Bernhard Schmalhofer wrote:
> Ron Blaschke via RT schrieb:
>> In all three sections a value is loaded into a register and then set as
>> an attribute on an object.
>>
>> In the first hunk only the used register is changed from 0x12 to 0x13.
>> In the second hunks it's register 0x11 to 0x12.
>>
>> With hunk three it's getting interesting because only the first
>> occurrence changes from 0x13 to 0x11. set_attribute still uses 0x13,
>> which is wrong I think.
>>
>> In the end, the wrong (Sub) value is put into the object's attribute
>> because the wrong register is used. The error that comes up later is
>> not because the arguments are wrong, but because the wrong sub is called.
>>
>> Can anyone tell if I'm on the right track?
>>
> Yes, I can see the pattern. One possibility to verify this, is to add a
> 'dummy_5' PMC.
> I'd expect three hunks again, but the third hunk should than conform to
> the two first hunks.
Here's what happens if ".local pmc dummy_5" is added, compared to the
current repository version with ".local pmc dummy_[1-4]".
--- lisp.pbc.workaround 2007-09-01 17:02:22.000000000 +0200
+++ lisp.pbc.workaround2 2007-09-02 20:24:32.000000000 +0200
@@ -1445,7 +1445,7 @@
116b: 00000262 00000006 0000008f
callmethodcc_p_sc
116e: 000002bb 00000003 00000045 new_p_sc
1171: 0000032f 00000019 000001a2 set_p_pc
- 1174: 000002a6 00000003 00000047 00000019
setattribute_p_sc_p
+ 1174: 000002a6 00000003 00000047 00000011
setattribute_p_sc_p
1178: 000002bb 0000001a 00000035 new_p_sc
117b: 00000336 0000001a 0000015d set_p_sc
117e: 00000024 0000000d set_args_pc
> Is this a register allocator bug?
Not sure yet. I think I've found the source that corresponds to the
opcodes. It's C<FUNCTION> in F<include/macros/types.pir>.
#.macro FUNCTION(F,L)
#
# .F = new "LispFunction"
116e: 000002bb 00000003 00000045 new_p_sc
== new, P3, constant 0x45 ("LispFunction")
# .const .Sub _func = .L
1171: 0000032f 00000019 000001a2 set_p_pc
== set P25, ???
# setattribute .F, "body", _func
1174: 000002a6 00000003 00000047 00000019 setattribute_p_sc_p
== setattribute P3, constant 0x47 ("body"), P25
# but when this go bad:
1174: 000002a6 00000003 00000047 00000011 setattribute_p_sc_p
== setattribute P3, constant 0x47 ("body"), P17
#
#.endm
The constants (0x45 and 0x47) are indexes into the constant pool.
# 69:
[ 'PFC_STRING', {
FLAGS => 0x61100,
CHARSET => 3961080,
SIZE => 12,
DATA => 'LispFunction'
} ],
# 71:
[ 'PFC_STRING', {
FLAGS => 0x61100,
CHARSET => 3961080,
SIZE => 4,
DATA => 'body'
} ],
The situation in the previous posting was this.
#.macro FUNCTION(F,L)
#
# .F = new "LispFunction"
1030: 000002bb 00000003 00000045 new_p_sc
== new, P3, constant 0x45 ("LispFunction")
# .const .Sub _func = .L
1033: 0000032f 00000013 000001b2 set_p_pc
== set P19, ???
# or:
1033: 0000032f 00000011 000001b2 set_p_pc
== set P17, ???
# setattribute .F, "body", _func
1036: 000002a6 00000003 00000047 00000013 setattribute_p_sc_p
== setattribute P3, constant 0x47 ("body"), P19
#
#.endm
I'm currently trying to understand the code well enough to step through
this with a debugger when the instructions are generated.
Ron
