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Have ScalarEvolution use SimplifyInstruction rather than hasConstantValue.

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While there, add a note about an inefficiency I noticed.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119458 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2010-11-17 04:18:45 +00:00
parent 6ac3386e10
commit a0c5244e85
1 changed files with 5 additions and 1 deletions
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6
lib/Analysis/ScalarEvolution.cpp
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@ -69,6 +69,7 @@
#include "llvm/Operator.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Assembly/Writer.h"
@ -2874,7 +2875,10 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
// PHI's incoming blocks are in a different loop, in which case doing so
// risks breaking LCSSA form. Instcombine would normally zap these, but
// it doesn't have DominatorTree information, so it may miss cases.
if (Value *V = PN->hasConstantValue(DT)) {
if (Value *V = SimplifyInstruction(PN, TD, DT)) {
// TODO: The following check is suboptimal. For example, it is pointless
// if V is a constant. Since the problematic case is if V is defined inside
// a deeper loop, it would be better to check for that directly.
bool AllSameLoop = true;
Loop *PNLoop = LI->getLoopFor(PN->getParent());
for (size_t i = 0, e = PN->getNumIncomingValues(); i != e; ++i)