This backport contains 1 patch from gcc main stream tree.
The commit id of these patchs list as following in the order of time.

0001-tree-optimization-94963-avoid-bogus-uninit-warning-with-store-motion.patch
371905d12259c180efb9b1f1b5716e969feb60f9

diff --git a/gcc/testsuite/gcc.dg/pr94963.c b/gcc/testsuite/gcc.dg/pr94963.c
new file mode 100644
index 00000000000..aca9e161301
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94963.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wall" } */
+
+typedef struct
+{
+  int p1;
+  int p2;
+  int p3;
+} P;
+struct S
+{
+  int field;
+};
+extern int v2;
+extern void foo (struct S *map);
+static struct S var;
+const P *pv;
+int ps;
+void
+f (void)
+{
+  if (pv != 0)
+    for (const P *ph = pv; ph < &pv[ps]; ++ph)
+      switch (ph->p1)
+	{
+	case 1:
+	v2 = ph->p2;
+	break;
+	case 2:
+	var.field = ph->p3;
+	break;
+	}
+  if (var.field != 0) /* { dg-bogus "uninitialized" } */
+    foo (&var);
+}
diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index 554dd4be5bb..3056b4bfed2 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -1994,8 +1994,6 @@ execute_sm_if_changed (edge ex, tree mem, tree tmp_var, tree flag,
   gsi = gsi_start_bb (then_bb);
   /* Insert actual store.  */
   stmt = gimple_build_assign (unshare_expr (mem), tmp_var);
-  /* Make sure to not warn about maybe-uninit uses of tmp_var here.  */
-  gimple_set_no_warning (stmt, true);
   gsi_insert_after (&gsi, stmt, GSI_CONTINUE_LINKING);
 
   edge e1 = single_succ_edge (new_bb);
@@ -2149,13 +2147,19 @@ execute_sm (class loop *loop, vec<edge> exits, im_mem_ref *ref)
      store then.  */
   if ((!always_stored && !multi_threaded_model_p)
       || (ref->loaded && bitmap_bit_p (ref->loaded, loop->num)))
+    load = gimple_build_assign (tmp_var, unshare_expr (ref->mem.ref));
+  else
     {
-      load = gimple_build_assign (tmp_var, unshare_expr (ref->mem.ref));
-      lim_data = init_lim_data (load);
-      lim_data->max_loop = loop;
-      lim_data->tgt_loop = loop;
-      gsi_insert_before (&gsi, load, GSI_SAME_STMT);
+      /* If not emitting a load mark the uninitialized state on the
+	 loop entry as not to be warned for.  */
+      tree uninit = create_tmp_reg (TREE_TYPE (tmp_var));
+      TREE_NO_WARNING (uninit) = 1;
+      load = gimple_build_assign (tmp_var, uninit);
     }
+  lim_data = init_lim_data (load);
+  lim_data->max_loop = loop;
+  lim_data->tgt_loop = loop;
+  gsi_insert_before (&gsi, load, GSI_SAME_STMT);
 
   if (multi_threaded_model_p)
     {