Q: Accessing signgam from the middle-end for builtin lgamma

["Kaveh R. GHAZI" <ghazi at caip dot rutgers dot edu>]

I'd like to work on using MPFR to handle builtin lgamma.  The lgamma
function requires setting the global int variable "signgam" in addition to
calculating the return value of lgamma.  I think I see how to do grab a
handle on signgam like so:

sg = maybe_get_identifier("signgam");
if (sg)
{
  sg = identifier_global_value(sg); /* Question 1 */
  if (sg)
  {
    if (TREE_TYPE (sg) == TYPE_DECL
        && DECL_ORIGINAL_TYPE (sg) == integer_type_node)
      return sg; /* Use this to set signgam. */
    else
      /* Question 2 */ ;
  }
  else
  {
    /* Question 3 */ ;
  }
else
{
  /* Question 4 */
}


I've marked above where I have questions about how to proceed.

1.  Only the C-family functions have identifier_global_value.  I need to
access this from the middle-end.  Should I use a langhook?  What should
the non-C languages default to returning?  NULL?  Should I punt in non-C
or just set the return value of lgamma without setting signgam?  I could
also declare signgam myself.

2.  I assume that if signgam is defined at global scope with something
other than int type then I punt, or should I proceed without setting
signgam?

3.  If signgam is declared somehow but not at global scope, then should I
declare it myself with type int and proceed to set it?  Or should I ignore
signgam but still generate the lgamma value?  Or do nothing?

4.  Likewise, if signgam is not declared at all, which of the three
choices from #3 should I do?

My guesses are:
1.  Do nothing for non-C.
2.  Punt.
3.  Declare signgam and proceed.
4.  Ditto.

		Thanks,
		--Kaveh
--
Kaveh R. Ghazi			ghazi@caip.rutgers.edu