[Patch][LoopVectorize] Print vectorization analysis when loop hint pragma is specified

[Mark Heffernan via llvm-commits]

Nice!

On Mon, Aug 10, 2015 at 6:57 PM, Tyler Nowicki <tnowicki at apple.com> wrote:

> Mark: Would you be interested in extending this to the loop unroller as
> well?
>

I'd be happy to. I'm about to head off on vacation, but I'll get to it when
I return.

Mark


>
> P.S. I assume we should add similar logic to the loop unroller (please add
> a FIXME if you're not going to do this yourself). Another place where this
> would be useful is to warn the user when a function marked always_inline is
> not actually inlined.
>
>
> Hal: Thanks for the all the reviews Hal!
>
> Committed in r244550, r244552,r244555, and r244556.
>
> Tyler
>
> On Aug 9, 2015, at 9:59 PM, Hal Finkel <hfinkel at anl.gov> wrote:
>
> Hi Tyler,
>
> Thanks for working on this!
>
> +    // If a loop hint is provided the diagnostic is always produced.
> +    const char *name = Hints.isForced() ? DiagnosticInfo::AlwaysPrint :
> LV_NAME;
>
> name -> Name
>
> These LGTM.
>
> P.S. I assume we should add similar logic to the loop unroller (please add
> a FIXME if you're not going to do this yourself). Another place where this
> would be useful is to warn the user when a function marked always_inline is
> not actually inlined.
>
> -Hal
>
> ----- Original Message -----
>
> From: "Tyler Nowicki" <tnowicki at apple.com>
> To: "Gonzalo BG" <gonzalobg88 at gmail.com>, "Hal J. Finkel" <hfinkel at anl.gov>,
> "Commit Messages and Patches for LLVM"
> <llvm-commits at lists.llvm.org>, "llvm cfe" <cfe-commits at lists.llvm.org>
> Cc: "Gerolf Hoflehner" <ghoflehner at apple.com>
> Sent: Friday, August 7, 2015 4:15:51 PM
> Subject: [Patch][LoopVectorize] Print vectorization analysis when loop
> hint pragma is specified
>
>
> Hi,
>
>
>
>
>
> Currently, when loop hint is used but vectorization fails we generate
> a warning. To get the analysis the user needs to provide the command
> line option -Rpass-analysis=<passname> with the correct pass name.
> BUT we don’t tell the user which pass name they will need to get the
> analysis message. We should be displaying the analysis without
> having to request it.
>
>
> These patches print the analysis information when vectorization fails
> on loops with hints when the compiler option ‘-Rpass-analysis’ is
> provided without ‘=<passname>'. Users of loop hints can provide the
> compiler option with their regular debug builds to ensure they
> always get the analysis when vectorization fails. This approach is
> preferred because diagnostic printing needs line number tracking
> which is not enabled by normally. Specifying the option without a
> pass-target enables line number tracking and makes viewing the
> messages optional.
>
>
> The LLVM patches modify the pass-name of the diagnostic to
> DiagnosticInfo::AlwaysPrint, which is an empty const char*. The use
> of DiagnosticInfo::AlwaysPrint is recognized when filtering the
> diagnostics allowing the message to be printed even if the filter
> doesn’t match. Note that the analysis of loops with hints will
> always be printed whenever the compiler option is provided even if
> ‘=<pass name>' is specified. This allows both types of analyses to
> be printed at the same time rather than hiding the analysis on loops
> with hints with an pass-target is given.
>
>
> *These patches build on several previous patches still in review to
> add late-diagnostics for fp-commut and aliasing. See threads ' Late
> evaluation of vectorization r equirements’ and ' Late evaluate of
> runtime pointer check's threshold' .
>
>
> Comments and reviews are much appreciated!
>
>
> Tyler
>
>
> (sorry if you received this twice. I used the wrong mailing list
> addresses)
>
>
>
>
>
>
>
>
>
>
>
>
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
>
>
>
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