re PR rtl-optimization/13299 (Unsafe treatment of extended givs)

        PR rtl-opt/13299
        * loop.c (get_monotonic_increment, biased_biv_fits_mode_p,
        biv_fits_mode_p, extension_within_bounds_p): New functions.
        (check_ext_dependent_givs): Use them.

From-SVN: r93000

gcc/ChangeLog

+2005-01-06  Richard Sandiford  <rsandifo@redhat.com>
+
+	PR rtl-opt/13299
+	* loop.c (get_monotonic_increment, biased_biv_fits_mode_p,
+	biv_fits_mode_p, extension_within_bounds_p): New functions.
+	(check_ext_dependent_givs): Use them.
+
 2005-01-06  Roger Sayle  <roger@eyesopen.com>
 
 	* cfgrtl.c (rtl_delete_block): A basic block may be followed by

gcc/testsuite/gcc.c-torture/execute/20030916-1.c

+/* "i" overflows in f().  Check that x[i] is not treated as a giv.  */
+#include <limits.h>
+
+#if CHAR_BIT == 8
+
+void f (unsigned int *x)
+{
+  unsigned char i;
+  int j;
+
+  i = 0x10;
+  for (j = 0; j < 0x10; j++)
+    {
+      i += 0xe8;
+      x[i] = 0;
+      i -= 0xe7;
+    }
+}
+
+int main ()
+{
+  unsigned int x[256];
+  int i;
+
+  for (i = 0; i < 256; i++)
+    x[i] = 1;
+  f (x);
+  for (i = 0; i < 256; i++)
+    if (x[i] != (i >= 0x08 && i < 0xf8))
+      abort ();
+  exit (0);
+}
+#else
+int main () { exit (0); }
+#endif