[gcc r13-1975] middle-end: Guard value_replacement and store_elim from seeing diamonds.

[Tamar Christina <tnfchris@gcc.gnu.org>]

https://gcc.gnu.org/g:1878ab3650d8c646a4db364df388adaec2a29870

commit r13-1975-g1878ab3650d8c646a4db364df388adaec2a29870
Author: Tamar Christina <tamar.christina@arm.com>
Date:   Fri Aug 5 14:53:28 2022 +0100

    middle-end: Guard value_replacement and store_elim from seeing diamonds.
    
    This excludes value_replacement and store_elim from diamonds as they don't
    handle the form properly.
    
    gcc/ChangeLog:
    
            PR middle-end/106534
            * tree-ssa-phiopt.cc (tree_ssa_phiopt_worker): Guard the
            value_replacement and store_elim from diamonds.

Diff:
---
 gcc/tree-ssa-phiopt.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index ef4c0b78f4e..0191b9cb254 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -283,7 +283,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
 	  || (e1->flags & EDGE_FALLTHRU) == 0)
         continue;
 
-      if (do_store_elim)
+      if (do_store_elim && !diamond_p)
 	{
 	  /* Also make sure that bb1 only have one predecessor and that it
 	     is bb.  */
@@ -310,7 +310,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
 
 	  /* Value replacement can work with more than one PHI
 	     so try that first. */
-	  if (!early_p)
+	  if (!early_p && !diamond_p)
 	    for (gsi = gsi_start (phis); !gsi_end_p (gsi); gsi_next (&gsi))
 	      {
 		phi = as_a <gphi *> (gsi_stmt (gsi));