forked from OSchip/llvm-project
642 lines
21 KiB
C++
642 lines
21 KiB
C++
//===-- Value.cpp - Implement the Value class -----------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the Value, ValueHandle, and User classes.
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//
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//===----------------------------------------------------------------------===//
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#include "LLVMContextImpl.h"
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#include "llvm/Constant.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/InstrTypes.h"
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#include "llvm/Instructions.h"
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#include "llvm/Operator.h"
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#include "llvm/Module.h"
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#include "llvm/ValueSymbolTable.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/LeakDetector.h"
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#include "llvm/Support/ManagedStatic.h"
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#include "llvm/Support/ValueHandle.h"
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#include "llvm/ADT/DenseMap.h"
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#include <algorithm>
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// Value Class
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//===----------------------------------------------------------------------===//
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static inline Type *checkType(Type *Ty) {
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assert(Ty && "Value defined with a null type: Error!");
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return const_cast<Type*>(Ty);
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}
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Value::Value(Type *ty, unsigned scid)
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: SubclassID(scid), HasValueHandle(0),
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SubclassOptionalData(0), SubclassData(0), VTy((Type*)checkType(ty)),
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UseList(0), Name(0) {
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// FIXME: Why isn't this in the subclass gunk??
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if (isa<CallInst>(this) || isa<InvokeInst>(this))
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assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) &&
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"invalid CallInst type!");
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else if (!isa<Constant>(this) && !isa<BasicBlock>(this))
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assert((VTy->isFirstClassType() || VTy->isVoidTy()) &&
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"Cannot create non-first-class values except for constants!");
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}
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Value::~Value() {
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// Notify all ValueHandles (if present) that this value is going away.
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if (HasValueHandle)
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ValueHandleBase::ValueIsDeleted(this);
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#ifndef NDEBUG // Only in -g mode...
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// Check to make sure that there are no uses of this value that are still
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// around when the value is destroyed. If there are, then we have a dangling
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// reference and something is wrong. This code is here to print out what is
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// still being referenced. The value in question should be printed as
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// a <badref>
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//
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if (!use_empty()) {
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dbgs() << "While deleting: " << *VTy << " %" << getName() << "\n";
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for (use_iterator I = use_begin(), E = use_end(); I != E; ++I)
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dbgs() << "Use still stuck around after Def is destroyed:"
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<< **I << "\n";
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}
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#endif
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assert(use_empty() && "Uses remain when a value is destroyed!");
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// If this value is named, destroy the name. This should not be in a symtab
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// at this point.
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if (Name)
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Name->Destroy();
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// There should be no uses of this object anymore, remove it.
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LeakDetector::removeGarbageObject(this);
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}
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/// hasNUses - Return true if this Value has exactly N users.
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///
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bool Value::hasNUses(unsigned N) const {
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const_use_iterator UI = use_begin(), E = use_end();
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for (; N; --N, ++UI)
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if (UI == E) return false; // Too few.
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return UI == E;
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}
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/// hasNUsesOrMore - Return true if this value has N users or more. This is
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/// logically equivalent to getNumUses() >= N.
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///
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bool Value::hasNUsesOrMore(unsigned N) const {
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const_use_iterator UI = use_begin(), E = use_end();
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for (; N; --N, ++UI)
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if (UI == E) return false; // Too few.
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return true;
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}
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/// isUsedInBasicBlock - Return true if this value is used in the specified
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/// basic block.
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bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
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// Start by scanning over the instructions looking for a use before we start
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// the expensive use iteration.
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unsigned MaxBlockSize = 3;
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for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
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if (std::find(I->op_begin(), I->op_end(), this) != I->op_end())
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return true;
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if (MaxBlockSize-- == 0) // If the block is larger fall back to use_iterator
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break;
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}
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if (MaxBlockSize != 0) // We scanned the entire block and found no use.
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return false;
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for (const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) {
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const Instruction *User = dyn_cast<Instruction>(*I);
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if (User && User->getParent() == BB)
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return true;
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}
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return false;
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}
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/// getNumUses - This method computes the number of uses of this Value. This
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/// is a linear time operation. Use hasOneUse or hasNUses to check for specific
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/// values.
