src/thread/pthread/SDL_systhread.c
author Sam Lantinga <slouken@libsdl.org>
Wed, 03 Jun 2009 04:37:27 +0000
changeset 3162 dc1eb82ffdaa
parent 2859 99210400e8b9
child 3578 0d1b16ee0bca
permissions -rw-r--r--
Von: Thomas Zimmermann
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
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/*
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    SDL - Simple DirectMedia Layer
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    Copyright (C) 1997-2009 Sam Lantinga
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    This library is free software; you can redistribute it and/or
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    modify it under the terms of the GNU Lesser General Public
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    License as published by the Free Software Foundation; either
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    version 2.1 of the License, or (at your option) any later version.
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    This library is distributed in the hope that it will be useful,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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    Lesser General Public License for more details.
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    You should have received a copy of the GNU Lesser General Public
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    License along with this library; if not, write to the Free Software
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    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
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    Sam Lantinga
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    slouken@libsdl.org
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*/
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#include "SDL_config.h"
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#include <pthread.h>
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#include <signal.h>
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#include "SDL_thread.h"
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#include "../SDL_thread_c.h"
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#include "../SDL_systhread.h"
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/* List of signals to mask in the subthreads */
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static const int sig_list[] = {
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    SIGHUP, SIGINT, SIGQUIT, SIGPIPE, SIGALRM, SIGTERM, SIGCHLD, SIGWINCH,
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    SIGVTALRM, SIGPROF, 0
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};
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#ifdef __RISCOS__
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/* RISC OS needs to know the main thread for
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 * it's timer and event processing. */
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int riscos_using_threads = 0;
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Uint32 riscos_main_thread = 0;  /* Thread running events */
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#endif
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static void *
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RunThread(void *data)
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{
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    SDL_RunThread(data);
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    pthread_exit((void *) 0);
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    return ((void *) 0);        /* Prevent compiler warning */
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}
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int
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SDL_SYS_CreateThread(SDL_Thread * thread, void *args)
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{
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    pthread_attr_t type;
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    /* Set the thread attributes */
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    if (pthread_attr_init(&type) != 0) {
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        SDL_SetError("Couldn't initialize pthread attributes");
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        return (-1);
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    }
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    pthread_attr_setdetachstate(&type, PTHREAD_CREATE_JOINABLE);
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    /* Create the thread and go! */
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    if (pthread_create(&thread->handle, &type, RunThread, args) != 0) {
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        SDL_SetError("Not enough resources to create thread");
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        return (-1);
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    }
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#ifdef __RISCOS__
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    if (riscos_using_threads == 0) {
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        riscos_using_threads = 1;
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        riscos_main_thread = SDL_ThreadID();
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    }
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#endif
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    return (0);
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}
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void
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SDL_SYS_SetupThread(void)
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{
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    int i;
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    sigset_t mask;
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    /* Mask asynchronous signals for this thread */
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    sigemptyset(&mask);
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    for (i = 0; sig_list[i]; ++i) {
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        sigaddset(&mask, sig_list[i]);
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    }
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    pthread_sigmask(SIG_BLOCK, &mask, 0);
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#ifdef PTHREAD_CANCEL_ASYNCHRONOUS
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    /* Allow ourselves to be asynchronously cancelled */
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    {
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        int oldstate;
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        pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldstate);
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    }
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#endif
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}
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/* WARNING:  This may not work for systems with 64-bit pid_t */
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Uint32
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SDL_ThreadID(void)
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{
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    return ((Uint32) pthread_self());
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}
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void
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SDL_SYS_WaitThread(SDL_Thread * thread)
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{
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    pthread_join(thread->handle, 0);
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}
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