Improve code generation for bounds checks.

src/arm64/lithium-arm64.cc

 // Copyright 2013 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 931 matching lines @@
 
 LInstruction* LChunkBuilder::DoBlockEntry(HBlockEntry* instr) {
   // V8 expects a label to be generated for each basic block.
   // This is used in some places like LAllocator::IsBlockBoundary
   // in lithium-allocator.cc
   return new(zone()) LLabel(instr->block());
 }
 
 
 LInstruction* LChunkBuilder::DoBoundsCheck(HBoundsCheck* instr) {
-  LOperand* value = UseRegisterOrConstantAtStart(instr->index());
-  LOperand* length = UseRegister(instr->length());
-  return AssignEnvironment(new(zone()) LBoundsCheck(value, length));
+  if (!FLAG_debug_code && instr->skip_check()) return NULL;
+  LOperand* index = UseRegisterOrConstantAtStart(instr->index());
+  LOperand* length = !index->IsConstantOperand()
+      ? UseRegisterOrConstantAtStart(instr->length())
+      : UseRegisterAtStart(instr->length());
+  LInstruction* result = new(zone()) LBoundsCheck(index, length);
+  if (!FLAG_debug_code || !instr->skip_check()) {
+    result = AssignEnvironment(result);
+  }
+  return result;
 }
 
 
 LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
   LInstruction* goto_instr = CheckElideControlInstruction(instr);
   if (goto_instr != NULL) return goto_instr;
 
   HValue* value = instr->value();
   Representation r = value->representation();
   HType type = value->type();
@@ skipping 1598 matching lines @@
 
 LInstruction* LChunkBuilder::DoWrapReceiver(HWrapReceiver* instr) {
   LOperand* receiver = UseRegister(instr->receiver());
   LOperand* function = UseRegister(instr->function());
   LWrapReceiver* result = new(zone()) LWrapReceiver(receiver, function);
   return AssignEnvironment(DefineAsRegister(result));
 }
 
 
 } }  // namespace v8::internal