http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52091
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |NEW
CC| |irar at gcc dot gnu.org
AssignedTo|jakub at gcc dot gnu.org |unassigned at gcc dot
| |gnu.org
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-02-02
12:06:27 UTC ---
Executable testcase:
/* PR tree-optimization/52091 */
int b, c, d, f;
unsigned h;
extern void abort (void);
int
main ()
{
d = -1;
h = 65;
asm volatile ("" : : : "memory");
for (f = 0; f < 4; f++)
{
h &= (unsigned short) d;
for (b = 0; b <= 1; b++)
{
c = 0;
d &= 1;
}
}
asm volatile ("" : : : "memory");
if (b != 2 || c != 0 || d != 1 || f != 4 || h != 1)
abort ();
return 0;
}
Following patch fixes the ICE:
--- gcc/tree-vect-stmts.c.jj 2012-02-01 10:33:58.000000000 +0100
+++ gcc/tree-vect-stmts.c 2012-02-02 11:50:42.623948066 +0100
@@ -1294,7 +1294,11 @@ vect_get_vec_def_for_operand (tree op, g
/* Get the def before the loop */
op = PHI_ARG_DEF_FROM_EDGE (def_stmt, loop_preheader_edge (loop));
- return get_initial_def_for_reduction (stmt, op, scalar_def);
+ vec_oprnd = get_initial_def_for_reduction (stmt, op, scalar_def);
+ if (!is_gimple_val (vec_oprnd))
+ vec_oprnd = vect_init_vector (stmt, vec_oprnd,
+ TREE_TYPE (vec_oprnd), NULL);
+ return vec_oprnd;
}
/* Case 5: operand is defined by loop-header phi - induction. */
but just turns ice-on-valid-code into wrong-code, h is 65 when vectorizing.
Ira, could you please look at this? Thanks.
OT, it is strange that we are creating a reduction for a loop which loops
exactly as many times as there are units in the vector, that doesn't seem to be
profitable.
My other attempt to fix the ICE was:
--- gcc/tree-vect-loop.c.jj 2011-12-16 08:37:45.000000000 +0100
+++ gcc/tree-vect-loop.c 2012-02-02 11:57:25.354607843 +0100
@@ -3370,7 +3370,10 @@ get_initial_def_for_reduction (gimple st
if (TREE_CONSTANT (init_val))
init_def = build_vector (vectype, t);
else
- init_def = build_constructor_from_list (vectype, t);
+ {
+ init_def = build_constructor_from_list (vectype, t);
+ init_def = vect_init_vector (stmt, init_def, vectype, NULL);
+ }
break;
but that ICEs on the testcase, because the other caller of
get_initial_def_for_reduction is calling vect_init_vector immediately after it,
with a different stmt than was passed to get_initial_def_for_reduction, and
this resulted in definition not dominating the use. Wonder if that isn't
another bug.
