llvm-6502/lib/VMCore/Value.cpp
Gabor Greif ae5a20a917 Rearrange operands of the BranchInst, to be able to
access each with a fixed negative index from op_end().

This has two important implications:
- getUser() will work faster, because there are less iterations
  for the waymarking algorithm to perform. This is important
  when running various analyses that want to determine callers
  of basic blocks.
- getSuccessor() now runs faster, because the indirection via OperandList
  is not necessary: Uses corresponding to the successors are at fixed
  offset to "this".

The price we pay is the slightly more complicated logic in the operator
User::delete, as it has to pick up the information whether it has to free
the memory of an original unconditional BranchInst or a BranchInst that
was originally conditional, but has been shortened to unconditional.
I was not able to come up with a nicer solution to this problem. (And
rest assured, I tried *a lot*).

Similar reorderings will follow for InvokeInst and CallInst. After that
some optimizations to pred_iterator and CallSite will fall out naturally.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66815 91177308-0d34-0410-b5e6-96231b3b80d8
2009-03-12 18:34:49 +00:00

409 lines
13 KiB
C++

//===-- Value.cpp - Implement the Value 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 Value and User classes.
//
//===----------------------------------------------------------------------===//
#include "llvm/Constant.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/InstrTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/ValueSymbolTable.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/LeakDetector.h"
#include <algorithm>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Value Class
//===----------------------------------------------------------------------===//
static inline const Type *checkType(const Type *Ty) {
assert(Ty && "Value defined with a null type: Error!");
return Ty;
}
Value::Value(const Type *ty, unsigned scid)
: SubclassID(scid), SubclassData(0), VTy(checkType(ty)),
UseList(0), Name(0) {
if (isa<CallInst>(this) || isa<InvokeInst>(this))
assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
isa<OpaqueType>(ty) || VTy->getTypeID() == Type::StructTyID) &&
"invalid CallInst type!");
else if (!isa<Constant>(this) && !isa<BasicBlock>(this))
assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
isa<OpaqueType>(ty)) &&
"Cannot create non-first-class values except for constants!");
}
Value::~Value() {
#ifndef NDEBUG // Only in -g mode...
// Check to make sure that there are no uses of this value that are still
// around when the value is destroyed. If there are, then we have a dangling
// reference and something is wrong. This code is here to print out what is
// still being referenced. The value in question should be printed as
// a <badref>
//
if (!use_empty()) {
cerr << "While deleting: " << *VTy << " %" << getNameStr() << "\n";
for (use_iterator I = use_begin(), E = use_end(); I != E; ++I)
cerr << "Use still stuck around after Def is destroyed:"
<< **I << "\n";
}
#endif
assert(use_empty() && "Uses remain when a value is destroyed!");
// If this value is named, destroy the name. This should not be in a symtab
// at this point.
if (Name)
Name->Destroy();
// There should be no uses of this object anymore, remove it.
LeakDetector::removeGarbageObject(this);
}
/// hasNUses - Return true if this Value has exactly N users.
///
bool Value::hasNUses(unsigned N) const {
use_const_iterator UI = use_begin(), E = use_end();
for (; N; --N, ++UI)
if (UI == E) return false; // Too few.
return UI == E;
}
/// hasNUsesOrMore - Return true if this value has N users or more. This is
/// logically equivalent to getNumUses() >= N.
///
bool Value::hasNUsesOrMore(unsigned N) const {
use_const_iterator UI = use_begin(), E = use_end();
for (; N; --N, ++UI)
if (UI == E) return false; // Too few.
return true;
}
/// isUsedInBasicBlock - Return true if this value is used in the specified
/// basic block.
bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
for (use_const_iterator I = use_begin(), E = use_end(); I != E; ++I) {
