When backend-byte is enabled, the access to the global variables of 6800 becomes strange.

[zu2]

When backend-byte is enabled, the access to the global variables of 6800 becomes strange. I'm looking for the cause of this, but I can't find it.

I made the following modifications to the current latest fizix CC for testing.

--- ../Fuzix-Compiler-Kit/be-codegen-6800.c 2024-11-22 02:02:22.472094724 +0000
+++ be-codegen-6800.c   2024-11-22 02:04:05.088549955 +0000
@@ -31,7 +31,10 @@
 #include "compiler.h"
 #include "backend.h"
 #include "backend-6800.h"
+#include "backend-byte.h"

+void dump_tree(register struct node *n, unsigned depth);
+void byte_label_tree(register struct node *n, unsigned opt);

 /*
  * Helpers for code generation and tracking
@@ -74,6 +77,7 @@
    propagation */
 struct node *gen_rewrite(struct node *n)
 {
+   byte_label_tree(n, BTF_RELABEL);
    return n;
 }

sample program:

char    x[8];

int main(int argc, char *argv[])
{
    char    k=7;

    for(k=0; k<8; k++){
        x[k]=-1;
    }

    return 0;
}

Before applying the byte_label_tree change to be-codegen-6800.c.

seems good.

        tsx
        ldb 0,x
        clra
        addb #<_x+0
        adca #>_x+0
        staa @tmp
        stab @tmp+1
        ldx @tmp
        ldab #255
        stb 0,x

After applying the byte_label_tree changes to be-codegen-6800.c

The address cannot be calculated correctly because adca #0 is missing.

;:load:
;T_EQ v0 t8 f6 NORETURN, UCHAR
;    T_PLUS v0 t8 f1  UCHAR
;        T_NAME v0 t9 f0  UCHAR x
;        T_CAST v0 t18 f0  USHORT
;            T_DEREF v0 t8 f0  UCHAR
;                T_LOCAL v0 t8 f1  UCHAR        k
;    T_CONSTANT vffffffffffffffff t8 f0  UCHAR
;:rewritten:
;T_EQ v0 t8 f706 NORETURN,BYTEROOT,BYTEOP, UCHAR
;    T_PLUS v0 t9 f301 BYTEOP, UCHAR
;        T_NAME v0 t9 f800 BYTETAIL, UCHAR      x
;        2003 v0 t8 f800 BYTETAIL, UCHAR        k
;    T_CONSTANT vffffffffffffffff t8 fb00 BYTEOP,BYTETAIL, UCHAR
        ldb #<_x+0
        lda #>_x+0
;make local ptr off 0, rlim 255 noff 0
        tsx
        addb 0,x
        staa @tmp
        stab @tmp+1
        ldx @tmp
        ldab #255
        stb 0,x