GCC Option -S

[LF28]

Hi everybody,

is there a way to make gcc insert the c++ source lines into the .s file? I am somewhat confuded with the assembler listing generated from a .cpp file.

Like this:

gcc -S somefile.cpp

outputs to somefile.s which is the assembler code representation of somefile.cpp

Any ideas?

Greets, Tobi

 

[xwb]

It doesn't work if the .s file is optimized. For instance, you may code

for (int i = 0; i < 10; i++)
{
dosomething ();
}

It could code it as the equivalent of

i = 0;
xxx:
if (i >= 10) goto yyy
dosomething ();
i++;
goto xxx;
yyy:

or

i = 0;
goto xxx;
yyy:
dosomething
i++;
xxx:
if (i < 10) goto yyy;

The latter is the option used by most optimizing compilers as it is one conditional branch less and is actually faster even though it looks a bit strange. It would be quite difficult to fit the source code to that.

 

[LF28]

@xwb
thanx for the reply. I know it would be difficult but anyway I would like to have this feature . The MS Visual C++ compiler is capable of doing just that and I thought it would be cool to have this feature while using a linux system.
BTW MS C++ shows the C++ code lines regardless of the code being optimized or not... (at least it tries)

Tobi