[PATCH] Documentation for loop unrolling pragmas.

[Mark Heffernan]

Thanks for the comments.  Tyler, I incorporated your suggested rewrite of the unrolling paragraph.  Hopefully it is clearer now.

I also split the vectorization/interleaving pragmas and the unrolling pragmas into separate sections.

Please take another look.

================
Comment at: docs/LanguageExtensions.rst:1791
@@ +1790,3 @@
+Loop unrolling replicates the body of a loop increasing the loop size
+and reducing the loop count.  Loop control overhead can be reduced or
+eliminated, and additional ILP can be exposed.  The unroller selects
----------------
Eli Bendersky wrote:
> Maybe s/loop count/loop trip count/ for clarify? There's another instance later on
Rewrote this bit.

================
Comment at: docs/LanguageExtensions.rst:1793
@@ +1792,3 @@
+eliminated, and additional ILP can be exposed.  The unroller selects
+an unroll count based on a limit on the growth of code size and
+whether the loop can be unrolled completely.
----------------
Eli Bendersky wrote:
> I find this sentence a bit confusing in the context of unroll pragmas which tell the unroller exactly how much we want to unroll. OTOH this sentence seems to be describing the unrolling heuristic?
Rewrote this bit.

http://reviews.llvm.org/D4198