[Bug tree-optimization/103226] [12 Regression] Recent change to copy-headers causes execution failure for gcc.dg/torture/pr80974

["aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103226

Aldy Hernandez <aldyh at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu.org

--- Comment #1 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
I can't opine on the intricacies of the loopch pass, but the decision the path
solver took was correct:

./cc1 a.c -fdump-tree-all-details -quiet -I/tmp -O2 --param threader-debug=all

Then in the *.ch2 dump file I see:

==============================================
path_range_query: compute_ranges for path: 5->12
range_defined_in_block (BB12) for h_8 is int [0, 0]

=========== BB 5 ============
b.0_3   int [0, 0][5, +INF]
    <bb 5> [local count: 60236916]:
    e = 1;
    goto <bb 12>; [100.00%]


=========== BB 12 ============
Imports: h_8  
Exports: h_8  
b.0_3   int [0, 0][5, +INF]
    <bb 12> [local count: 602369155]:
    # h_8 = PHI <0(5), h_11(11)>
    if (h_8 != 9)
      goto <bb 19>; [90.00%]
    else
      goto <bb 13>; [10.00%]

etc.

The conditional in BB12 resolves to true:

   loopch static returned: _Bool [1, 1]

Which I got from a small tweak to the ch source:

diff --git a/gcc/tree-ssa-loop-ch.c b/gcc/tree-ssa-loop-ch.c
index 566cc275317..d5d80e33450 100644
--- a/gcc/tree-ssa-loop-ch.c
+++ b/gcc/tree-ssa-loop-ch.c
@@ -74,7 +74,14 @@ entry_loop_condition_is_static (class loop *l,
path_range_query *query)
   int_range<2> r;
   query->compute_ranges (e);
   query->range_of_stmt (r, last);
-  return r == int_range<2> (desired_static_value, desired_static_value);
+  bool ret = (r == int_range<2> (desired_static_value, desired_static_value));
+  if (ret && dump_file)
+    {
+    fprintf (dump_file, "loopch static returned: ");
+    r.dump(dump_file);
+    fprintf (dump_file, "\n");
+    }
+  return ret;
 }