Revise llvm.vectorizer.width documentation

- clarify that vectorizer.width only applies if the vectorizer decides to
  vectorize.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182938 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Paul Redmond 2013-05-30 17:22:46 +00:00
parent 977de2d869
commit f95ac8a474

View File

@ -2680,8 +2680,10 @@ determined automatically.
'``llvm.vectorizer.width``' Metadata
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This metadata forces the loop vectorizer to widen scalar values to a vector
width of ``N`` rather than computing the width using a cost model.
This metadata sets the target width of the vectorizer to ``N``. Without
this metadata, the vectorizer will choose a width automatically.
Regardless of this metadata, the vectorizer will only vectorize loops if
it believes it is valid to do so.
The first operand is the string ``llvm.vectorizer.width`` and the second
operand is an integer specifying the width. For example: