[sdcc-devel] Re: [ sdcc-Bugs-477835 ] Regs used in a pcall are not saved

[Johan K. <joh...@id...>]

> void
> fptr(void (*fp)(void))
> {
>   int i;
>   for (i = 0; i < 50; i++)
>     (*fp)();
> }
>
> fails as the registers assigned to the local copy of fp are
> not saved across the call.  Visible on the z80 and mcs51
> stack based ports.  I'm looking into the z80 port.

saveRegisters() saved registeres that were in use (ic->rMask), but excluded
the ones used in this icode (ic->rUsed). Only a PCALL uses registers for
IC_LEFT(ic) and those were excluded as well. So I changed it (mcs51 only) to
exclude only the registers used for IC_RESULT(ic). An additional check
should be made to see if the live range of IC_LEFT(ic) ends here in which
case it doesn't need to be saved either. If I figured that out, ds390 and
pic can follow.

The Z80 port already had something like this in gen.c:1.61 but for some
reason it isn't there anymore. I don't feel comfortable changing it there, I
could find a _saveRegsForCall but not the corresponding _unsaveRegsForCall.
So I'd rather have Micheal to look at this.

I couldn't find either of them in the AVR port.

Now an new problem is that because of the extra push/pop, testfwk.c won't
compile anymore for mcs51 because of a jmp out of range. I thought that was
fixed a long time ago, anyone?
The additional check mentioned before would prevent that, but than the
offset would still be 0x84 which is extremely dangerous.

Johan