lib/VMCore/Instruction.cpp

   1 //===-- Instruction.cpp - Implement the Instruction class -----------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the Instruction class for the VMCore library.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Instruction.h"
  15 #include "llvm/Type.h"
  16 #include "llvm/Instructions.h"
  17 #include "llvm/Constants.h"
  18 #include "llvm/Module.h"
  19 #include "llvm/Support/CallSite.h"
  20 #include "llvm/Support/LeakDetector.h"
  21 using namespace llvm;
  22
  23 Instruction::Instruction(const Type *ty, unsigned it, Use *Ops, unsigned NumOps,
  24                          Instruction *InsertBefore)
  25   : User(ty, Value::InstructionVal + it, Ops, NumOps), Parent(0) {
  26   // Make sure that we get added to a basicblock
  27   LeakDetector::addGarbageObject(this);
  28
  29   // If requested, insert this instruction into a basic block...
  30   if (InsertBefore) {
  31     assert(InsertBefore->getParent() &&
  32            "Instruction to insert before is not in a basic block!");
  33     InsertBefore->getParent()->getInstList().insert(InsertBefore, this);
  34   }
  35 }
  36
  37 Instruction::Instruction(const Type *ty, unsigned it, Use *Ops, unsigned NumOps,
  38                          BasicBlock *InsertAtEnd)
  39   : User(ty, Value::InstructionVal + it, Ops, NumOps), Parent(0) {
  40   // Make sure that we get added to a basicblock
  41   LeakDetector::addGarbageObject(this);
  42
  43   // append this instruction into the basic block
  44   assert(InsertAtEnd && "Basic block to append to may not be NULL!");
  45   InsertAtEnd->getInstList().push_back(this);
  46 }
  47
  48
  49 // Out of line virtual method, so the vtable, etc has a home.
  50 Instruction::~Instruction() {
  51   assert(Parent == 0 && "Instruction still linked in the program!");
  52   if (hasMetadataHashEntry())
  53     clearMetadataHashEntries();
  54 }
  55
  56
  57 void Instruction::setParent(BasicBlock *P) {
  58   if (getParent()) {
  59     if (!P) LeakDetector::addGarbageObject(this);
  60   } else {
  61     if (P) LeakDetector::removeGarbageObject(this);
  62   }
  63
  64   Parent = P;
  65 }
  66
  67 void Instruction::removeFromParent() {
  68   getParent()->getInstList().remove(this);
  69 }
  70
  71 void Instruction::eraseFromParent() {
  72   getParent()->getInstList().erase(this);
  73 }
  74
  75 /// insertBefore - Insert an unlinked instructions into a basic block
  76 /// immediately before the specified instruction.
  77 void Instruction::insertBefore(Instruction *InsertPos) {
  78   InsertPos->getParent()->getInstList().insert(InsertPos, this);
  79 }
  80
  81 /// insertAfter - Insert an unlinked instructions into a basic block
  82 /// immediately after the specified instruction.
  83 void Instruction::insertAfter(Instruction *InsertPos) {
  84   InsertPos->getParent()->getInstList().insertAfter(InsertPos, this);
  85 }
  86
  87 /// moveBefore - Unlink this instruction from its current basic block and
  88 /// insert it into the basic block that MovePos lives in, right before
  89 /// MovePos.
  90 void Instruction::moveBefore(Instruction *MovePos) {
  91   MovePos->getParent()->getInstList().splice(MovePos,getParent()->getInstList(),
  92                                              this);
  93 }
  94
  95
  96 const char *Instruction::getOpcodeName(unsigned OpCode) {
  97   switch (OpCode) {
  98   // Terminators
  99   case Ret:    return "ret";
 100   case Br:     return "br";
 101   case Switch: return "switch";
 102   case IndirectBr: return "indirectbr";
 103   case Invoke: return "invoke";
 104   case Unwind: return "unwind";
 105   case Unreachable: return "unreachable";
 106
 107   // Standard binary operators...
 108   case Add: return "add";
 109   case FAdd: return "fadd";
 110   case Sub: return "sub";
 111   case FSub: return "fsub";
 112   case Mul: return "mul";
 113   case FMul: return "fmul";
 114   case UDiv: return "udiv";
 115   case SDiv: return "sdiv";
 116   case FDiv: return "fdiv";
 117   case URem: return "urem";
 118   case SRem: return "srem";
 119   case FRem: return "frem";
 120
 121   // Logical operators...
