New array bounds check elimination pass (focused on induction variables and bitwise operations).

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 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 4293 matching lines @@
 
   // Name is always in r2.
   __ mov(r2, Operand(instr->name()));
   Handle<Code> ic = (instr->strict_mode_flag() == kStrictMode)
       ? isolate()->builtins()->StoreIC_Initialize_Strict()
       : isolate()->builtins()->StoreIC_Initialize();
   CallCode(ic, RelocInfo::CODE_TARGET, instr, NEVER_INLINE_TARGET_ADDRESS);
 }
 
 
+void LCodeGen::ApplyCheckIf(Condition cc, LBoundsCheck* check) {
+  if (FLAG_debug_code && check->hydrogen()->skip_check()) {
+    Label done;
+    __ b(NegateCondition(cc), &done);
+    __ stop("eliminated bounds check failed");
+    __ bind(&done);
+  } else {
+    DeoptimizeIf(cc, check->environment());
+  }
+}
+
+
 void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
   if (instr->hydrogen()->skip_check()) return;
 
   if (instr->index()->IsConstantOperand()) {
     int constant_index =
         ToInteger32(LConstantOperand::cast(instr->index()));
     if (instr->hydrogen()->length()->representation().IsSmi()) {
       __ mov(ip, Operand(Smi::FromInt(constant_index)));
     } else {
       __ mov(ip, Operand(constant_index));
     }
     __ cmp(ip, ToRegister(instr->length()));
   } else {
     __ cmp(ToRegister(instr->index()), ToRegister(instr->length()));
   }
-  DeoptimizeIf(hs, instr->environment());
+  Condition condition = instr->hydrogen()->allow_equality() ? hi : hs;
+  ApplyCheckIf(condition, instr);
 }
 
 
 void LCodeGen::DoStoreKeyedExternalArray(LStoreKeyed* instr) {
   Register external_pointer = ToRegister(instr->elements());
   Register key = no_reg;
   ElementsKind elements_kind = instr->elements_kind();
   bool key_is_constant = instr->key()->IsConstantOperand();
   int constant_key = 0;
   if (key_is_constant) {
@@ skipping 1540 matching lines @@
   __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal