procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

h8300.c (two_insn_adds_subs_operand): Improve code for detecting profitable adds/subs sequences.

Browse source 
* h8300.c (two_insn_adds_subs_operand): Improve code for detecting
        profitable adds/subs sequences.

From-SVN: r35081
This commit is contained in:
Kazu Hirata 2000-07-17 08:55:51 +00:00 • committed by Jeff Law
parent 3b15076f36
commit 997e5af828
2 changed files with 30 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
gcc/ChangeLog
View file

@ -29,6 +29,9 @@ Mon Jul 17 02:37:06 2000 Marc Espie <espie@openbsd.org>
2000-07-17 Kazu Hirata <kazu@hxi.com>
* h8300.c (two_insn_adds_subs_operand): Improve code for detecting
profitable adds/subs sequences.
* fold-const.c: Fix comment typos.
2000-07-16 Laurynas Biveinis <lauras@softhome.net>

33
gcc/config/h8300/h8300.c
View file

@ -626,25 +626,46 @@ call_insn_operand (op, mode)
return 0;
}
/* Return 1 if a addition/subtraction of a constant integer can be
transformed into two consecutive adds/subs that are faster than the
straightforward way. Otherwise, return 0. */
int
two_insn_adds_subs_operand (op, mode)
rtx op;
enum machine_mode mode ATTRIBUTE_UNUSED;
enum machine_mode mode;
{
if (GET_CODE (op) == CONST_INT)
{
HOST_WIDE_INT value = INTVAL (op);
/* Force VALUE to be positive so that we do not have to consider
the negative case. */
if (value < 0)
value = -value;
if (TARGET_H8300H || TARGET_H8300S)
{
if (value >= -8 && value < -4 && value != -7)
return 1;
if (value > 4 && value <= 8 && value != 7)
return 1;
/* A constant addition/subtraction takes 2 states in QImode,
4 states in HImode, and 6 states in SImode. Thus, the
only case we can win is when SImode is used, in which
case, two adds/subs is used, taking 4 states. */
if (mode == SImode
&& (value == 2 + 1
|| value == 4 + 1
|| value == 4 + 2
|| value == 4 + 4))
return 1;
}
else
{
if (value == -4 || value == -3 || value == 3 || value == 4)
/* A constant addition/subtraction takes 2 states in
QImode. It takes 6 states in HImode, requiring the
constant to be loaded to a register first, and a lot more
in SImode. Thus the only case we can win is when either
HImode or SImode is used. */
if (mode != QImode
&& (value == 2 + 1
|| value == 2 + 2))
return 1;
}
}