https://llvm.org/bugs/show_bug.cgi?id=24603
Bug ID: 24603
Summary: doesNotAccessMemory documentation has wrong example
Product: libraries
Version: trunk
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Global Analyses
Assignee: unassignedb...@nondot.org
Reporter: schnet...@gmail.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
The file docs/AliasAnalysis.rst contains these lines:
{{{
The ``doesNotAccessMemory`` and ``onlyReadsMemory`` methods
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
These methods are used to provide very simple mod/ref information for function
calls. The ``doesNotAccessMemory`` method returns true for a function if the
analysis can prove that the function never reads or writes to memory, or if the
function only reads from constant memory. Functions with this property are
side-effect free and only depend on their input arguments, allowing them to be
eliminated if they form common subexpressions or be hoisted out of loops. Many
common functions behave this way (e.g., ``sin`` and ``cos``) but many others do
not (e.g., ``acos``, which modifies the ``errno`` variable).
}}}
I think the examples {sin} and {cos} are wrong, since they set errno (if the
argument is infinite). Better examples may be {fabs} and {copysign}.
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