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Fix a fixme in CondPropagate.cpp by moving a PhiNode optimization into

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BasicBlock's removePredecessor routine.  This requires shuffling around
the definition and implementation of hasContantValue from Utils.h,cpp into
Instructions.h,cpp


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22664 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman
2005-08-04 23:24:19 +00:00
parent f065f05397
commit a83ba0f5c9
9 changed files with 48 additions and 62 deletions
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34
lib/Transforms/Utils/Local.cpp
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@@ -406,37 +406,3 @@ bool llvm::dceInstruction(BasicBlock::iterator &BBI) {
}
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;
}

5
lib/Transforms/Utils/LoopSimplify.cpp
View File

@@ -41,7 +41,6 @@
#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"
@@ -257,7 +256,7 @@ BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
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);
@@ -443,7 +442,7 @@ static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorSet &DS,
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);

3
lib/Transforms/Utils/PromoteMemoryToRegister.cpp
View File

@@ -24,7 +24,6 @@
#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>
@@ -348,7 +347,7 @@ void PromoteMem2Reg::run() {
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]);