llvm dev - Jun 2011 - [LLVMdev] ARM thumb-2 instruction used for non-thumb2 CPUs

On Jun 22, 2011, at 4:02 PM, Damjan Marion wrote:
>> 
>> To get -integrated-as working so that we don't need to go through
the assembler at all should be mostly a matter of bug fixing, modulo inline
assembly support. For non-trivial inline assembly, and to get a system assembler
replacement based on the MC assembler, it'll be a bigger task. The ARM asm
parser is currently in need of some tender loving care. That's coming soon,
but it's a non-trivial task.
>> 
>> For -integrated-as, I would suggest giving it a try. I'm not
completely sure how complete the support is for ELF, but I think it's in
somewhat OK shape, at least. Worth trying. That would neatly avoid the problem
if it works. If it doesn't, we should fix the bugs so it does. ;)
> 
> I tried with FreeBSD kernel. Outcome is 2 different crashes. Output is
here:
> 
> http://web.me.com/dmarion/FreeBSD/integrated-as_crash.txt
> 
> I can provide more details if needed.

Thanks, Damjan. That's good information.

Crash #1 is an assembly source file. It's running into something it
doesn't understand on the line indicated. The assertion failure is a
secondary problem, and definitely shouldn't happen. As mentioned, though,
the asm parser isn't ready for prime time yet, so I suspect this may be just
the tip of the iceberg as far as the problems that (and similar) files would
encounter.

Crash #2 is a C file, but is also asserting in the assembly parser, which
indicates that there's inline assembly in the file somewhere that the parser
doesn't know how to handle yet.

Some Makefile magic should be able to take care of issues of the sort
encountered in #1 (don't pass -integrated-as when compiling .S files).

Inline assembly is a bit trickier. Temporarily, if those files compile/assemble
OK with the system assembler (i.e., don't have the rrx instruction mnemonic
in them), we could work around by not using -integrated-as for them. That's
pretty fugly, though, and would just be a quick workaround to allow you to keep
making progress while the real issues get fixed.

How much inline asm is there in that file that's causing issues? if it's
not too much, it might not be too bad to get at least that much of the asm
parsing working. That would be general goodness and would help move you forward.

-Jim

On Jun 23, 2011, at 1:13 AM, Jim Grosbach wrote:
> On Jun 22, 2011, at 4:02 PM, Damjan Marion wrote:
>>> 
>>> To get -integrated-as working so that we don't need to go
through the assembler at all should be mostly a matter of bug fixing, modulo
inline assembly support. For non-trivial inline assembly, and to get a system
assembler replacement based on the MC assembler, it'll be a bigger task. The
ARM asm parser is currently in need of some tender loving care. That's
coming soon, but it's a non-trivial task.
>>> 
>>> For -integrated-as, I would suggest giving it a try. I'm not
completely sure how complete the support is for ELF, but I think it's in
somewhat OK shape, at least. Worth trying. That would neatly avoid the problem
if it works. If it doesn't, we should fix the bugs so it does. ;)
>> 
>> I tried with FreeBSD kernel. Outcome is 2 different crashes. Output is
here:
>> 
>> http://web.me.com/dmarion/FreeBSD/integrated-as_crash.txt
>> 
>> I can provide more details if needed.
> 
> 
> Thanks, Damjan. That's good information.
> 
> Crash #1 is an assembly source file. It's running into something it
doesn't understand on the line indicated. The assertion failure is a
secondary problem, and definitely shouldn't happen. As mentioned, though,
the asm parser isn't ready for prime time yet, so I suspect this may be just
the tip of the iceberg as far as the problems that (and similar) files would
encounter.
> 
> Crash #2 is a C file, but is also asserting in the assembly parser, which
indicates that there's inline assembly in the file somewhere that the parser
doesn't know how to handle yet.
Seems that it fails even on simply inline asm. Here is test function:

void case2(unsigned int x)
{
 __asm volatile( "mov    %0, %0, ror #8\n" : "+r" (x));
}

