[Bug c/31782] New: Invalid assembly code on initial dollar signs

[Bug c/31782] New: Invalid assembly code on initial dollar signs

[truedfx at gentoo dot org]

Hi,

This code compiles fine with gcc:

void a$() {}
int main() { a$(); }

This generates invalid assembly code:

void $() {}
int main() { $(); }

To gas, an initial $ is not allowed in an identifier, but to gcc, it is, so gcc
can't simply copy the function name to the assembly output, unless $ also
becomes an invalid identifier in C.

The code can, of course, compile successfully with -fleading-underscore.


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           Summary: Invalid assembly code on initial dollar signs
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: truedfx at gentoo dot org
  GCC host triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31782

[Bug c/31782] Invalid assembly code on initial dollar signs

[truedfx at gentoo dot org]

------- Comment #1 from truedfx at gentoo dot org  2007-05-02 03:21 -------
Sorry, forgot to mention, I'm using gcc 4.1.2 with binutils 2.17, and I also
tried gcc 3.3.6 with binutils 2.16.1, which behaves the same for me.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31782

[Bug target/31782] Invalid assembly code on initial dollar signs

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2007-05-02 03:33 -------
> unless $ also becomes an invalid identifier in C.

Well read:
http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Dollar-Signs.html

it is can be but does not have to be.

This works for me targetting spu-elf and powerpc64-linux-gnu (with -m32 and
-m64) so this is a target issue.  Really I think this is a bug in binutils for
i386/x86_64 (I can reproduce it there).


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |target
   GCC host triplet|x86_64-pc-linux-gnu         |
 GCC target triplet|                            |x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31782

[Bug target/31782] Invalid assembly code on initial dollar signs

[truedfx at gentoo dot org]

------- Comment #3 from truedfx at gentoo dot org  2007-05-02 05:58 -------
Thanks for the link. I don't see how GAS could be fixed, though. How would the
assembler tell the difference between $0 the constant and $0 the identifier?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31782

[Bug target/31782] Invalid assembly code on initial dollar signs

[joseph at codesourcery dot com]

------- Comment #4 from joseph at codesourcery dot com  2007-05-02 12:58 -------
Subject: Re:  Invalid assembly code on initial dollar signs

On Wed, 2 May 2007, truedfx at gentoo dot org wrote:

> Thanks for the link. I don't see how GAS could be fixed, though. How would the
> assembler tell the difference between $0 the constant and $0 the identifier?

ELF supports arbitrary (possibly empty) sequences of non-NUL bytes as 
symbol names.  GAS should, in principle, provide an escaping mechanism for 
assembly files to represent all such names.  GCC should use that escaping 
mechanism as required.  (It's arguable whether such escaping should be 
applied to asm names given to variables or whether it's the user's 
responsibility to include the escaping in the string passed to asm in that 
case.)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31782