From: cross@spitfire.i.gajendra.net
In article <109mep8$84ft$1@paganini.bofh.team>,
Waldek Hebisch wrote:
>Dan Cross wrote:
>> In article <109g1s1$3jb20$1@paganini.bofh.team>,
>> Waldek Hebisch wrote:
>>>Lawrence Dâ??Oliveiro wrote:
>>>> On Fri, 5 Sep 2025 21:32:01 -0000 (UTC), Waldek Hebisch wrote:
>>>>
>>>>> All indicates that GNU assembler can not handle simple symbol
>>>>> equality as intended.
>>>>
>>>> I tried creating a source file test.s containing just your two problem
>>>> lines:
>>>>
>>>> .globl _ZN10__cxxabiv117__array_type_infoD1Ev
>>>> _ZN10__cxxabiv117__array_type_infoD1Ev =
>_ZN10__cxxabiv117__array_type_infoD2E
>>>>
>>>> and when I try to assemble it,
>>>>
>>>> gcc -c test.s
>>>>
>>>> there is no error, and test.o is created OK. Trying objdump on it
>>>>
>>>> objdump -t test.o
>>>>
>>>> shows it has the correct symbol reference in it, albeit undefined:
>>>>
>>>> test.o: file format elf64-x86-64
>>>>
>>>> SYMBOL TABLE:
>>>> 0000000000000000 *UND* 0000000000000000
>_ZN10__cxxabiv117__array_type_infoD2E
>>>>
>>>> So no, the issue is not with those two particular lines on their own.
>>>> Something else is involved.
>>>
>>>Yes. AFAICS main issue is creating alias name for an exported
>>>function. Internal aliases work fine. Probably data aliases too.
>>
>> I caution against putting it in those terms. What you are doing
>> in GNU `as` when you use the `a = e` syntax is creating a symbol
>> called "a" from that is set to the evalue of some expression.
>> In this contrived example, that expression is just "e", which I
>> used as a stand-in for any arbitrary expression, but if taken
>> literally, would just be valuated to the value of some other
>> symbol, called "e". If "e" was not defined already, it is
>> assumed to be an external.
>>
>> When you assemble troll's file, an object file is generated; the
>> results from `objdump` above show that there is a single symbol
>> in that object file's symbol table, one you referred to when
>> creating '_ZN10__cxxabiv117__array_type_infoD2E'. But note that
>> '_ZN10__cxxabiv117__array_type_infoD2E' itself (the symbol that
>> you created when you assigned to it) is not in the symbol table.
>>
>> However, the symbol that you created is not in the symbol table,
>> which is the fundamental problem.
>
>Well, one issue is if needed construct is supported at all.
>
>Other platforms have code like:
>
> .text
> .globl exp_fun
> .type exp_fun, @function
>exp_fun:
> ret
>.LFE0:
> .size exp_fun, .-exp_fun
> .globl alias_fun
> .set alias_fun,exp_fun
>
>Assembling this on x86 Linux gives object file exporting two symbols:
>exp_fun and alias_fun. IIUC this behaviour is wanted by C++
>compiler.
>
>Alpha VMS needs more complicated function definition. And more
>important: '.set alias_fun,exp_fun' causes assembler message
>about wrong syntax.
>
>In DEC assembler '=' apparently gives effect that you describe:
>new name is not exported. In DEC assembler '==' apparently creates
>an alias, but as a data symbol. I am not aware of DEC construct
>to get effect of '.set' as in x86 Linux example above (but up
>to now I did not look into macro manual). So '=' probably is
>wrong syntatx, I do not know why gcc uses it.
So the GNU `as` documentation says that `a = e` has the same
semamtics as `.set a, e`. Why isn't the Alpha version exporting
that symbol? I don't know off the top of my head. But it's not
specific to Alpha: my experiments were on x86. My suspcion
is that its because it is not used in the file itself.
- Dan C.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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