return getIncomingValue(getBasicBlockIndex(BB));
}
+ /// hasConstantValue - If the specified PHI node always merges together the
+ /// same value, return the value, otherwise return null.
+ ///
+ Value *hasConstantValue();
+
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const PHINode *) { return true; }
static inline bool classof(const Instruction *I) {
///
bool dceInstruction(BasicBlock::iterator &BBI);
-//===----------------------------------------------------------------------===//
-// PHI Instruction Simplification
-//
-
-/// hasConstantValue - If the specified PHI node always merges together the same
-/// value, return the value, otherwise return null.
-///
-Value *hasConstantValue(PHINode *PN);
-
-
//===----------------------------------------------------------------------===//
// Control Flow Graph Restructuring...
//
SimplifyPredecessors(SI);
}
- // See if we can fold any PHI nodes in this block now.
- // FIXME: This would not be required if removePredecessor did this for us!!
- PHINode *PN;
- for (BasicBlock::iterator I = BB->begin(); (PN = dyn_cast<PHINode>(I++)); )
- if (Value *PNV = hasConstantValue(PN))
- if (!isa<Instruction>(PNV)) {
- PN->replaceAllUsesWith(PNV);
- PN->eraseFromParent();
- MadeChange = true;
- }
-
// If possible, simplify the terminator of this block.
if (ConstantFoldTerminator(BB))
MadeChange = true;
// PHINode simplification
//
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
- if (Value *V = hasConstantValue(&PN)) {
+ if (Value *V = PN.hasConstantValue()) {
// If V is an instruction, we have to be certain that it dominates PN.
// However, because we don't have dom info, we can't do a perfect job.
if (Instruction *I = dyn_cast<Instruction>(V)) {
}
return false;
}
-
-//===----------------------------------------------------------------------===//
-// PHI Instruction Simplification
-//
-
-/// hasConstantValue - If the specified PHI node always merges together the same
-/// value, return the value, otherwise return null.
-///
-Value *llvm::hasConstantValue(PHINode *PN) {
- // If the PHI node only has one incoming value, eliminate the PHI node...
- if (PN->getNumIncomingValues() == 1)
- return PN->getIncomingValue(0);
-
- // Otherwise if all of the incoming values are the same for the PHI, replace
- // the PHI node with the incoming value.
- //
- Value *InVal = 0;
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- if (PN->getIncomingValue(i) != PN && // Not the PHI node itself...
- !isa<UndefValue>(PN->getIncomingValue(i)))
- if (InVal && PN->getIncomingValue(i) != InVal)
- return 0; // Not the same, bail out.
- else
- InVal = PN->getIncomingValue(i);
-
- // The only case that could cause InVal to be null is if we have a PHI node
- // that only has entries for itself. In this case, there is no entry into the
- // loop, so kill the PHI.
- //
- if (InVal == 0) InVal = UndefValue::get(PN->getType());
-
- // All of the incoming values are the same, return the value now.
- return InVal;
-}
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Support/CFG.h"
-#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
PN->addIncoming(InVal, NewBB);
// Can we eliminate this phi node now?
- if (Value *V = hasConstantValue(PN)) {
+ if (Value *V = PN->hasConstantValue()) {
if (!isa<Instruction>(V) ||
getAnalysis<DominatorSet>().dominates(cast<Instruction>(V), PN)) {
PN->replaceAllUsesWith(V);
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
++I;
- if (Value *V = hasConstantValue(PN))
+ if (Value *V = PN->hasConstantValue())
if (!isa<Instruction>(V) || DS.dominates(cast<Instruction>(V), PN)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/ADT/StringExtras.h"
-#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/StableBasicBlockNumbering.h"
#include <algorithm>
PHINode *SomePHI = 0;
for (unsigned i = 0, e = PNs.size(); i != e; ++i)
if (PNs[i]) {
- if (Value *V = hasConstantValue(PNs[i])) {
+ if (Value *V = PNs[i]->hasConstantValue()) {
if (!isa<Instruction>(V) || dominates(cast<Instruction>(V), PNs[i])) {
if (AST && isa<PointerType>(PNs[i]->getType()))
AST->deleteValue(PNs[i]);
// Okay, now we know that we need to remove predecessor #pred_idx from all
// PHI nodes. Iterate over each PHI node fixing them up
PHINode *PN;
- for (iterator II = begin(); (PN = dyn_cast<PHINode>(II)); ++II)
+ for (iterator II = begin(); (PN = dyn_cast<PHINode>(II)); ++II) {
PN->removeIncomingValue(Pred, false);
+ // If all incoming values to the Phi are the same, we can replace the Phi
+ // with that value.
+ if (Value *PNV = PN->hasConstantValue())
+ if (!isa<Instruction>(PNV)) {
+ PN->replaceAllUsesWith(PNV);
+ PN->eraseFromParent();
+ }
+ }
}
}
OperandList = NewOps;
}
+/// hasConstantValue - If the specified PHI node always merges together the same
+/// value, return the value, otherwise return null.
+///
+Value *PHINode::hasConstantValue() {
+ // If the PHI node only has one incoming value, eliminate the PHI node...
+ if (getNumIncomingValues() == 1)
+ return getIncomingValue(0);
+
+ // Otherwise if all of the incoming values are the same for the PHI, replace
+ // the PHI node with the incoming value.
+ //
+ Value *InVal = 0;
+ for (unsigned i = 0, e = getNumIncomingValues(); i != e; ++i)
+ if (getIncomingValue(i) != this && // Not the PHI node itself...
+ !isa<UndefValue>(getIncomingValue(i)))
+ if (InVal && getIncomingValue(i) != InVal)
+ return 0; // Not the same, bail out.
+ else
+ InVal = getIncomingValue(i);
+
+ // The only case that could cause InVal to be null is if we have a PHI node
+ // that only has entries for itself. In this case, there is no entry into the
+ // loop, so kill the PHI.
+ //
+ if (InVal == 0) InVal = UndefValue::get(getType());
+
+ // All of the incoming values are the same, return the value now.
+ return InVal;
+}
+
//===----------------------------------------------------------------------===//
// CallInst Implementation