[JumpThreading] Change a dyn_cast that is already protected by an isa…

… check to a static cast. Combine the with another static cast. NFC

Differential Revision: https://reviews.llvm.org/D32874

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302197 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/JumpThreading.cpp

@@ -581,16 +581,16 @@ bool JumpThreadingPass::ComputeValueKnownInPredecessors(
     // If comparing a live-in value against a constant, see if we know the
     // live-in value on any predecessors.
     if (isa<Constant>(Cmp->getOperand(1)) && Cmp->getType()->isIntegerTy()) {
+      Constant *CmpConst = cast<Constant>(Cmp->getOperand(1));
+
       if (!isa<Instruction>(Cmp->getOperand(0)) ||
           cast<Instruction>(Cmp->getOperand(0))->getParent() != BB) {
-        Constant *RHSCst = cast<Constant>(Cmp->getOperand(1));
-
         for (BasicBlock *P : predecessors(BB)) {
           // If the value is known by LazyValueInfo to be a constant in a
           // predecessor, use that information to try to thread this block.
           LazyValueInfo::Tristate Res =
             LVI->getPredicateOnEdge(Cmp->getPredicate(), Cmp->getOperand(0),
-                                    RHSCst, P, BB, CxtI ? CxtI : Cmp);
+                                    CmpConst, P, BB, CxtI ? CxtI : Cmp);
           if (Res == LazyValueInfo::Unknown)
             continue;
 
@@ -603,21 +603,19 @@ bool JumpThreadingPass::ComputeValueKnownInPredecessors(
 
       // Try to find a constant value for the LHS of a comparison,
       // and evaluate it statically if we can.
-      if (Constant *CmpConst = dyn_cast<Constant>(Cmp->getOperand(1))) {
-        PredValueInfoTy LHSVals;
-        ComputeValueKnownInPredecessors(I->getOperand(0), BB, LHSVals,
-                                        WantInteger, CxtI);
-
-        for (const auto &LHSVal : LHSVals) {
-          Constant *V = LHSVal.first;
-          Constant *Folded = ConstantExpr::getCompare(Cmp->getPredicate(),
-                                                      V, CmpConst);
-          if (Constant *KC = getKnownConstant(Folded, WantInteger))
-            Result.push_back(std::make_pair(KC, LHSVal.second));
-        }
+      PredValueInfoTy LHSVals;
+      ComputeValueKnownInPredecessors(I->getOperand(0), BB, LHSVals,
+                                      WantInteger, CxtI);
 
-        return !Result.empty();
+      for (const auto &LHSVal : LHSVals) {
+        Constant *V = LHSVal.first;
+        Constant *Folded = ConstantExpr::getCompare(Cmp->getPredicate(),
+                                                    V, CmpConst);
+        if (Constant *KC = getKnownConstant(Folded, WantInteger))
+          Result.push_back(std::make_pair(KC, LHSVal.second));
       }
+
+      return !Result.empty();
     }
   }