Re: [Qemu-devel] [PATCH 5/7] tcg-sparc: Implement setcond, movcond, setcond2, brcond2.

[Richard Henderson]

On 12/19/2009 02:31 AM, Blue Swirl wrote:
> >   static inline void tcg_out_movi_imm32(TCGContext *s, int ret, uint32_t arg)
> >   {
> > -    if (check_fit_tl(arg, 12))
> > +    if (check_fit_tl(arg, 13))
> >          tcg_out_movi_imm13(s, ret, arg);
>
> IIRC sign extension prevents this.

Pardon?  check_fit_tl checks a signed value, the OR opcode provides one. 
 Where's the conflict?

> > -    if (const_arg2&&  arg2 == 0)
> > -        /* orcc %g0, r, %g0 */
> > -        tcg_out_arith(s, TCG_REG_G0, TCG_REG_G0, arg1, ARITH_ORCC);
> > -    else
> > -        /* subcc r1, r2, %g0 */
> > -        tcg_out_arith(s, TCG_REG_G0, arg1, arg2, ARITH_SUBCC);
> > -    tcg_out_branch_i32(s, tcg_cond_to_bcond[cond], label_index);
> > +    tcg_out_cmp(s, arg1, arg2, const_arg2);
>
> What's wrong with 'orcc' (produces the synthetic instruction 'tst')?

What result does "orcc" give that isn't produced by "subcc"?  Unlike 
i386 where "test x,x" is one byte smaller than "cmp $0,x", it seems to 
me there's no reason to distingish the arg2 == constant zero case on sparc.


r~