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| author | Dan Gohman <gohman@apple.com> | 2009-07-27 21:53:46 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2009-07-27 21:53:46 +0000 |
| commit | 1639c3905e934654195318aba00f7eae3d5d677f (patch) | |
| tree | 480fc9d2338e97b45b6fd2b06657dd8f23620dfe /llvm/docs | |
| parent | 52d03b252eb4abae3ad24c5757ffe683bf3620d6 (diff) | |
| download | bcm5719-llvm-1639c3905e934654195318aba00f7eae3d5d677f.tar.gz bcm5719-llvm-1639c3905e934654195318aba00f7eae3d5d677f.zip | |
Add a new keyword 'inbounds' for use with getelementptr. See the
LangRef.html changes for details.
llvm-svn: 77259
Diffstat (limited to 'llvm/docs')
| -rw-r--r-- | llvm/docs/LangRef.html | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/llvm/docs/LangRef.html b/llvm/docs/LangRef.html index 1f9f80d6d43..adc5d9a143f 100644 --- a/llvm/docs/LangRef.html +++ b/llvm/docs/LangRef.html @@ -2091,6 +2091,7 @@ Classifications</a> </div> instruction</a>.</dd> <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt> + <dt><b><tt>getelementptr inbounds ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt> <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on constants. As with the <a href="#i_getelementptr">getelementptr</a> instruction, the index list may have zero or more indexes, which are @@ -3902,6 +3903,7 @@ Instruction</a> </div> <h5>Syntax:</h5> <pre> <result> = getelementptr <pty>* <ptrval>{, <ty> <idx>}* + <result> = getelementptr inbounds <pty>* <ptrval>{, <ty> <idx>}* </pre> <h5>Overview:</h5> @@ -3990,6 +3992,20 @@ entry: } </pre> +<p>If the <tt>inbounds</tt> keyword is present, the result value of the + <tt>getelementptr</tt> is undefined if the base pointer is not pointing + into an allocated object, or if any of the addresses formed by successive + addition of the offsets implied by the indices to the base address is + outside of the allocated object into which the base pointer points.</p> + +<p>If the <tt>inbounds</tt> keyword is not present, the offsets are added to + the base address with silently-wrapping two's complement arithmetic, and + the result value of the <tt>getelementptr</tt> may be outside the object + pointed to by the base pointer. The result value may not necessarily be + used to access memory though, even if it happens to point into allocated + storage. See the <a href="#pointeraliasing">Pointer Aliasing Rules</a> + section for more information.</p> + <p>The getelementptr instruction is often confusing. For some more insight into how it works, see <a href="GetElementPtr.html">the getelementptr FAQ</a>.</p> |
