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[doc] Removed obsolete -count-aa from AliasAnalysis documentation

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Summary:
This patch removes references to AliasAnalysisCounter pass from the AliasAnalysis documentation. That pass have been eliminated in 2015, at revision trunk@247167.

Reviewed By: hfinkel

Differential Revision: https://reviews.llvm.org/D45876

llvm-svn: 330590
This commit is contained in:
Marianne Mailhot-Sarrasin 2018-04-23 13:45:28 +00:00
parent 205b188e49
commit 8bbfcd7f9f
1 changed files with 3 additions and 30 deletions
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33
docs/AliasAnalysis.rst
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@ -389,11 +389,6 @@ in its ``getAnalysisUsage`` that it does so. Some passes attempt to use
``AU.addPreserved<AliasAnalysis>``, however this doesn't actually have any
effect.
``AliasAnalysisCounter`` (``-count-aa``) are implemented as ``ModulePass``
classes, so if your alias analysis uses ``FunctionPass``, it won't be able to
use these utilities. If you try to use them, the pass manager will silently
route alias analysis queries directly to ``BasicAliasAnalysis`` instead.
Similarly, the ``opt -p`` option introduces ``ModulePass`` passes between each
pass, which prevents the use of ``FunctionPass`` alias analysis passes.
@ -408,17 +403,10 @@ before it appears in an alias query. However, popular clients such as ``GVN``
don't support this, and are known to trigger errors when run with the
``AliasAnalysisDebugger``.
Due to several of the above limitations, the most obvious use for the
``AliasAnalysisCounter`` utility, collecting stats on all alias queries in a
compilation, doesn't work, even if the ``AliasAnalysis`` implementations don't
use ``FunctionPass``. There's no way to set a default, much less a default
sequence, and there's no way to preserve it.
The ``AliasSetTracker`` class (which is used by ``LICM``) makes a
non-deterministic number of alias queries. This can cause stats collected by
``AliasAnalysisCounter`` to have fluctuations among identical runs, for
example. Another consequence is that debugging techniques involving pausing
execution after a predetermined number of queries can be unreliable.
non-deterministic number of alias queries. This can cause debugging techniques
involving pausing execution after a predetermined number of queries to be
unreliable.
Many alias queries can be reformulated in terms of other alias queries. When
multiple ``AliasAnalysis`` queries are chained together, it would make sense to
@ -676,21 +664,6 @@ you're using the ``AliasSetTracker`` class. To use it, use something like:
% opt -ds-aa -print-alias-sets -disable-output
The ``-count-aa`` pass
^^^^^^^^^^^^^^^^^^^^^^
The ``-count-aa`` pass is useful to see how many queries a particular pass is
making and what responses are returned by the alias analysis. As an example:
.. code-block:: bash
% opt -basicaa -count-aa -ds-aa -count-aa -licm
will print out how many queries (and what responses are returned) by the
``-licm`` pass (of the ``-ds-aa`` pass) and how many queries are made of the
``-basicaa`` pass by the ``-ds-aa`` pass. This can be useful when debugging a
transformation or an alias analysis implementation.
The ``-aa-eval`` pass
^^^^^^^^^^^^^^^^^^^^^