[Bug tree-optimization/107505] [13 Regression] ICE: verify_flow_info failed (error: returns_twice call is not first in basic block 2)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107505

Alexander Monakov <amonakov at gcc dot gnu.org> changed:

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

--- Comment #1 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
Thanks. This is tree-ssa-sink relocating the call after 'zero' is discovered to
be const, so I think the fix may be as simple as

diff --git a/gcc/tree-ssa-sink.cc b/gcc/tree-ssa-sink.cc
index 921305201..631fc88c3 100644
--- a/gcc/tree-ssa-sink.cc
+++ b/gcc/tree-ssa-sink.cc
@@ -266,11 +266,11 @@ statement_sink_location (gimple *stmt, basic_block
frombb,
   /* We only can sink assignments and non-looping const/pure calls.  */
   int cf;
   if (!is_gimple_assign (stmt)
       && (!is_gimple_call (stmt)
          || !((cf = gimple_call_flags (stmt)) & (ECF_CONST|ECF_PURE))
-         || (cf & ECF_LOOPING_CONST_OR_PURE)))
+         || (cf & (ECF_LOOPING_CONST_OR_PURE|ECF_RETURNS_TWICE))))
     return false;

   /* We only can sink stmts with a single definition.  */
   def_p = single_ssa_def_operand (stmt, SSA_OP_ALL_DEFS);
   if (def_p == NULL_DEF_OPERAND_P)