[gcc r12-5292] Fix uninitialized access in merge_call_side_effects

[gcc r12-5292] Fix uninitialized access in merge_call_side_effects

[Jan Hubicka]

https://gcc.gnu.org/g:e69b7c5779863469479698f863ab25e0d9b4586e

commit r12-5292-ge69b7c5779863469479698f863ab25e0d9b4586e
Author: Jan Hubicka <jh@suse.cz>
Date:   Tue Nov 16 09:15:39 2021 +0100

    Fix uninitialized access in merge_call_side_effects
    
    gcc/ChangeLog:
    
            PR ipa/103262
            * ipa-modref.c (merge_call_side_effects): Fix uninitialized
            access.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/tree-ssa/modref-dse-5.c: New test.

Diff:
---
 gcc/ipa-modref.c                             | 64 ++++++++++++++--------------
 gcc/testsuite/gcc.dg/tree-ssa/modref-dse-5.c | 43 +++++++++++++++++++
 2 files changed, 75 insertions(+), 32 deletions(-)

diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index d9d48cc2291..57834303290 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -1014,38 +1014,6 @@ merge_call_side_effects (modref_summary *cur_summary,
       changed = true;
     }
 
-  if (always_executed
-      && callee_summary->kills.length ()
-      && (!cfun->can_throw_non_call_exceptions
-	  || !stmt_could_throw_p (cfun, stmt)))
-    {
-      /* Watch for self recursive updates.  */
-      auto_vec<modref_access_node, 32> saved_kills;
-
-      saved_kills.reserve_exact (callee_summary->kills.length ());
-      saved_kills.splice (callee_summary->kills);
-      for (auto kill : saved_kills)
-	{
-	  if (kill.parm_index >= (int)parm_map.length ())
-	    continue;
-	  modref_parm_map &m
-		  = kill.parm_index == MODREF_STATIC_CHAIN_PARM
-		    ? chain_map
-		    : parm_map[kill.parm_index];
-	  if (m.parm_index == MODREF_LOCAL_MEMORY_PARM
-	      || m.parm_index == MODREF_UNKNOWN_PARM
-	      || m.parm_index == MODREF_RETSLOT_PARM
-	      || !m.parm_offset_known)
-	    continue;
-	  modref_access_node n = kill;
-	  n.parm_index = m.parm_index;
-	  n.parm_offset += m.parm_offset;
-	  if (modref_access_node::insert_kill (cur_summary->kills, n,
-					       record_adjustments))
-	    changed = true;
-	}
-    }
-
   /* We can not safely optimize based on summary of callee if it does
      not always bind to current def: it is possible that memory load
      was optimized out earlier which may not happen in the interposed
@@ -1095,6 +1063,38 @@ merge_call_side_effects (modref_summary *cur_summary,
   if (dump_file)
     fprintf (dump_file, "\n");
 
+  if (always_executed
+      && callee_summary->kills.length ()
+      && (!cfun->can_throw_non_call_exceptions
+	  || !stmt_could_throw_p (cfun, stmt)))
+    {
+      /* Watch for self recursive updates.  */
+      auto_vec<modref_access_node, 32> saved_kills;
+
+      saved_kills.reserve_exact (callee_summary->kills.length ());
+      saved_kills.splice (callee_summary->kills);
+      for (auto kill : saved_kills)
+	{
+	  if (kill.parm_index >= (int)parm_map.length ())
+	    continue;
+	  modref_parm_map &m
+		  = kill.parm_index == MODREF_STATIC_CHAIN_PARM
+		    ? chain_map
+		    : parm_map[kill.parm_index];
+	  if (m.parm_index == MODREF_LOCAL_MEMORY_PARM
+	      || m.parm_index == MODREF_UNKNOWN_PARM
+	      || m.parm_index == MODREF_RETSLOT_PARM
+	      || !m.parm_offset_known)
+	    continue;
+	  modref_access_node n = kill;
+	  n.parm_index = m.parm_index;
+	  n.parm_offset += m.parm_offset;
+	  if (modref_access_node::insert_kill (cur_summary->kills, n,
+					       record_adjustments))
+	    changed = true;
+	}
+    }
+
   /* Merge with callee's summary.  */
   changed |= cur_summary->loads->merge (callee_summary->loads, &parm_map,
 					&chain_map, record_adjustments);
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-5.c b/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-5.c
new file mode 100644
index 00000000000..ad35b70136f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-5.c
@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-dse2-details"  } */
+struct a {int a,b,c;};
+__attribute__ ((noinline))
+void
+kill_me (struct a *a)
+{
+  a->a=0;
+  a->b=0;
+  a->c=0;
+}
+__attribute__ ((noinline))
+int
+wrap(int b, struct a *a)
+{
+   kill_me (a);
+   return b;
+}
+__attribute__ ((noinline))
+void
+my_pleasure (struct a *a)
+{
+  a->a=1;
+  a->c=2;
+}
+__attribute__ ((noinline))
+int
+wrap2(int b, struct a *a)
+{
+   my_pleasure (a);
+   return b;
+}
+
+int
+set (struct a *a)
+{
+  wrap (0, a);
+  int ret = wrap2 (0, a);
+  //int ret = my_pleasure (a);
+  a->b=1;
+  return ret;
+}
+/* { dg-final { scan-tree-dump "Deleted dead store: wrap" "dse2" } } */