1 //===-- InstructionWriter.cpp - Functions for writing instructions --------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the routines for encoding instruction opcodes to a
13 //===----------------------------------------------------------------------===//
15 #include "WriterInternals.h"
16 #include "llvm/Module.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/Instructions.h"
19 #include "Support/Statistic.h"
23 typedef unsigned char uchar;
25 // outputInstructionFormat0 - Output those wierd instructions that have a large
26 // number of operands or have large operands themselves...
28 // Format: [opcode] [type] [numargs] [arg0] [arg1] ... [arg<numargs-1>]
30 static void outputInstructionFormat0(const Instruction *I, unsigned Opcode,
31 const SlotCalculator &Table,
32 unsigned Type, std::deque<uchar> &Out) {
33 // Opcode must have top two bits clear...
34 output_vbr(Opcode << 2, Out); // Instruction Opcode ID
35 output_vbr(Type, Out); // Result type
37 unsigned NumArgs = I->getNumOperands();
38 output_vbr(NumArgs + (isa<CastInst>(I) || isa<VANextInst>(I) ||
39 isa<VAArgInst>(I)), Out);
41 for (unsigned i = 0; i < NumArgs; ++i) {
42 int Slot = Table.getSlot(I->getOperand(i));
43 assert(Slot >= 0 && "No slot number for value!?!?");
44 output_vbr((unsigned)Slot, Out);
47 if (isa<CastInst>(I) || isa<VAArgInst>(I)) {
48 int Slot = Table.getSlot(I->getType());
49 assert(Slot != -1 && "Cast return type unknown?");
50 output_vbr((unsigned)Slot, Out);
51 } else if (const VANextInst *VAI = dyn_cast<VANextInst>(I)) {
52 int Slot = Table.getSlot(VAI->getArgType());
53 assert(Slot != -1 && "VarArg argument type unknown?");
54 output_vbr((unsigned)Slot, Out);
57 align32(Out); // We must maintain correct alignment!
61 // outputInstrVarArgsCall - Output the absurdly annoying varargs function calls.
62 // This are more annoying than most because the signature of the call does not
63 // tell us anything about the types of the arguments in the varargs portion.
64 // Because of this, we encode (as type 0) all of the argument types explicitly
65 // before the argument value. This really sucks, but you shouldn't be using
66 // varargs functions in your code! *death to printf*!
68 // Format: [opcode] [type] [numargs] [arg0] [arg1] ... [arg<numargs-1>]
70 static void outputInstrVarArgsCall(const Instruction *I, unsigned Opcode,
71 const SlotCalculator &Table, unsigned Type,
72 std::deque<uchar> &Out) {
73 assert(isa<CallInst>(I) || isa<InvokeInst>(I));
74 // Opcode must have top two bits clear...
75 output_vbr(Opcode << 2, Out); // Instruction Opcode ID
76 output_vbr(Type, Out); // Result type (varargs type)
78 const PointerType *PTy = cast<PointerType>(I->getOperand(0)->getType());
79 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
80 unsigned NumParams = FTy->getNumParams();
82 unsigned NumFixedOperands;
83 if (isa<CallInst>(I)) {
84 // Output an operand for the callee and each fixed argument, then two for
85 // each variable argument.
86 NumFixedOperands = 1+NumParams;
88 assert(isa<InvokeInst>(I) && "Not call or invoke??");
89 // Output an operand for the callee and destinations, then two for each
91 NumFixedOperands = 3+NumParams;
93 output_vbr(2 * I->getNumOperands()-NumFixedOperands, Out);
95 // The type for the function has already been emitted in the type field of the
96 // instruction. Just emit the slot # now.
97 for (unsigned i = 0; i != NumFixedOperands; ++i) {
98 int Slot = Table.getSlot(I->getOperand(i));
99 assert(Slot >= 0 && "No slot number for value!?!?");
100 output_vbr((unsigned)Slot, Out);
103 for (unsigned i = NumFixedOperands, e = I->getNumOperands(); i != e; ++i) {
104 // Output Arg Type ID
105 int Slot = Table.getSlot(I->getOperand(i)->getType());
106 assert(Slot >= 0 && "No slot number for value!?!?");
107 output_vbr((unsigned)Slot, Out);
109 // Output arg ID itself
110 Slot = Table.getSlot(I->getOperand(i));
111 assert(Slot >= 0 && "No slot number for value!?!?");
112 output_vbr((unsigned)Slot, Out);
114 align32(Out); // We must maintain correct alignment!
118 // outputInstructionFormat1 - Output one operand instructions, knowing that no
119 // operand index is >= 2^12.
121 static void outputInstructionFormat1(const Instruction *I, unsigned Opcode,
122 const SlotCalculator &Table, int *Slots,
123 unsigned Type, std::deque<uchar> &Out) {
124 // bits Instruction format:
125 // --------------------------
126 // 01-00: Opcode type, fixed to 1.
128 // 19-08: Resulting type plane
129 // 31-20: Operand #1 (if set to (2^12-1), then zero operands)
131 unsigned Bits = 1 | (Opcode << 2) | (Type << 8) | (Slots[0] << 20);
132 // cerr << "1 " << IType << " " << Type << " " << Slots[0] << endl;
137 // outputInstructionFormat2 - Output two operand instructions, knowing that no
138 // operand index is >= 2^8.
140 static void outputInstructionFormat2(const Instruction *I, unsigned Opcode,
141 const SlotCalculator &Table, int *Slots,
142 unsigned Type, std::deque<uchar> &Out) {
143 // bits Instruction format:
144 // --------------------------
145 // 01-00: Opcode type, fixed to 2.
