Re: Expand from tuples

[Paolo Bonzini <bonzini at gnu dot org>]

On 09/01/2009 03:46 AM, Michael Matz wrote:
> * Interaction between builtins and call.  The whole builtins.c is full of
>    references to the tree (call) expression, calling back and forth between
>    it, calls.c, targets and folders.  It's a terrible maze, and will be
>    noisy to change.  Later.

Another problem is that builtins themselves build a lot of trees.  Steps 
towards untangling this could be (some of them have been on my TODO list 
for a long time, some I found out now after going a bit more through the 
code).

* change expand_builtin_interclass_mathfn to use UN*_EXPR instead of 
islessequal/isgreaterequal.  In some cases we can even produce better 
code, for example by doing ourselves the folding of TRUTH_NOT_EXPR to a 
xor, or changing !a && !b to !(a || b).

* use expand_expr_real_2 (introducing also expand_unary/expand_binary, 
maybe?) for things like these as well as COMPLEX_EXPR.  All these tree 
have the same location as the CALL_EXPR, so the glue code in 
expand_expr_real can be applied to the container CALL_EXPR rather than 
these subexpressions..

* change uses of builtin_save_expr from expand_ functions to really 
expand the argument.  I checked and in all cases we can control where to 
expand it and use the resulting VAR_DECL, as in

static rtx expand_save (tree exp, rtx target, tree *decl)
{
  rtx ret = expand_expr (exp, target, VOIDmode, EXPAND_NORMAL, NULL);
  tree val;

  /* Maybe also do the "then" if CONSTANT_P (ret)?  */
  if (TREE_ADDRESSABLE (exp) == 0
      && (TREE_CODE (exp) == PARM_DECL
          || TREE_CODE (exp) == SSA_NAME
          || (TREE_CODE (exp) == VAR_DECL && !TREE_STATIC (exp))))
    val = exp;
  else
    {
      val = build_decl (EXPR_LOCATION (exp),
                        VAR_DECL, NULL, TREE_TYPE (exp));
      DECL_ARTIFICIAL (val) = 1;
      DECL_IGNORED_P (val) = 1;
      if (!CONSTANT_P (ret))
        ret = copy_to_reg (ret);
      SET_DECL_RTL (val, ret);
    }

  if (decl)
    *decl = val;
  return ret;
}

BTW, builtin_save_expr currently misses the case where EXP is a 
SSA_NAME.  This I introduced in the function above.

* make a helper for expand_expr (build_call_nary (...), ...) that hides 
the creation of the tree

Paolo