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unsigned Value::getNumUses() const {
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return (unsigned)std::distance(use_begin(), use_end());
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}
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static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
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ST = 0;
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if (Instruction *I = dyn_cast<Instruction>(V)) {
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if (BasicBlock *P = I->getParent())
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if (Function *PP = P->getParent())
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ST = &PP->getValueSymbolTable();
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} else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
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if (Function *P = BB->getParent())
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ST = &P->getValueSymbolTable();
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} else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
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if (Module *P = GV->getParent())
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ST = &P->getValueSymbolTable();
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} else if (Argument *A = dyn_cast<Argument>(V)) {
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if (Function *P = A->getParent())
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ST = &P->getValueSymbolTable();
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} else if (isa<MDString>(V))
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return true;
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else {
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assert(isa<Constant>(V) && "Unknown value type!");
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return true; // no name is setable for this.
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}
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return false;
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}
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StringRef Value::getName() const {
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// Make sure the empty string is still a C string. For historical reasons,
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// some clients want to call .data() on the result and expect it to be null
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// terminated.
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if (!Name) return StringRef("", 0);
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return Name->getKey();
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}
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void Value::setName(const Twine &NewName) {
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// Fast path for common IRBuilder case of setName("") when there is no name.
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if (NewName.isTriviallyEmpty() && !hasName())
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return;
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SmallString<256> NameData;
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StringRef NameRef = NewName.toStringRef(NameData);
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// Name isn't changing?
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if (getName() == NameRef)
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return;
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assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");
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// Get the symbol table to update for this object.
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ValueSymbolTable *ST;
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if (getSymTab(this, ST))
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return; // Cannot set a name on this value (e.g. constant).
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if (!ST) { // No symbol table to update? Just do the change.
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if (NameRef.empty()) {
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// Free the name for this value.
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Name->Destroy();
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Name = 0;
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return;
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}
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if (Name)
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Name->Destroy();
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// NOTE: Could optimize for the case the name is shrinking to not deallocate
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// then reallocated.
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// Create the new name.
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Name = ValueName::Create(NameRef.begin(), NameRef.end());
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Name->setValue(this);
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return;
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}
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// NOTE: Could optimize for the case the name is shrinking to not deallocate
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// then reallocated.
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if (hasName()) {
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// Remove old name.
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ST->removeValueName(Name);
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Name->Destroy();
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Name = 0;
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if (NameRef.empty())
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return;
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}
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// Name is changing to something new.
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Name = ST->createValueName(NameRef, this);
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}
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/// takeName - transfer the name from V to this value, setting V's name to
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/// empty. It is an error to call V->takeName(V).
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void Value::takeName(Value *V) {
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ValueSymbolTable *ST = 0;
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// If this value has a name, drop it.
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if (hasName()) {
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// Get the symtab this is in.
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if (getSymTab(this, ST)) {
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// We can't set a name on this value, but we need to clear V's name if
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// it has one.
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if (V->hasName()) V->setName("");
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return; // Cannot set a name on this value (e.g. constant).
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}
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// Remove old name.
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if (ST)
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ST->removeValueName(Name);
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Name->Destroy();
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Name = 0;
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}
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// Now we know that this has no name.
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// If V has no name either, we're done.
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if (!V->hasName()) return;
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// Get this's symtab if we didn't before.
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if (!ST) {
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if (getSymTab(this, ST)) {
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// Clear V's name.
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V->setName("");
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return; // Cannot set a name on this value (e.g. constant).
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}
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}
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// Get V's ST, this should always succed, because V has a name.
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ValueSymbolTable *VST;
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bool Failure = getSymTab(V, VST);
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assert(!Failure && "V has a name, so it should have a ST!"); (void)Failure;
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// If these values are both in the same symtab, we can do this very fast.
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// This works even if both values have no symtab yet.
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if (ST == VST) {
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// Take the name!
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Name = V->Name;
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V->Name = 0;
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Name->setValue(this);
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return;
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}
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// Otherwise, things are slightly more complex. Remove V's name from VST and
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// then reinsert it into ST.
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if (VST)
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VST->removeValueName(V->Name);
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Name = V->Name;
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V->Name = 0;
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Name->setValue(this);
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if (ST)
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ST->reinsertValue(this);
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}
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void Value::replaceAllUsesWith(Value *New) {
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assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
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assert(New != this && "this->replaceAllUsesWith(this) is NOT valid!");
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assert(New->getType() == getType() &&
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"replaceAllUses of value with new value of different type!");
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// Notify all ValueHandles (if present) that this value is going away.
