Inline asm - only clobber list case sensitive?

Inline asm - only clobber list case sensitive?

[Michael Weise]

Hi,

yesterday I've been facing a strange problem with some inline asm
code (see below), emitting errors like these:
(gcc 4.7.3, targetting m68k-elf, Windows 7/64, msys):

rs232_2.c:2433:2: error: unknown register name '%CC' in 'asm'
rs232_2.c:2433:2: error: unknown register name '%D1' in 'asm'
rs232_2.c:2433:2: error: unknown register name '%D0' in 'asm'
rs232_2.c:2433:2: error: unknown register name '%A1' in 'asm'
rs232_2.c:2433:2: error: unknown register name '%A0' in 'asm'


Further investigation revealed that the problem is related to case
sensitivity of the register names. I played around with upper/lower case
to check this:

asm volatile (
    "    move.l   %[in1],%%a0 \n" // asm code
    "    move.l   %[in2],%%A1 \n"
    "    trap     #8          \n"
    "    move.b   %%D0,%[out1]\n"
    "    move.b   %%d1,%[out2]\n"
    :[out1] "=m" (*pc1),          // output
     [out2] "=m" (*pc2)
    :[in1]  "r"  (cmdadr),        // input
     [in2]  "r"  (DUMRadr)
    :"%a0","%A1","%d0","%D1",     // clobber list
     "memory","%CC"
    );

Results in:
rs232_2.c:2433:2: error: unknown register name '%CC' in 'asm'
rs232_2.c:2433:2: error: unknown register name '%D1' in 'asm'
rs232_2.c:2433:2: error: unknown register name '%A1' in 'asm'


The assembler does not complain about %a0 and %d0, which leads me to
the conclusion that:


* Register names being upper case are not recognized - but only in the
clobber list.

Is this intentional, a feature or a bug?


Best Regards
Michael Weise

Re: Inline asm - only clobber list case sensitive?

[Andrew Haley]

On 11/15/2013 09:26 AM, Michael Weise wrote:
> * Register names being upper case are not recognized - but only in the
> clobber list.

The clobber list is parsed by GCC, the instructions by the assembler.
I don't think GCC even looks at the register names in the assembly
code -- it just passes them through as strings.

Andrew.

Re: Inline asm - only clobber list case sensitive?

[Chung-Ju Wu]

On 11/15/13, 5:26 PM, Michael Weise wrote:
> Hi,
> 
> yesterday I've been facing a strange problem with some inline asm
> code (see below), emitting errors like these:
> (gcc 4.7.3, targetting m68k-elf, Windows 7/64, msys):
> 
[snip]
> 
> asm volatile (
>     "    move.l   %[in1],%%a0 \n" // asm code
>     "    move.l   %[in2],%%A1 \n"
>     "    trap     #8          \n"
>     "    move.b   %%D0,%[out1]\n"
>     "    move.b   %%d1,%[out2]\n"
>     :[out1] "=m" (*pc1),          // output
>      [out2] "=m" (*pc2)
>     :[in1]  "r"  (cmdadr),        // input
>      [in2]  "r"  (DUMRadr)
>     :"%a0","%A1","%d0","%D1",     // clobber list
>      "memory","%CC"
>     );
> 
> Results in:
> rs232_2.c:2433:2: error: unknown register name '%CC' in 'asm'
> rs232_2.c:2433:2: error: unknown register name '%D1' in 'asm'
> rs232_2.c:2433:2: error: unknown register name '%A1' in 'asm'
> 

Hi, Michael,

If you build m68k-elf on your own, you can implement
ADDITIONAL_REGISTER_NAMES in gcc/config/m68k/m68k.h to
define alias register names with upper case.

This can help gcc recognize them. :)


Best regards,
jasonwucj