8274130: C2: MulNode::Ideal chained transformations may act on wrong nodes

Reviewed-by: thartmann, kvn

Author: shipilev

src/hotspot/share/opto/mulnode.cpp

@@ -59,9 +59,9 @@ Node* MulNode::Identity(PhaseGVN* phase) {
 // We also canonicalize the Node, moving constants to the right input,
 // and flatten expressions (so that 1+x+2 becomes x+3).
 Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
-  const Type *t1 = phase->type( in(1) );
-  const Type *t2 = phase->type( in(2) );
-  Node *progress = NULL;        // Progress flag
+  Node* in1 = in(1);
+  Node* in2 = in(2);
+  Node* progress = NULL;        // Progress flag
 
   // This code is used by And nodes too, but some conversions are
   // only valid for the actual Mul nodes.
@@ -70,8 +70,6 @@ Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
                   (op == Op_MulF) || (op == Op_MulD);
 
   // Convert "(-a)*(-b)" into "a*b".
-  Node *in1 = in(1);
-  Node *in2 = in(2);
   if (real_mul && in1->is_Sub() && in2->is_Sub()) {
     if (phase->type(in1->in(1))->is_zero_type() &&
         phase->type(in2->in(1))->is_zero_type()) {
@@ -82,6 +80,8 @@ Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
         igvn->_worklist.push(in1);
         igvn->_worklist.push(in2);
       }
+      in1 = in(1);
+      in2 = in(2);
       progress = this;
     }
   }
@@ -104,10 +104,15 @@ Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
         igvn->_worklist.push(in1);
         igvn->_worklist.push(in2);
       }
+      in1 = in(1);
+      in2 = in(2);
       progress = this;
     }
   }
 
+  const Type* t1 = phase->type(in1);
+  const Type* t2 = phase->type(in2);
+
   // We are OK if right is a constant, or right is a load and
   // left is a non-constant.
   if( !(t2->singleton() ||