[OpenRISC] [PATCH v3 1/3] or1k: libgcc: initial support for openrisc

Stafford Horne
2018-10-29T13:44:24Z

On Sun, Oct 28, 2018 at 01:25:54AM +0000, Richard Henderson wrote:
> On 10/27/18 5:37 AM, Stafford Horne wrote:
> > +/* Here _init and _fini are empty because .init_array/.fini_array are used
> > + exclusively. However, the functions are still needed as required when
> > + linking. */
> > + .align 4
> > + .global _init
> > + .type _init, at function
> > +_init:
> > + .global _fini
> > + .type _fini, at function
> > +_fini:
> > + l.jr r9
> > + l.nop
>
> Where are they referenced from? Perhaps just a binutils bug, in that the
> linker script needs adjustment?

I was getting the issue with newlib. Here:

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=newlib/libc/misc/init.c
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=newlib/libc/misc/fini.c

The HAVE_INIT_FINI was not there when I last checked. Now, thanks to risc-v, we
can turn off the need for _init/_fini see:

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=commit;f=newlib/libc/misc/fini.c;h=6158b30e3e9b1b582ae60b15d64e775fa1705483

I guess thats what you were referring to before though, I just missed it.

> > + /* Given R = X * Y ... */
> > +1: l.sfeq r4, r0 /* while (y != 0) */
> > + l.bf 2f
> > + l.andi r5, r4, 1 /* if (y & 1) ... */
> > + l.add r12, r11, r3
> > + l.sfne r5, r0
> > +#if defined(__or1k_cmov__)
> > + l.cmov r11, r12, r11 /* ... r += x. */
> > + l.srli r4, r4, 1 /* y >>= 1 */
> > +#else
> > + l.bnf 3f
> > + l.srli r4, r4, 1 /* y >>= 1 */
> > + l.ori r11, r12, 0
>
> This move could be the add to save 1 cycle in the !cmov case.
>
> > + /* Shift Y back to the right again, subtracting from X. */
> > +2: l.add r7, r11, r6 /* tmp1 = quot + mask */
> > +3: l.srli r6, r6, 1 /* mask >>= 1 */
> > + l.sub r8, r12, r4 /* tmp2 = x - y */
> > + l.sfleu r4, r12 /* y <= x */
> > + l.srli r4, r4, 1 /* y >>= 1 */
> > +#if defined(__or1k_cmov__)
> > + l.cmov r11, r7, r11 /* if (y <= x) quot = tmp1 */
> > + l.cmov r12, r8, r12 /* if (y <= x) x = tmp2 */
> > +#else
> > + l.bnf 4f
> > + l.nop
> > + l.ori r11, r7, 0
> > + l.ori r12, r8, 0
>
> Simiarly.
>
> Although both mul nor div are correct as-is, and need not be fixed immediately.
> I'm only concerned about _init and _fini.

Sure, let me look into them.

-Stafford