147 // 15-08: Resulting type plane
151 unsigned Bits = 2 | (Opcode << 2) | (Type << 8) |
152 (Slots[0] << 16) | (Slots[1] << 24);
153 // cerr << "2 " << IType << " " << Type << " " << Slots[0] << " "
154 // << Slots[1] << endl;
159 // outputInstructionFormat3 - Output three operand instructions, knowing that no
160 // operand index is >= 2^6.
162 static void outputInstructionFormat3(const Instruction *I, unsigned Opcode,
163 const SlotCalculator &Table, int *Slots,
164 unsigned Type, std::deque<uchar> &Out) {
165 // bits Instruction format:
166 // --------------------------
167 // 01-00: Opcode type, fixed to 3.
169 // 13-08: Resulting type plane
174 unsigned Bits = 3 | (Opcode << 2) | (Type << 8) |
175 (Slots[0] << 14) | (Slots[1] << 20) | (Slots[2] << 26);
176 //cerr << "3 " << IType << " " << Type << " " << Slots[0] << " "
177 // << Slots[1] << " " << Slots[2] << endl;
181 void BytecodeWriter::outputInstruction(const Instruction &I) {
182 assert(I.getOpcode() < 62 && "Opcode too big???");
183 unsigned Opcode = I.getOpcode();
185 // Encode 'volatile load' as 62 and 'volatile store' as 63.
186 if (isa<LoadInst>(I) && cast<LoadInst>(I).isVolatile())
188 if (isa<StoreInst>(I) && cast<StoreInst>(I).isVolatile())
191 unsigned NumOperands = I.getNumOperands();
193 int Slots[3]; Slots[0] = (1 << 12)-1; // Marker to signify 0 operands
195 for (unsigned i = 0; i != NumOperands; ++i) {
196 int slot = Table.getSlot(I.getOperand(i));
197 assert(slot != -1 && "Broken bytecode!");
198 if (slot > MaxOpSlot) MaxOpSlot = slot;
199 if (i < 3) Slots[i] = slot;
202 // Figure out which type to encode with the instruction. Typically we want
203 // the type of the first parameter, as opposed to the type of the instruction
204 // (for example, with setcc, we always know it returns bool, but the type of
205 // the first param is actually interesting). But if we have no arguments
206 // we take the type of the instruction itself.
209 switch (I.getOpcode()) {
210 case Instruction::Malloc:
211 case Instruction::Alloca:
212 Ty = I.getType(); // Malloc & Alloca ALWAYS want to encode the return type
214 case Instruction::Store:
215 Ty = I.getOperand(1)->getType(); // Encode the pointer type...
216 assert(isa<PointerType>(Ty) && "Store to nonpointer type!?!?");
218 default: // Otherwise use the default behavior...
219 Ty = NumOperands ? I.getOperand(0)->getType() : I.getType();
224 int Slot = Table.getSlot(Ty);
225 assert(Slot != -1 && "Type not available!!?!");
226 Type = (unsigned)Slot;
228 // Make sure that we take the type number into consideration. We don't want
229 // to overflow the field size for the instruction format we select.
231 if (Slot > MaxOpSlot) MaxOpSlot = Slot;
233 // Handle the special case for cast...
234 if (isa<CastInst>(I) || isa<VAArgInst>(I)) {
235 // Cast has to encode the destination type as the second argument in the
236 // packet, or else we won't know what type to cast to!
237 Slots[1] = Table.getSlot(I.getType());
238 assert(Slots[1] != -1 && "Cast return type unknown?");
239 if (Slots[1] > MaxOpSlot) MaxOpSlot = Slots[1];
241 } else if (const VANextInst *VANI = dyn_cast<VANextInst>(&I)) {
242 Slots[1] = Table.getSlot(VANI->getArgType());
243 assert(Slots[1] != -1 && "va_next return type unknown?");
244 if (Slots[1] > MaxOpSlot) MaxOpSlot = Slots[1];
246 } else if (const CallInst *CI = dyn_cast<CallInst>(&I)){// Handle VarArg calls
247 const PointerType *Ty = cast<PointerType>(CI->getCalledValue()->getType());
248 if (cast<FunctionType>(Ty->getElementType())->isVarArg()) {
249 outputInstrVarArgsCall(CI, Opcode, Table, Type, Out);
252 } else if (const InvokeInst *II = dyn_cast<InvokeInst>(&I)) {// ... & Invokes
253 const PointerType *Ty = cast<PointerType>(II->getCalledValue()->getType());
254 if (cast<FunctionType>(Ty->getElementType())->isVarArg()) {
255 outputInstrVarArgsCall(II, Opcode, Table, Type, Out);
260 // Decide which instruction encoding to use. This is determined primarily by
261 // the number of operands, and secondarily by whether or not the max operand
262 // will fit into the instruction encoding. More operands == fewer bits per
265 switch (NumOperands) {
268 if (MaxOpSlot < (1 << 12)-1) { // -1 because we use 4095 to indicate 0 ops
269 outputInstructionFormat1(&I, Opcode, Table, Slots, Type, Out);
275 if (MaxOpSlot < (1 << 8)) {
276 outputInstructionFormat2(&I, Opcode, Table, Slots, Type, Out);
282 if (MaxOpSlot < (1 << 6)) {
283 outputInstructionFormat3(&I, Opcode, Table, Slots, Type, Out);
291 // If we weren't handled before here, we either have a large number of
292 // operands or a large operand index that we are referring to.
293 outputInstructionFormat0(&I, Opcode, Table, Type, Out);