The following testcase:
===========================================
struct s{
int m;
int n[N][N][N];
};
struct test1{
struct s a; /* array a.n is unaligned */
int b;
int c;
struct s e[N]; /* array e.n is aligned */
};
int main ()
{
int i,j;
struct test1 tmp1;
for (i = 0; i < N; i++)
for (j = 3; j < N-3; j++)
{
tmp1.e[i].n[1][2][j] = 8;
}
/* check results: */
for (i = 0; i < N; i++)
for (j = 3; j < N-3; j++)
{
if (tmp1.e[i].n[1][2][j] != 8)
abort ();
}
/* not consecutive */
for (i = 0; i < N; i++)
for (j = 3; j < N-3; j++)
{
tmp1.e[j].n[1][2][j] = 8;
}
/* check results: */
for (i = 0; i < N; i++)
for (j = 3; j < N-3; j++)
{
if (tmp1.e[j].n[1][2][j] != 8)
abort ();
}
return 0;
}
===========================================
currently produces wrong results. The problem is that only the indexes of the
last (rightmost) component are analyzed, and the rest are ignored, so we end up
computing wrong alignment (for the first loop) and wrong step (for the second
loop, where we conclude that the access is consecutive where it really isn't).
Both these problems will be addressed soon by the patch that switches to use
get_inner_reference (http://gcc.gnu.org/ml/gcc-patches/2004-10/msg01140.html).
--
Summary: vectorizer: wrong alignment/step/initial-address
computed for struct accesses
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: tree-optimization
AssignedTo: irar at il dot ibm dot com
ReportedBy: dorit at il dot ibm dot com
CC: dorit at il dot ibm dot com,gcc-bugs at gcc dot gnu dot
org
GCC build triplet: powerpc-apple-darwin7.0.0
GCC host triplet: powerpc-apple-darwin7.0.0
GCC target triplet: powerpc-apple-darwin7.0.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18179
