+2000-08-16 Richard Henderson <rth@cygnus.com>
+
+ * combine.c (simplify_shift_const): Revert previous two
+ changes. If SHIFT_COUNT_TRUNCATED, crop the shift count
+ before the main loop.
+
2000-08-15 Richard Henderson <rth@cygnus.com>
* combine.c (simplify_shift_const): Bound shift count when
count = input_count;
+ /* Make sure and truncate the "natural" shift on the way in. We don't
+ want to do this inside the loop as it makes it more difficult to
+ combine shifts. */
+#ifdef SHIFT_COUNT_TRUNCATED
+ if (SHIFT_COUNT_TRUNCATED)
+ count %= GET_MODE_BITSIZE (mode);
+#endif
+
/* Unless one of the branches of the `if' in this loop does a `continue',
we will `break' the loop after the `if'. */
? result_mode : mode);
/* Handle cases where the count is greater than the size of the mode
- minus 1. If SHIFT_COUNT_TRUNCATED, there aren't really any such
- cases. Otherwise, for ASHIFT, use the size minus one as the count
- (this can occur when simplifying (lshiftrt (ashiftrt ..))). For
- rotates, take the count modulo the size. For other shifts, the
- result is zero.
+ minus 1. For ASHIFT, use the size minus one as the count (this can
+ occur when simplifying (lshiftrt (ashiftrt ..))). For rotates,
+ take the count modulo the size. For other shifts, the result is
+ zero.
Since these shifts are being produced by the compiler by combining
multiple operations, each of which are defined, we know what the
if (count > GET_MODE_BITSIZE (shift_mode) - 1)
{
-#ifdef SHIFT_COUNT_TRUNCATED
- if (SHIFT_COUNT_TRUNCATED)
- count %= GET_MODE_BITSIZE (shift_mode);
- else
-#endif
if (code == ASHIFTRT)
count = GET_MODE_BITSIZE (shift_mode) - 1;
else if (code == ROTATE || code == ROTATERT)
break;
count += first_count;
- if (count >= GET_MODE_BITSIZE (shift_mode))
- count = GET_MODE_BITSIZE (shift_mode) - 1;
varop = XEXP (varop, 0);
continue;
}
else
count = signed_count;
- if (count >= GET_MODE_BITSIZE (shift_mode))
- count = GET_MODE_BITSIZE (shift_mode) - 1;
-
varop = XEXP (varop, 0);
continue;
}