Re: [ping] Fix PR debug/66728

[Mike Stump <mikestump@comcast.net>]

On Nov 4, 2015, at 4:15 AM, Richard Biener <richard.guenther@gmail.com> wrote:
> I wonder if we'll manage to to get mode_for_size return BLKmode
> in case of an original mode that was not of a size multiple of
> HOST_BITS_PER_WIDE_INT (and that's host dependent even…).

> We probably should use smallest_mode_for_size on a precision
> derived from the value

Once we want to go stomping around the value, we might as well just do everything.  I prefer this version over one that has a call to assert.  I thought about creating a helper function, but since there is only 1 client for it, and since it was only 4 lines, I didn’t create one.  I’d propose deferring creation until we have more clients.  The generated dwarf remains fixed, as expected.

> Please use gcc_checking_assert here.

Done.  My test suite run with the assert did finish, and on x86_64 linux, it was never hit.

Any other issues you can spot?


Index: dwarf2out.c
===================================================================
--- dwarf2out.c	(revision 229720)
+++ dwarf2out.c	(working copy)
@@ -15593,8 +15593,13 @@
       return true;
 
     case CONST_WIDE_INT:
-      add_AT_wide (die, DW_AT_const_value,
-		   std::make_pair (rtl, GET_MODE (rtl)));
+      {
+	wide_int w1 = std::make_pair (rtl, MAX_MODE_INT);
+	int prec = MIN (wi::min_precision (w1, UNSIGNED),
+			(unsigned int)CONST_WIDE_INT_NUNITS (rtl) * HOST_BITS_PER_WIDE_INT);
+	wide_int w = wide_int::from (w1, prec, UNSIGNED);
+	add_AT_wide (die, DW_AT_const_value, w);
+      }
       return true;
 
     case CONST_DOUBLE:
Index: rtl.h
===================================================================
--- rtl.h	(revision 229720)
+++ rtl.h	(working copy)
@@ -2086,6 +2086,7 @@
 inline unsigned int
 wi::int_traits <rtx_mode_t>::get_precision (const rtx_mode_t &x)
 {
+  gcc_checking_assert (x.second != BLKmode && x.second != VOIDmode);
   return GET_MODE_PRECISION (x.second);
 }