[Reassociate] Use a range loop for clarity. NFCI.

While here, rename `i` to `Rank` as the latter is more
self-explanatory (and this code also uses `I` two lines below to
identify an Instruction).

llvm-svn: 310238

diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 404daa7..9825a59 100644 (file)
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -149,17 +149,18 @@ static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode1,
 
 void ReassociatePass::BuildRankMap(Function &F,
                                    ReversePostOrderTraversal<Function*> &RPOT) {
-  unsigned i = 2;
+  unsigned Rank = 2;
 
   // Assign distinct ranks to function arguments.
-  for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) {
-    ValueRankMap[&*I] = ++i;
-    DEBUG(dbgs() << "Calculated Rank[" << I->getName() << "] = " << i << "\n");
+  for (auto &Arg : F.args()) {
+    ValueRankMap[&Arg] = ++Rank;
+    DEBUG(dbgs() << "Calculated Rank[" << Arg.getName() << "] = " << Rank
+                 << "\n");
   }
 
   // Traverse basic blocks in ReversePostOrder
   for (BasicBlock *BB : RPOT) {
-    unsigned BBRank = RankMap[BB] = ++i << 16;
+    unsigned BBRank = RankMap[BB] = ++Rank << 16;
 
     // Walk the basic block, adding precomputed ranks for any instructions that
     // we cannot move.  This ensures that the ranks for these instructions are