------- Additional Comments From rguenth at gcc dot gnu dot org 2005-02-09
11:15 -------
Another testcase is the following:
xtern void link_error(void);
void foo(int i)
{
int a[4];
if ((char*)&a[1] + 4*i + 4 != (char*)&a[i+2])
link_error();
if (&a[1] + i + 1 != &a[i+2])
link_error();
}
which I have a patch for that works for C++ by extending the existing
try_move_mult_to_index and trying to avoid inserting (unsinged) casts
there.
Unfortunately, for C (whose initial trees do not contain ARRAY_REF exprs),
the frontend already inserts casts to unsigned (.03.generic):
foo (i)
{
charD.1 * a.0D.1129;
intD.0 D.1130;
charD.1 * D.1131;
charD.1 * D.1132;
charD.1 * D.1133;
unsigned intD.3 i.1D.1134;
unsigned intD.3 D.1135;
intD.0 * D.1136;
intD.0 * D.1137;
intD.0 * D.1138;
charD.1 * D.1139;
intD.0 aD.1128[4];
a.0D.1129 = (charD.1 *) &aD.1128;
D.1130 = iD.1125 * 4;
D.1131 = (charD.1 *) D.1130;
D.1132 = a.0D.1129 + D.1131;
D.1133 = D.1132 + 8B;
i.1D.1134 = (unsigned intD.3) iD.1125;
D.1135 = i.1D.1134 * 4;
D.1136 = (intD.0 *) D.1135;
D.1137 = &aD.1128 + D.1136;
D.1138 = D.1137 + 8B;
D.1139 = (charD.1 *) D.1138;
if (D.1133 != D.1139)
{
link_error ();
}
else
{
}
if (0)
{
link_error ();
}
else
{
}
}
which maybe even wrong, if not hindering optimizations at least.
--
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Last reconfirmed|2005-02-07 19:30:41 |2005-02-09 11:15:29
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19807
