[llvm-commits] [llvm] r170567 - /llvm/trunk/docs/Vectorizers.rst

[Nadav Rotem]

Author: nadav
Date: Wed Dec 19 12:02:36 2012
New Revision: 170567

URL: http://llvm.org/viewvc/llvm-project?rev=170567&view=rev
Log:
DOC: document the use of O2, O3 and Os with -fvectorize.

Modified:
    llvm/trunk/docs/Vectorizers.rst

Modified: llvm/trunk/docs/Vectorizers.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/Vectorizers.rst?rev=170567&r1=170566&r2=170567&view=diff
==============================================================================
--- llvm/trunk/docs/Vectorizers.rst (original)
+++ llvm/trunk/docs/Vectorizers.rst Wed Dec 19 12:02:36 2012
@@ -18,7 +18,11 @@
 
 .. code-block:: console
 
-   $ clang -fvectorize file.c
+   $ clang -fvectorize -O3 file.c
+
+If the ``-fvectorize`` flag is used then the loop vectorizer will be enabled
+when running with ``-O3``, ``-O2``. When ``-Os`` is used, the loop vectorizer
+will only vectorize loops that do not require a major increase in code size.
 
 We plan to enable the Loop Vectorizer by default as part of the LLVM 3.3 release.
 
@@ -194,7 +198,7 @@
 This section shows the the execution time of Clang on a simple benchmark: 
 `gcc-loops <http://llvm.org/viewvc/llvm-project/test-suite/trunk/SingleSource/UnitTests/Vectorizer/>`_.
 This benchmarks is a collection of loops from the GCC autovectorization 
-`page <http://gcc.gnu.org/projects/tree-ssa/vectorization.html>`_ by Dorit Nuzman._
+`page <http://gcc.gnu.org/projects/tree-ssa/vectorization.html>`_ by Dorit Nuzman.
 
 The chart below compares GCC-4.7, ICC-13, and Clang-SVN at -O3, running on a Sandybridge.
 The Y-axis shows time in msec. Lower is better.