diff options
author | Nadav Rotem <nrotem@apple.com> | 2013-04-15 22:21:25 +0000 |
---|---|---|
committer | Nadav Rotem <nrotem@apple.com> | 2013-04-15 22:21:25 +0000 |
commit | 3fe91a4453cad041f038398de978679106b5ed67 (patch) | |
tree | 578fc26c6f7d7ca01a8e7e3d7a38658e373a4525 /docs/Vectorizers.rst | |
parent | 96e0b96a9104a4df0bb3e19f91c1493db2b7ab44 (diff) | |
download | external_llvm-3fe91a4453cad041f038398de978679106b5ed67.zip external_llvm-3fe91a4453cad041f038398de978679106b5ed67.tar.gz external_llvm-3fe91a4453cad041f038398de978679106b5ed67.tar.bz2 |
Fix a grammar mistake, and add a line about the two phases that the BB/SLP vectorizers have (top-down and bottom-up).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179566 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/Vectorizers.rst')
-rw-r--r-- | docs/Vectorizers.rst | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/docs/Vectorizers.rst b/docs/Vectorizers.rst index d5c286a..d565c21 100644 --- a/docs/Vectorizers.rst +++ b/docs/Vectorizers.rst @@ -5,11 +5,11 @@ Auto-Vectorization in LLVM .. contents:: :local: -LLVM has two kind vectorizers: The :ref:`Loop Vectorizer <loop-vectorizer>`, +LLVM has two vectorizers: The :ref:`Loop Vectorizer <loop-vectorizer>`, which operates on Loops, and the :ref:`SLP Vectorizer <slp-vectorizer>`, which optimizes straight-line code. These vectorizers focus on different optimization opportunities and use different techniques. -The BB vectorizer merges multiple scalars that are found in the code into +The SLP vectorizer merges multiple scalars that are found in the code into vectors while the Loop Vectorizer widens instructions in the original loop to operate on multiple consecutive loop iterations. @@ -318,6 +318,8 @@ into vector operations. A[1] = a2*(a2 + b2)/b2 + 50*b2/a2; } +The SLP-vectorizer has two phases, bottom-up, and top-down. The top-down vectorization +phase is more aggressive, but takes more time to run. Usage ------ @@ -329,7 +331,7 @@ through clang using the command line flag: $ clang -fslp-vectorize file.c -LLVM has a second phase basic block vectorization phase +LLVM has a second basic block vectorization phase which is more compile-time intensive (The BB vectorizer). This optimization can be enabled through clang using the command line flag: |