[PATCH] [lld] ELF: Support detection of relocation errors during processing

[Philip Reames]

Your concern is a legitimate one, but it's also not specific to this 
patch.  The JIT generally makes very little effort to report gracefully 
when a compile fails.  The current philosophy is more or less that the 
frontend is expected to generate IR that is valid to compile; if it 
doesn't, that's a fatal bug in the frontend.  There is a desire to 
change that, but no one has really volunteered to take that on.

Philip

On 01/15/2015 05:05 AM, Benoit Belley wrote:
> Hi Everyone,
>
> My understanding is that the ELF writer is also used by the MCJIT engine
> when filling an object buffer with jitted code. In that context, I am
> wondering if the call to llvm::report_fatal_error() is the appropriate way
> to report the error. Its effect will be to kill the entire host
> application simply because one LLVM module couldn¹t be jitted.
>
> Of course, fatal errors and assertions should never occur! ;-) And, if
> they never occur, then there isn¹t any issue. On the other hand,
> report_fatal_error() has the unfortunate consequence of killing our
> application before our users have any chance of saving their work.
>
> Is that a legitimate concern ? Comments ?
>
> Cheers,
> Benoit
>
> Benoit Belley
> Sr Principal Developer
> M&E-Product Development Group
> Autodesk, Inc.
> www.autodesk.com <http://www.autodesk.com/>
>
>
>
> On 2015-01-14 17:58, "Rui Ueyama" <ruiu at google.com> wrote:
>
>> LGTM with these fixes.
>>
>>
>> REPOSITORY
>>   rL LLVM
>>
>> ================
>> Comment at: lib/ReaderWriter/ELF/SectionChunks.h:424
>> @@ +423,3 @@
>> +    for (const auto ref : *definedAtom) {
>> +      if (std::error_code EC = relHandler.applyRelocation(*writer,
>> buffer,
>> +                                                          *ai, *ref)) {
>> ----------------
>> s/EC/ec/
>>
>> ================
>> Comment at: lib/ReaderWriter/ELF/SectionChunks.h:431
>> @@ -398,1 +430,3 @@
>>    });
>> +  if (success == false)
>> +    llvm::report_fatal_error("relocating output");
>> ----------------
>> if (!success)
>>
>> http://reviews.llvm.org/D6827
>>
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