Initial revision

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 184 insertions, 0 deletions

diff --git a/lib/Bytecode/Writer/InstructionWriter.cpp b/lib/Bytecode/Writer/InstructionWriter.cpp
new file mode 100644
index 0000000000..c7c04efb73
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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;
+}