src/share/vm/opto/compile.cpp

@@ -36,10 +36,11 @@
 #include "opto/addnode.hpp"
 #include "opto/block.hpp"
 #include "opto/c2compiler.hpp"
 #include "opto/callGenerator.hpp"
 #include "opto/callnode.hpp"
+#include "opto/castnode.hpp"
 #include "opto/cfgnode.hpp"
 #include "opto/chaitin.hpp"
 #include "opto/compile.hpp"
 #include "opto/connode.hpp"
 #include "opto/convertnode.hpp"

@@ -400,10 +401,17 @@
     Node* n = C->macro_node(i);
     if (!useful.member(n)) {
       remove_macro_node(n);
     }
   }
+  // Remove useless CastII nodes with range check dependency
+  for (int i = range_check_cast_count() - 1; i >= 0; i--) {
+    Node* cast = range_check_cast_node(i);
+    if (!useful.member(cast)) {
+      remove_range_check_cast(cast);
+    }
+  }
   // Remove useless expensive node
   for (int i = C->expensive_count()-1; i >= 0; i--) {
     Node* n = C->expensive_node(i);
     if (!useful.member(n)) {
       remove_expensive_node(n);

@@ -1176,10 +1184,11 @@
 
   _intrinsics = NULL;
   _macro_nodes = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
   _predicate_opaqs = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
   _expensive_nodes = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
+  _range_check_casts = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
   register_library_intrinsics();
 }
 
 //---------------------------init_start----------------------------------------
 // Install the StartNode on this compile object.

@@ -1922,10 +1931,26 @@
     igvn.replace_node(n, n->in(1));
   }
   assert(predicate_count()==0, "should be clean!");
 }
 
+void Compile::add_range_check_cast(Node* n) {
+  assert(n->isa_CastII()->has_range_check(), "CastII should have range check dependency");
+  assert(!_range_check_casts->contains(n), "duplicate entry in range check casts");
+  _range_check_casts->append(n);
+}
+
+// Remove all range check dependent CastIINodes.
+void Compile::remove_range_check_casts(PhaseIterGVN &igvn) {
+  for (int i = range_check_cast_count(); i > 0; i--) {
+    Node* cast = range_check_cast_node(i-1);
+    assert(cast->isa_CastII()->has_range_check(), "CastII should have range check dependency");
+    igvn.replace_node(cast, cast->in(1));
+  }
+  assert(range_check_cast_count() == 0, "should be empty");
+}
+
 // StringOpts and late inlining of string methods
 void Compile::inline_string_calls(bool parse_time) {
   {
     // remove useless nodes to make the usage analysis simpler
     ResourceMark rm;

@@ -2282,10 +2307,16 @@
     // at least to this point, even if no loop optimizations were done.
     TracePhase tp("idealLoopVerify", &timers[_t_idealLoopVerify]);
     PhaseIdealLoop::verify(igvn);
   }
 
+  if (range_check_cast_count() > 0) {
+    // No more loop optimizations. Remove all range check dependent CastIINodes.
+    C->remove_range_check_casts(igvn);
+    igvn.optimize();
+  }
+
   {
     TracePhase tp("macroExpand", &timers[_t_macroExpand]);
     PhaseMacroExpand  mex(igvn);
     if (mex.expand_macro_nodes()) {
       assert(failing(), "must bail out w/ explicit message");

@@ -3085,10 +3116,20 @@
     }
     break;
 
 #endif
 
+#ifdef ASSERT
+  case Op_CastII:
+    // Verify that all range check dependent CastII nodes were removed.
+    if (n->isa_CastII()->has_range_check()) {
+      n->dump(3);
+      assert(false, "Range check dependent CastII node was not removed");
+    }
+    break;
+#endif
+
   case Op_ModI:
     if (UseDivMod) {
       // Check if a%b and a/b both exist
       Node* d = n->find_similar(Op_DivI);
       if (d) {

@@ -3960,11 +4001,11 @@
   }
 
   return SSC_full_test;
 }
 
-Node* Compile::conv_I2X_index(PhaseGVN *phase, Node* idx, const TypeInt* sizetype) {
+Node* Compile::conv_I2X_index(PhaseGVN* phase, Node* idx, const TypeInt* sizetype, Node* ctrl) {
 #ifdef _LP64
   // The scaled index operand to AddP must be a clean 64-bit value.
   // Java allows a 32-bit int to be incremented to a negative
   // value, which appears in a 64-bit register as a large
   // positive number.  Using that large positive number as an

@@ -3974,16 +4015,34 @@
   // a type assertion that its value is known to be a small positive
   // number.  (The prior range check has ensured this.)
   // This assertion is used by ConvI2LNode::Ideal.
   int index_max = max_jint - 1;  // array size is max_jint, index is one less
   if (sizetype != NULL)  index_max = sizetype->_hi - 1;
-  const TypeLong* lidxtype = TypeLong::make(CONST64(0), index_max, Type::WidenMax);
-  idx = phase->transform(new ConvI2LNode(idx, lidxtype));
+  const TypeInt* iidxtype = TypeInt::make(0, index_max, Type::WidenMax);
+  idx = constrained_convI2L(phase, idx, iidxtype, ctrl);
 #endif
   return idx;
 }
 
+// Convert integer value to a narrowed long type dependent on ctrl (for example, a range check)
+Node* Compile::constrained_convI2L(PhaseGVN* phase, Node* value, const TypeInt* itype, Node* ctrl) {
+  if (ctrl != NULL) {
+    // Express control dependency by a CastII node with a narrow type.
+    value = new CastIINode(value, itype, false, true /* range check dependency */);
+    // Make the CastII node dependent on the control input to prevent the narrowed ConvI2L
+    // node from floating above the range check during loop optimizations. Otherwise, the
+    // ConvI2L node may be eliminated independently of the range check, causing the data path
+    // to become TOP while the control path is still there (although it's unreachable).
+    value->set_req(0, ctrl);
+    // Save CastII node to remove it after loop optimizations.
+    phase->C->add_range_check_cast(value);
+    value = phase->transform(value);
+  }
+  const TypeLong* ltype = TypeLong::make(itype->_lo, itype->_hi, itype->_widen);
+  return phase->transform(new ConvI2LNode(value, ltype));
+}
+
 // The message about the current inlining is accumulated in
 // _print_inlining_stream and transfered into the _print_inlining_list
 // once we know whether inlining succeeds or not. For regular
 // inlining, messages are appended to the buffer pointed by
 // _print_inlining_idx in the _print_inlining_list. For late inlining,