[SCEV] Improve code in isKnownPredicateViaConstantRanges (NFC) (#147335)

Author: artagnon

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -11376,11 +11376,9 @@ bool ScalarEvolution::isKnownPredicateViaConstantRanges(CmpPredicate Pred,
   if (HasSameValue(LHS, RHS))
     return ICmpInst::isTrueWhenEqual(Pred);
 
-  // This code is split out from isKnownPredicate because it is called from
-  // within isLoopEntryGuardedByCond.
-
-  auto CheckRanges = [&](const ConstantRange &RangeLHS,
-                         const ConstantRange &RangeRHS) {
+  auto CheckRange = [&](bool IsSigned) {
+    auto RangeLHS = IsSigned ? getSignedRange(LHS) : getUnsignedRange(LHS);
+    auto RangeRHS = IsSigned ? getSignedRange(RHS) : getUnsignedRange(RHS);
     return RangeLHS.icmp(Pred, RangeRHS);
   };
 
@@ -11390,27 +11388,13 @@ bool ScalarEvolution::isKnownPredicateViaConstantRanges(CmpPredicate Pred,
     return false;
 
   if (Pred == CmpInst::ICMP_NE) {
-    auto SL = getSignedRange(LHS);
-    auto SR = getSignedRange(RHS);
-    if (CheckRanges(SL, SR))
-      return true;
-    auto UL = getUnsignedRange(LHS);
-    auto UR = getUnsignedRange(RHS);
-    if (CheckRanges(UL, UR))
+    if (CheckRange(true) || CheckRange(false))
       return true;
     auto *Diff = getMinusSCEV(LHS, RHS);
     return !isa<SCEVCouldNotCompute>(Diff) && isKnownNonZero(Diff);
   }
 
-  if (CmpInst::isSigned(Pred)) {
-    auto SL = getSignedRange(LHS);
-    auto SR = getSignedRange(RHS);
-    return CheckRanges(SL, SR);
-  }
-
-  auto UL = getUnsignedRange(LHS);
-  auto UR = getUnsignedRange(RHS);
-  return CheckRanges(UL, UR);
+  return CheckRange(CmpInst::isSigned(Pred));
 }
 
 bool ScalarEvolution::isKnownPredicateViaNoOverflow(CmpPredicate Pred,