+2004-12-07 Roger Sayle <roger@eyesopen.com>
+
+ PR middle-end/18293
+ * expmed.c (EXACT_POWER_OF_2_OR_ZERO_P): Move definition earlier.
+ (expand_mult): Special case powers of two to avoid synth_mult.
+ * loop.c (product_cheap_p): Handle case where expand_mult does
+ require/generate any instructions (i.e. multiplication by zero).
+
2004-12-07 Richard Henderson <rth@redhat.com>
* tree-pretty-print.c (dump_array_domain): Split out from
static rtx expand_smod_pow2 (enum machine_mode, rtx, HOST_WIDE_INT);
static rtx expand_sdiv_pow2 (enum machine_mode, rtx, HOST_WIDE_INT);
+/* Test whether a value is zero of a power of two. */
+#define EXACT_POWER_OF_2_OR_ZERO_P(x) (((x) & ((x) - 1)) == 0)
+
/* Nonzero means divides or modulus operations are relatively cheap for
powers of two, so don't use branches; emit the operation instead.
Usually, this will mean that the MD file will emit non-branch
if (const_op1 && GET_CODE (const_op1) == CONST_INT
&& (unsignedp || !flag_trapv))
{
- int mult_cost = rtx_cost (gen_rtx_MULT (mode, op0, op1), SET);
+ HOST_WIDE_INT coeff = INTVAL (const_op1);
+ int mult_cost;
+
+ /* Special case powers of two. */
+ if (EXACT_POWER_OF_2_OR_ZERO_P (coeff))
+ {
+ if (coeff == 0)
+ return const0_rtx;
+ if (coeff == 1)
+ return op0;
+ return expand_shift (LSHIFT_EXPR, mode, op0,
+ build_int_cst (NULL_TREE, floor_log2 (coeff)),
+ target, unsignedp);
+ }
- if (choose_mult_variant (mode, INTVAL (const_op1), &algorithm, &variant,
+ mult_cost = rtx_cost (gen_rtx_MULT (mode, op0, op1), SET);
+ if (choose_mult_variant (mode, coeff, &algorithm, &variant,
mult_cost))
- return expand_mult_const (mode, op0, INTVAL (const_op1), target,
+ return expand_mult_const (mode, op0, coeff, target,
&algorithm, variant);
}
(x mod 12) == (((x & 1023) + ((x >> 8) & ~3)) * 0x15555558 >> 2 * 3) >> 28
*/
-#define EXACT_POWER_OF_2_OR_ZERO_P(x) (((x) & ((x) - 1)) == 0)
-
rtx
expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
rtx op0, rtx op1, rtx target, int unsignedp)