[LLVMdev] Pragma for Loop Unrolling

[Hal Finkel]

Jingyue,

In my limited experience from playing with some simple examples, the metadata is pretty stable; some work has recently been done in this area to clean up some of the lose ends (just the other day, a patch was committed to prevent loop rotation from breaking it).

The work to be done is pretty minimal -- you can take advantage of the infrastructure used to generate the metadata to support OpenMP loop pragmas. Only some of this is upstream (for the rest, see https://github.com/clang-omp/clang_trunk -- lib/CodeGen/CGLoopInfo.cpp in that repository is especially relevant).

 -Hal

----- Original Message -----
> From: "Jingyue Wu" <jingyue at google.com>
> To: llvmdev at cs.uiuc.edu
> Sent: Monday, April 7, 2014 11:08:59 PM
> Subject: [LLVMdev] Pragma for Loop Unrolling
> 
> 
> 
> 
> We are considering supporting loop unrolling pragma in clang for
> CUDA, and want to scope what needs to be done. I came across a
> 3-year old post discussing this (
> http://lists.cs.uiuc.edu/pipermail/llvmdev/2010-June/032074.html ).
> Is there any follow-up work/discussion on this topic? For instance,
> does Clang translate per-loop pragma to metadata? How stable is such
> metadata against LLVM standard optimizations?
> 
> 
> Thanks,
> Jingyue
> 
> 
> 
> 
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-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory