[PATCH] DCE dead IFN_GOMP_SIMD_LANE

[Jakub Jelinek]

Hi!

When looking at PR59984, I've noticed that in certain cases we leave
around GOMP_SIMD_LANE calls without lhs.
This internal call is intentionally not ECF_CONST, we don't want it moved
before the loop, and the argument is magic.  But, if nothing uses it
anymore, it isn't needed.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2014-11-14  Jakub Jelinek  <ja...@redhat.com>

        * tree-ssa.dce.c (eliminate_unnecessary_stmts): Eliminate
        IFN_GOMP_SIMD_LANE without lhs as useless.

--- gcc/tree-ssa-dce.c.jj       2014-11-12 13:28:47.000000000 +0100
+++ gcc/tree-ssa-dce.c  2014-11-14 16:15:10.356124955 +0100
@@ -1402,6 +1402,11 @@ eliminate_unnecessary_stmts (void)
                  maybe_clean_or_replace_eh_stmt (stmt, stmt);
                  update_stmt (stmt);
                  release_ssa_name (name);
+
+                 /* GOMP_SIMD_LANE without lhs is not needed.  */
+                 if (gimple_call_internal_p (stmt)
+                     && gimple_call_internal_fn (stmt) == IFN_GOMP_SIMD_LANE)
+                   remove_dead_stmt (&gsi, bb);
                }
              else if (gimple_call_internal_p (stmt))
                switch (gimple_call_internal_fn (stmt))

        Jakub