 122   case And: return "and";
 123   case Or : return "or";
 124   case Xor: return "xor";
 125
 126   // Memory instructions...
 127   case Alloca:        return "alloca";
 128   case Load:          return "load";
 129   case Store:         return "store";
 130   case GetElementPtr: return "getelementptr";
 131
 132   // Convert instructions...
 133   case Trunc:     return "trunc";
 134   case ZExt:      return "zext";
 135   case SExt:      return "sext";
 136   case FPTrunc:   return "fptrunc";
 137   case FPExt:     return "fpext";
 138   case FPToUI:    return "fptoui";
 139   case FPToSI:    return "fptosi";
 140   case UIToFP:    return "uitofp";
 141   case SIToFP:    return "sitofp";
 142   case IntToPtr:  return "inttoptr";
 143   case PtrToInt:  return "ptrtoint";
 144   case BitCast:   return "bitcast";
 145
 146   // Other instructions...
 147   case ICmp:           return "icmp";
 148   case FCmp:           return "fcmp";
 149   case PHI:            return "phi";
 150   case Select:         return "select";
 151   case Call:           return "call";
 152   case Shl:            return "shl";
 153   case LShr:           return "lshr";
 154   case AShr:           return "ashr";
 155   case VAArg:          return "va_arg";
 156   case ExtractElement: return "extractelement";
 157   case InsertElement:  return "insertelement";
 158   case ShuffleVector:  return "shufflevector";
 159   case ExtractValue:   return "extractvalue";
 160   case InsertValue:    return "insertvalue";
 161
 162   default: return "<Invalid operator> ";
 163   }
 164
 165   return 0;
 166 }
 167
 168 /// isIdenticalTo - Return true if the specified instruction is exactly
 169 /// identical to the current one.  This means that all operands match and any
 170 /// extra information (e.g. load is volatile) agree.
 171 bool Instruction::isIdenticalTo(const Instruction *I) const {
 172   return isIdenticalToWhenDefined(I) &&
 173          SubclassOptionalData == I->SubclassOptionalData;
 174 }
 175
 176 /// isIdenticalToWhenDefined - This is like isIdenticalTo, except that it
 177 /// ignores the SubclassOptionalData flags, which specify conditions
 178 /// under which the instruction's result is undefined.
 179 bool Instruction::isIdenticalToWhenDefined(const Instruction *I) const {
 180   if (getOpcode() != I->getOpcode() ||
 181       getNumOperands() != I->getNumOperands() ||
 182       getType() != I->getType())
 183     return false;
 184
 185   // We have two instructions of identical opcode and #operands.  Check to see
 186   // if all operands are the same.
 187   for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
 188     if (getOperand(i) != I->getOperand(i))
 189       return false;
 190
 191   // Check special state that is a part of some instructions.
 192   if (const LoadInst *LI = dyn_cast<LoadInst>(this))
 193     return LI->isVolatile() == cast<LoadInst>(I)->isVolatile() &&
 194            LI->getAlignment() == cast<LoadInst>(I)->getAlignment();
 195   if (const StoreInst *SI = dyn_cast<StoreInst>(this))
 196     return SI->isVolatile() == cast<StoreInst>(I)->isVolatile() &&
 197            SI->getAlignment() == cast<StoreInst>(I)->getAlignment();
 198   if (const CmpInst *CI = dyn_cast<CmpInst>(this))
 199     return CI->getPredicate() == cast<CmpInst>(I)->getPredicate();
 200   if (const CallInst *CI = dyn_cast<CallInst>(this))
 201     return CI->isTailCall() == cast<CallInst>(I)->isTailCall() &&
 202            CI->getCallingConv() == cast<CallInst>(I)->getCallingConv() &&
 203            CI->getAttributes() == cast<CallInst>(I)->getAttributes();
 204   if (const InvokeInst *CI = dyn_cast<InvokeInst>(this))
 205     return CI->getCallingConv() == cast<InvokeInst>(I)->getCallingConv() &&
 206            CI->getAttributes() == cast<InvokeInst>(I)->getAttributes();
 207   if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(this)) {
 208     if (IVI->getNumIndices() != cast<InsertValueInst>(I)->getNumIndices())
 209       return false;
 210     for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
 211       if (IVI->idx_begin()[i] != cast<InsertValueInst>(I)->idx_begin()[i])
 212         return false;
 213     return true;
 214   }
 215   if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(this)) {
 216     if (EVI->getNumIndices() != cast<ExtractValueInst>(I)->getNumIndices())
 217       return false;
 218     for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
 219       if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I)->idx_begin()[i])
 220         return false;
 221     return true;
 222   }
 223
 224   return true;
 225 }
 226
 227 // isSameOperationAs
 228 // This should be kept in sync with isEquivalentOperation in
 229 // lib/Transforms/IPO/MergeFunctions.cpp.
