llvm-6502/lib/IR/Value.cpp
David Majnemer c3b47b30ab [IR] Switch static const to an enum to silence MSVC linker warnings
Integral class statics are handled oddly in MSVC, we don't need them
in this case, use an enum instead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241958 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-10 22:46:02 +00:00

759 lines
24 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, ValueHandle, and User classes.
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/Value.h"
#include "LLVMContextImpl.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/Statepoint.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/IR/ValueSymbolTable.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Value Class
//===----------------------------------------------------------------------===//
static inline Type *checkType(Type *Ty) {
assert(Ty && "Value defined with a null type: Error!");
return Ty;
}
Value::Value(Type *ty, unsigned scid)
: VTy(checkType(ty)), UseList(nullptr), SubclassID(scid),
HasValueHandle(0), SubclassOptionalData(0), SubclassData(0),
NumUserOperands(0), IsUsedByMD(false), HasName(false) {
// FIXME: Why isn't this in the subclass gunk??
// Note, we cannot call isa<CallInst> before the CallInst has been
// constructed.
if (SubclassID == Instruction::Call || SubclassID == Instruction::Invoke)
assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) &&
"invalid CallInst type!");
else if (SubclassID != BasicBlockVal &&
(SubclassID < ConstantFirstVal || SubclassID > ConstantLastVal))
assert((VTy->isFirstClassType() || VTy->isVoidTy()) &&
"Cannot create non-first-class values except for constants!");
}
Value::~Value() {
// Notify all ValueHandles (if present) that this value is going away.
if (HasValueHandle)
ValueHandleBase::ValueIsDeleted(this);
if (isUsedByMetadata())
ValueAsMetadata::handleDeletion(this);
#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 where
// the value is still being referenced.
//
if (!use_empty()) {
dbgs() << "While deleting: " << *VTy << " %" << getName() << "\n";
for (auto *U : users())
dbgs() << "Use still stuck around after Def is destroyed:" << *U << "\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.
destroyValueName();
}
void Value::destroyValueName() {
ValueName *Name = getValueName();
if (Name)
Name->Destroy();
setValueName(nullptr);
}
bool Value::hasNUses(unsigned N) const {
const_use_iterator UI = use_begin(), E = use_end();
for (; N; --N, ++UI)
if (UI == E) return false; // Too few.
return UI == E;
}
bool Value::hasNUsesOrMore(unsigned N) const {
const_use_iterator UI = use_begin(), E = use_end();
for (; N; --N, ++UI)
if (UI == E) return false; // Too few.
return true;
}
bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
// This can be computed either by scanning the instructions in BB, or by
// scanning the use list of this Value. Both lists can be very long, but
// usually one is quite short.
//
// Scan both lists simultaneously until one is exhausted. This limits the
// search to the shorter list.
BasicBlock::const_iterator BI = BB->begin(), BE = BB->end();
const_user_iterator UI = user_begin(), UE = user_end();
for (; BI != BE && UI != UE; ++BI, ++UI) {
// Scan basic block: Check if this Value is used by the instruction at BI.
if (std::find(BI->op_begin(), BI->op_end(), this) != BI->op_end())
return true;
// Scan use list: Check if the use at UI is in BB.
const Instruction *User = dyn_cast<Instruction>(*UI);
if (User && User->getParent() == BB)
return true;
}
return false;
}
unsigned Value::getNumUses() const {
return (unsigned)std::distance(use_begin(), use_end());
}
static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
ST = nullptr;
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;
}
ValueName *Value::getValueName() const {
if (!HasName) return nullptr;
LLVMContext &Ctx = getContext();
auto I = Ctx.pImpl->ValueNames.find(this);
assert(I != Ctx.pImpl->ValueNames.end() &&
"No name entry found!");
return I->second;
}
void Value::setValueName(ValueName *VN) {
LLVMContext &Ctx = getContext();
assert(HasName == Ctx.pImpl->ValueNames.count(this) &&
"HasName bit out of sync!");
if (!VN) {
if (HasName)
Ctx.pImpl->ValueNames.erase(this);
HasName = false;
return;
}
HasName = true;
Ctx.pImpl->ValueNames[this] = VN;
}
StringRef Value::getName() const {
// Make sure the empty string is still a C string. For historical reasons,
// some clients want to call .data() on the result and expect it to be null
// terminated.
if (!hasName())
return StringRef("", 0);
return getValueName()->getKey();
}
void Value::setNameImpl(const Twine &NewName) {
// Fast path for common IRBuilder case of setName("") when there is no name.
if (NewName.isTriviallyEmpty() && !hasName())
return;
SmallString<256> NameData;
StringRef NameRef = NewName.toStringRef(NameData);
assert(NameRef.find_first_of(0) == StringRef::npos &&
"Null bytes are not allowed in names");
// Name isn't changing?
if (getName() == NameRef)
return;
assert(!getType()->isVoidTy() && "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 (NameRef.empty()) {
// Free the name for this value.
destroyValueName();
return;
}
// NOTE: Could optimize for the case the name is shrinking to not deallocate
// then reallocated.
destroyValueName();
// Create the new name.
setValueName(ValueName::Create(NameRef));
getValueName()->setValue(this);
return;
}
// NOTE: Could optimize for the case the name is shrinking to not deallocate
// then reallocated.
if (hasName()) {
// Remove old name.
