Respect TargetLibraryInfo CustomNames in getAllocationData

[Nuno Lopes]

>> Hi all,
>>
>> Currently, getAllocationData in MemoryBuiltins.cpp (a helper used for
>> functions like isAllocLikeFn) uses TargetLibraryInfo::getLibFunc on
>> the
>> passed in function name to determine if it corresponds to a
>> LibFunc::Func. Unfortunately, getLibFunc looks up Funcs by
>> StandardName
>> (e.g. "malloc" -> LibFunc::Func::malloc) and doesn't respect any
>> overridden names set by TargetLibraryInfo::setAvailableWithName. This
>> is
>> perhaps a bug in getLibFunc (if it isn't, getLibFunc should probably
>> be
>> static), but since existing code may depend on this behavior
>
> Someone else may disagree ;) -- but I see no reason to do it this way. If 
> the current code ignores name substitutions made using 
> setAvailableWithName, then it is broken, and should be fixed. Please 
> submit a patch to properly fix the code in getLibFunc, thanks!

I second that. I did a quick grep for getLibFunc() usage and it seems that 
the desired behavior is the proper one that you describe.
So, I agree with Hal in that it should be getLibFunc() that should be fixed.

Thanks,
Nuno


> -Hal
>
>> the
>> attached patch instead modifies getAllocationData to compare the name
>> associated with each of the Funcs in AllocationFnData with the
>> passed-in
>> function names, and if it matches (which will by the way never be
>> true
>> if the Func is not enabled for that TLI) then that is the Func used
>> for
>> the rest of the function.
>>
>> My test case for this was compiling some IR that had a superfluous
>> call
>> to GC_malloc (return value unused) using a PassManagerBuilder at -O3.
>> By
>> default, the call wasn't optimized away (as expected), but when I set
>> the builder's LibraryInfo to one with Func::malloc set to
>> "GC_malloc",
>> it was optimized away only with this patch applied.
>>
>> Cheers,
>> Shea Levy
>>
>> P.S. I am not currently subscribed to the list, so please CC me in
>> replies (though I'll check the list archives periodically for replies
>> as
>> well)