------- Comment #14 from rguenth at gcc dot gnu dot org 2008-04-17 15:09
-------
Created an attachment (id=15491)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15491&action=view)
gimple semantics change patch
This is the variant I thought about with changing the way types are interpreted
for the *CREMENT_EXPRs. The usual problem with vectorizer tests appear as SCEV
doesn't handle for example
<bb 3>:
# i_14 = PHI <i_7(5), 0(2)>
D.1560_4 = (int) i_14;
a[D.1560_4] = D.1560_4;
D.1561_6 = D.1560_4 + 1;
i_7 = (short int) D.1561_6;
if (i_7 <= 63)
goto <bb 5>;
else
goto <bb 4>;
but for correctness reasons we cannot do the increment in signed short int
due to the undefined overflow issue. We can avoid the promotion if the
result is truncated to an unsigned type (but this is an optimization that
I didn't want to put into this patch addressing correctness only).
I will re-test this patch, a slightly oder version tested ok apart from
the vectorizer fallout.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35634
