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* Factor out (into new fn) a loop emitting operand shifts into the instruction

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* Reverse instruction bit components for a LittleEndian-style encoding
* Fix some comments and spacing


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16975 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Misha Brukman 2004-10-14 05:53:01 +00:00
parent 35e83cc970
commit 28eefa5464
2 changed files with 84 additions and 46 deletions
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122
utils/TableGen/CodeEmitterGen.cpp
View File

@ -19,6 +19,58 @@
#include "llvm/Support/Debug.h"
using namespace llvm;
void CodeEmitterGen::emitInstrOpBits(std::ostream &o,
const std::vector<RecordVal> &Vals,
std::map<std::string, unsigned> &OpOrder,
std::map<std::string, bool> &OpContinuous)
{
for (unsigned f = 0, e = Vals.size(); f != e; ++f) {
if (Vals[f].getPrefix()) {
BitsInit *FieldInitializer = (BitsInit*)Vals[f].getValue();
// Scan through the field looking for bit initializers of the current
// variable...
for (int i = FieldInitializer->getNumBits()-1; i >= 0; --i) {
Init *I = FieldInitializer->getBit(i);
if (BitInit *BI = dynamic_cast<BitInit*>(I)) {
DEBUG(o << " // bit init: f: " << f << ", i: " << i << "\n");
} else if (UnsetInit *UI = dynamic_cast<UnsetInit*>(I)) {
DEBUG(o << " // unset init: f: " << f << ", i: " << i << "\n");
} else if (VarBitInit *VBI = dynamic_cast<VarBitInit*>(I)) {
TypedInit *TI = VBI->getVariable();
if (VarInit *VI = dynamic_cast<VarInit*>(TI)) {
// If the bits of the field are laid out consecutively in the
// instruction, then instead of separately ORing in bits, just
// mask and shift the entire field for efficiency.
if (OpContinuous[VI->getName()]) {
// already taken care of in the loop above, thus there is no
// need to individually OR in the bits
// for debugging, output the regular version anyway, commented
DEBUG(o << " // Value |= getValueBit(op"
<< OpOrder[VI->getName()] << ", " << VBI->getBitNum()
<< ")" << " << " << i << ";\n");
} else {
o << " Value |= getValueBit(op" << OpOrder[VI->getName()]
<< ", " << VBI->getBitNum()
<< ")" << " << " << i << ";\n";
}
} else if (FieldInit *FI = dynamic_cast<FieldInit*>(TI)) {
// FIXME: implement this!
std::cerr << "Error: FieldInit not implemented!\n";
abort();
} else {
std::cerr << "Error: unimplemented case in "
<< "CodeEmitterGen::emitInstrOpBits()\n";
abort();
}
}
}
}
}
}
void CodeEmitterGen::run(std::ostream &o) {
CodeGenTarget Target;
std::vector<Record*> Insts = Records.getAllDerivedDefinitions("Instruction");
@ -43,6 +95,24 @@ void CodeEmitterGen::run(std::ostream &o) {
BitsInit *BI = R->getValueAsBitsInit("Inst");
// For little-endian instruction bit encodings, reverse the bit order
if (Target.isLittleEndianEncoding()) {
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));
}
BI = NewBI;
}
unsigned Value = 0;
const std::vector<RecordVal> &Vals = R->getValues();
@ -61,17 +131,16 @@ void CodeEmitterGen::run(std::ostream &o) {
DEBUG(o << " // " << *R->getValue("Inst") << "\n");
o << " Value = " << Value << "U;\n\n";
// Loop over all of the fields in the instruction determining which are the
// Loop over all of the fields in the instruction, determining which are the
// operands to the instruction.
//
unsigned op = 0;
std::map<std::string, unsigned> OpOrder;
std::map<std::string, bool> OpContinuous;
for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
if (!Vals[i].getPrefix() && !Vals[i].getValue()->isComplete()) {
if (!Vals[i].getPrefix() && !Vals[i].getValue()->isComplete()) {
// Is the operand continuous? If so, we can just mask and OR it in
// instead of doing it bit-by-bit, saving a lot in runtime cost.
const BitsInit *InstInit = BI;
BitsInit *InstInit = BI;
int beginBitInVar = -1, endBitInVar = -1;
int beginBitInInst = -1, endBitInInst = -1;
bool continuous = true;
@ -173,58 +242,19 @@ void CodeEmitterGen::run(std::ostream &o) {
}
}
for (unsigned f = 0, e = Vals.size(); f != e; ++f) {
if (Vals[f].getPrefix()) {
BitsInit *FieldInitializer = (BitsInit*)Vals[f].getValue();
// Scan through the field looking for bit initializers of the current
// variable...
for (int i = FieldInitializer->getNumBits()-1; i >= 0; --i) {
Init *I = FieldInitializer->getBit(i);
if (BitInit *BI = dynamic_cast<BitInit*>(I)) {
DEBUG(o << " // bit init: f: " << f << ", i: " << i << "\n");
} else if (UnsetInit *UI = dynamic_cast<UnsetInit*>(I)) {
DEBUG(o << " // unset init: f: " << f << ", i: " << i << "\n");
} else if (VarBitInit *VBI = dynamic_cast<VarBitInit*>(I)) {
TypedInit *TI = VBI->getVariable();
if (VarInit *VI = dynamic_cast<VarInit*>(TI)) {
// If the bits of the field are laid out consecutively in the
// instruction, then instead of separately ORing in bits, just
// mask and shift the entire field for efficiency.
if (OpContinuous[VI->getName()]) {
// already taken care of in the loop above, thus there is no
// need to individually OR in the bits
// for debugging, output the regular version anyway, commented
DEBUG(o << " // Value |= getValueBit(op"
<< OpOrder[VI->getName()] << ", " << VBI->getBitNum()
<< ")" << " << " << i << ";\n");
} else {
o << " Value |= getValueBit(op" << OpOrder[VI->getName()]
<< ", " << VBI->getBitNum()
<< ")" << " << " << i << ";\n";
}
} else if (FieldInit *FI = dynamic_cast<FieldInit*>(TI)) {
// FIXME: implement this!
o << "FIELD INIT not implemented yet!\n";
} else {
o << "Error: UNIMPLEMENTED\n";
}
}
}
}
}
emitInstrOpBits(o, Vals, OpOrder, OpContinuous);
o << " break;\n"
<< " }\n";
}
// Default case: unhandled opcode
o << " default:\n"
<< " std::cerr << \"Not supported instr: \" << MI << \"\\n\";\n"
<< " abort();\n"
<< " }\n"
<< " return Value;\n"
<< "}\n";
<< "}\n\n";
o << "} // End llvm namespace \n";
}

8
utils/TableGen/CodeEmitterGen.h
View File

@ -15,9 +15,13 @@
#define CODEMITTERGEN_H
#include "TableGenBackend.h"
#include <map>
#include <vector>
namespace llvm {
class RecordVal;
class CodeEmitterGen : public TableGenBackend {
RecordKeeper &Records;
public:
@ -28,6 +32,10 @@ public:
private:
void emitMachineOpEmitter(std::ostream &o, const std::string &Namespace);
void emitGetValueBit(std::ostream &o, const std::string &Namespace);
void emitInstrOpBits(std::ostream &o,
const std::vector<RecordVal> &Vals,
std::map<std::string, unsigned> &OpOrder,
std::map<std::string, bool> &OpContinuous);
};
} // End llvm namespace