[Reassociate] Try to bail out early when canonicalizing.

This commit rearranges the checks to avoid calls to getRank()
when not needed (e.g. when RHS == LHS).

llvm-svn: 310237

diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 29d1ba4..404daa7 100644 (file)
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -207,13 +207,9 @@ void ReassociatePass::canonicalizeOperands(Instruction *I) {
 
   Value *LHS = I->getOperand(0);
   Value *RHS = I->getOperand(1);
-  unsigned LHSRank = getRank(LHS);
-  unsigned RHSRank = getRank(RHS);
-
-  if (isa<Constant>(RHS))
+  if (LHS == RHS || isa<Constant>(RHS))
     return;
-
-  if (isa<Constant>(LHS) || RHSRank < LHSRank)
+  if (isa<Constant>(LHS) || getRank(RHS) < getRank(LHS))
     cast<BinaryOperator>(I)->swapOperands();
 }