We shouldn't throw under FLAG_debug_code, rather abort.

src/arm/macro-assembler-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 3415 matching lines @@
   return stack_passed_words;
 }
 
 
 void MacroAssembler::EmitSeqStringSetCharCheck(Register string,
                                                Register index,
                                                Register value,
                                                uint32_t encoding_mask) {
   Label is_object;
   SmiTst(string);
-  ThrowIf(eq, kNonObject);
+  Check(ne, kNonObject);
 
   ldr(ip, FieldMemOperand(string, HeapObject::kMapOffset));
   ldrb(ip, FieldMemOperand(ip, Map::kInstanceTypeOffset));
 
   and_(ip, ip, Operand(kStringRepresentationMask | kStringEncodingMask));
   cmp(ip, Operand(encoding_mask));
-  ThrowIf(ne, kUnexpectedStringType);
+  Check(eq, kUnexpectedStringType);
 
   // The index is assumed to be untagged coming in, tag it to compare with the
   // string length without using a temp register, it is restored at the end of
   // this function.
   Label index_tag_ok, index_tag_bad;
   TrySmiTag(index, index, &index_tag_bad);
   b(&index_tag_ok);
   bind(&index_tag_bad);
-  Throw(kIndexIsTooLarge);
+  Abort(kIndexIsTooLarge);
   bind(&index_tag_ok);
 
   ldr(ip, FieldMemOperand(string, String::kLengthOffset));
   cmp(index, ip);
-  ThrowIf(ge, kIndexIsTooLarge);
+  Check(lt, kIndexIsTooLarge);
 
   cmp(index, Operand(Smi::FromInt(0)));
-  ThrowIf(lt, kIndexIsNegative);
+  Check(ge, kIndexIsNegative);
 
   SmiUntag(index, index);
 }
 
 
 void MacroAssembler::PrepareCallCFunction(int num_reg_arguments,
                                           int num_double_arguments,
                                           Register scratch) {
   int frame_alignment = ActivationFrameAlignment();
   int stack_passed_arguments = CalculateStackPassedWords(
@@ skipping 605 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM