modify be-codegen-6800.c gen_direct() for optimize constant assignment.

[zu2]

I tried to modify gen_direct() for optimize constant assignment. This reduces 9-10 bytes per long/float assignment.

There is also room for improvement in pushing arguments when calling functions. This change is dirty, so a common framework is needed.

--- ../Fuzix-Compiler-Kit/be-codegen-6800.c 2024-11-01 00:40:37
+++ be-codegen-6800.c   2024-11-02 00:04:07
@@ -1236,6 +1356,8 @@
        return 0;
    case T_EQ:  /* Our left is the address */
    case T_EQPLUS:
+       if((l->type&FLOAT)!=(r->type&FLOAT))
+           return 0;
        v = n->value;
        if (can_load_r_simple(l, 0)) {
            if (r->op == T_CONSTANT && nr && r->value == 0) {
@@ -1243,6 +1365,15 @@
                   we don't also need the value */
                v += load_x_with(l, 0);
                uniop_on_ptr("clr", v, s);
+               return 1;
+           }
+           if (cpu == 6800 && nr && s == 4 && r->op == T_CONSTANT && n->op == T_EQ){
+               printf("; gen_shortcut T_EQ T_CONSTANT %08x\n",r->value);
+               v += load_x_with(l, 0);
+               load_d_const((r->value)&0xffff);
+               op16_on_ptr("st", "st", v+2);
+               load_d_const((r->value)>>16);
+               op16_on_ptr("st", "st", v);
                return 1;
            }
            codegen_lr(r);

sample program.

int
main(int argc, char **argv)
{
    long a = 0x87654321;
}

from:

        ldaa #135
        ldab #101
        staa @hireg
        stab @hireg+1
        ldaa #67
        ldab #33
        tsx
        stab 3,x
        staa 2,x
        psha
        ldaa @hireg+1
        staa 1,x
        ldaa @hireg
        staa 0,x
        pula

to:

    tsx
    ldaa #67
    ldab #33
    stb 3,x
    sta 2,x
    ldaa #135
    ldab #101
    stb 1,x
    sta 0,x

[EtchedPixels]

+       if((l->type&FLOAT)!=(r->type&FLOAT))
+           return 0;

Seems to make no sense. The rest does. Applied but slightly modified so it also improves 6803/6303