> 
> Some Makefile magic should be able to take care of issues of the sort
encountered in #1 (don't pass -integrated-as when compiling .S files).
> 
> Inline assembly is a bit trickier. Temporarily, if those files
compile/assemble OK with the system assembler (i.e., don't have the rrx
instruction mnemonic in them), we could work around by not using -integrated-as
for them. That's pretty fugly, though, and would just be a quick workaround
to allow you to keep making progress while the real issues get fixed.
> 
> How much inline asm is there in that file that's causing issues? if
it's not too much, it might not be too bad to get at least that much of the
asm parsing working. That would be general goodness and would help move you
forward.
> 
I tried to compile FreeBSD kernel using -integrated-asm and except ~30 files
containing inline asm everything else went smoothly in compiling phase.
I removed -integrated-as for files with inline assembly and now linker fails:

error: Source object ata_all.o has EABI version 0, but target kernel.debug has
EABI version 5

Seems that -integrated-as is producing EABI v5 files, while my binutils is
producing EABI v0.

Is there any way to force EABI version 0?

Thanks,

On Wednesday, June 22, 2011, Damjan Marion <damjan.marion at gmail.com>
wrote:
>
> On Jun 23, 2011, at 1:13 AM, Jim Grosbach wrote:
>
>> On Jun 22, 2011, at 4:02 PM, Damjan Marion wrote:
>>>>
>>>> To get -integrated-as working so that we don't need to go
through the assembler at all should be mostly a matter of bug fixing, modulo
inline assembly support. For non-trivial inline assembly, and to get a system
assembler replacement based on the MC assembler, it'll be a bigger task. The
ARM asm parser is currently in need of some tender loving care. That's
coming soon, but it's a non-trivial task.
>>>>
>>>> For -integrated-as, I would suggest giving it a try. I'm
not completely sure how complete the support is for ELF, but I think it's in
somewhat OK shape, at least. Worth trying. That would neatly avoid the problem
if it works. If it doesn't, we should fix the bugs so it does. ;)
>>>
>>> I tried with FreeBSD kernel. Outcome is 2 different crashes. Output
is here:
>>>
>>> http://web.me.com/dmarion/FreeBSD/integrated-as_crash.txt
>>>
>>> I can provide more details if needed.
>>
>>
>> Thanks, Damjan. That's good information.
>>
>> Crash #1 is an assembly source file. It's running into something it
doesn't understand on the line indicated. The assertion failure is a
secondary problem, and definitely shouldn't happen. As mentioned, though,
the asm parser isn't ready for prime time yet, so I suspect this may be just
the tip of the iceberg as far as the problems that (and similar) files would
encounter.
>>
>> Crash #2 is a C file, but is also asserting in the assembly parser,
which indicates that there's inline assembly in the file somewhere that the
parser doesn't know how to handle yet.
>
> Seems that it fails even on simply inline asm. Here is test function:
>
> void case2(unsigned int x)
> {
>  __asm volatile( "mov    %0, %0, ror #8\n" : "+r" (x));
> }
IIRC, this fails because the support for optional args isn't yet
supported for every instruction, only for the cases that people cared!
Please file bugs!
>
>>
>> Some Makefile magic should be able to take care of issues of the sort
encountered in #1 (don't pass -integrated-as when compiling .S files).
>>
>> Inline assembly is a bit trickier. Temporarily, if those files
compile/assemble OK with the system assembler (i.e., don't have the rrx
instruction mnemonic in them), we could work around by not using -integrated-as
for them. That's pretty fugly, though, and would just be a quick workaround
to allow you to keep making progress while the real issues get fixed.
>>
>> How much inline asm is there in that file that's causing issues? if
it's not too much, it might not be too bad to get at least that much of the
asm parsing working. That would be general goodness and would help move you
forward.
>>
>
> I tried to compile FreeBSD kernel using -integrated-asm and except ~30
files containing inline asm everything else went smoothly in compiling phase.
> I removed -integrated-as for files with inline assembly and now linker
fails:
>
> error: Source object ata_all.o has EABI version 0, but target kernel.debug
has EABI version 5
>
> Seems that -integrated-as is producing EABI v5 files, while my binutils is
producing EABI v0.
>
> Is there any way to force EABI version 0?
>
> Thanks,
>
>
>
>
>
>
>
>
>
>
>
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-- 
Bruno Cardoso Lopes
http://www.brunocardoso.cc