r189440 - Disable loop vectorizer unrolling when no unrolling requested

[Hal Finkel]

----- Original Message -----
> ----- Original Message -----
> > 
> > 
> > 
> > 
> > On Tue, Aug 27, 2013 at 9:40 PM, Hal Finkel < hfinkel at anl.gov >
> > wrote:
> > 
> > 
> > 
> > + // In addition to the regular loop unrolling transformation, the
> > loop
> > + // vectorizer can also unroll loops. If no unrolling has
> > specifically been
> > + // requested, then also prevent the loop vectorizer from
> > unrolling
> > loops.
> > + if (Args.hasFlag(options::OPT_fno_unroll_loops,
> > + options::OPT_funroll_loops, false)) {
> > + CmdArgs.push_back("-backend-option");
> > + CmdArgs.push_back("-force-vector-unroll=1");
> > Please don't use -backend-option. Essentially ever.
> > 
> > 
> > These options force the setting of thread hostile and un-resettable
> > LLVM commandline flags that are only really suitable for debugging.
> > When they are used directly in the Clang driver, tools which invoke
> > CC1 actions with flagsets derived from the driver multiple times in
> > a single process the result of this flag will cause a crash on the
> > second invocation.
> > 
> > 
> > I fixed most of the vectorizer flags to not do this, and wrote a
> > commit message explaining why. Especially when committing with
> > post-commit review, please make sure that you are following the
> > commit lists.
> 
> Ack... you're right. Sorry about that. I'll revert and fix this
> another way.

I fixed this by extending the interaction between the loop vectorizer and the pass manager builder in r189499. Thanks again for the prompt feedback.

 -Hal

> 
>  -Hal
> 
> 
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
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-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory