RFR 8191278: MappedByteBuffer bulk access memory failures are not handled gracefully

[Jamsheed]

Hi Dan,

Thanks for the review.

Best regards,

Jamsheed

On 01/06/19 6:29 PM, Daniel D. Daugherty wrote:
> That's even better. Thanks.
>
> Dan
>
>
> On 6/1/19 5:11 AM, Jamsheed wrote:
>>
>> Hi Dan,
>>
>> updated webrev in place
>>
>> added only assert
>>
>> +  BasicType doing_unsafe_access_bt = T_BYTE;
>> +  assert((sizeof(bool) * CHAR_BIT) == 8, "not implemented");
>>
>> Best regards,
>>
>> Jamsheed
>>
>> On 01/06/19 12:56 PM, Jamsheed wrote:
>>>
>>> Hi Dan,
>>>
>>> i understand it is incorrect to assume bool(cpp compiler) 
>>> implementation above byte level.
>>>
>>> in that case i will just put an assert.
>>>
>>> +  BasicType doing_unsafe_access_bt = T_BYTE;
>>>
>>> + assert(sizeof(bool) == 1, "not implemented");
>>>
>>> Best regards,
>>>
>>> Jamsheed
>>>
>>> On 31/05/19 10:34 PM, Jamsheed wrote:
>>>>> src/hotspot/share/opto/library_call.cpp
>>>>>     In src/hotspot/share/runtime/thread.hpp:
>>>>>     L1090:   volatile bool         _doing_unsafe_access;
>>>>>
>>>>>     L4220:   store_to_memory(control(), doing_unsafe_access_addr, 
>>>>> intcon(1), T_BYTE, Compile::AliasIdxRaw, MemNode::unordered);
>>>>>     L4230:   store_to_memory(control(), doing_unsafe_access_addr, 
>>>>> intcon(0), T_BYTE, Compile::AliasIdxRaw, MemNode::unordered);
>>>>>         Is T_BYTE a safe assumption (size wise) for writing to a 
>>>>> C++ bool?
>>>>
>>>> Thanks for pointing this.
>>>>
>>>> hope [1] will work ?
>>> [1]
>>> +  BasicType doing_unsafe_access_bt = T_BYTE;
>>> +  switch(sizeof(bool)) {
>>> +    case 1: doing_unsafe_access_bt = T_BYTE;  break;
>>> +    case 2: doing_unsafe_access_bt = T_SHORT; break;
>>> +    case 4: doing_unsafe_access_bt = T_INT;   break;
>>> +    case 8: doing_unsafe_access_bt = T_LONG;  break;
>>> +    default: ShouldNotReachHere();
>>> +  }
>>>
>>>    // update volatile field
>>> -  store_to_memory(control(), doing_unsafe_access_addr, intcon(1), 
>>> T_BYTE, Compile::AliasIdxRaw, MemNode::unordered);
>>> +  store_to_memory(control(), doing_unsafe_access_addr, intcon(1), 
>>> doing_unsafe_access_bt, Compile::AliasIdxRaw, MemNode::unordered);
>>>
>>>    // Call it.  Note that the length argument is not scaled.
>>>    make_runtime_call(RC_LEAF|RC_NO_FP,
>>>                      OptoRuntime::fast_arraycopy_Type(),
>>>                      StubRoutines::unsafe_arraycopy(),
>>>                      "unsafe_arraycopy",
>>>                      TypeRawPtr::BOTTOM,
>>>                      src, dst, size XTOP);
>>>
>>> -  store_to_memory(control(), doing_unsafe_access_addr, intcon(0), 
>>> T_BYTE, Compile::AliasIdxRaw, MemNode::unordered);
>>> +  store_to_memory(control(), doing_unsafe_access_addr, intcon(0), 
>>> doing_unsafe_access_bt, Compile::AliasIdxRaw, MemNode::unordered); 
>