[PATCH] D74935: [LangRef][AliasAnalysis] Clarify `noalias` affects only modified objects
Johannes Doerfert via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Sat Feb 22 15:11:39 PST 2020
jdoerfert updated this revision to Diff 246088.
jdoerfert added a comment.
Update language to memory locations instead of objects
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D74935/new/
https://reviews.llvm.org/D74935
Files:
llvm/docs/LangRef.rst
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -1107,14 +1107,16 @@
.. _noalias:
``noalias``
- This indicates that objects accessed via pointer values
+ This indicates that memory locations accessed via pointer values
:ref:`based <pointeraliasing>` on the argument or return value are not also
accessed, during the execution of the function, via pointer values not
- *based* on the argument or return value. The attribute on a return value
- also has additional semantics described below. The caller shares the
- responsibility with the callee for ensuring that these requirements are met.
- For further details, please see the discussion of the NoAlias response in
- :ref:`alias analysis <Must, May, or No>`.
+ *based* on the argument or return value. This guarantee only holds for
+ memory locations that are *modified*, by any means, during the execution of
+ the function. The attribute on a return value also has additional semantics
+ described below. The caller shares the responsibility with the callee for
+ ensuring that these requirements are met. For further details, please see
+ the discussion of the NoAlias response in :ref:`alias analysis <Must, May,
+ or No>`.
Note that this definition of ``noalias`` is intentionally similar
to the definition of ``restrict`` in C99 for function arguments.
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