• Sam Lantinga's avatar
    Von: Thomas Zimmermann · e526b618
    Sam Lantinga authored
    Betreff: [SDL] [PATCH] Make static variables const
    Datum: Tue, 19 May 2009 19:45:37 +0200
    
    Hi,
    
    this is a set of simple changes which make some of SDL's internal static
    arrays constant. The purpose is to shrink the number of write-able
    static bytes and thus increase the number of memory pages shared between
    SDL applications.
    
    The patch set is against trunk@4513. Each of the attached patch files is
    specific to a sub-system. The set is completed by a second mail, because
    of the list's 40 KiB limit.
    
    The files readelf-r4513.txt and readelf-const-patch.txt where made by
    calling 'readelf -S libSDL.so'. They show the difference in ELF sections
    without and with the patch. Some numbers measured on my x86-64:
    
    Before
    
     [13] .rodata           PROGBITS         00000000000eaaa0  000eaaa0
          0000000000008170  0000000000000000   A       0     0     32
     [19] .data.rel.ro      PROGBITS         00000000003045e0  001045e0
          00000000000023d0  0000000000000000  WA       0     0     32
     [23] .data             PROGBITS         00000000003076e0  001076e0
          0000000000004988  0000000000000000  WA       0     0     32
    
    After
    
     [13] .rodata           PROGBITS         00000000000eaaa0  000eaaa0
          0000000000009a50  0000000000000000   A       0     0     32
     [19] .data.rel.ro      PROGBITS         0000000000306040  00106040
          0000000000002608  0000000000000000  WA       0     0     32
     [23] .data             PROGBITS         0000000000309360  00109360
          0000000000002e88  0000000000000000  WA       0     0     32
    
    The size of the write-able data section decreased considerably. Some
    entries became const-after-relocation, while most of its content went
    straight into the read-only data section.
    
    Best regards, Thomas
    
    --HG--
    extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403618
    e526b618
s_fabs.c 893 Bytes
/* @(#)s_fabs.c 5.1 93/09/24 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#if defined(LIBM_SCCS) && !defined(lint)
static const char rcsid[] =
    "$NetBSD: s_fabs.c,v 1.7 1995/05/10 20:47:13 jtc Exp $";
#endif

/*
 * fabs(x) returns the absolute value of x.
 */

#include "math.h"
#include "math_private.h"

libm_hidden_proto(fabs)
#ifdef __STDC__
     double fabs(double x)
#else
     double fabs(x)
     double x;
#endif
{
    u_int32_t high;
    GET_HIGH_WORD(high, x);
    SET_HIGH_WORD(x, high & 0x7fffffff);
    return x;
}

libm_hidden_def(fabs)