llvm dev - Feb 2014 - [LLVMdev] PassManagerBuilder::LibraryInfo has no effect?

Hi all,

I'm using a library (the llvm-general haskell library, if it matters)
that uses the PassManagerBuilder interface to build a PassManger given
an optimization level, etc. I've extended this to make it possible to
set the PassManagerBuilder's LibraryInfo member, and as a test I created
a TargetLibraryInfo where LibFunc::malloc was set to
"GC_malloc_atomic"
(the allocator for boehm-gc). I've verified that, just before building
the PassManager, pmb->LibraryInfo->getName(LibFunc::malloc) does indeed
return "GC_malloc", yet when I use the PassManager on a module with a
call to GC_malloc whose return value isn't used the call is not
optimized away, while it is when I replace that GC_malloc call with a
call to malloc. Am I misunderstanding the point of LibraryInfo here, or
is something not working correctly? I am using llvm-3.4.

Thanks,
Shea Levy

I figured out the issue and posted a patch [1] to the commits ml.

Cheers,
Shea

[1]
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140203/204401.html

On Mon, Feb 03, 2014 at 11:14:26PM -0500, Shea Levy
wrote:
> Hi all,
> 
> I'm using a library (the llvm-general haskell library, if it matters)
> that uses the PassManagerBuilder interface to build a PassManger given
> an optimization level, etc. I've extended this to make it possible to
> set the PassManagerBuilder's LibraryInfo member, and as a test I
created
> a TargetLibraryInfo where LibFunc::malloc was set to
"GC_malloc_atomic"
> (the allocator for boehm-gc). I've verified that, just before building
> the PassManager, pmb->LibraryInfo->getName(LibFunc::malloc) does
indeed
> return "GC_malloc", yet when I use the PassManager on a module
with a
> call to GC_malloc whose return value isn't used the call is not
> optimized away, while it is when I replace that GC_malloc call with a
> call to malloc. Am I misunderstanding the point of LibraryInfo here, or
> is something not working correctly? I am using llvm-3.4.
> 
> Thanks,
> Shea Levy