Remove uses of SIGILL for CPU extension detection, that method is not acceptable

in a library.
Should not change anything for PPC, the autodetection is currently pointless due
to other code being compiled with -maltivec as well (and detection for OSX and
AmigaOS remains in place).
SPARC binaries built with VIS support can now only run on systems with VIS.

Originally committed as revision 10648 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/ppc/check_altivec.c

@@ -28,23 +28,6 @@
 #include <exec/exec.h>
 #include <interfaces/exec.h>
 #include <proto/exec.h>
-#else
-#include <signal.h>
-#include <setjmp.h>
-
-static sigjmp_buf jmpbuf;
-static volatile sig_atomic_t canjump = 0;
-
-static void sigill_handler (int sig)
-{
-    if (!canjump) {
-        signal (sig, SIG_DFL);
-        raise (sig);
-    }
-
-    canjump = 0;
-    siglongjmp (jmpbuf, 1);
-}
 #endif /* __APPLE__ */
 
 /**
@@ -72,24 +55,9 @@ int has_altivec(void)
     if (err == 0) return (has_vu != 0);
     return 0;
 #else
-/* Do it the brute-force way, borrowed from the libmpeg2 library. */
-    {
-      signal (SIGILL, sigill_handler);
-      if (sigsetjmp (jmpbuf, 1)) {
-        signal (SIGILL, SIG_DFL);
-      } else {
-        canjump = 1;
-
-        asm volatile ("mtspr 256, %0\n\t"
-                      "vand %%v0, %%v0, %%v0"
-                      :
-                      : "r" (-1));
-
-        signal (SIGILL, SIG_DFL);
-        return 1;
-      }
-    }
-    return 0;
+    // since we were compiled for altivec, just assume we have it
+    // until someone comes up with a proper way (not involving signal hacks).
+    return 1;
 #endif /* __AMIGAOS4__ */
 }
 

libavcodec/sparc/dsputil_vis.c

@@ -26,8 +26,6 @@
 #include "config.h"
 
 #include <inttypes.h>
-#include <signal.h>
-#include <setjmp.h>
 
 #include "dsputil.h"
 
@@ -3987,56 +3985,13 @@ static void MC_avg_no_round_xy_8_vis (uint8_t * dest, const uint8_t * _ref,
 
 /* End of no rounding code */
 
-static sigjmp_buf jmpbuf;
-static volatile sig_atomic_t canjump = 0;
-
-static void sigill_handler (int sig)
-{
-    if (!canjump) {
-        signal (sig, SIG_DFL);
-        raise (sig);
-    }
-
-    canjump = 0;
-    siglongjmp (jmpbuf, 1);
-}
-
 #define ACCEL_SPARC_VIS 1
 #define ACCEL_SPARC_VIS2 2
 
 static int vis_level ()
 {
-    int accel = 0;
-
-    signal (SIGILL, sigill_handler);
-    if (sigsetjmp (jmpbuf, 1)) {
-        signal (SIGILL, SIG_DFL);
-        return accel;
-    }
-
-    canjump = 1;
-
-    /* pdist %f0, %f0, %f0 */
-    __asm__ __volatile__(".word\t0x81b007c0");
-
-    canjump = 0;
     accel |= ACCEL_SPARC_VIS;
-
-    if (sigsetjmp (jmpbuf, 1)) {
-        signal (SIGILL, SIG_DFL);
-        return accel;
-    }
-
-    canjump = 1;
-
-    /* edge8n %g0, %g0, %g0 */
-    __asm__ __volatile__(".word\t0x81b00020");
-
-    canjump = 0;
     accel |= ACCEL_SPARC_VIS2;
-
-    signal (SIGILL, SIG_DFL);
-
     return accel;
 }