llvm-6502/utils/TableGen/FastISelEmitter.cpp

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//===- FastISelEmitter.cpp - Generate an instruction selector -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This tablegen backend emits a "fast" instruction selector.
//
// This instruction selection method is designed to emit very poor code
// quickly. Also, it is not designed to do much lowering, so most illegal
// types (e.g. i64 on 32-bit targets) and operations (e.g. calls) are not
// supported and cannot easily be added. Blocks containing operations
// that are not supported need to be handled by a more capable selector,
// such as the SelectionDAG selector.
//
// The intended use for "fast" instruction selection is "-O0" mode
// compilation, where the quality of the generated code is irrelevant when
// weighed against the speed at which the code can be generated.
//
// If compile time is so important, you might wonder why we don't just
// skip codegen all-together, emit LLVM bytecode files, and execute them
// with an interpreter. The answer is that it would complicate linking and
// debugging, and also because that isn't how a compiler is expected to
// work in some circles.
//
// If you need better generated code or more lowering than what this
// instruction selector provides, use the SelectionDAG (DAGISel) instruction
// selector instead. If you're looking here because SelectionDAG isn't fast
// enough, consider looking into improving the SelectionDAG infastructure
// instead. At the time of this writing there remain several major
// opportunities for improvement.
//
//===----------------------------------------------------------------------===//
#include "FastISelEmitter.h"
#include "Record.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Streams.h"
#include "llvm/ADT/VectorExtras.h"
using namespace llvm;
namespace {
/// OperandsSignature - This class holds a description of a list of operand
/// types. It has utility methods for emitting text based on the operands.
///
struct OperandsSignature {
std::vector<std::string> Operands;
bool operator<(const OperandsSignature &O) const {
return Operands < O.Operands;
}
bool empty() const { return Operands.empty(); }
void PrintParameters(std::ostream &OS) const {
for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
if (Operands[i] == "r") {
OS << "unsigned Op" << i;
} else {
assert("Unknown operand kind!");
abort();
}
if (i + 1 != e)
OS << ", ";
}
}
void PrintArguments(std::ostream &OS) const {
for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
if (Operands[i] == "r") {
OS << "Op" << i;
} else {
assert("Unknown operand kind!");
abort();
}
if (i + 1 != e)
OS << ", ";
}
}
void PrintManglingSuffix(std::ostream &OS) const {
for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
OS << Operands[i];
}
}
};
/// InstructionMemo - This class holds additional information about an
/// instruction needed to emit code for it.
///
struct InstructionMemo {
std::string Name;
const CodeGenRegisterClass *RC;
};
}
static std::string getOpcodeName(Record *Op, CodeGenDAGPatterns &CGP) {
return CGP.getSDNodeInfo(Op).getEnumName();
}
static std::string getLegalCName(std::string OpName) {
std::string::size_type pos = OpName.find("::");
if (pos != std::string::npos)
OpName.replace(pos, 2, "_");
return OpName;
}
void FastISelEmitter::run(std::ostream &OS) {
EmitSourceFileHeader("\"Fast\" Instruction Selector for the " +
CGP.getTargetInfo().getName() + " target", OS);
const CodeGenTarget &Target = CGP.getTargetInfo();
// Get the namespace to insert instructions into. Make sure not to pick up
// "TargetInstrInfo" by accidentally getting the namespace off the PHI
// instruction or something.
std::string InstNS;
for (CodeGenTarget::inst_iterator i = Target.inst_begin(),
e = Target.inst_end(); i != e; ++i) {
InstNS = i->second.Namespace;
if (InstNS != "TargetInstrInfo")
break;
}
OS << "namespace llvm {\n";
OS << "namespace " << InstNS << " {\n";
OS << "class FastISel;\n";
OS << "}\n";
OS << "}\n";
OS << "\n";
if (!InstNS.empty()) InstNS += "::";
typedef std::map<MVT::SimpleValueType, InstructionMemo> TypeMap;
typedef std::map<std::string, TypeMap> OpcodeTypeMap;
typedef std::map<OperandsSignature, OpcodeTypeMap> OperandsOpcodeTypeMap;
OperandsOpcodeTypeMap SimplePatterns;
// Create the supported type signatures.
