Revert "[Reassociate] As the expression tree is rewritten make sure the operands are"

This reverts commit r222142.  This is causing/exposing an execution-time regression
in spec2006/gcc and coremark on AArch64/A57/Ofast.

Conflicts:

	test/Transforms/Reassociate/optional-flags.ll

llvm-svn: 222398

1 files changed, 7 insertions, 8 deletions

diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index e75fa8017bd..1bbaaf34603 100644
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -791,11 +791,14 @@ void Reassociate::RewriteExprTree(BinaryOperator *I,
       Value *OldLHS = Op->getOperand(0);
       Value *OldRHS = Op->getOperand(1);
 
-      // The new operation differs trivially from the original.
-      if ((NewLHS == OldLHS && NewRHS == OldRHS) ||
-          (NewLHS == OldRHS && NewRHS == OldLHS)) {
+      if (NewLHS == OldLHS && NewRHS == OldRHS)
+        // Nothing changed, leave it alone.
+        break;
+
+      if (NewLHS == OldRHS && NewRHS == OldLHS) {
+        // The order of the operands was reversed.  Swap them.
         DEBUG(dbgs() << "RA: " << *Op << '\n');
-        canonicalizeOperands(Op);
+        Op->swapOperands();
         DEBUG(dbgs() << "TO: " << *Op << '\n');
         MadeChange = true;
         ++NumChanged;
@@ -817,8 +820,6 @@ void Reassociate::RewriteExprTree(BinaryOperator *I,
           NodesToRewrite.push_back(BO);
         Op->setOperand(1, NewRHS);
       }
-      // Put the operands in canonical form.
-      canonicalizeOperands(Op);
       DEBUG(dbgs() << "TO: " << *Op << '\n');
 
       ExpressionChanged = Op;
@@ -855,7 +856,6 @@ void Reassociate::RewriteExprTree(BinaryOperator *I,
     // into it.
     BinaryOperator *BO = isReassociableOp(Op->getOperand(0), Opcode);
     if (BO && !NotRewritable.count(BO)) {
-      canonicalizeOperands(Op);
       Op = BO;
       continue;
     }
@@ -880,7 +880,6 @@ void Reassociate::RewriteExprTree(BinaryOperator *I,
 
     DEBUG(dbgs() << "RA: " << *Op << '\n');
     Op->setOperand(0, NewOp);
-    canonicalizeOperands(Op);
     DEBUG(dbgs() << "TO: " << *Op << '\n');
     ExpressionChanged = Op;
     MadeChange = true;