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authorSean Silva <silvas@purdue.edu>2012-12-20 22:59:36 +0000
committerSean Silva <silvas@purdue.edu>2012-12-20 22:59:36 +0000
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docs: Cleanup trailing whitespace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170799 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/Vectorizers.rst')
-rw-r--r--docs/Vectorizers.rst22
1 files changed, 11 insertions, 11 deletions
diff --git a/docs/Vectorizers.rst b/docs/Vectorizers.rst
index fe6a986..5ec3da4 100644
--- a/docs/Vectorizers.rst
+++ b/docs/Vectorizers.rst
@@ -70,7 +70,7 @@ pointers are disjointed, but in our example, the Loop Vectorizer has no way of
knowing that the pointers A and B are unique. The Loop Vectorizer handles this
loop by placing code that checks, at runtime, if the arrays A and B point to
disjointed memory locations. If arrays A and B overlap, then the scalar version
-of the loop is executed.
+of the loop is executed.
.. code-block:: c++
@@ -83,11 +83,11 @@ of the loop is executed.
Reductions
^^^^^^^^^^
-In this example the ``sum`` variable is used by consecutive iterations of
+In this example the ``sum`` variable is used by consecutive iterations of
the loop. Normally, this would prevent vectorization, but the vectorizer can
detect that 'sum' is a reduction variable. The variable 'sum' becomes a vector
of integers, and at the end of the loop the elements of the array are added
-together to create the correct result. We support a number of different
+together to create the correct result. We support a number of different
reduction operations, such as addition, multiplication, XOR, AND and OR.
.. code-block:: c++
@@ -95,7 +95,7 @@ reduction operations, such as addition, multiplication, XOR, AND and OR.
int foo(int *A, int *B, int n) {
unsigned sum = 0;
for (int i = 0; i < n; ++i)
- sum += A[i] + 5;
+ sum += A[i] + 5;
return sum;
}
@@ -159,8 +159,8 @@ The Loop Vectorizer can vectorize loops that count backwards.
Scatter / Gather
^^^^^^^^^^^^^^^^
-The Loop Vectorizer can vectorize code that becomes scatter/gather
-memory accesses.
+The Loop Vectorizer can vectorize code that becomes scatter/gather
+memory accesses.
.. code-block:: c++
@@ -204,13 +204,13 @@ See the table below for a list of these functions.
Performance
-----------
-This section shows the the execution time of Clang on a simple benchmark:
+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
+This benchmarks is a collection of loops from the GCC autovectorization
`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 with and without loop vectorization at -O3, tuned for "corei7-avx", running on a Sandybridge iMac.
-The Y-axis shows the time in msec. Lower is better. The last column shows the geomean of all the kernels.
+The Y-axis shows the time in msec. Lower is better. The last column shows the geomean of all the kernels.
.. image:: gcc-loops.png
:width: 100%
@@ -228,7 +228,7 @@ through clang using the command line flag:
.. code-block:: console
- $ clang -fslp-vectorize file.c
+ $ clang -fslp-vectorize file.c
Details
-------
@@ -237,7 +237,7 @@ The goal of basic-block vectorization (a.k.a. superword-level parallelism) is
to combine similar independent instructions within simple control-flow regions
into vector instructions. Memory accesses, arithemetic operations, comparison
operations and some math functions can all be vectorized using this technique
-(subject to the capabilities of the target architecture).
+(subject to the capabilities of the target architecture).
For example, the following function performs very similar operations on its
inputs (a1, b1) and (a2, b2). The basic-block vectorizer may combine these