Speedup HInstruction::Verify() for pathological cases

src/hydrogen-instructions.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 569 matching lines @@
 
 #ifdef DEBUG
 void HInstruction::Verify() {
   // Verify that input operands are defined before use.
   HBasicBlock* cur_block = block();
   for (int i = 0; i < OperandCount(); ++i) {
     HValue* other_operand = OperandAt(i);
     HBasicBlock* other_block = other_operand->block();
     if (cur_block == other_block) {
       if (!other_operand->IsPhi()) {
-        HInstruction* cur = cur_block->first();
+        HInstruction* cur = this->previous();
         while (cur != NULL) {
-          ASSERT(cur != this);  // We should reach other_operand before!
           if (cur == other_operand) break;
-          cur = cur->next();
+          cur = cur->previous();
         }
         // Must reach other operand in the same block!
         ASSERT(cur == other_operand);
       }
     } else {
       // If the following assert fires, you may have forgotten an
       // AddInstruction.
       ASSERT(other_block->Dominates(cur_block));
     }
   }
@@ skipping 1360 matching lines @@
 
 
 void HCheckPrototypeMaps::Verify() {
   HInstruction::Verify();
   ASSERT(HasNoUses());
 }
 
 #endif
 
 } }  // namespace v8::internal