const Instruction *User = dyn_cast<Instruction>(*I);
if (User && User->getParent() == BB)
return true;
}
return false;
}
/// getNumUses - This method computes the number of uses of this Value. This
/// is a linear time operation. Use hasOneUse or hasNUses to check for specific
/// values.
unsigned Value::getNumUses() const {
return (unsigned)std::distance(use_begin(), use_end());
}
static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
ST = 0;
if (Instruction *I = dyn_cast<Instruction>(V)) {
if (BasicBlock *P = I->getParent())
if (Function *PP = P->getParent())
ST = &PP->getValueSymbolTable();
} else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
if (Function *P = BB->getParent())
ST = &P->getValueSymbolTable();
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
if (Module *P = GV->getParent())
ST = &P->getValueSymbolTable();
} else if (Argument *A = dyn_cast<Argument>(V)) {
if (Function *P = A->getParent())
ST = &P->getValueSymbolTable();
} else {
assert(isa<Constant>(V) && "Unknown value type!");
return true; // no name is setable for this.
}
return false;
}
/// getNameStart - Return a pointer to a null terminated string for this name.
/// Note that names can have null characters within the string as well as at
/// their end. This always returns a non-null pointer.
const char *Value::getNameStart() const {
if (Name == 0) return "";
return Name->getKeyData();
}
/// getNameLen - Return the length of the string, correctly handling nul
/// characters embedded into them.
unsigned Value::getNameLen() const {
return Name ? Name->getKeyLength() : 0;
}
/// isName - Return true if this value has the name specified by the provided
/// nul terminated string.
bool Value::isName(const char *N) const {
unsigned InLen = strlen(N);
return InLen == getNameLen() && memcmp(getNameStart(), N, InLen) == 0;
}
std::string Value::getNameStr() const {
if (Name == 0) return "";
return std::string(Name->getKeyData(),
Name->getKeyData()+Name->getKeyLength());
}
void Value::setName(const std::string &name) {
setName(&name[0], name.size());
}
void Value::setName(const char *Name) {
setName(Name, Name ? strlen(Name) : 0);
}
void Value::setName(const char *NameStr, unsigned NameLen) {
if (NameLen == 0 && !hasName()) return;
assert(getType() != Type::VoidTy && "Cannot assign a name to void values!");
// Get the symbol table to update for this object.
ValueSymbolTable *ST;
if (getSymTab(this, ST))
return; // Cannot set a name on this value (e.g. constant).
if (!ST) { // No symbol table to update? Just do the change.
if (NameLen == 0) {
// Free the name for this value.
Name->Destroy();
Name = 0;
return;
}
if (Name) {
// Name isn't changing?
if (NameLen == Name->getKeyLength() &&
!memcmp(Name->getKeyData(), NameStr, NameLen))
return;
Name->Destroy();
}
// NOTE: Could optimize for the case the name is shrinking to not deallocate
// then reallocated.
// Create the new name.
Name = ValueName::Create(NameStr, NameStr+NameLen);
Name->setValue(this);
return;
}
// NOTE: Could optimize for the case the name is shrinking to not deallocate
// then reallocated.
if (hasName()) {
// Name isn't changing?
if (NameLen == Name->getKeyLength() &&
!memcmp(Name->getKeyData(), NameStr, NameLen))
return;
// Remove old name.
ST->removeValueName(Name);
Name->Destroy();
Name = 0;
if (NameLen == 0)
return;
}
// Name is changing to something new.
Name = ST->createValueName(NameStr, NameLen, this);
}
/// takeName - transfer the name from V to this value, setting V's name to
/// empty. It is an error to call V->takeName(V).
void Value::takeName(Value *V) {
ValueSymbolTable *ST = 0;
// If this value has a name, drop it.
if (hasName()) {
// Get the symtab this is in.
if (getSymTab(this, ST)) {
// We can't set a name on this value, but we need to clear V's name if
// it has one.
if (V->hasName()) V->setName(0, 0);
return; // Cannot set a name on this value (e.g. constant).
}
// Remove old name.
if (ST)
ST->removeValueName(Name);
Name->Destroy();
Name = 0;
}
// Now we know that this has no name.
// If V has no name either, we're done.
if (!V->hasName()) return;
// Get this's symtab if we didn't before.
if (!ST) {
if (getSymTab(this, ST)) {
// Clear V's name.
