This fixes PR54767 - in VRP we may not propagate symbolical range
information (such as equivalences - see the original fix for
PR53465) across backedges. The following patch makes sure we
don't by cleaning all such information when visiting PHI nodes
for incoming edges marked with EDGE_DFS_BACK.
Honza - if we compute EDGE_DFS_BACK at which places can we
rely (for correctnes) on it being set? On CFG confluence points
(thus, PHI node incoming edges)? It seems split_edge doesn't
"preserve" EDGE_DFS_BACK (the gimple variant places the new
block at e->dest, thus the forwarder edge will retain
EDGE_DFS_BACK). That's unfortunate and requires EDGE_DFS_BACK
compute to be after assert expr insertion (even though it's
also used by it ... just not relied on for correctness).
Bootstrap and regtest pending on x86_64-unknown-linux-gnu
(I verified PR53465 still fails w/o its original fix and is
fixed by the new patch as well).
Thanks,
Richard.
2013-01-15 Richard Biener <rguent...@suse.de>
PR tree-optimization/54767
PR tree-optimization/53465
* tree-vrp.c (vrp_meet_1): Revert original fix for PR53465.
(vrp_visit_phi_node): For PHI arguments coming via backedges
drop all symbolical range information.
(execute_vrp): Compute backedges.
* gfortran.fortran-torture/execute/pr54767.f90: New testcase.
Index: gcc/tree-vrp.c
===================================================================
*** gcc/tree-vrp.c (revision 195190)
--- gcc/tree-vrp.c (working copy)
*************** vrp_meet_1 (value_range_t *vr0, value_ra
*** 7877,7893 ****
if (vr0->type == VR_UNDEFINED)
{
! /* Drop equivalences. See PR53465. */
! set_value_range (vr0, vr1->type, vr1->min, vr1->max, NULL);
return;
}
if (vr1->type == VR_UNDEFINED)
{
! /* VR0 already has the resulting range, just drop equivalences.
! See PR53465. */
! if (vr0->equiv)
! bitmap_clear (vr0->equiv);
return;
}
--- 7877,7889 ----
if (vr0->type == VR_UNDEFINED)
{
! set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr1->equiv);
return;
}
if (vr1->type == VR_UNDEFINED)
{
! /* VR0 already has the resulting range. */
return;
}
*************** vrp_visit_phi_node (gimple phi)
*** 8012,8017 ****
--- 8008,8027 ----
if (TREE_CODE (arg) == SSA_NAME)
{
vr_arg = *(get_value_range (arg));
+ /* Do not allow equivalences or symbolic ranges to leak in from
+ backedges. That creates invalid equivalencies. */
+ if (e->flags & EDGE_DFS_BACK
+ && (vr_arg.type == VR_RANGE
+ || vr_arg.type == VR_ANTI_RANGE))
+ {
+ vr_arg.equiv = NULL;
+ if (symbolic_range_p (&vr_arg))
+ {
+ vr_arg.type = VR_VARYING;
+ vr_arg.min = NULL_TREE;
+ vr_arg.max = NULL_TREE;
+ }
+ }
}
else
{
*************** execute_vrp (void)
*** 9260,9271 ****
--- 9270,9287 ----
rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
scev_initialize ();
+ /* ??? This ends up using stale EDGE_DFS_BACK for liveness computation.
+ Inserting assertions may split edges which will invalidate
+ EDGE_DFS_BACK. */
insert_range_assertions ();
to_remove_edges.create (10);
to_update_switch_stmts.create (5);
threadedge_initialize_values ();
+ /* For visiting PHI nodes we need EDGE_DFS_BACK computed. */
+ mark_dfs_back_edges ();
+
vrp_initialize ();
ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
vrp_finalize ();
Index: gcc/testsuite/gfortran.fortran-torture/execute/pr54767.f90
===================================================================
*** gcc/testsuite/gfortran.fortran-torture/execute/pr54767.f90 (revision 0)
--- gcc/testsuite/gfortran.fortran-torture/execute/pr54767.f90 (working copy)
***************
*** 0 ****
--- 1,31 ----
+ SUBROUTINE XXX (IL, IU)
+ implicit none
+ integer, INTENT(IN) :: IL, IU
+
+ integer :: NXX (14) = (/ 0, 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14 /)
+ integer :: ivvv, ia, ja, iaii
+ logical :: qop
+
+ QOP=.FALSE.
+
+ DO IA=IL,IU
+ JA=NXX(IA)
+ IF (.NOT. QOP .and. JA.GT.0) THEN
+ IAII=IA
+ QOP=.TRUE.
+ ENDIF
+
+ IF (QOP) THEN
+ ivvv=IA-IAII+1 ! mis-compiled
+ ENDIF
+ ENDDO
+
+ IF (ivvv.NE.2) THEN
+ call abort
+ ENDIF
+ END subroutine
+
+ program p
+ implicit none
+ CALL XXX (1, 3)
+ end
