[LLVMdev] built-in longjmp and setjmp

[Akira Hatanaka]

I have another basic question about setjmp/longjmp.

When I compile and run the following program, is it expected that global
variable gi2 will be incremented twice? It seems that the code generated
with clang and llc increments it only once (line 37-43 of attached file).

$ clang setjmp6.c -o setjmp6.arm.ll -emit-llvm -O3 -S -ccc-host-triple
arm-unknown-darwin -ccc-clang-archs arm
$ llc setjmp6.arm.ll -o setjmp6.arm.s

#include <stdio.h>
#include <stdlib.h>
void *buf[20];

int gi2 = 0;

void __attribute__ ((noinline)) sub2 (void)
{
  __builtin_longjmp (buf, 1);
}

int
main (int argc, char **argv)
{
  int n = atoi (argv[1]);
  int r = __builtin_setjmp (buf);
  ++gi2;

  if (r)
    {
      printf ("setjmp %d\n", n + gi2);
      return 0;
    }

  sub2 ();

  return 0;
}


On Wed, Apr 13, 2011 at 10:05 AM, Jakob Stoklund Olesen <stoklund at 2pi.dk>wrote:

>
> On Apr 13, 2011, at 9:51 AM, Akira Hatanaka wrote:
>
> > int
> > main (int argc, char** argv)
> > {
> >   int n = atoi(argv[1]), r;
> >
> >   if ((r = setjmp (buf)))
> >     {
> >       printf("n = %d\n", n);
> >       return 0;
> >     }
>
>
> /jakob
>
>
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