OperandsSignature KnownOperands;
SimplePatterns[KnownOperands] = OpcodeTypeMap();
KnownOperands.Operands.push_back("r");
SimplePatterns[KnownOperands] = OpcodeTypeMap();
KnownOperands.Operands.push_back("r");
SimplePatterns[KnownOperands] = OpcodeTypeMap();
for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(),
E = CGP.ptm_end(); I != E; ++I) {
const PatternToMatch &Pattern = *I;
// For now, just look at Instructions, so that we don't have to worry
// about emitting multiple instructions for a pattern.
TreePatternNode *Dst = Pattern.getDstPattern();
if (Dst->isLeaf()) continue;
Record *Op = Dst->getOperator();
if (!Op->isSubClassOf("Instruction"))
continue;
CodeGenInstruction &II = CGP.getTargetInfo().getInstruction(Op->getName());
if (II.OperandList.empty())
continue;
Record *Op0Rec = II.OperandList[0].Rec;
if (!Op0Rec->isSubClassOf("RegisterClass"))
continue;
const CodeGenRegisterClass *DstRC = &Target.getRegisterClass(Op0Rec);
if (!DstRC)
continue;
// Inspect the pattern.
TreePatternNode *InstPatNode = Pattern.getSrcPattern();
if (!InstPatNode) continue;
if (InstPatNode->isLeaf()) continue;
Record *InstPatOp = InstPatNode->getOperator();
std::string OpcodeName = getOpcodeName(InstPatOp, CGP);
MVT::SimpleValueType VT = InstPatNode->getTypeNum(0);
// For now, filter out instructions which just set a register to
// an Operand, like MOV32ri.
if (InstPatOp->isSubClassOf("Operand"))
continue;
// Check all the operands. For now only accept register operands.
OperandsSignature Operands;
for (unsigned i = 0, e = InstPatNode->getNumChildren(); i != e; ++i) {
TreePatternNode *Op = InstPatNode->getChild(i);
if (!Op->isLeaf())
goto continue_label;
DefInit *OpDI = dynamic_cast<DefInit*>(Op->getLeafValue());
if (!OpDI)
goto continue_label;
Record *OpLeafRec = OpDI->getDef();
if (!OpLeafRec->isSubClassOf("RegisterClass"))
goto continue_label;
const CodeGenRegisterClass *RC = &Target.getRegisterClass(OpLeafRec);
if (!RC)
goto continue_label;
if (Op->getTypeNum(0) != VT)
goto continue_label;
Operands.Operands.push_back("r");
}
// If it's not a known signature, ignore it.
if (!SimplePatterns.count(Operands))
continue;
// Ok, we found a pattern that we can handle. Remember it.
{
InstructionMemo Memo = {
Pattern.getDstPattern()->getOperator()->getName(),
DstRC
};
SimplePatterns[Operands][OpcodeName][VT] = Memo;
}
continue_label:;
}
OS << "#include \"llvm/CodeGen/FastISel.h\"\n";
OS << "\n";
OS << "namespace llvm {\n";
OS << "\n";
// Declare the target FastISel class.
OS << "class " << InstNS << "FastISel : public llvm::FastISel {\n";
for (OperandsOpcodeTypeMap::const_iterator OI = SimplePatterns.begin(),
OE = SimplePatterns.end(); OI != OE; ++OI) {
const OperandsSignature &Operands = OI->first;
const OpcodeTypeMap &OTM = OI->second;
for (OpcodeTypeMap::const_iterator I = OTM.begin(), E = OTM.end();
I != E; ++I) {
const std::string &Opcode = I->first;
const TypeMap &TM = I->second;
for (TypeMap::const_iterator TI = TM.begin(), TE = TM.end();
TI != TE; ++TI) {
MVT::SimpleValueType VT = TI->first;
OS << " unsigned FastEmit_" << getLegalCName(Opcode)
<< "_" << getLegalCName(getName(VT)) << "(";
Operands.PrintParameters(OS);
OS << ");\n";
}
OS << " unsigned FastEmit_" << getLegalCName(Opcode)
<< "(MVT::SimpleValueType VT";
if (!Operands.empty())
OS << ", ";
Operands.PrintParameters(OS);
OS << ");\n";
}
OS << "unsigned FastEmit_";
Operands.PrintManglingSuffix(OS);
OS << "(MVT::SimpleValueType VT, ISD::NodeType Opcode";
if (!Operands.empty())
OS << ", ";
Operands.PrintParameters(OS);
OS << ");\n";
}
OS << "public:\n";
OS << " FastISel(MachineBasicBlock *mbb, MachineFunction *mf, ";
OS << "const TargetInstrInfo *tii) : llvm::FastISel(mbb, mf, tii) {}\n";
OS << "};\n";
OS << "\n";
// Define the target FastISel creation function.
