llvm-6502/lib/VMCore/Instruction.cpp
Dan Gohman 4d70a29490 Factor out Instruction::isSafeToSpeculativelyExecute's code for
testing for dereferenceable pointers into a helper function,
isDereferenceablePointer.  Teach it how to reason about GEPs
with simple non-zero indices.

Also eliminate ArgumentPromtion's IsAlwaysValidPointer,
which didn't check for weak externals or out of range gep
indices.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118840 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-11 21:23:25 +00:00

440 lines
15 KiB
C++

//===-- Instruction.cpp - Implement the Instruction class -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Instruction class for the VMCore library.
//
//===----------------------------------------------------------------------===//
#include "llvm/Instruction.h"
#include "llvm/Type.h"
#include "llvm/Instructions.h"
#include "llvm/Constants.h"
#include "llvm/Module.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/LeakDetector.h"
using namespace llvm;
Instruction::Instruction(const Type *ty, unsigned it, Use *Ops, unsigned NumOps,
Instruction *InsertBefore)
: User(ty, Value::InstructionVal + it, Ops, NumOps), Parent(0) {
// Make sure that we get added to a basicblock
LeakDetector::addGarbageObject(this);
// If requested, insert this instruction into a basic block...
if (InsertBefore) {
assert(InsertBefore->getParent() &&
"Instruction to insert before is not in a basic block!");
InsertBefore->getParent()->getInstList().insert(InsertBefore, this);
}
}
Instruction::Instruction(const Type *ty, unsigned it, Use *Ops, unsigned NumOps,
BasicBlock *InsertAtEnd)
: User(ty, Value::InstructionVal + it, Ops, NumOps), Parent(0) {
// Make sure that we get added to a basicblock
LeakDetector::addGarbageObject(this);
// append this instruction into the basic block
assert(InsertAtEnd && "Basic block to append to may not be NULL!");
InsertAtEnd->getInstList().push_back(this);
}
// Out of line virtual method, so the vtable, etc has a home.
Instruction::~Instruction() {
assert(Parent == 0 && "Instruction still linked in the program!");
if (hasMetadataHashEntry())
clearMetadataHashEntries();
}
void Instruction::setParent(BasicBlock *P) {
if (getParent()) {
if (!P) LeakDetector::addGarbageObject(this);
} else {
if (P) LeakDetector::removeGarbageObject(this);
}
Parent = P;
}
void Instruction::removeFromParent() {
getParent()->getInstList().remove(this);
}
void Instruction::eraseFromParent() {
getParent()->getInstList().erase(this);
}
/// insertBefore - Insert an unlinked instructions into a basic block
/// immediately before the specified instruction.
void Instruction::insertBefore(Instruction *InsertPos) {
InsertPos->getParent()->getInstList().insert(InsertPos, this);
}
/// insertAfter - Insert an unlinked instructions into a basic block
/// immediately after the specified instruction.
void Instruction::insertAfter(Instruction *InsertPos) {
InsertPos->getParent()->getInstList().insertAfter(InsertPos, this);
}
/// moveBefore - Unlink this instruction from its current basic block and
/// insert it into the basic block that MovePos lives in, right before
/// MovePos.
void Instruction::moveBefore(Instruction *MovePos) {
MovePos->getParent()->getInstList().splice(MovePos,getParent()->getInstList(),
this);
}
const char *Instruction::getOpcodeName(unsigned OpCode) {
switch (OpCode) {
// Terminators
case Ret: return "ret";
case Br: return "br";
case Switch: return "switch";
case IndirectBr: return "indirectbr";
case Invoke: return "invoke";
case Unwind: return "unwind";
case Unreachable: return "unreachable";
// Standard binary operators...
case Add: return "add";
case FAdd: return "fadd";
case Sub: return "sub";
case FSub: return "fsub";
case Mul: return "mul";
case FMul: return "fmul";
case UDiv: return "udiv";
case SDiv: return "sdiv";
case FDiv: return "fdiv";
case URem: return "urem";
case SRem: return "srem";
case FRem: return "frem";
// Logical operators...
case And: return "and";
case Or : return "or";
case Xor: return "xor";
// Memory instructions...
case Alloca: return "alloca";
case Load: return "load";
case Store: return "store";
case GetElementPtr: return "getelementptr";
// Convert instructions...
case Trunc: return "trunc";
case ZExt: return "zext";
case SExt: return "sext";
case FPTrunc: return "fptrunc";
case FPExt: return "fpext";
case FPToUI: return "fptoui";
case FPToSI: return "fptosi";
case UIToFP: return "uitofp";
case SIToFP: return "sitofp";
case IntToPtr: return "inttoptr";
case PtrToInt: return "ptrtoint";
case BitCast: return "bitcast";
// Other instructions...