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if (HasValueHandle)
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ValueHandleBase::ValueIsRAUWd(this, New);
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while (!use_empty()) {
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Use &U = *UseList;
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// Must handle Constants specially, we cannot call replaceUsesOfWith on a
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// constant because they are uniqued.
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if (Constant *C = dyn_cast<Constant>(U.getUser())) {
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if (!isa<GlobalValue>(C)) {
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C->replaceUsesOfWithOnConstant(this, New, &U);
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continue;
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}
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}
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U.set(New);
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}
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if (BasicBlock *BB = dyn_cast<BasicBlock>(this))
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BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New));
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}
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Value *Value::stripPointerCasts() {
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if (!getType()->isPointerTy())
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return this;
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// Even though we don't look through PHI nodes, we could be called on an
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// instruction in an unreachable block, which may be on a cycle.
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SmallPtrSet<Value *, 4> Visited;
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Value *V = this;
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Visited.insert(V);
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do {
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if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
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if (!GEP->hasAllZeroIndices())
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return V;
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V = GEP->getPointerOperand();
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} else if (Operator::getOpcode(V) == Instruction::BitCast) {
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V = cast<Operator>(V)->getOperand(0);
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} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
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if (GA->mayBeOverridden())
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return V;
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V = GA->getAliasee();
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} else {
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return V;
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}
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assert(V->getType()->isPointerTy() && "Unexpected operand type!");
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} while (Visited.insert(V));
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return V;
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}
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/// isDereferenceablePointer - Test if this value is always a pointer to
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/// allocated and suitably aligned memory for a simple load or store.
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bool Value::isDereferenceablePointer() const {
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// Note that it is not safe to speculate into a malloc'd region because
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// malloc may return null.
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// It's also not always safe to follow a bitcast, for example:
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// bitcast i8* (alloca i8) to i32*
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// would result in a 4-byte load from a 1-byte alloca. Some cases could
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// be handled using TargetData to check sizes and alignments though.
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// These are obviously ok.
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if (isa<AllocaInst>(this)) return true;
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// Global variables which can't collapse to null are ok.
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if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
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return !GV->hasExternalWeakLinkage();
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// byval arguments are ok.
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if (const Argument *A = dyn_cast<Argument>(this))
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return A->hasByValAttr();
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// For GEPs, determine if the indexing lands within the allocated object.
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if (const GEPOperator *GEP = dyn_cast<GEPOperator>(this)) {
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// Conservatively require that the base pointer be fully dereferenceable.
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if (!GEP->getOperand(0)->isDereferenceablePointer())
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return false;
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// Check the indices.
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gep_type_iterator GTI = gep_type_begin(GEP);
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for (User::const_op_iterator I = GEP->op_begin()+1,
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E = GEP->op_end(); I != E; ++I) {
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Value *Index = *I;
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Type *Ty = *GTI++;
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// Struct indices can't be out of bounds.
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if (isa<StructType>(Ty))
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continue;
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ConstantInt *CI = dyn_cast<ConstantInt>(Index);
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if (!CI)
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return false;
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// Zero is always ok.
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if (CI->isZero())
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continue;
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// Check to see that it's within the bounds of an array.
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ArrayType *ATy = dyn_cast<ArrayType>(Ty);
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if (!ATy)
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return false;
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if (CI->getValue().getActiveBits() > 64)
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return false;
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if (CI->getZExtValue() >= ATy->getNumElements())
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return false;
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}
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// Indices check out; this is dereferenceable.
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return true;
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}
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// If we don't know, assume the worst.
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return false;
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}
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/// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
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/// return the value in the PHI node corresponding to PredBB. If not, return
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/// ourself. This is useful if you want to know the value something has in a
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/// predecessor block.
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Value *Value::DoPHITranslation(const BasicBlock *CurBB,
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const BasicBlock *PredBB) {
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PHINode *PN = dyn_cast<PHINode>(this);
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if (PN && PN->getParent() == CurBB)
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return PN->getIncomingValueForBlock(PredBB);
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return this;
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}
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LLVMContext &Value::getContext() const { return VTy->getContext(); }
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//===----------------------------------------------------------------------===//
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// ValueHandleBase Class
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//===----------------------------------------------------------------------===//
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/// AddToExistingUseList - Add this ValueHandle to the use list for VP, where
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/// List is known to point into the existing use list.
