VBCC: How to use small code/data models with nostdlib

[Hedeon]

Nice! Thanks for the help!

[patrik]

Originally Posted by phx

Hmmm... yes. The reason is in the linker libraries, not in your code. Even if you compile with -sc and -sd and link with -lvcs, the vcs.lib itself was only compiled with -sd, but not with -sc. So all calls from the vcs.lib are absolute.

I wonder if I should change that for the upcoming release. When you link with a small-data library, does it make sense to always have small-code as well? Probably.

Would it also be possible to have it automatically link with a small-code link library when compiling only with -sc?

A somewhat unorthodox idea maybe, but would it be feasible to compile the link library on the fly with the same options as the code?

[phx]

Originally Posted by patrik

Would it also be possible to have it automatically link with a small-code link library when compiling only with -sc?

Theoretically, yes.
The problem I have is that I do not like to compile libraries for all combinations of -sc and -sd.

A somewhat unorthodox idea maybe, but would it be feasible to compile the link library on the fly with the same options as the code?

You mean, that the linker patches all absolute jumps with relative ones (or branches)? Not impossible. But you would probably like relative jumps to be two bytes smaller, and moving code is something the linker cannot easily do.

What I could imagine is to compile all small-data libraries with -sc, and whenever the distance becomes too large the linker might generate ALVs (automatic link vectors - adding absolute JMP instructions at the object unit's section borders).

I wanted to add ALVs to vlink long ago, but never really needed them. So this would be a reason...

[patrik]

Originally Posted by phx

Theoretically, yes.
The problem I have is that I do not like to compile libraries for all combinations of -sc and -sd.

I see the point, but I do wish .

Originally Posted by phx

You mean, that the linker patches all absolute jumps with relative ones (or branches)? Not impossible. But you would probably like relative jumps to be two bytes smaller, and moving code is something the linker cannot easily do

My idea was way more crude and as said unorthodox: vbcc would also ask vasm (?) to compile the linker library from source with the options used and pass that result along to the linker to link with

Originally Posted by phx

What I could imagine is to compile all small-data libraries with -sc, and whenever the distance becomes too large the linker might generate ALVs (automatic link vectors - adding absolute JMP instructions at the object unit's section borders).

I wanted to add ALVs to vlink long ago, but never really needed them. So this would be a reason...