 230 bool Instruction::isSameOperationAs(const Instruction *I) const {
 231   if (getOpcode() != I->getOpcode() ||
 232       getNumOperands() != I->getNumOperands() ||
 233       getType() != I->getType())
 234     return false;
 235
 236   // We have two instructions of identical opcode and #operands.  Check to see
 237   // if all operands are the same type
 238   for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
 239     if (getOperand(i)->getType() != I->getOperand(i)->getType())
 240       return false;
 241
 242   // Check special state that is a part of some instructions.
 243   if (const LoadInst *LI = dyn_cast<LoadInst>(this))
 244     return LI->isVolatile() == cast<LoadInst>(I)->isVolatile() &&
 245            LI->getAlignment() == cast<LoadInst>(I)->getAlignment();
 246   if (const StoreInst *SI = dyn_cast<StoreInst>(this))
 247     return SI->isVolatile() == cast<StoreInst>(I)->isVolatile() &&
 248            SI->getAlignment() == cast<StoreInst>(I)->getAlignment();
 249   if (const CmpInst *CI = dyn_cast<CmpInst>(this))
 250     return CI->getPredicate() == cast<CmpInst>(I)->getPredicate();
 251   if (const CallInst *CI = dyn_cast<CallInst>(this))
 252     return CI->isTailCall() == cast<CallInst>(I)->isTailCall() &&
 253            CI->getCallingConv() == cast<CallInst>(I)->getCallingConv() &&
 254            CI->getAttributes() == cast<CallInst>(I)->getAttributes();
 255   if (const InvokeInst *CI = dyn_cast<InvokeInst>(this))
 256     return CI->getCallingConv() == cast<InvokeInst>(I)->getCallingConv() &&
 257            CI->getAttributes() ==
 258              cast<InvokeInst>(I)->getAttributes();
 259   if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(this)) {
 260     if (IVI->getNumIndices() != cast<InsertValueInst>(I)->getNumIndices())
 261       return false;
 262     for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
 263       if (IVI->idx_begin()[i] != cast<InsertValueInst>(I)->idx_begin()[i])
 264         return false;
 265     return true;
 266   }
 267   if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(this)) {
 268     if (EVI->getNumIndices() != cast<ExtractValueInst>(I)->getNumIndices())
 269       return false;
 270     for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
 271       if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I)->idx_begin()[i])
 272         return false;
 273     return true;
 274   }
 275
 276   return true;
 277 }
 278
 279 /// isUsedOutsideOfBlock - Return true if there are any uses of I outside of the
 280 /// specified block.  Note that PHI nodes are considered to evaluate their
 281 /// operands in the corresponding predecessor block.
 282 bool Instruction::isUsedOutsideOfBlock(const BasicBlock *BB) const {
 283   for (const_use_iterator UI = use_begin(), E = use_end(); UI != E; ++UI) {
 284     // PHI nodes uses values in the corresponding predecessor block.  For other
 285     // instructions, just check to see whether the parent of the use matches up.
 286     const User *U = *UI;
 287     const PHINode *PN = dyn_cast<PHINode>(U);
 288     if (PN == 0) {
 289       if (cast<Instruction>(U)->getParent() != BB)
 290         return true;
 291       continue;
 292     }
 293
 294     if (PN->getIncomingBlock(UI) != BB)
 295       return true;
 296   }
 297   return false;
 298 }
 299
 300 /// mayReadFromMemory - Return true if this instruction may read memory.
 301 ///
 302 bool Instruction::mayReadFromMemory() const {
 303   switch (getOpcode()) {
 304   default: return false;
 305   case Instruction::VAArg:
 306   case Instruction::Load:
 307     return true;
 308   case Instruction::Call:
 309     return !cast<CallInst>(this)->doesNotAccessMemory();
 310   case Instruction::Invoke:
 311     return !cast<InvokeInst>(this)->doesNotAccessMemory();
 312   case Instruction::Store:
 313     return cast<StoreInst>(this)->isVolatile();
 314   }
 315 }
 316
 317 /// mayWriteToMemory - Return true if this instruction may modify memory.