OS << "llvm::FastISel *" << InstNS
<< "createFastISel(MachineBasicBlock *mbb, MachineFunction *mf, ";
OS << "const TargetInstrInfo *tii) {\n";
OS << " return new " << InstNS << "FastISel(mbb, mf, tii);\n";
OS << "}\n";
OS << "\n";
// Now emit code for all the patterns that we collected.
for (OperandsOpcodeTypeMap::const_iterator OI = SimplePatterns.begin(),
OE = SimplePatterns.end(); OI != OE; ++OI) {
const OperandsSignature &Operands = OI->first;
const OpcodeTypeMap &OTM = OI->second;
for (OpcodeTypeMap::const_iterator I = OTM.begin(), E = OTM.end();
I != E; ++I) {
const std::string &Opcode = I->first;
const TypeMap &TM = I->second;
OS << "// FastEmit functions for " << Opcode << ".\n";
OS << "\n";
// Emit one function for each opcode,type pair.
for (TypeMap::const_iterator TI = TM.begin(), TE = TM.end();
TI != TE; ++TI) {
MVT::SimpleValueType VT = TI->first;
const InstructionMemo &Memo = TI->second;
OS << "unsigned " << InstNS << "FastISel::FastEmit_"
<< getLegalCName(Opcode)
<< "_" << getLegalCName(getName(VT)) << "(";
Operands.PrintParameters(OS);
OS << ") {\n";
OS << " return FastEmitInst_";
Operands.PrintManglingSuffix(OS);
OS << "(" << InstNS << Memo.Name << ", ";
OS << InstNS << Memo.RC->getName() << "RegisterClass";
if (!Operands.empty())
OS << ", ";
Operands.PrintArguments(OS);
OS << ");\n";
OS << "}\n";
OS << "\n";
}
// Emit one function for the opcode that demultiplexes based on the type.
OS << "unsigned " << InstNS << "FastISel::FastEmit_"
<< getLegalCName(Opcode) << "(MVT::SimpleValueType VT";
if (!Operands.empty())
OS << ", ";
Operands.PrintParameters(OS);
OS << ") {\n";
OS << " switch (VT) {\n";
for (TypeMap::const_iterator TI = TM.begin(), TE = TM.end();
TI != TE; ++TI) {
MVT::SimpleValueType VT = TI->first;
std::string TypeName = getName(VT);
OS << " case " << TypeName << ": return FastEmit_"
<< getLegalCName(Opcode) << "_" << getLegalCName(TypeName) << "(";
Operands.PrintArguments(OS);
OS << ");\n";
}
OS << " default: return 0;\n";
OS << " }\n";
OS << "}\n";
OS << "\n";
}
// Emit one function for the operand signature that demultiplexes based
// on opcode and type.
OS << "unsigned " << InstNS << "FastISel::FastEmit_";
Operands.PrintManglingSuffix(OS);
OS << "(MVT::SimpleValueType VT, ISD::NodeType Opcode";
if (!Operands.empty())
OS << ", ";
Operands.PrintParameters(OS);
OS << ") {\n";
OS << " switch (Opcode) {\n";
for (OpcodeTypeMap::const_iterator I = OTM.begin(), E = OTM.end();
I != E; ++I) {
const std::string &Opcode = I->first;
OS << " case " << Opcode << ": return FastEmit_"
<< getLegalCName(Opcode) << "(VT";
if (!Operands.empty())
OS << ", ";
Operands.PrintArguments(OS);
OS << ");\n";
}
OS << " default: return 0;\n";
OS << " }\n";
OS << "}\n";
OS << "\n";
}
OS << "}\n";
}
// todo: really filter out Constants