On Wed, Aug 09, 2023 at 01:06:22PM -0700, Andrew Pinski wrote:
> That was my next thought, returning NULL from
> single_non_singleton_phi_for_edges if it would return a virtual OP
> might be better even.
> Either version of these patches are ok with me (though I am not the
> maintainer here).
In patch form that would be (but so far untested):
2023-08-09 <ja...@redhat.com>
PR c/102989
* tree-ssa-phiopt.cc (single_non_singleton_phi_for_edges): Never
return virtual phis and return NULL if there is a virtual phi
where the arguments from E0 and E1 edges aren't equal.
--- gcc/tree-ssa-phiopt.cc.jj 2023-08-09 22:08:07.974563266 +0200
+++ gcc/tree-ssa-phiopt.cc 2023-08-09 22:11:37.291517911 +0200
@@ -63,7 +63,13 @@ single_non_singleton_phi_for_edges (gimp
gimple_stmt_iterator i;
gphi *phi = NULL;
if (gimple_seq_singleton_p (seq))
- return as_a <gphi *> (gsi_stmt (gsi_start (seq)));
+ {
+ phi = as_a <gphi *> (gsi_stmt (gsi_start (seq)));
+ /* Never return virtual phis. */
+ if (virtual_operand_p (gimple_phi_result (phi)))
+ return NULL;
+ return phi;
+ }
for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i))
{
gphi *p = as_a <gphi *> (gsi_stmt (i));
@@ -72,6 +78,10 @@ single_non_singleton_phi_for_edges (gimp
gimple_phi_arg_def (p, e1->dest_idx)))
continue;
+ /* Punt on virtual phis with different arguments from the edges. */
+ if (virtual_operand_p (gimple_phi_result (p)))
+ return NULL;
+
/* If we already have a PHI that has the two edge arguments are
different, then return it is not a singleton for these PHIs. */
if (phi)
Jakub
