Fixed crashes exposed though fuzzing.

src/arm/full-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 3467 matching lines @@
     __ jmp(&done);
   }
 
   __ bind(&not_date_object);
   __ CallRuntime(Runtime::kThrowNotDateError, 0);
   __ bind(&done);
   context()->Plug(r0);
 }
 
 
-void FullCodeGenerator::EmitSeqStringSetCharCheck(Register string,
-                                                  Register index,
-                                                  Register value,
-                                                  uint32_t encoding_mask) {
-  __ SmiTst(index);
-  __ Check(eq, kNonSmiIndex);
-  __ SmiTst(value);
-  __ Check(eq, kNonSmiValue);
-
-  __ ldr(ip, FieldMemOperand(string, String::kLengthOffset));
-  __ cmp(index, ip);
-  __ Check(lt, kIndexIsTooLarge);
-
-  __ cmp(index, Operand(Smi::FromInt(0)));
-  __ Check(ge, kIndexIsNegative);
-
-  __ ldr(ip, FieldMemOperand(string, HeapObject::kMapOffset));
-  __ ldrb(ip, FieldMemOperand(ip, Map::kInstanceTypeOffset));
-
-  __ and_(ip, ip, Operand(kStringRepresentationMask | kStringEncodingMask));
-  __ cmp(ip, Operand(encoding_mask));
-  __ Check(eq, kUnexpectedStringType);
-}
-
-
 void FullCodeGenerator::EmitOneByteSeqStringSetChar(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT_EQ(3, args->length());
 
   Register string = r0;
   Register index = r1;
   Register value = r2;
 
   VisitForStackValue(args->at(1));  // index
   VisitForStackValue(args->at(2));  // value
   __ Pop(index, value);
   VisitForAccumulatorValue(args->at(0));  // string
 
   if (FLAG_debug_code) {
+    __ SmiTst(value);
+    __ ThrowIf(ne, kNonSmiValue);
+    __ SmiTst(index);
+    __ ThrowIf(ne, kNonSmiIndex);
+    __ SmiUntag(index, index);
     static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
-    EmitSeqStringSetCharCheck(string, index, value, one_byte_seq_type);
+    __ EmitSeqStringSetCharCheck(string, index, value, one_byte_seq_type);
+    __ SmiTag(index, index);
   }
 
   __ SmiUntag(value, value);
   __ add(ip,
          string,
          Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
   __ strb(value, MemOperand(ip, index, LSR, kSmiTagSize));
   context()->Plug(string);
 }
 
 
 void FullCodeGenerator::EmitTwoByteSeqStringSetChar(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT_EQ(3, args->length());
 
   Register string = r0;
   Register index = r1;
   Register value = r2;
 
   VisitForStackValue(args->at(1));  // index
   VisitForStackValue(args->at(2));  // value
   __ Pop(index, value);
   VisitForAccumulatorValue(args->at(0));  // string
 
   if (FLAG_debug_code) {
+    __ SmiTst(value);
+    __ ThrowIf(ne, kNonSmiValue);
+    __ SmiTst(index);
+    __ ThrowIf(ne, kNonSmiIndex);
+    __ SmiUntag(index, index);
     static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
-    EmitSeqStringSetCharCheck(string, index, value, two_byte_seq_type);
+    __ EmitSeqStringSetCharCheck(string, index, value, two_byte_seq_type);
+    __ SmiTag(index, index);
   }
 
   __ SmiUntag(value, value);
   __ add(ip,
          string,
          Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
   STATIC_ASSERT(kSmiTagSize == 1 && kSmiTag == 0);
   __ strh(value, MemOperand(ip, index));
   context()->Plug(string);
 }
@@ skipping 1412 matching lines @@
   ASSERT(Memory::uint32_at(interrupt_address_pointer) ==
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM