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llvm-project/llvm/utils/TableGen/PseudoLoweringEmitter.cpp

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//===- PseudoLoweringEmitter.cpp - PseudoLowering Generator -----*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "CodeGenInstruction.h"
#include "CodeGenTarget.h"
#include "llvm/ADT/IndexedMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/TableGen/Error.h"
#include "llvm/TableGen/Record.h"
#include "llvm/TableGen/TableGenBackend.h"
#include <vector>
using namespace llvm;
#define DEBUG_TYPE "pseudo-lowering"
namespace {
class PseudoLoweringEmitter {
struct OpData {
enum MapKind { Operand, Imm, Reg };
MapKind Kind;
union {
unsigned Operand; // Operand number mapped to.
uint64_t Imm; // Integer immedate value.
Record *Reg; // Physical register.
} Data;
};
struct PseudoExpansion {
CodeGenInstruction Source; // The source pseudo instruction definition.
CodeGenInstruction Dest; // The destination instruction to lower to.
IndexedMap<OpData> OperandMap;
PseudoExpansion(CodeGenInstruction &s, CodeGenInstruction &d,
IndexedMap<OpData> &m) :
Source(s), Dest(d), OperandMap(m) {}
};
RecordKeeper &Records;
// It's overkill to have an instance of the full CodeGenTarget object,
// but it loads everything on demand, not in the constructor, so it's
// lightweight in performance, so it works out OK.
CodeGenTarget Target;
SmallVector<PseudoExpansion, 64> Expansions;
unsigned addDagOperandMapping(Record *Rec, DagInit *Dag,
CodeGenInstruction &Insn,
IndexedMap<OpData> &OperandMap,
unsigned BaseIdx);
void evaluateExpansion(Record *Pseudo);
void emitLoweringEmitter(raw_ostream &o);
public:
PseudoLoweringEmitter(RecordKeeper &R) : Records(R), Target(R) {}
/// run - Output the pseudo-lowerings.
void run(raw_ostream &o);
};
} // End anonymous namespace
// FIXME: This pass currently can only expand a pseudo to a single instruction.
// The pseudo expansion really should take a list of dags, not just
// a single dag, so we can do fancier things.
unsigned PseudoLoweringEmitter::
addDagOperandMapping(Record *Rec, DagInit *Dag, CodeGenInstruction &Insn,
IndexedMap<OpData> &OperandMap, unsigned BaseIdx) {
unsigned OpsAdded = 0;
for (unsigned i = 0, e = Dag->getNumArgs(); i != e; ++i) {
if (DefInit *DI = dyn_cast<DefInit>(Dag->getArg(i))) {
// Physical register reference. Explicit check for the special case
// "zero_reg" definition.
if (DI->getDef()->isSubClassOf("Register") ||
DI->getDef()->getName() == "zero_reg") {
OperandMap[BaseIdx + i].Kind = OpData::Reg;
OperandMap[BaseIdx + i].Data.Reg = DI->getDef();
++OpsAdded;
continue;
}
// Normal operands should always have the same type, or we have a
// problem.
// FIXME: We probably shouldn't ever get a non-zero BaseIdx here.
assert(BaseIdx == 0 && "Named subargument in pseudo expansion?!");
// FIXME: Are the message operand types backward?
if (DI->getDef() != Insn.Operands[BaseIdx + i].Rec) {
PrintError(Rec, "In pseudo instruction '" + Rec->getName() +
"', operand type '" + DI->getDef()->getName() +
"' does not match expansion operand type '" +
Insn.Operands[BaseIdx + i].Rec->getName() + "'");
PrintFatalNote(DI->getDef(),
"Value was assigned at the following location:");
}
// Source operand maps to destination operand. The Data element
// will be filled in later, just set the Kind for now. Do it
// for each corresponding MachineInstr operand, not just the first.
for (unsigned I = 0, E = Insn.Operands[i].MINumOperands; I != E; ++I)
OperandMap[BaseIdx + i + I].Kind = OpData::Operand;
OpsAdded += Insn.Operands[i].MINumOperands;
} else if (IntInit *II = dyn_cast<IntInit>(Dag->getArg(i))) {
OperandMap[BaseIdx + i].Kind = OpData::Imm;
OperandMap[BaseIdx + i].Data.Imm = II->getValue();
++OpsAdded;
} else if (auto *BI = dyn_cast<BitsInit>(Dag->getArg(i))) {
auto *II = cast<IntInit>(BI->convertInitializerTo(IntRecTy::get()));
OperandMap[BaseIdx + i].Kind = OpData::Imm;
OperandMap[BaseIdx + i].Data.Imm = II->getValue();
++OpsAdded;
} else if (DagInit *SubDag = dyn_cast<DagInit>(Dag->getArg(i))) {
// Just add the operands recursively. This is almost certainly
// a constant value for a complex operand (> 1 MI operand).
unsigned NewOps =
addDagOperandMapping(Rec, SubDag, Insn, OperandMap, BaseIdx + i);
OpsAdded += NewOps;
// Since we added more than one, we also need to adjust the base.
BaseIdx += NewOps - 1;
} else
llvm_unreachable("Unhandled pseudo-expansion argument type!");
}
return OpsAdded;
}
void PseudoLoweringEmitter::evaluateExpansion(Record *Rec) {
LLVM_DEBUG(dbgs() << "Pseudo definition: " << Rec->getName() << "\n");
// Validate that the result pattern has the corrent number and types
// of arguments for the instruction it references.
DagInit *Dag = Rec->getValueAsDag("ResultInst");
assert(Dag && "Missing result instruction in pseudo expansion!");
LLVM_DEBUG(dbgs() << " Result: " << *Dag << "\n");
DefInit *OpDef = dyn_cast<DefInit>(Dag->getOperator());
if (!OpDef) {
PrintError(Rec, "In pseudo instruction '" + Rec->getName() +
"', result operator is not a record");
PrintFatalNote(Rec->getValue("ResultInst"),
"Result was assigned at the following location:");
}
Record *Operator = OpDef->getDef();
if (!Operator->isSubClassOf("Instruction")) {
PrintError(Rec, "In pseudo instruction '" + Rec->getName() +
"', result operator '" + Operator->getName() +
"' is not an instruction");
PrintFatalNote(Rec->getValue("ResultInst"),
"Result was assigned at the following location:");
}
CodeGenInstruction Insn(Operator);
if (Insn.isCodeGenOnly || Insn.isPseudo) {
PrintError(Rec, "In pseudo instruction '" + Rec->getName() +
"', result operator '" + Operator->getName() +
"' cannot be a pseudo instruction");
PrintFatalNote(Rec->getValue("ResultInst"),
"Result was assigned at the following location:");
}
if (Insn.Operands.size() != Dag->getNumArgs()) {
PrintError(Rec, "In pseudo instruction '" + Rec->getName() +
"', result operator '" + Operator->getName() +
"' has the wrong number of operands");
PrintFatalNote(Rec->getValue("ResultInst"),
"Result was assigned at the following location:");
}
unsigned NumMIOperands = 0;
for (unsigned i = 0, e = Insn.Operands.size(); i != e; ++i)
NumMIOperands += Insn.Operands[i].MINumOperands;
IndexedMap<OpData> OperandMap;
OperandMap.grow(NumMIOperands);
addDagOperandMapping(Rec, Dag, Insn, OperandMap, 0);
// If there are more operands that weren't in the DAG, they have to
// be operands that have default values, or we have an error. Currently,
// Operands that are a subclass of OperandWithDefaultOp have default values.
// Validate that each result pattern argument has a matching (by name)
// argument in the source instruction, in either the (outs) or (ins) list.
// Also check that the type of the arguments match.
//
// Record the mapping of the source to result arguments for use by
// the lowering emitter.
CodeGenInstruction SourceInsn(Rec);
StringMap<unsigned> SourceOperands;
for (unsigned i = 0, e = SourceInsn.Operands.size(); i != e; ++i)
SourceOperands[SourceInsn.Operands[i].Name] = i;
LLVM_DEBUG(dbgs() << " Operand mapping:\n");
for (unsigned i = 0, e = Insn.Operands.size(); i != e; ++i) {
// We've already handled constant values. Just map instruction operands
// here.
if (OperandMap[Insn.Operands[i].MIOperandNo].Kind != OpData::Operand)
continue;
StringMap<unsigned>::iterator SourceOp =
SourceOperands.find(Dag->getArgNameStr(i));
if (SourceOp == SourceOperands.end()) {
PrintError(Rec, "In pseudo instruction '" + Rec->getName() +
"', output operand '" + Dag->getArgNameStr(i) +
"' has no matching source operand");
PrintFatalNote(Rec->getValue("ResultInst"),
"Value was assigned at the following location:");
}
// Map the source operand to the destination operand index for each
// MachineInstr operand.
