C:/Users/Dennis/src/lang/russell.orig/src/gc/setjmp_test.c

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/* Check whether setjmp actually saves registers in jmp_buf. */
/* If it doesn't, the generic mark_regs code won't work.     */
/* Compilers vary as to whether they will put x in a         */
/* (callee-save) register without -O.  The code is           */
/* contrived such that any decent compiler should put x in   */
/* a callee-save register with -O.  Thus it is is            */
/* recommended that this be run optimized.  (If the machine  */
/* has no callee-save registers, then the generic code is    */
/* safe, but this will not be noticed by this piece of       */
/* code.)                                                    */
#include <stdio.h>
#include <setjmp.h>
#include "config.h"

#ifdef __hpux
/* X/OPEN PG3 defines "void* sbrk();" and this clashes with the definition */
/* in gc_private.h, so we set the clock backwards with _CLASSIC_XOPEN_TYPES. */
/* This is for HP-UX 8.0.
/* sbrk() is not used in this file, of course.  W. Underwood, 15 Jun 1992 */
#define _CLASSIC_XOPEN_TYPES
#include <unistd.h>
int
getpagesize()
{
    return sysconf(_SC_PAGE_SIZE);
}
#endif

#if defined(SUNOS5)
#define _CLASSIC_XOPEN_TYPES
#include <unistd.h>
int
getpagesize()
{
    return sysconf(_SC_PAGESIZE);
}
#endif

#ifdef _AUX_SOURCE
#include <sys/mmu.h>
int
getpagesize()
{
   return PAGESIZE;
}
#endif

#ifdef __OS2__
#define INCL_DOSFILEMGR
#define INCL_DOSMISC
#define INCL_DOSERRORS
#include <os2.h>

int
getpagesize()
{
    ULONG result[1];
    
    if (DosQuerySysInfo(QSV_PAGE_SIZE, QSV_PAGE_SIZE,
                        (void *)result, sizeof(ULONG)) != NO_ERROR) {
        fprintf(stderr, "DosQuerySysInfo failed\n");
        result[0] = 4096;
    }
    return((int)(result[0]));
}
#endif

struct {char a_a; char * a_b;} a;

int * nested_sp()
{
    int dummy;
    
    return(&dummy);
}

main()
{
        int dummy;
        long ps = getpagesize();
        jmp_buf b;
        register int x = strlen("a");  /* 1, slightly disguised */
        static int y = 0;

        if (nested_sp() < &dummy) {
          printf("Stack appears to grow down, which is the default.\n");
          printf("A good guess for STACKBOTTOM on this machine is 0x%X.\n",
                 ((long)(&dummy) + ps) & ~(ps-1));
        } else {
          printf("Stack appears to grow up.\n");
          printf("Define STACK_GROWS_UP in gc_private.h\n");
          printf("A good guess for STACKBOTTOM on this machine is 0x%X.\n",
                 ((long)(&dummy) + ps) & ~(ps-1));
        }
        printf("Note that this may vary between machines of ostensibly\n");
        printf("the same architecture (e.g. Sun 3/50s and 3/80s).\n");
        printf("A good guess for ALIGNMENT on this machine is %d.\n",
               (unsigned long)(&(a.a_b))-(unsigned long)(&a));
        
        /* Encourage the compiler to keep x in a callee-save register */
        x = 2*x-1;
        printf("");
        x = 2*x-1;
        setjmp(b);
        if (y == 1) {
            if (x == 2) {
                printf("Generic mark_regs code probably wont work\n");
#               if defined(SPARC) || defined(IBMRS6000)
                    printf("Assembly code supplied\n");
#               else
                    printf("Need assembly code\n");
#               endif
            } else if (x == 1) {
                printf("Generic mark_regs code may work\n");
            } else {
                printf("Very strange setjmp implementation\n");
            }
        }
        y++;
        x = 2;
        if (y == 1) longjmp(b,1);
        return(0);
}

int g(x)
int x;
{
        return(x);
}

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