be-codegen-6800.c gen_shortcut += -= on char produces inefficient code for large numbers.

[zu2]

--- ../Fuzix-Compiler-Kit/be-codegen-6800.c	2024-11-13 00:32:04
+++ be-codegen-6800.c	2024-11-16 21:25:36
@@ -1350,15 +1416,17 @@
 		}
 		return 0;
 	case T_PLUSEQ:
-		if (s == 1 && memop_const(n, "inc", nr, 2))
+		v = r->value;
+		if (s == 1 && v<2+optsize && memop_const(n, "inc", nr, 2))
 			return 1;
-		if (s == 2 && add_to_node(n, 1, 1))
+		if (s <= 2 && add_to_node(n, 1, 1))
 			return 1;
 		return do_xeqop(n, "xpluseq");
 	case T_MINUSEQ:
-		if (s == 1 && memop_const(n, "dec", nr, 2))
+		v = r->value;
+		if (s == 1 && v<2+optsize && memop_const(n, "dec", nr, 2))
 			return 1;
-		if (s == 2 && add_to_node(n, -1, 1))
+		if (s <= 2 && add_to_node(n, -1, 1))
 			return 1;
 		return do_xeqop(n, "xminuseq");
 	case T_PLUSPLUS:

test program:

int
sub(unsigned char x,unsigned char y)
{
	x += 10;
	y -= 10;
	return x+y;
}

int
main(int argc, char **argv)
{
	unsigned char x,y;

	x = 100;
	y = 50;

	if (sub(x,y)!=150)
		return 1;

	return 0;
}

before

_sub:
;:rewritten:
;T_PLUSEQ v0 t8 f6 NORETURN, UCHAR
;    T_ARGUMENT v0 t9 f1  UCHAR	x
;    T_CONSTANT va t8 f900 BYTETAIL, UCHAR
;make local ptr off 2, rlim 252 noff 2
	tsx
	inc 2,x
	inc 2,x
	inc 2,x
	inc 2,x
	inc 2,x
	inc 2,x
	inc 2,x
	inc 2,x
	inc 2,x
	inc 2,x
;
;:rewritten:
;T_MINUSEQ v0 t8 f6 NORETURN, UCHAR
;    T_ARGUMENT v1 t9 f1  UCHAR	y
;    T_CONSTANT va t8 f900 BYTETAIL, UCHAR
;make local ptr off 3, rlim 252 noff 3
	dec 3,x
	dec 3,x
	dec 3,x
	dec 3,x
	dec 3,x
	dec 3,x
	dec 3,x
	dec 3,x
	dec 3,x
	dec 3,x

after

_sub:
;:rewritten:
;T_PLUSEQ v0 t8 f6 NORETURN, UCHAR
;    T_ARGUMENT v0 t9 f1  UCHAR	x
;    T_CONSTANT va t8 f900 BYTETAIL, UCHAR
;make local ptr off 2, rlim 252 noff 2
	tsx
	ldb 2,x
	addb #10
	stb 2,x
;
;:rewritten:
;T_MINUSEQ v0 t8 f6 NORETURN, UCHAR
;    T_ARGUMENT v1 t9 f1  UCHAR	y
;    T_CONSTANT va t8 f900 BYTETAIL, UCHAR
;make local ptr off 3, rlim 252 noff 3
	ldb 3,x
	addb #246
	stb 3,x