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| author | Dan Gohman <gohman@apple.com> | 2010-07-02 23:46:54 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2010-07-02 23:46:54 +0000 |
| commit | de25629e4f360e86758813dff753beca6065dc3a (patch) | |
| tree | 0e2fc965807df9e3b64cbca24ed574291518c4b1 /llvm | |
| parent | a6d695057cbebb1b08e0f4a9dd3730e4c3ecf9da (diff) | |
| download | bcm5719-llvm-de25629e4f360e86758813dff753beca6065dc3a.tar.gz bcm5719-llvm-de25629e4f360e86758813dff753beca6065dc3a.zip | |
Describe which dependencies are relevant to noalias, and document how
AliasAnalyses have the choice to respect noalias.
llvm-svn: 107544
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/docs/AliasAnalysis.html | 5 | ||||
| -rw-r--r-- | llvm/docs/LangRef.html | 7 |
2 files changed, 11 insertions, 1 deletions
diff --git a/llvm/docs/AliasAnalysis.html b/llvm/docs/AliasAnalysis.html index 5e931d77a89..591694a983c 100644 --- a/llvm/docs/AliasAnalysis.html +++ b/llvm/docs/AliasAnalysis.html @@ -201,6 +201,11 @@ freed and reallocated between accesses through one pointer and accesses through the other -- in this case, there is a dependence, but it's mediated by the free and reallocation.</p> +<p>As an exception to this is with the +<a href="LangRef.html#noalias"><tt>noalias</tt></a> keyword. AliasAnalysis +implementations may choose to ignore the "irrelevant" dependencies, provided +their clients do not need to be aware of these dependencies for correctness.</p> + <p>The MayAlias response is used whenever the two pointers might refer to the same object. If the two memory objects overlap, but do not start at the same location, return MayAlias.</p> diff --git a/llvm/docs/LangRef.html b/llvm/docs/LangRef.html index 7d8f14bca6b..ad730deffb8 100644 --- a/llvm/docs/LangRef.html +++ b/llvm/docs/LangRef.html @@ -1053,7 +1053,12 @@ declare signext i8 @returns_signed_char() <dt><tt><b><a name="noalias">noalias</a></b></tt></dt> <dd>This indicates that pointer values <a href="#pointeraliasing"><i>based</i></a> on the argument or return - value do not alias pointer values which are not <i>based</i> on it. + value do not alias pointer values which are not <i>based</i> on it, + ignoring certain "irrelevant" dependencies. + For a call to the parent function, dependencies between memory + references from before or after the call and from those during the call + are "irrelevant" to the <tt>noalias</tt> keyword for the arguments and + return value used in that call. 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 |
