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-rw-r--r--utils/TableGen/CodeEmitterGen.cpp257
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diff --git a/utils/TableGen/CodeEmitterGen.cpp b/utils/TableGen/CodeEmitterGen.cpp
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+//===- CodeEmitterGen.cpp - Code Emitter Generator ------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and 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/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");
+
+ EmitSourceFileHeader("Machine Code Emitter", o);
+ std::string Namespace = Insts[0]->getValueAsString("Namespace") + "::";
+
+ // Emit function declaration
+ o << "unsigned " << Target.getName() << "CodeEmitter::"
+ << "getBinaryCodeForInstr(MachineInstr &MI) {\n"
+ << " unsigned Value = 0;\n"
+ << " DEBUG(std::cerr << MI);\n"
+ << " switch (MI.getOpcode()) {\n";
+
+ // Emit a case statement for each opcode
+ for (std::vector<Record*>::iterator I = Insts.begin(), E = Insts.end();
+ I != E; ++I) {
+ Record *R = *I;
+ o << " case " << Namespace << R->getName() << ": {\n"
+ << " DEBUG(std::cerr << \"Emitting " << R->getName() << "\\n\");\n";
+
+ 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();
+
+ DEBUG(o << " // prefilling: ");
+ // Start by filling in fixed values...
+ 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);
+ DEBUG(o << B->getValue());
+ } else {
+ DEBUG(o << "0");
+ }
+ }
+ DEBUG(o << "\n");
+
+ 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
+ // 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()) {
+ // 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.
+ BitsInit *InstInit = BI;
+ int beginBitInVar = -1, endBitInVar = -1;
+ int beginBitInInst = -1, endBitInInst = -1;
+ bool continuous = true;
+
+ for (int bit = InstInit->getNumBits()-1; bit >= 0; --bit) {
+ if (VarBitInit *VBI =
+ dynamic_cast<VarBitInit*>(InstInit->getBit(bit))) {
+ TypedInit *TI = VBI->getVariable();
+ if (VarInit *VI = dynamic_cast<VarInit*>(TI)) {
+ // only process the current variable
+ if (VI->getName() != Vals[i].getName())
+ continue;
+
+ if (beginBitInVar == -1)
+ beginBitInVar = VBI->getBitNum();
+
+ if (endBitInVar == -1)
+ endBitInVar = VBI->getBitNum();
+ else {
+ if (endBitInVar == (int)VBI->getBitNum() + 1)
+ endBitInVar = VBI->getBitNum();
+ else {
+ continuous = false;
+ break;
+ }
+ }
+
+ if (beginBitInInst == -1)
+ beginBitInInst = bit;
+ if (endBitInInst == -1)
+ endBitInInst = bit;
+ else {
+ if (endBitInInst == bit + 1)
+ endBitInInst = bit;
+ else {
+ continuous = false;
+ break;
+ }
+ }
+
+ // maintain same distance between bits in field and bits in
+ // instruction. if the relative distances stay the same
+ // throughout,
+ if (beginBitInVar - (int)VBI->getBitNum() !=
+ beginBitInInst - bit) {
+ continuous = false;
+ break;
+ }
+ }
+ }
+ }
+
+ // If we have found no bit in "Inst" which comes from this field, then
+ // this is not an operand!!
+ if (beginBitInInst != -1) {
+ o << " // op" << op << ": " << Vals[i].getName() << "\n"
+ << " int op" << op
+ <<" = getMachineOpValue(MI, MI.getOperand("<<op<<"));\n";
+ //<< " MachineOperand &op" << op <<" = MI.getOperand("<<op<<");\n";
+ OpOrder[Vals[i].getName()] = op++;
+
+ DEBUG(o << " // Var: begin = " << beginBitInVar
+ << ", end = " << endBitInVar
+ << "; Inst: begin = " << beginBitInInst
+ << ", end = " << endBitInInst << "\n");
+
+ if (continuous) {
+ DEBUG(o << " // continuous: op" << OpOrder[Vals[i].getName()]
+ << "\n");
+
+ // Mask off the right bits
+ // Low mask (ie. shift, if necessary)
+ assert(endBitInVar >= 0 && "Negative shift amount in masking!");
+ if (endBitInVar != 0) {
+ o << " op" << OpOrder[Vals[i].getName()]
+ << " >>= " << endBitInVar << ";\n";
+ beginBitInVar -= endBitInVar;
+ endBitInVar = 0;
+ }
+
+ // High mask
+ o << " op" << OpOrder[Vals[i].getName()]
+ << " &= (1<<" << beginBitInVar+1 << ") - 1;\n";
+
+ // Shift the value to the correct place (according to place in inst)
+ assert(endBitInInst >= 0 && "Negative shift amount!");
+ if (endBitInInst != 0)
+ o << " op" << OpOrder[Vals[i].getName()]
+ << " <<= " << endBitInInst << ";\n";
+
+ // Just OR in the result
+ o << " Value |= op" << OpOrder[Vals[i].getName()] << ";\n";
+ }
+
+ // otherwise, will be taken care of in the loop below using this
+ // value:
+ OpContinuous[Vals[i].getName()] = continuous;
+ }
+ }
+ }
+
+ 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";
+}
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