ack/util/ego/descr/m68020.descr
George Koehler b1b737ed6c Optimize procedures that do both a / b and a % b.
Enable this in CS for PowerPC; disable it for all other machines.
PowerPC has no remainder instruction; the back end uses division to
compute remainder.  If CS finds both a / b and a % b, then CS now
rewrites a % b as a - b * (a / b) and computes a / b only once.  This
removes an extra division in the PowerPC code, so it saves both time
and space.

I have not considered whether to enable this optimization for other
machines.  It might be less useful in machines with a remainder
instruction.  Also, if a % b occurs before a / b, the EM code gets a
DUP.  PowerPC ncg handles this DUP well; other back ends might not.
2018-03-05 13:32:06 -05:00

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wordsize: 4
pointersize: 4
%%RA
general registers: 5
address registers: 4
floating point registers: 0
use general as pointer: no
register score parameters:
local variable:
(2 cases)
pointer,pointer
(1 size)
default -> (6,4)
general,general
(1 size)
default -> (4,2)
address of local variable:
(2 cases)
pointer,pointer
(1 size)
default -> (0,0)
general,pointer
(1 size)
default -> (1,2)
constant:
(3 sizes)
in_0_8 -> (-1,-1)
fitbyte -> (-1,-1)
default -> (-1,-1)
double constant:
(1 size)
default -> (-1,-1)
address of global variable:
(1 size)
default -> (1,4)
address of procedure:
(1 size)
default -> (1,4)
opening cost parameters:
local variable:
(2 cases)
pointer
(1 size)
default -> (6,4)
general
(1 size)
default -> (6,4)
address of local variable:
(2 cases)
pointer
(1 size)
default -> (4,4)
general
(1 size)
general -> (4,4)
constant:
(2 sizes)
fitbyte -> (1000,1000)
default -> (1000,1000)
double constant:
(1 size)
default -> (1000,1000)
address of global variable:
(1 size)
default -> (6,6)
address of procedure:
(1 size)
default -> (6,6)
register save costs:
(11 cases)
0 -> (0,0)
1 -> (12,6)
2 -> (24,10)
3 -> (34,10)
4 -> (42,10)
5 -> (50,10)
6 -> (58,10)
7 -> (66,10)
8 -> (74,10)
9 -> (82,10)
0 -> (0,0)
%%UD
access costs of global variables:
(1 size)
default -> (7,4)
access costs of local variables:
(1 size)
default -> (4,2)
%%SR
overflow harmful?: no
array bound harmful?: no
reduce sli if shift count larger than: 3
%%CS
#include "em_mnem.h"
first time then space:
addressing modes: op_ads op_adp op_lof op_ldf op_loi op_dch op_lpb -1
op_ads op_adp op_lof op_ldf op_loi op_dch op_lpb -1
cheap operations: op_cii op_ciu op_cui op_cuu op_cmi op_cmu op_cmp -1
op_cii op_ciu op_cui op_cuu op_cmi op_cmu op_cmp -1
lexical tresholds: 1 1
indirection limit: 8
convert remainder to division?: no no
do not eliminate sli if index on shiftcounts: 1 2 3 -1
1 2 3 -1
forbidden operators: -1 -1
%%SP
global stack pollution allowed?: yes