Initial revision
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Bytecode/Writer/InstructionWriter.cpp b/lib/Bytecode/Writer/InstructionWriter.cpp
new file mode 100644
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+++ b/lib/Bytecode/Writer/InstructionWriter.cpp
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+//===-- 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;
+}