V->setName(0, 0);
return; // Cannot set a name on this value (e.g. constant).
}
}
// Get V's ST, this should always succed, because V has a name.
ValueSymbolTable *VST;
bool Failure = getSymTab(V, VST);
assert(!Failure && "V has a name, so it should have a ST!"); Failure=Failure;
// If these values are both in the same symtab, we can do this very fast.
// This works even if both values have no symtab yet.
if (ST == VST) {
// Take the name!
Name = V->Name;
V->Name = 0;
Name->setValue(this);
return;
}
// Otherwise, things are slightly more complex. Remove V's name from VST and
// then reinsert it into ST.
if (VST)
VST->removeValueName(V->Name);
Name = V->Name;
V->Name = 0;
Name->setValue(this);
if (ST)
ST->reinsertValue(this);
}
// uncheckedReplaceAllUsesWith - This is exactly the same as replaceAllUsesWith,
// except that it doesn't have all of the asserts. The asserts fail because we
// are half-way done resolving types, which causes some types to exist as two
// different Type*'s at the same time. This is a sledgehammer to work around
// this problem.
//
void Value::uncheckedReplaceAllUsesWith(Value *New) {
while (!use_empty()) {
Use &U = *UseList;
// Must handle Constants specially, we cannot call replaceUsesOfWith on a
// constant because they are uniqued.
if (Constant *C = dyn_cast<Constant>(U.getUser())) {
if (!isa<GlobalValue>(C)) {
C->replaceUsesOfWithOnConstant(this, New, &U);
continue;
}
}
U.set(New);
}
}
void Value::replaceAllUsesWith(Value *New) {
assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
assert(New != this && "this->replaceAllUsesWith(this) is NOT valid!");
assert(New->getType() == getType() &&
"replaceAllUses of value with new value of different type!");
uncheckedReplaceAllUsesWith(New);
}
Value *Value::stripPointerCasts() {
if (!isa<PointerType>(getType()))
return this;
Value *V = this;
do {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
if (!CE->getOperand(i)->isNullValue())
return V;
V = CE->getOperand(0);
} else if (CE->getOpcode() == Instruction::BitCast) {
V = CE->getOperand(0);
} else {
return V;
}
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
if (!GEP->hasAllZeroIndices())
return V;
V = GEP->getOperand(0);
} else if (BitCastInst *CI = dyn_cast<BitCastInst>(V)) {
V = CI->getOperand(0);
} else {
return V;
}
assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
} while (1);
}
Value *Value::getUnderlyingObject() {
if (!isa<PointerType>(getType()))
return this;
Value *V = this;
do {
if (Instruction *I = dyn_cast<Instruction>(V)) {
if (!isa<BitCastInst>(I) && !isa<GetElementPtrInst>(I))
return V;
V = I->getOperand(0);
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() != Instruction::BitCast &&
CE->getOpcode() != Instruction::GetElementPtr)
return V;
V = CE->getOperand(0);
} else {
return V;
}
assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
} while (1);
}
/// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
/// return the value in the PHI node corresponding to PredBB. If not, return
/// ourself. This is useful if you want to know the value something has in a
/// predecessor block.
Value *Value::DoPHITranslation(const BasicBlock *CurBB,
const BasicBlock *PredBB) {
PHINode *PN = dyn_cast<PHINode>(this);
if (PN && PN->getParent() == CurBB)
return PN->getIncomingValueForBlock(PredBB);
return this;
}
//===----------------------------------------------------------------------===//
// User Class
//===----------------------------------------------------------------------===//
// replaceUsesOfWith - Replaces all references to the "From" definition with
// references to the "To" definition.
//
void User::replaceUsesOfWith(Value *From, Value *To) {
if (From == To) return; // Duh what?
assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
"Cannot call User::replaceUsesofWith on a constant!");
for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
if (getOperand(i) == From) { // Is This operand is pointing to oldval?
// The side effects of this setOperand call include linking to
// "To", adding "this" to the uses list of To, and
// most importantly, removing "this" from the use list of "From".
setOperand(i, To); // Fix it now...
}
}