Revert 278107 which causes buildbot failures and in addition has wrong commit message

llvm-svn: 278109

1 files changed, 19 insertions, 33 deletions

diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index e6c375a8..2728687 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1197,44 +1197,30 @@ bool getValueFromCondition(Value *Val, Value *Cond, LVILatticeVal &Result,
         Result = LVILatticeVal::getNot(cast<Constant>(RHS));
       return true;
     }
-  }
-
-  // Use ConstantRange::makeAllowedICmpRegion in order to determine the possible
-  // range of Val guaranteed by the condition. Recognize comparisons in the from
-  // of:
-  //  icmp <pred> Val, ...
-  //  icmp ult (add Val, Offset), ...
-  // The latter is the range checking idiom that InstCombine produces. Subtract
-  // the offset from the allowed range for RHS in this case.
-
-  // Val or (add Val, Offset) can be on either hand of the comparison
-  if (LHS != Val && !match(LHS, m_Add(m_Specific(Val), m_ConstantInt()))) {
-    std::swap(LHS, RHS);
-    Predicate = CmpInst::getSwappedPredicate(Predicate);
-  }
 
-  ConstantInt *Offset = nullptr;
-  if (Predicate == ICmpInst::ICMP_ULT)
-    match(LHS, m_Add(m_Specific(Val), m_ConstantInt(Offset)));
+    // Recognize the range checking idiom that InstCombine produces.
+    // (X+C1) u< C2 --> [-C1, C2-C1)
+    ConstantInt *Offset = nullptr;
+    if (Predicate == ICmpInst::ICMP_ULT)
+      match(LHS, m_Add(m_Specific(Val), m_ConstantInt(Offset)));
 
-  if (LHS == Val || Offset) {
-    // Calculate the range of values that are allowed by the comparison
-    ConstantRange RHSRange(RHS->getType()->getIntegerBitWidth(),
-                           /*isFullSet=*/true);
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS))
-      RHSRange = ConstantRange(CI->getValue());
+    ConstantInt *CI = dyn_cast<ConstantInt>(RHS);
+    if (CI && (LHS == Val || Offset)) {
+      // Calculate the range of values that are allowed by the comparison
+      ConstantRange CmpRange(CI->getValue());
 
-    // If we're interested in the false dest, invert the condition
-    CmpInst::Predicate Pred =
-            isTrueDest ? Predicate : CmpInst::getInversePredicate(Predicate);
-    ConstantRange TrueValues =
-            ConstantRange::makeAllowedICmpRegion(Pred, RHSRange);
+      // If we're interested in the false dest, invert the condition
+      CmpInst::Predicate Pred =
+          isTrueDest ? Predicate : CmpInst::getInversePredicate(Predicate);
+      ConstantRange TrueValues =
+          ConstantRange::makeAllowedICmpRegion(Pred, CmpRange);
 
-    if (Offset) // Apply the offset from above.
-      TrueValues = TrueValues.subtract(Offset->getValue());
+      if (Offset) // Apply the offset from above.
+        TrueValues = TrueValues.subtract(Offset->getValue());
 
-    Result = LVILatticeVal::getRange(std::move(TrueValues));
-    return true;
+      Result = LVILatticeVal::getRange(std::move(TrueValues));
+      return true;
+    }
   }
 
   return false;