On Sat 07 Mar 2020 at 01:59:03 +0100, Johnny Billquist wrote: > In the end, that is a different thing. Absolute addressing is not what Bob > was thinking about here... > > Here is what MACRO-11 does: > > 1 000000 .ASECT > 2 001000 .=1000 > 3 001234 X=1234 > 4 > 5 001000 005067 000230 CLR X > 6 > > Note that the addressing is still relative. But the actual offset required > can be computed by MACRO-11 at compile time.
This is the output of dumpobj for that code. It looks like indeed there
is an unneeded relocation record in there:
GSD:
GLOBAL X =1234 DEF ABS flags=110
MODNAME TEST =0 flags=0
PSECT =0 CON RW REL LCL I flags=40
PSECT . ABS.=1004 OVR RW ABS GBL I flags=104
XFER . ABS.=1 flags=10
ENDGSD
RLD
Location counter definition . ABS.+1000
TEXT ADDR=1000 LEN=4
001000: 005067 001234 7...
RLD
Internal displaced 1002=1234
ENDMOD
It looks like the 2nd RLD record is generated by the code
text_displaced_word() in object.c. That in turn must be called from this
code in assemble_aux.c, since there are no other callers to
store_displaced_word():
void mode_extension(
...
if (value->type == EX_LIT) {
if (mode->rel) /* PC-relative? */
store_displaced_word(str, tr, 2, value->data.lit);
else
store_word(str, tr, 2, value->data.lit); /* Just a
known
value. */
My guess is that this could become something like
if (value->type == EX_LIT) {
if (mode->rel) { /* PC-relative? */
if (current_pc->section->flags & PSECT_REL) {
store_displaced_word(str, tr, 2, value->data.lit);
} else {
/* I can compute this myself. */
store_word(str, tr, 2, value->data.lit - DOT - 2);
}
} else {
store_word(str, tr, 2, value->data.lit); /* Just a
known
value. */
}
It seems like this case didn't come up in any previous tests; the
regression tests show no change at all. (I have tested somewhat strictly
by hand that various RSX-Kermit-11 source files generated the same
object files as on RSX and that the listings, including macro expansion,
didn't have any unexplained differences).
Any interesting test cases I can use with this, so see if it is correct
this way?
1 .TITLE TEST RELOCATABLE
REFERENCES
2 000000 .ASECT
3 001000 .=1000
4 001234 X == 1234
5 001000 005067 000230 CLR X
. =****** X =001234 G
. ABS. 001004 000 (RW,I,GBL,ABS,OVR,NOSAV)
> Johnny
-Olaf.
--
Olaf 'Rhialto' Seibert -- rhialto at falu dot nl
___ Anyone who is capable of getting themselves made President should on
\X/ no account be allowed to do the job. --Douglas Adams, "THGTTG"
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