Re: [gomp4] rewrite simd clone argument adjustment to avoid regimplification

[Aldy Hernandez]

On 11/07/13 00:38, Jakub Jelinek wrote:
On Wed, Nov 06, 2013 at 05:37:03PM -0700, Aldy Hernandez wrote:
Hmmm, good point.  I've moved update_stmt and company to the caller,
and modified the caller to call regimplify_operands only for
GIMPLE_RETURN which is the special case.

Can't you (later) handle that without regimplification too?

Sure!  See attached patch.

But as discussed on IRC, I wonder whether we can do without the 
following in the attached patch:

+                   tree repl = make_ssa_name (TREE_TYPE (retval), NULL);
+                   stmt = gimple_build_assign (repl, retval);
+                   gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
+                   stmt = gimple_build_assign (ref, repl);

...and unconditionally do:

+                 stmt = gimple_build_assign (ref, retval);

...since it seems all the GIMPLE_RETURNs I see can be replaced by 
``retval_array[iter] = whatever'' without creating something non-gimple 
(thus avoiding an SSA variable).

Either way, I'm ok.  Let me know.

Aldy
gcc/ChangeLog.gomp

        * omp-low.c (ipa_simd_modify_function_body): Avoid
        regimplification of GIMPLE_RETURNs.

diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 14b8571..6039de9 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -11175,26 +11175,31 @@ ipa_simd_modify_function_body (struct cgraph_node 
*node,
            {
            case GIMPLE_RETURN:
              {
-               tree old_retval = gimple_return_retval (stmt);
-               if (old_retval)
+               tree retval = gimple_return_retval (stmt);
+               if (!retval)
                  {
-                   /* Replace `return foo' by `retval_array[iter] = foo'.  */
-                   stmt = gimple_build_assign (build4 (ARRAY_REF,
-                                                       TREE_TYPE (old_retval),
-                                                       retval_array, iter,
-                                                       NULL, NULL),
-                                               old_retval);
-                   gsi_replace (&gsi, stmt, true);
-                   gimple_regimplify_operands (stmt, &gsi);
-                   info.modified = true;
+                   gsi_remove (&gsi, true);
+                   continue;
                  }
+
+               /* Replace `return foo' with `retval_array[iter] = foo'.  */
+               tree ref = build4 (ARRAY_REF,
+                                  TREE_TYPE (retval),
+                                  retval_array, iter,
+                                  NULL, NULL);
+               if (is_gimple_reg (retval))
+                 stmt = gimple_build_assign (ref, retval);
                else
                  {
-                   gsi_remove (&gsi, true);
-                   continue;
+                   tree repl = make_ssa_name (TREE_TYPE (retval), NULL);
+                   stmt = gimple_build_assign (repl, retval);
+                   gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
+                   stmt = gimple_build_assign (ref, repl);
                  }
-               break;
+               gsi_replace (&gsi, stmt, true);
+               info.modified = true;
              }
+             break;
 
            default:
              walk_gimple_op (stmt, ipa_simd_modify_stmt_ops, &wi);