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void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
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assert(List && "Handle list is null?");
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// Splice ourselves into the list.
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Next = *List;
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*List = this;
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setPrevPtr(List);
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if (Next) {
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Next->setPrevPtr(&Next);
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assert(VP == Next->VP && "Added to wrong list?");
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}
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}
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void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) {
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assert(List && "Must insert after existing node");
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Next = List->Next;
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setPrevPtr(&List->Next);
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List->Next = this;
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if (Next)
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Next->setPrevPtr(&Next);
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}
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/// AddToUseList - Add this ValueHandle to the use list for VP.
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void ValueHandleBase::AddToUseList() {
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assert(VP && "Null pointer doesn't have a use list!");
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LLVMContextImpl *pImpl = VP->getContext().pImpl;
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if (VP->HasValueHandle) {
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// If this value already has a ValueHandle, then it must be in the
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// ValueHandles map already.
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ValueHandleBase *&Entry = pImpl->ValueHandles[VP];
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assert(Entry != 0 && "Value doesn't have any handles?");
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AddToExistingUseList(&Entry);
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return;
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}
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// Ok, it doesn't have any handles yet, so we must insert it into the
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// DenseMap. However, doing this insertion could cause the DenseMap to
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// reallocate itself, which would invalidate all of the PrevP pointers that
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// point into the old table. Handle this by checking for reallocation and
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// updating the stale pointers only if needed.
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DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
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const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
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ValueHandleBase *&Entry = Handles[VP];
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assert(Entry == 0 && "Value really did already have handles?");
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AddToExistingUseList(&Entry);
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VP->HasValueHandle = true;
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// If reallocation didn't happen or if this was the first insertion, don't
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// walk the table.
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if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
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Handles.size() == 1) {
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return;
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}
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// Okay, reallocation did happen. Fix the Prev Pointers.
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for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
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E = Handles.end(); I != E; ++I) {
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assert(I->second && I->first == I->second->VP && "List invariant broken!");
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I->second->setPrevPtr(&I->second);
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}
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}
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/// RemoveFromUseList - Remove this ValueHandle from its current use list.
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void ValueHandleBase::RemoveFromUseList() {
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assert(VP && VP->HasValueHandle && "Pointer doesn't have a use list!");
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// Unlink this from its use list.
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ValueHandleBase **PrevPtr = getPrevPtr();
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assert(*PrevPtr == this && "List invariant broken");
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*PrevPtr = Next;
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if (Next) {
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assert(Next->getPrevPtr() == &Next && "List invariant broken");
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Next->setPrevPtr(PrevPtr);
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return;
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}
|
|
|
|
// If the Next pointer was null, then it is possible that this was the last
|
|
// ValueHandle watching VP. If so, delete its entry from the ValueHandles
|
|
// map.
|
|
LLVMContextImpl *pImpl = VP->getContext().pImpl;
|
|
DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
|
|
if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
|
|
Handles.erase(VP);
|
|
VP->HasValueHandle = false;
|
|
}
|
|
}
|
|
|
|
|
|
void ValueHandleBase::ValueIsDeleted(Value *V) {
|
|
assert(V->HasValueHandle && "Should only be called if ValueHandles present");
|
|
|
|
// Get the linked list base, which is guaranteed to exist since the
|
|
// HasValueHandle flag is set.
|
|
LLVMContextImpl *pImpl = V->getContext().pImpl;
|
|
ValueHandleBase *Entry = pImpl->ValueHandles[V];
|
|
assert(Entry && "Value bit set but no entries exist");
|
|
|
|
// We use a local ValueHandleBase as an iterator so that ValueHandles can add
|
|
// and remove themselves from the list without breaking our iteration. This
|
|
// is not really an AssertingVH; we just have to give ValueHandleBase a kind.
|
|
// Note that we deliberately do not the support the case when dropping a value
|
|
// handle results in a new value handle being permanently added to the list
|
|
// (as might occur in theory for CallbackVH's): the new value handle will not
|
|
// be processed and the checking code will mete out righteous punishment if
|
|
// the handle is still present once we have finished processing all the other
|
|
// value handles (it is fine to momentarily add then remove a value handle).
