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Diffstat (limited to 'docs/LangRef.html')
| -rw-r--r-- | docs/LangRef.html | 16 |
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diff --git a/docs/LangRef.html b/docs/LangRef.html index 3fac48d..73e7e2d 100644 --- a/docs/LangRef.html +++ b/docs/LangRef.html @@ -717,6 +717,14 @@ be any type with a size.</p> </td> </tr> </table> + +<p>Note that 'variable sized arrays' can be implemented in LLVM With a zero +length array. Normally accesses past the end of an array are undefined in +LLVM (e.g. it is illegal to access the 5th element of a 3 element array). +As a special case, however, zero length arrays are recognized to be variable +length. This allows implementation of 'pascal style arrays' with the LLVM +type "{ int, [0 x float]}", for example.</p> + </div> <!-- _______________________________________________________________________ --> @@ -1989,7 +1997,15 @@ the LLVM code for the given testcase is equivalent to:</p> ret int* %t5 } </pre> + +<p>Note that it is undefined to access an array out of bounds: array and +pointer indexes must always be within the defined bounds of the array type. +The one exception for this rules is zero length arrays. These arrays are +defined to be accessible as variable length arrays, which requires access +beyond the zero'th element.</p> + <h5>Example:</h5> + <pre> <i>; yields [12 x ubyte]*:aptr</i> %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1 |