r221804 - Use the return of readBytes to find out if we are at the end of the stream.

[Jordan Rose]

Committed in r221840.

Jordan


> On Nov 12, 2014, at 15:59 , Jordan Rose <jordan_rose at apple.com> wrote:
> 
> I'm just going to write a gtest unit test for this. That's easy enough.
> 
> Jordan
> 
>> On Nov 12, 2014, at 15:58 , Rafael Avila de Espindola <rafael.espindola at gmail.com> wrote:
>> 
>> Would it reproduce with opt and an empty file?
>> 
>> Sent from my iPhone
>> 
>>> On Nov 12, 2014, at 18:54, Jordan Rose <jordan_rose at apple.com> wrote:
>>> 
>>> 
>>>> On Nov 12, 2014, at 15:38, Rafael Avila de Espindola <rafael.espindola at gmail.com> wrote:
>>>> 
>>>> 
>>>> 
>>>> Sent from my iPhone
>>>> 
>>>>> On Nov 12, 2014, at 18:22, Jordan Rose <jordan_rose at apple.com> wrote:
>>>>> 
>>>>> Looks like it's just this:
>>>>> 
>>>>> diff --git a/include/llvm/Bitcode/BitstreamReader.h b/include/llvm/Bitcode/BitstreamReader.h
>>>>> index 6b9c858..41e50e1 100644
>>>>> --- a/include/llvm/Bitcode/BitstreamReader.h
>>>>> +++ b/include/llvm/Bitcode/BitstreamReader.h
>>>>> @@ -227,7 +227,7 @@ public:
>>>>> bool AtEndOfStream() {
>>>>> if (BitsInCurWord != 0)
>>>>>   return false;
>>>>> -    if (Size == NextChar)
>>>>> +    if (Size != 0 && Size == NextChar)
>>>>>   return true;
>>>>> fillCurWord();
>>>>> return BitsInCurWord == 0;
>>>>> 
>>>>> i.e. you forgot about the fact that we /start/ with both Size and NextChar equal to 0. Does this look like the right fix to you?
>>>> 
>>>> 
>>>> Oh, so a call at the very start would fail. LGTM
>>> 
>>> Yup, I don't have a test case in LLVM's code, but Swift is checking explicitly for an empty file. Took me a while to track that down.
>>> 
>>> Thanks, I'll commit.
>>> Jordan
>>> 
>