|
|
for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
|
|
Iterator.RemoveFromUseList();
|
|
Iterator.AddToExistingUseListAfter(Entry);
|
|
assert(Entry->Next == &Iterator && "Loop invariant broken.");
|
|
|
|
switch (Entry->getKind()) {
|
|
case Assert:
|
|
break;
|
|
case Tracking:
|
|
// Mark that this value has been deleted by setting it to an invalid Value
|
|
// pointer.
|
|
Entry->operator=(DenseMapInfo<Value *>::getTombstoneKey());
|
|
break;
|
|
case Weak:
|
|
// Weak just goes to null, which will unlink it from the list.
|
|
Entry->operator=(0);
|
|
break;
|
|
case Callback:
|
|
// Forward to the subclass's implementation.
|
|
static_cast<CallbackVH*>(Entry)->deleted();
|
|
break;
|
|
}
|
|
}
|
|
|
|
// All callbacks, weak references, and assertingVHs should be dropped by now.
|
|
if (V->HasValueHandle) {
|
|
#ifndef NDEBUG // Only in +Asserts mode...
|
|
dbgs() << "While deleting: " << *V->getType() << " %" << V->getName()
|
|
<< "\n";
|
|
if (pImpl->ValueHandles[V]->getKind() == Assert)
|
|
llvm_unreachable("An asserting value handle still pointed to this"
|
|
" value!");
|
|
|
|
#endif
|
|
llvm_unreachable("All references to V were not removed?");
|
|
}
|
|
}
|
|
|
|
|
|
void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
|
|
assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
|
|
assert(Old != New && "Changing value into itself!");
|
|
|
|
// Get the linked list base, which is guaranteed to exist since the
|
|
// HasValueHandle flag is set.
|
|
LLVMContextImpl *pImpl = Old->getContext().pImpl;
|
|
ValueHandleBase *Entry = pImpl->ValueHandles[Old];
|
|
|
|
assert(Entry && "Value bit set but no entries exist");
|
|
|
|
// We use a local ValueHandleBase as an iterator so that
|
|
// ValueHandles can add and remove themselves from the list without
|
|
// breaking our iteration. This is not really an AssertingVH; we
|
|
// just have to give ValueHandleBase some kind.
|
|
for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
|
|
Iterator.RemoveFromUseList();
|
|
Iterator.AddToExistingUseListAfter(Entry);
|
|
assert(Entry->Next == &Iterator && "Loop invariant broken.");
|
|
|
|
switch (Entry->getKind()) {
|
|
case Assert:
|
|
// Asserting handle does not follow RAUW implicitly.
|
|
break;
|
|
case Tracking:
|
|
// Tracking goes to new value like a WeakVH. Note that this may make it
|
|
// something incompatible with its templated type. We don't want to have a
|
|
// virtual (or inline) interface to handle this though, so instead we make
|
|
// the TrackingVH accessors guarantee that a client never sees this value.
|
|
|
|
// FALLTHROUGH
|
|
case Weak:
|
|
// Weak goes to the new value, which will unlink it from Old's list.
|
|
Entry->operator=(New);
|
|
break;
|
|
case Callback:
|
|
// Forward to the subclass's implementation.
|
|
static_cast<CallbackVH*>(Entry)->allUsesReplacedWith(New);
|
|
break;
|
|
}
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
// If any new tracking or weak value handles were added while processing the
|
|
// list, then complain about it now.
|
|
if (Old->HasValueHandle)
|
|
for (Entry = pImpl->ValueHandles[Old]; Entry; Entry = Entry->Next)
|
|
switch (Entry->getKind()) {
|
|
case Tracking:
|
|
case Weak:
|
|
dbgs() << "After RAUW from " << *Old->getType() << " %"
|
|
<< Old->getName() << " to " << *New->getType() << " %"
|
|
<< New->getName() << "\n";
|
|
llvm_unreachable("A tracking or weak value handle still pointed to the"
|
|
" old value!\n");
|
|
default:
|
|
break;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/// ~CallbackVH. Empty, but defined here to avoid emitting the vtable
|
|
/// more than once.
|
|
CallbackVH::~CallbackVH() {}
|