[MLton-user] experimental release 20051109

[Matthew Fluet]

> I tried compiling with -codegen c -profile time using the following
> two versions of {Declare,}ProfileLabel on my Linux machine with gcc
> 3.3.5.
>
> ----------------------------------------------------------------------
> #define DeclareProfileLabel(l)                  \
>        void l()
> #define ProfileLabel(l)                                         \
>        __asm__ __volatile__ (".globl _" #l "\n_" #l ":" : : )
> ----------------------------------------------------------------------
> #define DeclareProfileLabel(l)                                  \
> 	extern void l () asm (#l "_internal")
> #define ProfileLabel(l)                                 \
>        __asm__ __volatile__ (#l "_internal:" : : )
> ----------------------------------------------------------------------
>
> Both of them failed, when trying to run the executable, with
>
>  Max profile label is 0 -- something is wrong.
>
> Am I doing something wrong?

There are actually two DeclareProfileLabel macros; one in include/main.h 
and one in include/c-chunk.h.  They both need to agree on what to call the 
label from assembly.  Then, because we are extern importing the symbol, C 
won't attempt to make the symbol visible outside the single object file. 
So, we can use the .globl trick from the __APPLE_CC__ branch.  So, the 
following appears to work:

#define DeclareProfileLabel(l)                                  \
         extern void l () asm (#l "_internal")

#define ProfileLabel(l)                                 \
         __asm__ __volatile__ (".globl " #l "_internal\n" #l "_internal :" : : )

Note that the DeclareProfileLabel macro needs to appear both in main.h and 
c-chunk.h.

Actually, I don't know why files with c-chunk.h need to declare their 
profile labels.  C doesn't see these labels at all.

Also, I don't recall why we add the _internal suffix to profile labels in 
C, but if we adopt the above, then the x86-codegen needs to emit profile 
labels with the same suffix.  (Which is a trivial change.)