llvm dev - Mar 2012 - [LLVMdev] Mangling of UTF-8 characters in symbol names

On Fri, Mar 30, 2012 at 15:22, Eli Friedman <eli.friedman at gmail.com>
wrote:
> On Fri, Mar 30, 2012 at 12:12 PM, Sean Hunt <scshunt at
csclub.uwaterloo.ca>
> wrote:
> > Why is it that high (>127) bytes in symbol names get mangled by
LLVM into
> > _XX_, where XX is the hex representation of the character? Is this
> required
> > by ELF or some similar standard? This behavior is inconsistent with
GCC.
>
> I think it's just so that we have a way to actually write out the
> symbol into the assembly file.  What does gcc do?
>
> -Eli
>
>
It emits the high bits literally. The consequence is that UTF-8-encoded
identifiers come out in UTF-8:

scshunt at natural-flavours:~$ gcc -fextended-identifiers -std=c99 -x c -c -o
test.o -
int i\u03bb;
scshunt at natural-flavours:~$ nm test.o
00000004 C iλ
scshunt at natural-flavours:~$

As you can see, the nm output includes the literal lambda.

Sean
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On Fri, Mar 30, 2012 at 6:17 PM, Sean Hunt <scshunt at
csclub.uwaterloo.ca> wrote:
> On Fri, Mar 30, 2012 at 15:22, Eli Friedman <eli.friedman at
gmail.com> wrote:
>>
>> On Fri, Mar 30, 2012 at 12:12 PM, Sean Hunt <scshunt at
csclub.uwaterloo.ca>
>> wrote:
>> > Why is it that high (>127) bytes in symbol names get mangled by
LLVM
>> > into
>> > _XX_, where XX is the hex representation of the character? Is this
>> > required
>> > by ELF or some similar standard? This behavior is inconsistent
with GCC.
>>
>> I think it's just so that we have a way to actually write out the
>> symbol into the assembly file.  What does gcc do?
>>
>> -Eli
>>
>
> It emits the high bits literally. The consequence is that UTF-8-encoded
> identifiers come out in UTF-8:
>
> scshunt at natural-flavours:~$ gcc -fextended-identifiers -std=c99 -x c -c
-o
> test.o -
> int i\u03bb;
> scshunt at natural-flavours:~$ nm test.o
> 00000004 C iλ
> scshunt at natural-flavours:~$
>
> As you can see, the nm output includes the literal lambda.
Okay... then we should probably support that as well.  Might need to
be a bit careful to make sure the assembly files work correctly.

-Eli

On Fri, Mar 30, 2012 at 21:22, Eli Friedman <eli.friedman at gmail.com>
wrote:
> Okay... then we should probably support that as well.  Might need to
> be a bit careful to make sure the assembly files work correctly.
>
> -Eli
>
You mean machine assembly and not IR, right?

Sean