R->getValueAsBit("isPseudo"))
       continue;

     BitsInit *BI = R->getValueAsBitsInit("Inst");

     unsigned numBits = BI->getNumBits();

     SmallVector<Init *, 16> NewBits(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);
       NewBits[bit]        = BitSwap;
       NewBits[bitSwapIdx] = OrigBit;
     }
     if (numBits % 2) {
       unsigned middle = (numBits + 1) / 2;
       NewBits[middle] = BI->getBit(middle);
     }

     BitsInit *NewBI = BitsInit::get(NewBits);

     // 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();
   } else if (VarInit *VI = dynamic_cast<VarInit*>(BI->getBit(bit))) {
     if (VI->getName() == VarName)
       return 0;
   }

   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" ||
         R->getValueAsBit("isPseudo")) {
       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" ||
         R->getValueAsBit("isPseudo"))
       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";
 }
	//===- 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 "llvm/TableGen/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" \|\|
	R->getValueAsBit("isPseudo"))
	continue;

	BitsInit *BI = R->getValueAsBitsInit("Inst");

	unsigned numBits = BI->getNumBits();

	SmallVector<Init *, 16> NewBits(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);
	NewBits[bit] = BitSwap;
	NewBits[bitSwapIdx] = OrigBit;
	}
	if (numBits % 2) {
	unsigned middle = (numBits + 1) / 2;
	NewBits[middle] = BI->getBit(middle);
	}

	BitsInit *NewBI = BitsInit::get(NewBits);

	// 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();
	} else if (VarInit VI = dynamic_cast<VarInit>(BI->getBit(bit))) {
	if (VI->getName() == VarName)
	return 0;
	}

	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" \|\|
	R->getValueAsBit("isPseudo")) {
	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" \|\|
	R->getValueAsBit("isPseudo"))
	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";
	}