case ICmp: return "icmp";
case FCmp: return "fcmp";
case PHI: return "phi";
case Select: return "select";
case Call: return "call";
case Shl: return "shl";
case LShr: return "lshr";
case AShr: return "ashr";
case VAArg: return "va_arg";
case ExtractElement: return "extractelement";
case InsertElement: return "insertelement";
case ShuffleVector: return "shufflevector";
case ExtractValue: return "extractvalue";
case InsertValue: return "insertvalue";
default: return "<Invalid operator> ";
}
return 0;
}
/// isIdenticalTo - Return true if the specified instruction is exactly
/// identical to the current one. This means that all operands match and any
/// extra information (e.g. load is volatile) agree.
bool Instruction::isIdenticalTo(const Instruction *I) const {
return isIdenticalToWhenDefined(I) &&
SubclassOptionalData == I->SubclassOptionalData;
}
/// isIdenticalToWhenDefined - This is like isIdenticalTo, except that it
/// ignores the SubclassOptionalData flags, which specify conditions
/// under which the instruction's result is undefined.
bool Instruction::isIdenticalToWhenDefined(const Instruction *I) const {
if (getOpcode() != I->getOpcode() ||
getNumOperands() != I->getNumOperands() ||
getType() != I->getType())
return false;
// We have two instructions of identical opcode and #operands. Check to see
// if all operands are the same.
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (getOperand(i) != I->getOperand(i))
return false;
// Check special state that is a part of some instructions.
if (const LoadInst *LI = dyn_cast<LoadInst>(this))
return LI->isVolatile() == cast<LoadInst>(I)->isVolatile() &&
LI->getAlignment() == cast<LoadInst>(I)->getAlignment();
if (const StoreInst *SI = dyn_cast<StoreInst>(this))
return SI->isVolatile() == cast<StoreInst>(I)->isVolatile() &&
SI->getAlignment() == cast<StoreInst>(I)->getAlignment();
if (const CmpInst *CI = dyn_cast<CmpInst>(this))
return CI->getPredicate() == cast<CmpInst>(I)->getPredicate();
if (const CallInst *CI = dyn_cast<CallInst>(this))
return CI->isTailCall() == cast<CallInst>(I)->isTailCall() &&
CI->getCallingConv() == cast<CallInst>(I)->getCallingConv() &&
CI->getAttributes().getRawPointer() ==
cast<CallInst>(I)->getAttributes().getRawPointer();
if (const InvokeInst *CI = dyn_cast<InvokeInst>(this))
return CI->getCallingConv() == cast<InvokeInst>(I)->getCallingConv() &&
CI->getAttributes().getRawPointer() ==
cast<InvokeInst>(I)->getAttributes().getRawPointer();
if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(this)) {
if (IVI->getNumIndices() != cast<InsertValueInst>(I)->getNumIndices())
return false;
for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
if (IVI->idx_begin()[i] != cast<InsertValueInst>(I)->idx_begin()[i])
return false;
return true;
}
if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(this)) {
if (EVI->getNumIndices() != cast<ExtractValueInst>(I)->getNumIndices())
return false;
for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I)->idx_begin()[i])
return false;
return true;
}
return true;
}
// isSameOperationAs
// This should be kept in sync with isEquivalentOperation in
// lib/Transforms/IPO/MergeFunctions.cpp.
bool Instruction::isSameOperationAs(const Instruction *I) const {
if (getOpcode() != I->getOpcode() ||
getNumOperands() != I->getNumOperands() ||
getType() != I->getType())
return false;
// We have two instructions of identical opcode and #operands. Check to see
// if all operands are the same type
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (getOperand(i)->getType() != I->getOperand(i)->getType())
return false;
// Check special state that is a part of some instructions.
if (const LoadInst *LI = dyn_cast<LoadInst>(this))
return LI->isVolatile() == cast<LoadInst>(I)->isVolatile() &&
LI->getAlignment() == cast<LoadInst>(I)->getAlignment();
if (const StoreInst *SI = dyn_cast<StoreInst>(this))
return SI->isVolatile() == cast<StoreInst>(I)->isVolatile() &&
SI->getAlignment() == cast<StoreInst>(I)->getAlignment();
if (const CmpInst *CI = dyn_cast<CmpInst>(this))
return CI->getPredicate() == cast<CmpInst>(I)->getPredicate();
if (const CallInst *CI = dyn_cast<CallInst>(this))
return CI->isTailCall() == cast<CallInst>(I)->isTailCall() &&
CI->getCallingConv() == cast<CallInst>(I)->getCallingConv() &&
CI->getAttributes().getRawPointer() ==
cast<CallInst>(I)->getAttributes().getRawPointer();
if (const InvokeInst *CI = dyn_cast<InvokeInst>(this))
return CI->getCallingConv() == cast<InvokeInst>(I)->getCallingConv() &&
CI->getAttributes().getRawPointer() ==
cast<InvokeInst>(I)->getAttributes().getRawPointer();
if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(this)) {
if (IVI->getNumIndices() != cast<InsertValueInst>(I)->getNumIndices())
return false;
for (unsigned i = 0, e = IVI->getNumIndices(); i != e; ++i)
if (IVI->idx_begin()[i] != cast<InsertValueInst>(I)->idx_begin()[i])
return false;
return true;
}
if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(this)) {
if (EVI->getNumIndices() != cast<ExtractValueInst>(I)->getNumIndices())
return false;
for (unsigned i = 0, e = EVI->getNumIndices(); i != e; ++i)
if (EVI->idx_begin()[i] != cast<ExtractValueInst>(I)->idx_begin()[i])
return false;
return true;
}
return true;
}
/// isUsedOutsideOfBlock - Return true if there are any uses of I outside of the
/// specified block. Note that PHI nodes are considered to evaluate their
/// operands in the corresponding predecessor block.
