===================================================================
@@ -3755,10 +3755,17 @@ rtx_cost (rtx x, enum rtx_code outer_cod
enum rtx_code code;
const char *fmt;
int total;
+ int factor;
if (x == 0)
return 0;
+ /* A size N times larger than UNITS_PER_WORD likely needs N times as
+ many insns, taking N times as long. */
+ factor = GET_MODE_SIZE (GET_MODE (x)) / UNITS_PER_WORD;
+ if (factor == 0)
+ factor = 1;
+
/* Compute the default costs of certain things.
Note that targetm.rtx_costs can override the defaults. */
@@ -3766,20 +3773,31 @@ rtx_cost (rtx x, enum rtx_code outer_cod
switch (code)
{
case MULT:
- total = COSTS_N_INSNS (5);
+ /* Multiplication has time-complexity O(N*N), where N is the
+ number of units (translated from digits) when using
+ schoolbook long multiplication. */
+ total = factor * factor * COSTS_N_INSNS (5);
break;
case DIV:
case UDIV:
case MOD:
case UMOD:
- total = COSTS_N_INSNS (7);
+ /* Similarly, complexity for schoolbook long division. */
+ total = factor * factor * COSTS_N_INSNS (7);
break;
case USE:
/* Used in combine.c as a marker. */
total = 0;
break;
+ case SET:
+ /* A SET doesn't have a mode, so let's look at the SET_DEST to get
+ the mode for the factor. */
+ factor = GET_MODE_SIZE (GET_MODE (SET_DEST (x))) / UNITS_PER_WORD;
+ if (factor == 0)
+ factor = 1;
+ /* Pass through. */
default:
- total = COSTS_N_INSNS (1);
+ total = factor * COSTS_N_INSNS (1);
}
switch (code)
@@ -3792,8 +3810,7 @@ rtx_cost (rtx x, enum rtx_code outer_cod
/* If we can't tie these modes, make this expensive. The larger
the mode, the more expensive it is. */
if (! MODES_TIEABLE_P (GET_MODE (x), GET_MODE (SUBREG_REG (x))))
- return COSTS_N_INSNS (2
- + GET_MODE_SIZE (GET_MODE (x)) / UNITS_PER_WORD);
+ return COSTS_N_INSNS (2 + factor);
break;
default: