8151988: Hotspot deoptimizes div/mod pair usage

Don't remove control edge of Mod node until DivMod node matching

Reviewed-by: kvn

hotspot/src/share/vm/opto/compile.cpp

@@ -3159,45 +3159,65 @@ void Compile::final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc) {
     break;
 #endif
 
-  case Op_ModI:
+  case Op_ModI: {
+    Node* di = NULL;
     if (UseDivMod) {
       // Check if a%b and a/b both exist
-      Node* d = n->find_similar(Op_DivI);
-      if (d) {
+      di = n->find_similar(Op_DivI);
+      if (di) {
         // Replace them with a fused divmod if supported
         if (Matcher::has_match_rule(Op_DivModI)) {
           DivModINode* divmod = DivModINode::make(n);
-          d->subsume_by(divmod->div_proj(), this);
+          di->subsume_by(divmod->div_proj(), this);
           n->subsume_by(divmod->mod_proj(), this);
         } else {
           // replace a%b with a-((a/b)*b)
-          Node* mult = new MulINode(d, d->in(2));
-          Node* sub  = new SubINode(d->in(1), mult);
+          Node* mult = new MulINode(di, di->in(2));
+          Node* sub  = new SubINode(di->in(1), mult);
           n->subsume_by(sub, this);
         }
       }
     }
+    if (di == NULL) {
+      // Remove useless control edge in case of not mod-zero.
+      const Type *t = n->in(2)->bottom_type();
+      const TypeInt *ti = t->is_int();
+      if (n->in(0) && (ti->_hi < 0 || ti->_lo > 0)) {
+        n->set_req(0, NULL);
+      }
+    }
     break;
+  }
 
-  case Op_ModL:
+  case Op_ModL: {
+    Node* dl = NULL;
     if (UseDivMod) {
       // Check if a%b and a/b both exist
-      Node* d = n->find_similar(Op_DivL);
-      if (d) {
+      dl = n->find_similar(Op_DivL);
+      if (dl) {
         // Replace them with a fused divmod if supported
         if (Matcher::has_match_rule(Op_DivModL)) {
           DivModLNode* divmod = DivModLNode::make(n);
-          d->subsume_by(divmod->div_proj(), this);
+          dl->subsume_by(divmod->div_proj(), this);
           n->subsume_by(divmod->mod_proj(), this);
         } else {
           // replace a%b with a-((a/b)*b)
-          Node* mult = new MulLNode(d, d->in(2));
-          Node* sub  = new SubLNode(d->in(1), mult);
+          Node* mult = new MulLNode(dl, dl->in(2));
+          Node* sub  = new SubLNode(dl->in(1), mult);
           n->subsume_by(sub, this);
         }
       }
     }
+    if (dl == NULL) {
+      // Remove useless control edge in case of not mod-zero.
+      const Type *t = n->in(2)->bottom_type();
+      const TypeLong *tl = t->is_long();
+      if (n->in(0) && (tl->_hi < 0 || tl->_lo > 0)) {
+        n->set_req(0, NULL);
+      }
+    }
     break;
+  }
 
   case Op_LoadVector:
   case Op_StoreVector:

hotspot/src/share/vm/opto/divnode.cpp

@@ -853,13 +853,6 @@ Node *ModINode::Ideal(PhaseGVN *phase, bool can_reshape) {
   if( t == Type::TOP ) return NULL;
   const TypeInt *ti = t->is_int();
 
-  // Check for useless control input
-  // Check for excluding mod-zero case
-  if( in(0) && (ti->_hi < 0 || ti->_lo > 0) ) {
-    set_req(0, NULL);        // Yank control input
-    return this;
-  }
-
   // See if we are MOD'ing by 2^k or 2^k-1.
   if( !ti->is_con() ) return NULL;
   jint con = ti->get_con();
@@ -1024,13 +1017,6 @@ Node *ModLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
   if( t == Type::TOP ) return NULL;
   const TypeLong *tl = t->is_long();
 
-  // Check for useless control input
-  // Check for excluding mod-zero case
-  if( in(0) && (tl->_hi < 0 || tl->_lo > 0) ) {
-    set_req(0, NULL);        // Yank control input
-    return this;
-  }
-
   // See if we are MOD'ing by 2^k or 2^k-1.
   if( !tl->is_con() ) return NULL;
   jlong con = tl->get_con();