Re: [RFApproval, trunk] Optimization of Complex OP Real.

[Toon Moene <toon at moene dot indiv dot nluug dot nl>]

L.S.,

Here's the improved patch, including all Richards recommendations and
silencing the bleating of the sheep (i.e., -Wparentheses);

Bootstrapped C and Fortran only, make check Fortran and a comparison of
Fortran output of a run with the clean compiler with the updated one on
LAPACK (using their checking procedures).

-- 
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html
Join GNU Fortran 95: http://g95.sourceforge.net/ (under construction)
2002-05-18  Toon Moene  <toon@moene.indiv.nluug.nl>

	* optabs.c (complex_part_zero_p): New.
	* (expand_cmplxdiv_straight): Use.
	* (expand_cmplxdiv_wide): Ditto.
	* (expand_binop): Ditto.

*** optabs.c.orig	Sun Mar 31 13:29:17 2002
--- optabs.c	Sat May 18 10:46:56 2002
*************** static optab new_optab	PARAMS ((void));
*** 109,112 ****
--- 109,114 ----
  static inline optab init_optab	PARAMS ((enum rtx_code));
  static inline optab init_optabv	PARAMS ((enum rtx_code));
+ static inline int complex_part_zero_p PARAMS ((rtx, enum mode_class,
+ 						enum machine_mode));
  static void init_libfuncs PARAMS ((optab, int, int, const char *, int));
  static void init_integral_libfuncs PARAMS ((optab, const char *, int));
*************** widen_operand (op, mode, oldmode, unsign
*** 213,216 ****
--- 215,234 ----
  }
  
+ /* Test whether either the real or imaginary part of a complex floating
+    point number is 0.0, so that it can be ignored (when compiling
+    with -funsafe-math-optimizations). */
+ 
+ static inline int
+ complex_part_zero_p (part, class, submode)
+   rtx part;
+   enum mode_class class;
+   enum machine_mode submode;
+ {
+   return part == 0 ||
+ 	  (flag_unsafe_math_optimizations
+ 	   && class == MODE_COMPLEX_FLOAT
+ 	   && part == CONST0_RTX (submode));
+ }
+ 
  /* Generate code to perform a straightforward complex divide.  */
  
*************** expand_cmplxdiv_straight (real0, real1, 
*** 266,270 ****
      return 0;
  
!   if (imag0 == 0)
      {
        /* Mathematically, ((a)(c-id))/divisor.  */
--- 284,288 ----
      return 0;
  
!   if (complex_part_zero_p (imag0, class, submode))
      {
        /* Mathematically, ((a)(c-id))/divisor.  */
*************** expand_cmplxdiv_wide (real0, real1, imag
*** 432,436 ****
    /* Calculate dividend.  */
  
!   if (imag0 == 0)
      {
        real_t = real0;
--- 450,454 ----
    /* Calculate dividend.  */
  
!   if (complex_part_zero_p (imag0, class, submode))
      {
        real_t = real0;
*************** expand_binop (mode, binoptab, op0, op1, 
*** 1658,1662 ****
  	  /* (a+ib) / (c+id) = ((ac+bd)/(cc+dd)) + i((bc-ad)/(cc+dd)) */
  	  
! 	  if (imag1 == 0)
  	    {
  	      /* (a+ib) / (c+i0) = (a/c) + i(b/c) */
--- 1676,1680 ----
  	  /* (a+ib) / (c+id) = ((ac+bd)/(cc+dd)) + i((bc-ad)/(cc+dd)) */
  	  
! 	  if (complex_part_zero_p (imag1, class, submode))
  	    {
  	      /* (a+ib) / (c+i0) = (a/c) + i(b/c) */