ST->removeValueName(getValueName());
destroyValueName();
if (NameRef.empty())
return;
}
// Name is changing to something new.
setValueName(ST->createValueName(NameRef, this));
}
void Value::setName(const Twine &NewName) {
setNameImpl(NewName);
if (Function *F = dyn_cast<Function>(this))
F->recalculateIntrinsicID();
}
void Value::takeName(Value *V) {
ValueSymbolTable *ST = nullptr;
// 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("");
return; // Cannot set a name on this value (e.g. constant).
}
// Remove old name.
if (ST)
ST->removeValueName(getValueName());
destroyValueName();
}
// 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("");
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!"); (void)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!
setValueName(V->getValueName());
V->setValueName(nullptr);
getValueName()->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->getValueName());
setValueName(V->getValueName());
V->setValueName(nullptr);
getValueName()->setValue(this);
if (ST)
ST->reinsertValue(this);
}
#ifndef NDEBUG
static bool contains(SmallPtrSetImpl<ConstantExpr *> &Cache, ConstantExpr *Expr,
Constant *C) {
if (!Cache.insert(Expr).second)
return false;
for (auto &O : Expr->operands()) {
if (O == C)
return true;
auto *CE = dyn_cast<ConstantExpr>(O);
if (!CE)
continue;
if (contains(Cache, CE, C))
return true;
}
return false;
}
static bool contains(Value *Expr, Value *V) {
if (Expr == V)
return true;
auto *C = dyn_cast<Constant>(V);
if (!C)
return false;
auto *CE = dyn_cast<ConstantExpr>(Expr);
if (!CE)
return false;
SmallPtrSet<ConstantExpr *, 4> Cache;
return contains(Cache, CE, C);
}
#endif
void Value::replaceAllUsesWith(Value *New) {
assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
assert(!contains(New, this) &&
"this->replaceAllUsesWith(expr(this)) is NOT valid!");
assert(New->getType() == getType() &&
"replaceAllUses of value with new value of different type!");
// Notify all ValueHandles (if present) that this value is going away.
if (HasValueHandle)
ValueHandleBase::ValueIsRAUWd(this, New);
if (isUsedByMetadata())
ValueAsMetadata::handleRAUW(this, New);
while (!use_empty()) {
Use &U = *UseList;
// Must handle Constants specially, we cannot call replaceUsesOfWith on a
// constant because they are uniqued.
if (auto *C = dyn_cast<Constant>(U.getUser())) {
if (!isa<GlobalValue>(C)) {
C->handleOperandChange(this, New, &U);
continue;
}
}
U.set(New);
}
if (BasicBlock *BB = dyn_cast<BasicBlock>(this))
BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New));
}
// Like replaceAllUsesWith except it does not handle constants or basic blocks.
// This routine leaves uses within BB.
void Value::replaceUsesOutsideBlock(Value *New, BasicBlock *BB) {
assert(New && "Value::replaceUsesOutsideBlock(<null>, BB) is invalid!");
assert(!contains(New, this) &&
"this->replaceUsesOutsideBlock(expr(this), BB) is NOT valid!");
assert(New->getType() == getType() &&
"replaceUses of value with new value of different type!");
assert(BB && "Basic block that may contain a use of 'New' must be defined\n");
use_iterator UI = use_begin(), E = use_end();
for (; UI != E;) {
Use &U = *UI;
++UI;
auto *Usr = dyn_cast<Instruction>(U.getUser());
if (Usr && Usr->getParent() == BB)
continue;
U.set(New);
}
return;
}
namespace {
// Various metrics for how much to strip off of pointers.
enum PointerStripKind {
PSK_ZeroIndices,
PSK_ZeroIndicesAndAliases,
PSK_InBoundsConstantIndices,
PSK_InBounds
};
template <PointerStripKind StripKind>
static Value *stripPointerCastsAndOffsets(Value *V) {
if (!V->getType()->isPointerTy())
return V;
// Even though we don't look through PHI nodes, we could be called on an
// instruction in an unreachable block, which may be on a cycle.
