Revert "[ScalarEvolution] Handling for ICmp occuring in the evolution chain."

This reverts commit r316054.  There was some confusion over the review process:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20171016/495884.html

llvm-svn: 316129

1 files changed, 3 insertions, 42 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index e872e81a5e7..c69bd601aff 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -4756,26 +4756,11 @@ const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
           Ops.push_back(Add->getOperand(i));
       const SCEV *Accum = getAddExpr(Ops);
 
-      bool InvariantF = isLoopInvariant(Accum, L);
-
-      if (!InvariantF && Accum->getSCEVType() == scZeroExtend) {
-        const SCEV *Op = dyn_cast<SCEVZeroExtendExpr>(Accum)->getOperand();
-        const SCEVUnknown *Un = dyn_cast<SCEVUnknown>(Op);
-        if (Un && Un->getValue() && isa<Instruction>(Un->getValue()) &&
-            dyn_cast<Instruction>(Un->getValue())->getOpcode() ==
-                Instruction::ICmp) {
-          const SCEV *ICmpSC = evaluateForICmp(cast<ICmpInst>(Un->getValue()));
-          bool IsConstSC = ICmpSC->getSCEVType() == scConstant;
-          Accum =
-              IsConstSC ? getZeroExtendExpr(ICmpSC, Accum->getType()) : Accum;
-          InvariantF = IsConstSC ? true : false;
-        }
-      }
-
       // This is not a valid addrec if the step amount is varying each
       // loop iteration, but is not itself an addrec in this loop.
-      if (InvariantF || (isa<SCEVAddRecExpr>(Accum) &&
-                         cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
+      if (isLoopInvariant(Accum, L) ||
+          (isa<SCEVAddRecExpr>(Accum) &&
+           cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
         SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
 
         if (auto BO = MatchBinaryOp(BEValueV, DT)) {
@@ -6458,30 +6443,6 @@ void ScalarEvolution::forgetLoop(const Loop *L) {
   }
 }
 
-
-const SCEV *ScalarEvolution::evaluateForICmp(ICmpInst *IC) {
-  BasicBlock *Latch = nullptr;
-  const Loop *L = LI.getLoopFor(IC->getParent());
-
-  // If compare instruction is same or inverse of the compare in the
-  // branch of the loop latch, then return a constant evolution
-  // node. This shall facilitate computations of loop exit counts
-  // in cases where compare appears in the evolution chain of induction
-  // variables.
-  if (L && (Latch = L->getLoopLatch())) {
-    BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator());
-    if (BI && BI->isConditional() && BI->getCondition() == IC) {
-      if (BI->getSuccessor(0) != L->getHeader())
-        return getZero(Type::getInt1Ty(getContext()));
-      else
-        return getOne(Type::getInt1Ty(getContext()));
-    }
-  }
-
-  return getUnknown(IC);
-}
-
-
 void ScalarEvolution::forgetValue(Value *V) {
   Instruction *I = dyn_cast<Instruction>(V);
   if (!I) return;