 318 ///
 319 bool Instruction::mayWriteToMemory() const {
 320   switch (getOpcode()) {
 321   default: return false;
 322   case Instruction::Store:
 323   case Instruction::VAArg:
 324     return true;
 325   case Instruction::Call:
 326     return !cast<CallInst>(this)->onlyReadsMemory();
 327   case Instruction::Invoke:
 328     return !cast<InvokeInst>(this)->onlyReadsMemory();
 329   case Instruction::Load:
 330     return cast<LoadInst>(this)->isVolatile();
 331   }
 332 }
 333
 334 /// mayThrow - Return true if this instruction may throw an exception.
 335 ///
 336 bool Instruction::mayThrow() const {
 337   if (const CallInst *CI = dyn_cast<CallInst>(this))
 338     return !CI->doesNotThrow();
 339   return false;
 340 }
 341
 342 /// isAssociative - Return true if the instruction is associative:
 343 ///
 344 ///   Associative operators satisfy:  x op (y op z) === (x op y) op z
 345 ///
 346 /// In LLVM, the Add, Mul, And, Or, and Xor operators are associative.
 347 ///
 348 bool Instruction::isAssociative(unsigned Opcode) {
 349   return Opcode == And || Opcode == Or || Opcode == Xor ||
 350          Opcode == Add || Opcode == Mul;
 351 }
 352
 353 /// isCommutative - Return true if the instruction is commutative:
 354 ///
 355 ///   Commutative operators satisfy: (x op y) === (y op x)
 356 ///
 357 /// In LLVM, these are the associative operators, plus SetEQ and SetNE, when
 358 /// applied to any type.
 359 ///
 360 bool Instruction::isCommutative(unsigned op) {
 361   switch (op) {
 362   case Add:
 363   case FAdd:
 364   case Mul:
 365   case FMul:
 366   case And:
 367   case Or:
 368   case Xor:
 369     return true;
 370   default:
 371     return false;
 372   }
 373 }
 374
 375 bool Instruction::isSafeToSpeculativelyExecute() const {
 376   for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
 377     if (Constant *C = dyn_cast<Constant>(getOperand(i)))
 378       if (C->canTrap())
 379         return false;
 380
 381   switch (getOpcode()) {
 382   default:
 383     return true;
 384   case UDiv:
 385   case URem: {
 386     // x / y is undefined if y == 0, but calcuations like x / 3 are safe.
 387     ConstantInt *Op = dyn_cast<ConstantInt>(getOperand(1));
 388     return Op && !Op->isNullValue();
 389   }
 390   case SDiv:
 391   case SRem: {
 392     // x / y is undefined if y == 0, and might be undefined if y == -1,
 393     // but calcuations like x / 3 are safe.
 394     ConstantInt *Op = dyn_cast<ConstantInt>(getOperand(1));
 395     return Op && !Op->isNullValue() && !Op->isAllOnesValue();
 396   }
 397   case Load: {
 398     const LoadInst *LI = cast<LoadInst>(this);
 399     if (LI->isVolatile())
 400       return false;
 401     return LI->getPointerOperand()->isDereferenceablePointer();
 402   }
 403   case Call:
 404     return false; // The called function could have undefined behavior or
 405                   // side-effects.
 406                   // FIXME: We should special-case some intrinsics (bswap,
 407                   // overflow-checking arithmetic, etc.)
 408   case VAArg:
 409   case Alloca:
 410   case Invoke:
 411   case PHI:
 412   case Store:
 413   case Ret:
 414   case Br:
 415   case IndirectBr:
 416   case Switch:
 417   case Unwind:
 418   case Unreachable:
 419     return false; // Misc instructions which have effects
 420   }
 421 }
 422
 423 Instruction *Instruction::clone() const {
 424   Instruction *New = clone_impl();
 425   New->SubclassOptionalData = SubclassOptionalData;
 426   if (!hasMetadata())
 427     return New;
 428
 429   // Otherwise, enumerate and copy over metadata from the old instruction to the
 430   // new one.
 431   SmallVector<std::pair<unsigned, MDNode*>, 4> TheMDs;
 432   getAllMetadata(TheMDs);
 433   for (unsigned i = 0, e = TheMDs.size(); i != e; ++i)
 434     New->setMetadata(TheMDs[i].first, TheMDs[i].second);
 435   return New;
 436 }