Re: [Lightning] sse instructions and gcc warnings

[Paolo Bonzini]

On 07/26/2010 10:35 PM, Paulo César Pereira de Andrade wrote:
> > >     This started happening when I added calls to jit_str_c, jit_str_uc,
> > > etc, and apparently doesn't happen if there are only calls to
> > > jit_stxi_s, jit_stxi_us, etc, but I am not 100% sure now.
> >
> > Yes, jit_str_c and jit_str_uc are indeed responsible.
>
>    It does not happen in x86_64.

All x86_64 registers are 8-bit-accessible.

> > > > >      Also about @subject, I needed to add a global function to check
> > > > > if a double is zero, because apparently the i387 goes nonsense if
> > > > > a function using vector instructions was called.
>
>    Also does not happen in x86_64.

x86_64 uses SSE.

>    Now the bad news :-)
>
>    Load/store of float32 simply does not work, examples:
>      jit_ldr_f(JIT_FPR0, JIT_R1);
>      jit_stxi_d(..., JIT_V1, JIT_FPR0);
> and
>      jit_ldxi_d(JIT_FPR0, JIT_V1, ....);
>      [...]
>      jit_str_f(JIT_R1, JIT_FPR0);
>
>    Another problem is that:
>      jit_ldr_c or jit_ldr_s   (JIT_R0, JIT_R1)
>      [...]
>      jit_stxi_l(JIT_R0, JIT_V1, ...);
> does not sign extend the top 32 bits, but jit_stxi_ul paired with
> jit_ldr_uc or jit_ldr_us sign extends (zeros out top 32 bits). From
> the test cases I currently use, it appears to sign extend int32, but
> I just added all small ints to the same fallback for now...

Thanks, I'll look at it.

Paolo