revert rL345717 : [InstSimplify] fold icmp based on range of abs/nabs

This can miscompile as shown in PR39510:
https://bugs.llvm.org/show_bug.cgi?id=39510

llvm-svn: 345780

1 files changed, 0 insertions, 42 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 8571dc2cf2f..c4b076341fc 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2996,45 +2996,6 @@ static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS,
   return nullptr;
 }
 
-static Value *simplifyICmpWithAbsNabs(CmpInst::Predicate Pred, Value *Op0,
-                                      Value *Op1) {
-  // We need a comparison with a constant.
-  const APInt *C;
-  if (!match(Op1, m_APInt(C)))
-    return nullptr;
-
-  // matchSelectPattern returns the negation part of an abs pattern in SP1.
-  // If the negate has an NSW flag, abs(INT_MIN) is undefined. Without that
-  // constraint, we can't make a contiguous range for the result of abs.
-  ICmpInst::Predicate AbsPred = ICmpInst::BAD_ICMP_PREDICATE;
-  Value *SP0, *SP1;
-  SelectPatternFlavor SPF = matchSelectPattern(Op0, SP0, SP1).Flavor;
-  if (SPF == SelectPatternFlavor::SPF_ABS &&
-      cast<Instruction>(SP1)->hasNoSignedWrap())
-    // The result of abs(X) is >= 0 (with nsw).
-    AbsPred = ICmpInst::ICMP_SGE;
-  if (SPF == SelectPatternFlavor::SPF_NABS)
-    // The result of -abs(X) is <= 0.
-    AbsPred = ICmpInst::ICMP_SLE;
-
-  if (AbsPred == ICmpInst::BAD_ICMP_PREDICATE)
-    return nullptr;
-
-  // Intersect the range of abs/nabs with the range of this icmp.
-  // If there is no intersection, the icmp must be false.
-  // If the intersection equals the range of abs/nabs, the icmp must be true.
-  APInt Zero = APInt::getNullValue(C->getBitWidth());
-  ConstantRange AbsRange = ConstantRange::makeExactICmpRegion(AbsPred, Zero);
-  ConstantRange CmpRange = ConstantRange::makeExactICmpRegion(Pred, *C);
-  ConstantRange Intersection = AbsRange.intersectWith(CmpRange);
-  if (Intersection.isEmptySet())
-    return getFalse(GetCompareTy(Op0));
-  if (Intersection == AbsRange)
-    return getTrue(GetCompareTy(Op0));
-
-  return nullptr;
-}
-
 /// Simplify integer comparisons where at least one operand of the compare
 /// matches an integer min/max idiom.
 static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS,
@@ -3466,9 +3427,6 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
   if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse))
     return V;
 
-  if (Value *V = simplifyICmpWithAbsNabs(Pred, LHS, RHS))
-    return V;
-
   // Simplify comparisons of related pointers using a powerful, recursive
   // GEP-walk when we have target data available..
   if (LHS->getType()->isPointerTy())