[Bug tree-optimization/68317] [6 regression] ice in set_value_range, at tree-vrp.c:380

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68317

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |6.0

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
(gdb) p debug_generic_expr (max)
4294443008(OVF)

We have OVF in the IL before VRP:

fn1 ()
{
  unsigned int ivtmp.8;
  int i;
  int _5;

  <bb 2>:

  <bb 3>:
  # ivtmp.8_8 = PHI <4294443008(OVF)(2), ivtmp.8_11(3)>
  _5 = (int) ivtmp.8_8;
  fn2 (_5);
  ivtmp.8_11 = ivtmp.8_8 - 524288;
  goto <bb 3>;

introduced by IVOPTs which does

 fn1 ()
 {
+  unsigned int ivtmp.8;
   int i;
-  int _4;
   int _5;

   <bb 2>:

   <bb 3>:
-  # i_1 = PHI <7(2), i_7(4)>
-  _4 = i_1 + 8184;
-  _5 = _4 * 524288;
+  # ivtmp.8_8 = PHI <4294443008(OVF)(2), ivtmp.8_11(4)>
+  _5 = (int) ivtmp.8_8;
   fn2 (_5);
-  i_7 = i_1 + -1;

   <bb 4>:
+  ivtmp.8_11 = ivtmp.8_8 - 524288;
   goto <bb 3>;

 }

note that the infinite loop contains undefined overflow.

IVOPTs should simply strip the overflow flag (using drop_tree_overflow).