Re: [Fwd: Re: [PATCH] Add powi-to-multiply expansion to cse_sincos pass]

["William J. Schmidt" <wschmidt at linux dot vnet dot ibm dot com>]

On Tue, 2011-05-24 at 16:44 +0200, Richard Guenther wrote:
> On Tue, May 24, 2011 at 3:38 PM, William J. Schmidt
> <wschmidt@linux.vnet.ibm.com> wrote:
> >
> > On Tue, 2011-05-24 at 15:11 +0200, Richard Guenther wrote:
> >> On Tue, May 24, 2011 at 2:26 PM, William J. Schmidt
> >> <wschmidt@linux.vnet.ibm.com> wrote:
> >> > Sure, I'll give that a try this morning.  Much obliged.
> >>
> >> Seems it won't work that way without some major changes elsewhere.
> >> Instead follow what update_call_from_tree () does before calling
> >> gsi_replace.
> >
> > Bother.  This won't work, unfortunately.  I can't use gimple_set_vuse ()
> > and gimple_set_vdef () on statements without memory ops.
> 
> You should do
> 
>   if (!gimple_has_mem_ops (new_stmt))
>     unlink_stmt_vdef (old_stmt);

OK, thanks, that's the interface I was struggling to find.

That solved the issue I ran into.  The handling for powi now looks like
this:

		CASE_FLT_FN (BUILT_IN_POWI):
		  arg0 = gimple_call_arg (stmt, 0);
		  arg1 = gimple_call_arg (stmt, 1);
		  if (!host_integerp (arg1, 0))
		    break;

		  n = TREE_INT_CST_LOW (arg1);
		  loc = gimple_location (stmt);
		  result = gimple_expand_builtin_powi (&gsi, loc, arg0, n);

		  if (result)
		    {
		      tree lhs = gimple_get_lhs (stmt);
		      gimple new_stmt = gimple_build_assign (lhs, result);
		      gimple_set_location (new_stmt, loc);
		      move_ssa_defining_stmt_for_defs (new_stmt, stmt);

		      if (gimple_vdef (stmt))
			{
			  gcc_assert (!gimple_has_mem_ops (new_stmt));
			  unlink_stmt_vdef (stmt);
			}

		      gsi_replace (&gsi, new_stmt, true);
		    }
		  break;

gimple_has_mem_ops (new_stmt) will always return false.  The assert is
in place in case we add other powi transforms in the future.

The call to move_ssa_defining_stmt_for_defs requires adding the header
file tree-ssa-propagate.h, and the corresponding dependency in
Makefile.in.

Currently regression testing the "final" fix.  Let me know if you want
to see it one more time before commit.

Thanks as always for your help!

Bill

> 
> > Bill
> >
> >>
> >> Richard.
> >>
> >
> >
> >