Remove the "special case" for zero-length arrays, and rephrase this

paragraph to be more precise.

llvm-svn: 86572
This commit is contained in:
Dan Gohman 2009-11-09 18:40:39 +00:00
parent e4310c8273
commit 66c4d61010
1 changed files with 7 additions and 6 deletions

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@ -1576,12 +1576,13 @@ Classifications</a> </div>
</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 "<tt>{ i32, [0 x float]}</tt>", for example.</p>
<p>Except when the <tt>inbounds</tt> keyword is present, there is no limitation
on indexing beyond the end of the array implied by the static type (though
any loads or stores must of course be within the bounds of the allocated
object!). This means that single-dimension 'variable sized array' addressing
can be implemented in LLVM with a zero length array type. An implementation
of 'pascal style arrays' in LLVM could use the type
"<tt>{ i32, [0 x float]}</tt>", for example.</p>
<p>Note that the code generator does not yet support large aggregate types to be
used as function return types. The specific limit on how large an aggregate