Re: function pointer

[Joern Rennecke <amylaar at redhat dot com>]

> It seems that in the assembly translation the address of
> another_function() is pushed into register %ebx first, and then a
> indirect call(i.e. call *%ebx) is used to transfer control flow to
> another_function(). Is this the standare way that gcc handles function
> calls which are invoked through function pointer variable? I would like 

No, gcc is free to use any suitable register.

> to
> add some assembly instructions right before every this kind of indirect 
> funciton call? (i.e. so every fucntion call invoked through function
> pointer will be tranlated as follows:

The straightforward way to do this is to hack the *call_1 pattern in i386.md.

> Besides, as you know the C source code will be translated into RTL form
> first. Then the RTL form will be tranlated into assembly code and the
> assembly code will be saved into a temporary file. After all the 
> assembly
> code is generated and saved into the temporary file, what function of 
> the
> gcc souce code is called to process the temporary assembly file? If I 

It's not just a function call - the gcc compiler driver invokes the assembler,
which is a separate executable.  As is the cc1 compiler.

> add
> some assembly instructions into the temporary file right before it is
> further processed, will this caused any problem?

Maybe.  Depends.