[PATCH] Add pass to CSE sin (x) and cos (x) to sincos (x)

[Richard Guenther]

On Fri, 19 Jan 2007, Uros Bizjak wrote:

> Hello Richard!
> 
> > This is the revised patch I am going to commit after a few days of
> > no further objection.
> 
> > 2006-12-27  Richard Guenther  <rguenther@suse.de>
> 
> >  PR tree-optimization/30028
> > * tree-ssa-math-opts.c (maybe_record_sincos): New static helper
> > function.
> > (execute_cse_sincos_1): Likewise.
> 
> For some reason your patch misses transformation for the testcase below:
> 
> --cut here--
> typedef struct cmplx { double x,y; } CMPLX;
> 
> void Complex_Sin (CMPLX *target, CMPLX *source)
> {
>  target->x = sin(source->x) * cosh(source->y);
>  target->y = cos(source->x) * sinh(source->y);
> } /* End Complex_Sin() */

The reason is aliasing.  The store to target->x aliases source->x,
so we cannot prove that the arguments to sin and cos are the same.

Also you need to provide -fno-math-errno, as appearantly cosh/sinh
otherwise force clobbering of global memory:

  # VUSE <SMT.4_13(D)>
  D.1519_2 = source_1(D)->x;
  D.1520_3 = sin (D.1519_2);
  # VUSE <SMT.4_13(D)>
  D.1521_4 = source_1(D)->y;
  # SMT.4_14 = VDEF <SMT.4_13(D)>
  D.1522_5 = cosh (D.1521_4);

which is because cosh may raise a range error through errno for
too large argument:

DEF_LIB_BUILTIN        (BUILT_IN_COSH, "cosh", BT_FN_DOUBLE_DOUBLE, 
ATTR_MATHFN_FPROUNDING_ERRNO)

Richard.

> --cut here--
> 
> .sincos tree dump says:
> 
> Complex_Sin (target, source)
> {
>  double D.1627;
>  double D.1626;
>  double D.1625;
>  double D.1624;
>  double D.1623;
>  double D.1622;
>  double D.1621;
>  double D.1620;
> 
> <bb 2>:
>  D.1620_2 = source_1(D)->x;
>  D.1621_3 = sin (D.1620_2);
>  D.1622_4 = source_1(D)->y;
>  D.1623_5 = cosh (D.1622_4);
>  D.1624_6 = D.1621_3 * D.1623_5;
>  target_7(D)->x = D.1624_6;
>  D.1620_8 = source_1(D)->x;
>  D.1625_9 = cos (D.1620_8);
>  D.1622_10 = source_1(D)->y;
>  D.1626_11 = sinh (D.1622_10);
>  D.1627_12 = D.1625_9 * D.1626_11;
>  target_7(D)->y = D.1627_12;
>  return;
> 
> }
> 
> Uros.
> 
> 
> 

--
Richard Guenther <rguenther@suse.de>
Novell / SUSE Labs