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Expand SJLJ exceptions as tablejump/casesi

Message ID CABu31nO_vKWWVn++3-+5zUWxLYLaY1OCdnE5rjTkq5QAS16wzA@mail.gmail.com
State New
Headers show

Commit Message

Steven Bosscher Sept. 11, 2012, 5:53 p.m. UTC 
Hello,

Thanks for the quick review!

On Tue, Sep 11, 2012 at 5:03 PM, Richard Henderson wrote:
> On 09/10/2012 04:26 PM, Steven Bosscher wrote:
>> +      rtx index = force_reg (index_mode, dispatch_index);
>
> You can't modify the result of force_reg.  Use copy_to_{mode_,}reg instead.

Done.

>> +       rtx tmp = expand_simple_binop (index_mode, MINUS,
>> +                                      index, CONST1_RTX (index_mode),
>> +                                      index, 0, OPTAB_DIRECT);
>> +       gcc_assert (REG_P (tmp));
>> +       if (tmp != index)
>> +         emit_move_insn (index, tmp);
>
> This pattern is force_expand_binop.

Didn't know about this one :-)

> Of course, you don't really need to force index be the same all
> the way down the chain.  You could just as well use
>
>   index = expand_simple_binop (index_mode, MINUS, index, one,
>                                index, 0, OPTAB_DIRECT);
>
> and use any new pseudo in the next iteration.

Right, I've made the changes to do so.

> Otherwise this looks good.

I made the following changes:

$ interdiff sjlj_tablejump.diff.20120910 sjlj_tablejump.diff

and I'm re-testing the updated patch. OK for trunk if it passes?

Ciao!
Steven

Comments

Richard Henderson Sept. 11, 2012, 6:43 p.m. UTC | #1 
On 09/11/2012 10:53 AM, Steven Bosscher wrote:
> +	  force_expand_binop (index_mode, code_to_optab (MINUS),

Use sub_optab directly, rather than code_to_optab.

Otherwise ok.


r~
diff mbox

Patch

diff -u stmt.c stmt.c
--- stmt.c	(working copy)
+++ stmt.c	(working copy)
@@ -2129,19 +2129,16 @@ 
 	 This is more efficient than a dispatch table on most machines.
 	 The last "index--" is redundant but the code is trivially dead
 	 and will be cleaned up by later passes.  */
-      rtx index = force_reg (index_mode, dispatch_index);
+      rtx index = copy_to_mode_reg (index_mode, dispatch_index);
       rtx zero = CONST0_RTX (index_mode);
       for (int i = 0; i < ncases; i++)
         {
 	  tree elt = VEC_index (tree, dispatch_table, i);
 	  rtx lab = label_rtx (CASE_LABEL (elt));
 	  do_jump_if_equal (index_mode, index, zero, lab, 0);
-	  rtx tmp = expand_simple_binop (index_mode, MINUS,
-					 index, CONST1_RTX (index_mode),
-					 index, 0, OPTAB_DIRECT);
-	  gcc_assert (REG_P (tmp));
-	  if (tmp != index)
-	    emit_move_insn (index, tmp);
+	  force_expand_binop (index_mode, code_to_optab (MINUS),
+			      index, CONST1_RTX (index_mode),
+			      index, 0, OPTAB_DIRECT);
 	}
     }
   else