[LLVMdev] Loop Metadata?

Hal Finkel hfinkel at anl.gov
Fri Feb 10 10:19:48 PST 2012

Is there currently a good way of attaching metadata to loops?

The use case that I have in mind is implementing a feature whereby the
user can put
#pragma unroll(N)
above a loop and that serves has an instruction to the optimizer to
unroll the loop N times.

I understand that LLVM does not have a first-class loop construct, but
would attaching the metadata to the instructions that branch to the loop
header be a good idea?

I also wonder whether whatever mechanism would work for this purpose
would also work for implementing OpenMP support.

Thanks again,

Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory

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