I'm porting gcc to a 16 bit processor. Occasionally compiling
source such as
short v1;
long global;
....
global = (long)v1;
results in ...
(insn 11 10 12 2 (set (subreg:HI (mem/c:SI (symbol_ref:HI
("global") <var_decl 0xb7076000 global>) [2 global+0 S4 A16]) 2)
(const_int 0 [0])) t.c:15 -1
(nil))
(insn 12 11 13 2 (set (subreg:HI (mem/c:SI (symbol_ref:HI
("global") <var_decl 0xb7076000 global>) [2 global+0 S4 A16]) 0)
(reg:HI 24 [ D.1348 ])) t.c:15 -1
(nil))
The second of these instructions successfully matches a movhi
pattern which is found via the define_expand below
;the INTEGER iterator includes [QI HI SI]
(define_expand "mov<mode>"
[(set (match_operand:INTEGER 0 "nonimmediate_operand" "")
(match_operand:INTEGER 1 "general_operand" ""))]
""
{
if( can_create_pseudo_p() )
{
if( !register_operand( operands[0], <MODE>mode )
&& !register_operand( operands[1], <MODE>mode ))
{
/* one of the operands must be in a register. */
operands[1] = copy_to_mode_reg (<MODE>mode,
operands[1]);
}
}
However the first instruction fails to match and be expanded so
that the const_int is forced into a register. I defined an
instruction which is an exact match
(define_insn "*storesic"
[
(set (subreg:HI (mem:SI (match_operand:HI 0
"symbol_ref_operand" "")) 2)
(match_operand:HI 1 "const_int_operand"))
]
This matches, however I need a scratch register (R? below) to
transform this into
load R?, const_int_operand
store R?, address
and as soon as I add the match_scratch
(clobber(match_scratch:HI 2 "=r"))
the pattern no longer matches because expand calls recog() with
pnum_clobbers = 0 (NULL)
I a similar vein to the way CC setting instructions are handled I
tried defining a second instruction containing the required
match_scratch prior to the define_insn "*storesic" (see above) in
the hope that it may match subsequent to the expand pass, however
it is never seen.
Can anyone offer any insight to what I'm doing wrong and how I
might proceed ?
Thanks, Paul.
