src/share/vm/opto/ifg.cpp

@@ -483,12 +483,13 @@
     hrp_index[0] = hrp_index[1] = last_inst+1;
     b->_reg_pressure = b->_freg_pressure = 0;
     // Liveout things are presumed live for the whole block.  We accumulate
     // 'area' accordingly.  If they get killed in the block, we'll subtract
     // the unused part of the block from the area.
-    double cost = b->_freq * double(last_inst-last_phi);
-    assert( cost >= 0, "negative spill cost" );
+    int inst_count = last_inst - last_phi;
+    double cost = (inst_count <= 0) ? 0.0 : b->_freq * double(inst_count);
+    assert(cost >= 0.0, "negative spill cost" );
     IndexSetIterator elements(&liveout);
     uint lidx;
     while ((lidx = elements.next()) != 0) {
       LRG &lrg = lrgs(lidx);
       lrg._area += cost;

@@ -588,11 +589,11 @@
           }
 
         } else {                // Else it is live
           // A DEF also ends 'area' partway through the block.
           lrgs(r)._area -= cost;
-          assert( lrgs(r)._area >= 0, "negative spill area" );
+          assert(!(lrgs(r)._area < 0.0), "negative spill area" );
 
           // Insure high score for immediate-use spill copies so they get a color
           if( n->is_SpillCopy()
               && lrgs(r).is_singledef()        // MultiDef live range can still split
               && n->outcnt() == 1              // and use must be in this block

@@ -701,12 +702,13 @@
         // compatible register sets.
         interfere_with_live(r,&liveout);
 
       } // End of if normal register-allocated value
 
-      cost -= b->_freq;         // Area remaining in the block
-      if( cost < 0.0 ) cost = 0.0;  // Cost goes negative in the Phi area
+      // Area remaining in the block
+      inst_count--;
+      cost = (inst_count <= 0) ? 0.0 : b->_freq * double(inst_count);
 
       // Make all inputs live
       if( !n->is_Phi() ) {      // Phi function uses come from prior block
         JVMState* jvms = n->jvms();
         uint debug_start = jvms ? jvms->debug_start() : 999999;

@@ -749,11 +751,11 @@
               }
             }
             assert( pressure[0] == count_int_pressure  (&liveout), "" );
             assert( pressure[1] == count_float_pressure(&liveout), "" );
           }
-          assert( lrg._area >= 0, "negative spill area" );
+          assert(!(lrg._area < 0.0), "negative spill area" );
         }
       }
     } // End of reverse pass over all instructions in block
 
     // If we run off the top of the block with high pressure and