bool Instruction::isUsedOutsideOfBlock(const BasicBlock *BB) const {
for (const_use_iterator UI = use_begin(), E = use_end(); UI != E; ++UI) {
// PHI nodes uses values in the corresponding predecessor block. For other
// instructions, just check to see whether the parent of the use matches up.
const User *U = *UI;
const PHINode *PN = dyn_cast<PHINode>(U);
if (PN == 0) {
if (cast<Instruction>(U)->getParent() != BB)
return true;
continue;
}
if (PN->getIncomingBlock(UI) != BB)
return true;
}
return false;
}
/// mayReadFromMemory - Return true if this instruction may read memory.
///
bool Instruction::mayReadFromMemory() const {
switch (getOpcode()) {
default: return false;
case Instruction::VAArg:
case Instruction::Load:
return true;
case Instruction::Call:
return !cast<CallInst>(this)->doesNotAccessMemory();
case Instruction::Invoke:
return !cast<InvokeInst>(this)->doesNotAccessMemory();
case Instruction::Store:
return cast<StoreInst>(this)->isVolatile();
}
}
/// mayWriteToMemory - Return true if this instruction may modify memory.
///
bool Instruction::mayWriteToMemory() const {
switch (getOpcode()) {
default: return false;
case Instruction::Store:
case Instruction::VAArg:
return true;
case Instruction::Call:
return !cast<CallInst>(this)->onlyReadsMemory();
case Instruction::Invoke:
return !cast<InvokeInst>(this)->onlyReadsMemory();
case Instruction::Load:
return cast<LoadInst>(this)->isVolatile();
}
}
/// mayThrow - Return true if this instruction may throw an exception.
///
bool Instruction::mayThrow() const {
if (const CallInst *CI = dyn_cast<CallInst>(this))
return !CI->doesNotThrow();
return false;
}
/// isAssociative - Return true if the instruction is associative:
///
/// Associative operators satisfy: x op (y op z) === (x op y) op z
///
/// In LLVM, the Add, Mul, And, Or, and Xor operators are associative.
///
bool Instruction::isAssociative(unsigned Opcode, const Type *Ty) {
return Opcode == And || Opcode == Or || Opcode == Xor ||
Opcode == Add || Opcode == Mul;
}
/// isCommutative - Return true if the instruction is commutative:
///
/// Commutative operators satisfy: (x op y) === (y op x)
///
/// In LLVM, these are the associative operators, plus SetEQ and SetNE, when
/// applied to any type.
///
bool Instruction::isCommutative(unsigned op) {
switch (op) {
case Add:
case FAdd:
case Mul:
case FMul:
case And:
case Or:
case Xor:
return true;
default:
return false;
}
}
bool Instruction::isSafeToSpeculativelyExecute() const {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (Constant *C = dyn_cast<Constant>(getOperand(i)))
if (C->canTrap())
return false;
switch (getOpcode()) {
default:
return true;
case UDiv:
case URem: {
// x / y is undefined if y == 0, but calcuations like x / 3 are safe.
ConstantInt *Op = dyn_cast<ConstantInt>(getOperand(1));
return Op && !Op->isNullValue();
}
case SDiv:
case SRem: {
// x / y is undefined if y == 0, and might be undefined if y == -1,
// but calcuations like x / 3 are safe.
ConstantInt *Op = dyn_cast<ConstantInt>(getOperand(1));
return Op && !Op->isNullValue() && !Op->isAllOnesValue();
}
case Load: {
const LoadInst *LI = cast<LoadInst>(this);
if (LI->isVolatile())
return false;
return LI->getPointerOperand()->isDereferenceablePointer();
}
case Call:
return false; // The called function could have undefined behavior or
// side-effects.
// FIXME: We should special-case some intrinsics (bswap,
// overflow-checking arithmetic, etc.)
case VAArg:
case Alloca:
case Invoke:
case PHI:
case Store:
case Ret:
case Br:
case IndirectBr:
case Switch:
case Unwind:
case Unreachable:
return false; // Misc instructions which have effects
}
}
Instruction *Instruction::clone() const {
Instruction *New = clone_impl();
New->SubclassOptionalData = SubclassOptionalData;
if (!hasMetadata())
return New;
// Otherwise, enumerate and copy over metadata from the old instruction to the
// new one.
SmallVector<std::pair<unsigned, MDNode*>, 4> TheMDs;
getAllMetadata(TheMDs);
for (unsigned i = 0, e = TheMDs.size(); i != e; ++i)
New->setMetadata(TheMDs[i].first, TheMDs[i].second);
return New;
}