[Bug tree-optimization/108819] [12/13 Regression] ICE on valid code at -O1 with "-fno-tree-ccp -fno-tree-forwprop" on x86_64-linux-gnu: tree check: expected ssa_name, have integer_cst in number_of_iterations_cltz, at tree-ssa-loop-niter.cc:2394

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108819

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

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

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
I have a patch to make niter analysis more defensive, the 1 & 1 is introduced
by reassoc:

@@ -30,8 +54,8 @@
   <bb 4> [local count: 114863530]:
   _20 = a.0_1 == 0;
   _21 = a.0_1 > 0;
-  _22 = _20 & _21;
-  if (_22 != 0)
+  _7 = 1 & 1;
+  if (_7 != 0)

where update_range_test gets a '1' as result and forces that to an SSA name
and things go downhill from that.  With

diff --git a/gcc/tree-ssa-reassoc.cc b/gcc/tree-ssa-reassoc.cc
index f163612f140..c2b30a03a9d 100644
--- a/gcc/tree-ssa-reassoc.cc
+++ b/gcc/tree-ssa-reassoc.cc
@@ -2950,6 +2950,9 @@ update_range_test (struct range_entry *range, struct
range_entry *otherrange,
     }
   if (stmt == NULL)
     gcc_checking_assert (tem == op);
+  /* When range->exp is a constant, we can use it as-is.  */
+  else if (is_gimple_min_invariant (tem))
+    ;
   /* In rare cases range->exp can be equal to lhs of stmt.
      In that case we have to insert after the stmt rather then before
      it.  If stmt is a PHI, insert it at the start of the basic block.  */

this is resolved (but we still get the intermediate 1 & 1 created).  Jakub,
you know this code more(?), can you see whether there's a better place to
handle this?

I'm testing the niter fortification.