math code optimisation

[P.Stephenson@xxxxxxxxxxxxx]

I just happened to look at mathevall() and noticed it was doing a lot
of unncecessary memory moving, as well as keeping some stack space
around when it wasn't using it.  Actual, tidying this up seems to make
the code (OSF/1 3.0, using `size') 170 bytes larger, though there's
less in data/bss, and it looked like it made about 8k difference
(using `ps') at run time (which I don't understand since it should be
about 1.5k, even with 64-bit longs; perhaps it's getting rounded up
somewhere).

*** Src/math.c.stk	Tue May 30 14:29:00 1995
--- Src/math.c	Tue May 30 15:25:03 1995
***************
*** 146,152 ****
  /* list of lvalues (variables) */
  
  static int lvc;
! static char *lvals[LVCOUNT];
  
  
  /**/
--- 146,152 ----
  /* list of lvalues (variables) */
  
  static int lvc;
! static char **lvals;
  
  
  /**/
***************
*** 463,471 ****
  struct mathvalue {
      LV lval;
      long val;
! }
  
! stack[STACKSZ];
  
  static void push _((long val, LV lval));
  
--- 463,471 ----
  struct mathvalue {
      LV lval;
      long val;
! };
  
! static struct mathvalue *stack;
  
  static void push _((long val, LV lval));
  
***************
*** 782,790 ****
      char *xptr;
      long xyyval;
      LV xyylval;
!     char *xlvals[LVCOUNT];
      int xmtok, xsp;
!     struct mathvalue xstack[STACKSZ];
      long ret;
  
      xlastbase = xnoeval = xunary = xlvc = xyyval = xyylval = xsp = xmtok = 0;
--- 782,790 ----
      char *xptr;
      long xyyval;
      LV xyylval;
!     char **xlvals = 0;
      int xmtok, xsp;
!     struct mathvalue *xstack = 0;
      long ret;
  
      xlastbase = xnoeval = xunary = xlvc = xyyval = xyylval = xsp = xmtok = 0;
***************
*** 797,811 ****
  	xptr = ptr;
  	xyyval = yyval;
  	xyylval = yylval;
! 	memcpy(xlvals, lvals, LVCOUNT * sizeof(char *));
  
  	xmtok = mtok;
  	xsp = sp;
! 	memcpy(xstack, stack, STACKSZ * sizeof(struct mathvalue));
      }
      lastbase = -1;
!     for (t0 = 0; t0 != LVCOUNT; t0++)
! 	lvals[t0] = NULL;
      lvc = 0;
      ptr = s;
      sp = -1;
--- 797,811 ----
  	xptr = ptr;
  	xyyval = yyval;
  	xyylval = yylval;
! 	xlvals = lvals;
  
  	xmtok = mtok;
  	xsp = sp;
! 	xstack = stack;
      }
+     stack = (struct mathvalue *)zalloc(STACKSZ*sizeof(struct mathvalue));
      lastbase = -1;
!     lvals = (char **)zcalloc(LVCOUNT*sizeof(char *));
      lvc = 0;
      ptr = s;
      sp = -1;
***************
*** 819,824 ****
--- 819,826 ----
  
      ret = stack[0].val;
  
+     zfree(lvals, LVCOUNT*sizeof(char *));
+     zfree(stack, STACKSZ*sizeof(struct mathvalue));
      if (--mlevel) {
  	lastbase = xlastbase;
  	noeval = xnoeval;
***************
*** 827,837 ****
  	ptr = xptr;
  	yyval = xyyval;
  	yylval = xyylval;
! 	memcpy(lvals, xlvals, LVCOUNT * sizeof(char *));
  
- 	sp = xsp;
  	mtok = xmtok;
! 	memcpy(stack, xstack, STACKSZ * sizeof(struct mathvalue));
      }
      return ret;
  }
--- 829,839 ----
  	ptr = xptr;
  	yyval = xyyval;
  	yylval = xyylval;
! 	lvals = xlvals;
  
  	mtok = xmtok;
! 	sp = xsp;
! 	stack = xstack;
      }
      return ret;
  }

-- 
Peter Stephenson <P.Stephenson@xxxxxxxxxxxxx>  Tel: +44 1792 205678 extn. 4461
WWW:  http://python.swan.ac.uk/~pypeters/      Fax: +44 1792 295324
Department of Physics, University of Wales, Swansea,
Singleton Park, Swansea, SA2 8PP, U.K.