[docs] loop pragmas: options implying transformations
Following our discussion on the cfe dev list:
http://lists.llvm.org/pipermail/cfe-dev/2019-August/063054.html,
I have added a paragraph that is explicit about loop pragmas, and
transformation options implying the corresponding transformation.
Differential Revision: https://reviews.llvm.org/D66199
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@374756 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/LanguageExtensions.rst b/docs/LanguageExtensions.rst
index 903d450..967f4ad 100644
--- a/docs/LanguageExtensions.rst
+++ b/docs/LanguageExtensions.rst
@@ -3027,6 +3027,14 @@
distribution. Loop hints can be specified before any loop and will be ignored if
the optimization is not safe to apply.
+There are loop hints that control transformations (e.g. vectorization, loop
+unrolling) and there are loop hints that set transformation options (e.g.
+``vectorize_width``, ``unroll_count``). Pragmas setting transformation options
+imply the transformation is enabled, as if it was enabled via the corresponding
+transformation pragma (e.g. ``vectorize(enable)``). If the transformation is
+disabled (e.g. ``vectorize(disable)``), that takes precedence over
+transformations option pragmas implying that transformation.
+
Vectorization, Interleaving, and Predication
--------------------------------------------
