Re: [Tinycc-devel] Jump optimization questions - commit: 8227db3a

[grischka]

On 25.08.2022 13:06, Ekaitz Zarraga wrote:
> Hi,
>
> Sorry for insisting but I kept working on this and found no solution.
>
> vtop->r and vtop->cmp_r are used interchangeably in some parts of the codebase 
> and I don't really understand why.

I don't know where you see this?

Also, what is "all the C constructs modern TinyCC is using nowadays" that
0.9.27 was not using and that prevent you from just porting your patches
to current tcc?

--gr

> I tried using vtop->r but it just generates invalid values.
>
> Also RISC-V does not use flags so the process is different than in the other 
> architectures so I don't have a good reference to look at in any others.
>
> Does anyone have an idea about how can I tackle this?
>
> I managed to make the code generate the correct branch instructions but I can't 
> figure out how to obtain the correct registers.
>
> Thanks a lot,
> Ekaitz
>
>
> ------- Original Message -------
> On Thursday, August 11th, 2022 at 1:36 PM, Ekaitz Zarraga <ekaitz@elenq.tech> 
> wrote:
>
>
> > Hi,
> >
> > I think I have it mostly working following your advice but I cannot find how to 
> > map v->cmp_r to the field that was storing that information before the commit.
> >
> >
> > In the gjmp_cond in riscv:
> >
> > ``` c
> > ST_FUNC int gjmp_cond(int op, int t)
> > {
> > int tmp;
> > int a = vtop->cmp_r & 0xff;
> >
> > int b = (vtop->cmp_r >> 8) & 0xff;
> >
> > switch (op) {
> > ```
> >
> > What do I need to replace `a` and `b` with to use the previous register access 
> > but I can't find how to do that.
> >
> > Could you please help me?
> >
> > Thank you,
> > Ekaitz
> >
> >
> > ------- Original Message -------
> > On Wednesday, August 10th, 2022 at 1:53 PM, Ekaitz Zarraga ekaitz@elenq.tech 
> > wrote:
> >
> >
> >
> > > Hi,
> > >
> > > On Wednesday, August 10th, 2022 at 1:43 PM, grischka grishka@gmx.de wrote:
> > >
> > > > On 09.08.2022 20:39, Ekaitz Zarraga wrote:
> > > >
> > > > > Hi all,
> > > > >
> > > > > I'm working on the RISC-V bootstrapping efforts for Guix, and I have to 
> > > > > backport the RISC-V backend to an older TinyCC version we have patched in order 
> > > > > to be able to build it with a simpler compiler.
> > > >
> > > > I wonder why not just apply these patches to the newer tcc then?
> > >
> > > Mostly because the compiler we use to compile TinyCC does not provide all the C 
> > > constructs modern TinyCC is using nowadays, so we can't use it now.
> > > We may be able to do it in the future, but our current compiler chain does not 
> > > allow us to do that.
> > >
> > > > > The process worked mostly ok, but I can't understand very well the `gtst` 
> > > > > function in the generation part, and I need to write it from scratch as the 
> > > > > commit 8227db3a changed how the tests and jumps are managed.
> > > >
> > > > Actually that commit was to put the former gtst() function in its pieces,
> > > > now gjmp_cond(t, op) to handle VT_CMP, and gjmp_append(n, t) for the
> > > > former VT_JMP "optimization" part.
> > >
> > > Do you mean the commit was done to split the function in two?
> > > I'll take a deeper look and see if I can undo it properly.
> > >
> > > Thanks for the help
> > >
> > > _______________________________________________
> > > Tinycc-devel mailing list
> > > Tinycc-devel@nongnu.org
> > > https://lists.nongnu.org/mailman/listinfo/tinycc-devel