SmallPtrSet<Value *, 4> Visited;
Visited.insert(V);
do {
if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
switch (StripKind) {
case PSK_ZeroIndicesAndAliases:
case PSK_ZeroIndices:
if (!GEP->hasAllZeroIndices())
return V;
break;
case PSK_InBoundsConstantIndices:
if (!GEP->hasAllConstantIndices())
return V;
// fallthrough
case PSK_InBounds:
if (!GEP->isInBounds())
return V;
break;
}
V = GEP->getPointerOperand();
} else if (Operator::getOpcode(V) == Instruction::BitCast ||
Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
V = cast<Operator>(V)->getOperand(0);
} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
if (StripKind == PSK_ZeroIndices || GA->mayBeOverridden())
return V;
V = GA->getAliasee();
} else {
return V;
}
assert(V->getType()->isPointerTy() && "Unexpected operand type!");
} while (Visited.insert(V).second);
return V;
}
} // namespace
Value *Value::stripPointerCasts() {
return stripPointerCastsAndOffsets<PSK_ZeroIndicesAndAliases>(this);
}
Value *Value::stripPointerCastsNoFollowAliases() {
return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this);
}
Value *Value::stripInBoundsConstantOffsets() {
return stripPointerCastsAndOffsets<PSK_InBoundsConstantIndices>(this);
}
Value *Value::stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
APInt &Offset) {
if (!getType()->isPointerTy())
return this;
assert(Offset.getBitWidth() == DL.getPointerSizeInBits(cast<PointerType>(
getType())->getAddressSpace()) &&
"The offset must have exactly as many bits as our pointer.");
// Even though we don't look through PHI nodes, we could be called on an
// instruction in an unreachable block, which may be on a cycle.
SmallPtrSet<Value *, 4> Visited;
Visited.insert(this);
Value *V = this;
do {
if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
if (!GEP->isInBounds())
return V;
APInt GEPOffset(Offset);
if (!GEP->accumulateConstantOffset(DL, GEPOffset))
return V;
Offset = GEPOffset;
V = GEP->getPointerOperand();
} else if (Operator::getOpcode(V) == Instruction::BitCast ||
Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
V = cast<Operator>(V)->getOperand(0);
} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
V = GA->getAliasee();
} else {
return V;
}
assert(V->getType()->isPointerTy() && "Unexpected operand type!");
} while (Visited.insert(V).second);
return V;
}
Value *Value::stripInBoundsOffsets() {
return stripPointerCastsAndOffsets<PSK_InBounds>(this);
}
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;
}
LLVMContext &Value::getContext() const { return VTy->getContext(); }
void Value::reverseUseList() {
if (!UseList || !UseList->Next)
// No need to reverse 0 or 1 uses.
return;
Use *Head = UseList;
Use *Current = UseList->Next;
Head->Next = nullptr;
while (Current) {
Use *Next = Current->Next;
Current->Next = Head;
Head->setPrev(&Current->Next);
Head = Current;
Current = Next;
}
UseList = Head;
Head->setPrev(&UseList);
}
//===----------------------------------------------------------------------===//
// ValueHandleBase Class
//===----------------------------------------------------------------------===//
void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
assert(List && "Handle list is null?");
// Splice ourselves into the list.
Next = *List;
*List = this;
setPrevPtr(List);
if (Next) {
Next->setPrevPtr(&Next);
assert(V == Next->V && "Added to wrong list?");
}
}
void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) {
assert(List && "Must insert after existing node");
Next = List->Next;
setPrevPtr(&List->Next);
List->Next = this;
if (Next)
Next->setPrevPtr(&Next);
}
void ValueHandleBase::AddToUseList() {
assert(V && "Null pointer doesn't have a use list!");
LLVMContextImpl *pImpl = V->getContext().pImpl;
if (V->HasValueHandle) {
// If this value already has a ValueHandle, then it must be in the
// ValueHandles map already.
ValueHandleBase *&Entry = pImpl->ValueHandles[V];
assert(Entry && "Value doesn't have any handles?");
AddToExistingUseList(&Entry);
return;
}
// Ok, it doesn't have any handles yet, so we must insert it into the
// DenseMap. However, doing this insertion could cause the DenseMap to
// reallocate itself, which would invalidate all of the PrevP pointers that
// point into the old table. Handle this by checking for reallocation and
// updating the stale pointers only if needed.
DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
ValueHandleBase *&Entry = Handles[V];
assert(!Entry && "Value really did already have handles?");
AddToExistingUseList(&Entry);
V->HasValueHandle = true;
// If reallocation didn't happen or if this was the first insertion, don't
// walk the table.
if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
Handles.size() == 1) {
return;
}
// Okay, reallocation did happen. Fix the Prev Pointers.
for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
E = Handles.end(); I != E; ++I) {
assert(I->second && I->first == I->second->V &&
"List invariant broken!");
I->second->setPrevPtr(&I->second);
}
}
void ValueHandleBase::RemoveFromUseList() {
assert(V && V->HasValueHandle &&
"Pointer doesn't have a use list!");
// Unlink this from its use list.
ValueHandleBase **PrevPtr = getPrevPtr();
assert(*PrevPtr == this && "List invariant broken");
*PrevPtr = Next;
if (Next) {
assert(Next->getPrevPtr() == &Next && "List invariant broken");
Next->setPrevPtr(PrevPtr);
return;
}
// 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 = V->getContext().pImpl;
DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
Handles.erase(V);
V->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=(nullptr);
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!");
assert(Old->getType() == New->getType() &&
"replaceAllUses of value with new value of different type!");
// 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
}
// Pin the vtable to this file.
void CallbackVH::anchor() {}