for (unsigned I = 0, E = Insn.Operands[i].MINumOperands; I != E; ++I)
OperandMap[Insn.Operands[i].MIOperandNo + I].Data.Operand =
SourceOp->getValue();
LLVM_DEBUG(dbgs() << " " << SourceOp->getValue() << " ==> " << i
<< "\n");
}
Expansions.push_back(PseudoExpansion(SourceInsn, Insn, OperandMap));
}
void PseudoLoweringEmitter::emitLoweringEmitter(raw_ostream &o) {
// Emit file header.
emitSourceFileHeader("Pseudo-instruction MC lowering Source Fragment", o);
o << "bool " << Target.getName() + "AsmPrinter" << "::\n"
<< "emitPseudoExpansionLowering(MCStreamer &OutStreamer,\n"
<< " const MachineInstr *MI) {\n";
if (!Expansions.empty()) {
o << " switch (MI->getOpcode()) {\n"
<< " default: return false;\n";
for (auto &Expansion : Expansions) {
CodeGenInstruction &Source = Expansion.Source;
CodeGenInstruction &Dest = Expansion.Dest;
o << " case " << Source.Namespace << "::"
<< Source.TheDef->getName() << ": {\n"
<< " MCInst TmpInst;\n"
<< " MCOperand MCOp;\n"
<< " TmpInst.setOpcode(" << Dest.Namespace << "::"
<< Dest.TheDef->getName() << ");\n";
// Copy the operands from the source instruction.
// FIXME: Instruction operands with defaults values (predicates and cc_out
// in ARM, for example shouldn't need explicit values in the
// expansion DAG.
unsigned MIOpNo = 0;
for (const auto &DestOperand : Dest.Operands) {
o << " // Operand: " << DestOperand.Name << "\n";
for (unsigned i = 0, e = DestOperand.MINumOperands; i != e; ++i) {
switch (Expansion.OperandMap[MIOpNo + i].Kind) {
case OpData::Operand:
o << " lowerOperand(MI->getOperand("
<< Source.Operands[Expansion.OperandMap[MIOpNo].Data
.Operand].MIOperandNo + i
<< "), MCOp);\n"
<< " TmpInst.addOperand(MCOp);\n";
break;
case OpData::Imm:
o << " TmpInst.addOperand(MCOperand::createImm("
<< Expansion.OperandMap[MIOpNo + i].Data.Imm << "));\n";
break;
case OpData::Reg: {
Record *Reg = Expansion.OperandMap[MIOpNo + i].Data.Reg;
o << " TmpInst.addOperand(MCOperand::createReg(";
// "zero_reg" is special.
if (Reg->getName() == "zero_reg")
o << "0";
else
o << Reg->getValueAsString("Namespace") << "::"
<< Reg->getName();
o << "));\n";
break;
}
}
}
MIOpNo += DestOperand.MINumOperands;
}
if (Dest.Operands.isVariadic) {
MIOpNo = Source.Operands.size() + 1;
o << " // variable_ops\n";
o << " for (unsigned i = " << MIOpNo
<< ", e = MI->getNumOperands(); i != e; ++i)\n"
<< " if (lowerOperand(MI->getOperand(i), MCOp))\n"
<< " TmpInst.addOperand(MCOp);\n";
}
o << " EmitToStreamer(OutStreamer, TmpInst);\n"
<< " break;\n"
<< " }\n";
}
o << " }\n return true;";
} else
o << " return false;";
o << "\n}\n\n";
}
void PseudoLoweringEmitter::run(raw_ostream &o) {
StringRef Classes[] = {"PseudoInstExpansion", "Instruction"};
std::vector<Record *> Insts =
Records.getAllDerivedDefinitions(makeArrayRef(Classes));
// Process the pseudo expansion definitions, validating them as we do so.
Records.startTimer("Process definitions");
for (unsigned i = 0, e = Insts.size(); i != e; ++i)
evaluateExpansion(Insts[i]);
// Generate expansion code to lower the pseudo to an MCInst of the real
// instruction.
Records.startTimer("Emit expansion code");
emitLoweringEmitter(o);
}
namespace llvm {
void EmitPseudoLowering(RecordKeeper &RK, raw_ostream &OS) {
PseudoLoweringEmitter(RK).run(OS);
}
} // End llvm namespace
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