Re: [PATCH] libgccjit: Handle truncation and extension for casts [PR 95498]

[Antoni Boucher via Gcc-patches]

Hi.
I'd like to know what's the status of the review for this patch.
(Same for my other patch 96889: add some reflection functions in the jit 
C api)
Thanks.
On Tue, Jul 21, 2020 at 11:29:57PM +0200, Andrea Corallo wrote:
Hi Antoni,

a couple of nits and some thoughts.

Antoni Boucher via Gcc-patches <gcc-patches@gcc.gnu.org> writes:

2020-07-12  Antoni Boucher  <boua...@zoho.com>

gcc/jit/
        PR target/95498
        * jit-playback.c: Add support to handle truncation and extension
                      ^^^
                      here we usually add the function that gets
modified, you can look at other changelog entries as example.

diff --git a/gcc/jit/jit-playback.c b/gcc/jit/jit-playback.c
index 0fddf04da87..4f4a1080c36 100644
--- a/gcc/jit/jit-playback.c
+++ b/gcc/jit/jit-playback.c
@@ -61,22 +61,39 @@ along with GCC; see the file COPYING3.  If not see

 /* gcc::jit::playback::context::build_cast uses the convert.h API,
    which in turn requires the frontend to provide a "convert"
-   function, apparently as a fallback.
-
-   Hence we provide this dummy one, with the requirement that any casts
-   are handled before reaching this.  */
+   function, apparently as a fallback for casts that can be simplified
+   (truncation, extension). */
 extern tree convert (tree type, tree expr);

 tree
 convert (tree dst_type, tree expr)
 {
-  gcc_assert (gcc::jit::active_playback_ctxt);
-  gcc::jit::active_playback_ctxt->add_error (NULL, "unhandled conversion");
-  fprintf (stderr, "input expression:\n");
-  debug_tree (expr);
-  fprintf (stderr, "requested type:\n");
-  debug_tree (dst_type);
-  return error_mark_node;
+  tree t_ret = NULL;
+  t_ret = targetm.convert_to_type (dst_type, expr);
+  if (t_ret)
+      return t_ret;
       ^^^
       indent nit
+  enum tree_code dst_code = TREE_CODE (dst_type);
+  switch (dst_code)
+    {
+    case INTEGER_TYPE:
+    case ENUMERAL_TYPE:
+      t_ret = convert_to_integer (dst_type, expr);
+      goto maybe_fold;
+
+    default:
+      gcc_assert (gcc::jit::active_playback_ctxt);
+      gcc::jit::active_playback_ctxt->add_error (NULL, "unhandled conversion");
+      fprintf (stderr, "input expression:\n");
+      debug_tree (expr);
+      fprintf (stderr, "requested type:\n");
+      debug_tree (dst_type);
+      return error_mark_node;
+
+    maybe_fold:
+      if (TREE_CODE (t_ret) != C_MAYBE_CONST_EXPR)
+       t_ret = fold (t_ret);
+      return t_ret;
+    }
 }

Looking at 'convert' at c-convert.c:66 the INTEGER_TYPE case here looks
good, but given the set of casts we accept as input I guess we should
handle also POINTER_TYPE, BOOLEAN_TYPE and REAL_TYPE.  What do you think
about?

Hope it helps

Bests

 Andrea