Revert "[IndVars] Generate zext nneg when locally obvious"

This reverts commit a6c8e27b3a052913a15a13ee0d4ac466c5ab3f92.  It appears likely to have caused https://lab.llvm.org/buildbot/#/builders/57/builds/30988.

1 files changed, 0 insertions, 19 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index a618d72..f325698 100644
--- a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -1201,15 +1201,6 @@ Value *WidenIV::createExtendInst(Value *NarrowOper, Type *WideType,
        L = L->getParentLoop())
     Builder.SetInsertPoint(L->getLoopPreheader()->getTerminator());
 
-  // If we know the operand is never negative, prefer zext nneg.
-  // For constant expressions, fall back to plain sext or zext.
-  if (SE->isKnownNonNegative(SE->getSCEV(NarrowOper))) {
-    auto *Res = Builder.CreateZExt(NarrowOper, WideType);
-    if (auto *I = dyn_cast<Instruction>(Res))
-      I->setNonNeg(true);
-    return Res;
-  }
-
   return IsSigned ? Builder.CreateSExt(NarrowOper, WideType) :
                     Builder.CreateZExt(NarrowOper, WideType);
 }
@@ -1711,16 +1702,6 @@ bool WidenIV::widenWithVariantUse(WidenIV::NarrowIVDefUse DU) {
     auto ExtendedOp = [&](Value * V)->Value * {
       if (V == NarrowUse)
         return WideBO;
-
-      // If we know the operand is never negative, prefer zext nneg.
-      // For constant expressions, fall back to plain sext or zext.
-      if (SE->isKnownNonNegative(SE->getSCEV(V))) {
-        auto *Res = Builder.CreateZExt(V, WideBO->getType());
-        if (auto *I = dyn_cast<Instruction>(Res))
-          I->setNonNeg(true);
-        return Res;
-      }
-
       if (ExtKind == ExtendKind::Zero)
         return Builder.CreateZExt(V, WideBO->getType());
       else