[PATCH] Support constant expressions, including non-type template parameters, in pragma loop hints

[Hal Finkel]

Tyler,

Thanks for working on this!

First, this patch contains a few things that looks like unrelated cleanup (formatting changes and extra CHECK lines in the tests). Please separate these out (and commit them separately).

Except, not the formatting part of this change (because it makes the lines too long):

-  /// State of the loop optimization specified by the spelling.

   let Args = [EnumArgument<"Option", "OptionType",

-                          ["vectorize", "vectorize_width", "interleave", "interleave_count",

-                           "unroll", "unroll_count"],

-                          ["Vectorize", "VectorizeWidth", "Interleave", "InterleaveCount",

-                           "Unroll", "UnrollCount"]>,

-              DefaultIntArgument<"Value", 1>];

+                          ["vectorize", "vectorize_width", "interleave", "interleave_count", "unroll", "unroll_count"],

+                          ["Vectorize", "VectorizeWidth", "Interleave", "InterleaveCount", "Unroll", "UnrollCount"]>,

+              DefaultBoolArgument<"Enabled", 0>,

+              ExprArgument<"Value", 0>];

And, regarding errors like this:
+/* expected-error {{invalid argument; expected a positive integer value}} */ #pragma clang loop interleave_count(10 / 5 - 2)

I think it is important that we provide the evaluated integer value in the error message (it is obvious in this example, but if the numbers some from preprocessor macros and/or template parameters, it likely won't be obvious). Similarly, if we're given something of the wrong type (like a floating-point value), we should provide the name of the bad type.

Thanks again,
Hal

----- Original Message -----
> From: "Tyler Nowicki" <tnowicki at apple.com>
> To: "llvm cfe" <cfe-commits at cs.uiuc.edu>, "Hal Finkel" <hfinkel at anl.gov>, "Aaron Ballman" <aaron.ballman at gmail.com>,
> "Richard Smith" <richard at metafoo.co.uk>
> Cc: "Nadav Rotem" <nrotem at apple.com>
> Sent: Friday, June 27, 2014 4:11:17 PM
> Subject: [PATCH] Support constant expressions, including non-type template parameters, in pragma loop hints
> 
> Hi Hal, Aaron, Richard,
> 
> This patch adds support for constant expressions, including non-type
> template parameters, in pragma loop hints.
> 
> Support for constant expressions is done using
> ParseConstantExpression() in the pragma parser, modifying the
> LoopHintAttr to hold an Expr, and transforming the LoopHintAttr
> expression during template instantiation.
> 
> Previously it was suggested that I also split the LoopHintAttr into
> an Attr for enable/disable loop hints and an Attr for loop hints
> with an expression. I gave it a try but it caused a lot of
> duplication without much of a reduction in the complexity of loop
> hint handling. I am willing to give it another look if you think it
> would be better in the long run.
> 
> Tyler
> 
> 
> 

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