Re: [PATCH, ARM] stop changing signedness in PROMOTE_MODE

[Jim Wilson <jim.wilson@linaro.org>]

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On Tue, Jul 7, 2015 at 2:35 PM, Richard Biener
<richard.guenther@gmail.com> wrote:
> On July 7, 2015 6:29:21 PM GMT+02:00, Jim Wilson <jim.wilson@linaro.org> wrote:
>>signed sub-word locals.  Thus to detect the need for a conversion, you
>>have to have the decls, and we don't have them here.  There is also
>
> It probably is.  The decks for the parameter based SSA names are available, for the PHI destination there might be no decl.

I tried looking again, and found the decls.  I'm able to get correct
code for my testcase with the attached patch to force the conversion.
It is rather inelegant, but I think I can cache the values I need to
make this simpler and cleaner.  I still don't have decls from
insert_part_to_rtx_on_edge and insert_rtx_to_part_on_edge, but it
looks like those are for breaking cycles, and hence might not need
conversions.

Jim

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Index: tree-outof-ssa.c
===================================================================
--- tree-outof-ssa.c	(revision 225477)
+++ tree-outof-ssa.c	(working copy)
@@ -230,11 +230,32 @@ set_location_for_edge (edge e)
    SRC/DEST might be BLKmode memory locations SIZEEXP is a tree from
    which we deduce the size to copy in that case.  */
 
-static inline rtx_insn *
-emit_partition_copy (rtx dest, rtx src, int unsignedsrcp, tree sizeexp)
+rtx_insn *
+emit_partition_copy (rtx dest, rtx src, int unsignedsrcp, tree sizeexp,
+		     tree var2 ATTRIBUTE_UNUSED)
 {
   start_sequence ();
 
+  /* If var2 is set, then sizeexp is the src decl and var2 is the dest decl.  */
+  if (var2)
+    {
+      tree src_var = (TREE_CODE (sizeexp) == SSA_NAME
+		      ? SSA_NAME_VAR (sizeexp) : sizeexp);
+      tree dest_var = (TREE_CODE (var2) == SSA_NAME
+		       ? SSA_NAME_VAR (var2) : var2);
+      int src_unsignedp = TYPE_UNSIGNED (TREE_TYPE (src_var));
+      int dest_unsignedp = TYPE_UNSIGNED (TREE_TYPE (dest_var));
+      machine_mode src_mode = promote_decl_mode (src_var, &src_unsignedp);
+      machine_mode dest_mode = promote_decl_mode (dest_var, &dest_unsignedp);
+      if (src_unsignedp != dest_unsignedp
+	  && src_mode != DECL_MODE (src_var)
+	  && dest_mode != DECL_MODE (dest_var))
+	{
+	  src = gen_lowpart_common (DECL_MODE (src_var), src);
+	  unsignedsrcp = dest_unsignedp;
+	}
+    }
+
   if (GET_MODE (src) != VOIDmode && GET_MODE (src) != GET_MODE (dest))
     src = convert_to_mode (GET_MODE (dest), src, unsignedsrcp);
   if (GET_MODE (src) == BLKmode)
@@ -256,7 +277,7 @@ emit_partition_copy (rtx dest, rtx src,
 static void
 insert_partition_copy_on_edge (edge e, int dest, int src, source_location locus)
 {
-  tree var;
+  tree var, var2;
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
       fprintf (dump_file,
@@ -276,10 +297,11 @@ insert_partition_copy_on_edge (edge e, i
     set_curr_insn_location (locus);
 
   var = partition_to_var (SA.map, src);
+  var2 = partition_to_var (SA.map, dest);
   rtx_insn *seq = emit_partition_copy (copy_rtx (SA.partition_to_pseudo[dest]),
 				       copy_rtx (SA.partition_to_pseudo[src]),
 				       TYPE_UNSIGNED (TREE_TYPE (var)),
-				       var);
+				       var, var2);
 
   insert_insn_on_edge (seq, e);
 }
@@ -373,7 +395,8 @@ insert_rtx_to_part_on_edge (edge e, int
      involved), so it doesn't matter.  */
   rtx_insn *seq = emit_partition_copy (copy_rtx (SA.partition_to_pseudo[dest]),
 				       src, unsignedsrcp,
-				       partition_to_var (SA.map, dest));
+				       partition_to_var (SA.map, dest), 0);
+
 
   insert_insn_on_edge (seq, e);
 }
@@ -406,7 +429,7 @@ insert_part_to_rtx_on_edge (edge e, rtx
   rtx_insn *seq = emit_partition_copy (dest,
 				       copy_rtx (SA.partition_to_pseudo[src]),
 				       TYPE_UNSIGNED (TREE_TYPE (var)),
-				       var);
+				       var, 0);
 
   insert_insn_on_edge (seq, e);
 }