| //===-- WriteInst.cpp - Functions for writing instructions -------*- C++ -*--=// |
| // |
| // This file implements the routines for encoding instruction opcodes to a |
| // bytecode stream. |
| // |
| // Note that the performance of this library is not terribly important, because |
| // it shouldn't be used by JIT type applications... so it is not a huge focus |
| // at least. :) |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "WriterInternals.h" |
| #include "llvm/Module.h" |
| #include "llvm/Method.h" |
| #include "llvm/BasicBlock.h" |
| #include "llvm/Instruction.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Tools/DataTypes.h" |
| #include <algorithm> |
| |
| typedef unsigned char uchar; |
| |
| // outputInstructionFormat0 - Output those wierd instructions that have a large |
| // number of operands or have large operands themselves... |
| // |
| // Format: [opcode] [type] [numargs] [arg0] [arg1] ... [arg<numargs-1>] |
| // |
| static void outputInstructionFormat0(const Instruction *I, |
| const SlotCalculator &Table, |
| unsigned Type, vector<uchar> &Out) { |
| // Opcode must have top two bits clear... |
| output_vbr(I->getInstType(), Out); // Instruction Opcode ID |
| output_vbr(Type, Out); // Result type |
| |
| unsigned NumArgs; // Count the number of arguments to the instruction |
| for (NumArgs = 0; I->getOperand(NumArgs); NumArgs++) /*empty*/; |
| output_vbr(NumArgs, Out); |
| |
| for (unsigned i = 0; const Value *N = I->getOperand(i); i++) { |
| assert(i < NumArgs && "Count of arguments failed!"); |
| |
| int Slot = Table.getValSlot(N); |
| output_vbr((unsigned)Slot, Out); |
| } |
| align32(Out); // We must maintain correct alignment! |
| } |
| |
| |
| // outputInstructionFormat1 - Output one operand instructions, knowing that no |
| // operand index is >= 2^12. |
| // |
| static void outputInstructionFormat1(const Instruction *I, |
| const SlotCalculator &Table, int *Slots, |
| unsigned Type, vector<uchar> &Out) { |
| unsigned IType = I->getInstType(); // Instruction Opcode ID |
| |
| // bits Instruction format: |
| // -------------------------- |
| // 31-30: Opcode type, fixed to 1. |
| // 29-24: Opcode |
| // 23-12: Resulting type plane |
| // 11- 0: Operand #1 (if set to (2^12-1), then zero operands) |
| // |
| unsigned Opcode = (1 << 30) | (IType << 24) | (Type << 12) | Slots[0]; |
| // cerr << "1 " << IType << " " << Type << " " << Slots[0] << endl; |
| output(Opcode, Out); |
| } |
| |
| |
| // outputInstructionFormat2 - Output two operand instructions, knowing that no |
| // operand index is >= 2^8. |
| // |
| static void outputInstructionFormat2(const Instruction *I, |
| const SlotCalculator &Table, int *Slots, |
| unsigned Type, vector<uchar> &Out) { |
| unsigned IType = I->getInstType(); // Instruction Opcode ID |
| |
| // bits Instruction format: |
| // -------------------------- |
| // 31-30: Opcode type, fixed to 2. |
| // 29-24: Opcode |
| // 23-16: Resulting type plane |
| // 15- 8: Operand #1 |
| // 7- 0: Operand #2 |
| // |
| unsigned Opcode = (2 << 30) | (IType << 24) | (Type << 16) | |
| (Slots[0] << 8) | (Slots[1] << 0); |
| // cerr << "2 " << IType << " " << Type << " " << Slots[0] << " " |
| // << Slots[1] << endl; |
| output(Opcode, Out); |
| } |
| |
| |
| // outputInstructionFormat3 - Output three operand instructions, knowing that no |
| // operand index is >= 2^6. |
| // |
| static void outputInstructionFormat3(const Instruction *I, |
| const SlotCalculator &Table, int *Slots, |
| unsigned Type, vector<uchar> &Out) { |
| unsigned IType = I->getInstType(); // Instruction Opcode ID |
| |
| // bits Instruction format: |
| // -------------------------- |
| // 31-30: Opcode type, fixed to 3 |
| // 29-24: Opcode |
| // 23-18: Resulting type plane |
| // 17-12: Operand #1 |
| // 11- 6: Operand #2 |
| // 5- 0: Operand #3 |
| // |
| unsigned Opcode = (3 << 30) | (IType << 24) | (Type << 18) | |
| (Slots[0] << 12) | (Slots[1] << 6) | (Slots[2] << 0); |
| // cerr << "3 " << IType << " " << Type << " " << Slots[0] << " " |
| // << Slots[1] << " " << Slots[2] << endl; |
| output(Opcode, Out); |
| } |
| |
| bool BytecodeWriter::processInstruction(const Instruction *I) { |
| assert(I->getInstType() < 64 && "Opcode too big???"); |
| |
| unsigned NumOperands = 0; |
| int MaxOpSlot = 0; |
| int Slots[3]; Slots[0] = (1 << 12)-1; |
| |
| const Value *Def; |
| while ((Def = I->getOperand(NumOperands))) { |
| int slot = Table.getValSlot(Def); |
| assert(slot != -1 && "Broken bytecode!"); |
| if (slot > MaxOpSlot) MaxOpSlot = slot; |
| if (NumOperands < 3) Slots[NumOperands] = slot; |
| NumOperands++; |
| } |
| |
| // Figure out which type to encode with the instruction. Typically we want |
| // the type of the first parameter, as opposed to the type of the instruction |
| // (for example, with setcc, we always know it returns bool, but the type of |
| // the first param is actually interesting). But if we have no arguments |
| // we take the type of the instruction itself. |
| // |
| |
| const Type *Ty; |
| if (NumOperands) |
| Ty = I->getOperand(0)->getType(); |
| else |
| Ty = I->getType(); |
| |
| unsigned Type; |
| int Slot = Table.getValSlot(Ty); |
| assert(Slot != -1 && "Type not available!!?!"); |
| Type = (unsigned)Slot; |
| |
| |
| // Decide which instruction encoding to use. This is determined primarily by |
| // the number of operands, and secondarily by whether or not the max operand |
| // will fit into the instruction encoding. More operands == fewer bits per |
| // operand. |
| // |
| switch (NumOperands) { |
| case 0: |
| case 1: |
| if (MaxOpSlot < (1 << 12)-1) { // -1 because we use 4095 to indicate 0 ops |
| outputInstructionFormat1(I, Table, Slots, Type, Out); |
| return false; |
| } |
| break; |
| |
| case 2: |
| if (MaxOpSlot < (1 << 8)) { |
| outputInstructionFormat2(I, Table, Slots, Type, Out); |
| return false; |
| } |
| break; |
| |
| case 3: |
| if (MaxOpSlot < (1 << 6)) { |
| outputInstructionFormat3(I, Table, Slots, Type, Out); |
| return false; |
| } |
| break; |
| } |
| |
| outputInstructionFormat0(I, Table, Type, Out); |
| return false; |
| } |