| Message ID | 1349526621-13939-14-git-send-email-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Sat, Oct 6, 2012 at 12:30 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: > This is looking at EFLAGS, but it can do so more efficiently with > setcond. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Blue Swirl <blauwirbel@gmail.com> > --- > target-i386/translate.c | 7 +++---- > 1 file modificato, 3 inserzioni(+), 4 rimozioni(-) > > diff --git a/target-i386/translate.c b/target-i386/translate.c > index fb44839..342b9ec 100644 > --- a/target-i386/translate.c > +++ b/target-i386/translate.c > @@ -1031,10 +1031,9 @@ static inline void gen_setcc_slow(DisasContext *s, int jcc_op, TCGv reg, bool in > return; > case JCC_BE: > gen_compute_eflags(s); > - tcg_gen_shri_tl(reg, cpu_cc_src, 6); > - tcg_gen_or_tl(reg, reg, cpu_cc_src); > - tcg_gen_andi_tl(reg, reg, 1); > - break; > + tcg_gen_andi_tl(reg, cpu_cc_src, 0x41); Symbolic names for the flags would be nice. > + tcg_gen_setcondi_tl(inv ? TCG_COND_EQ : TCG_COND_NE, reg, reg, 0); > + return; > case JCC_S: > gen_compute_eflags_s(s, reg, inv); > return; > -- > 1.7.12.1 > > >
On 10/06/2012 05:30 AM, Paolo Bonzini wrote: > gen_compute_eflags(s); > - tcg_gen_shri_tl(reg, cpu_cc_src, 6); > - tcg_gen_or_tl(reg, reg, cpu_cc_src); > - tcg_gen_andi_tl(reg, reg, 1); > - break; > + tcg_gen_andi_tl(reg, cpu_cc_src, 0x41); > + tcg_gen_setcondi_tl(inv ? TCG_COND_EQ : TCG_COND_NE, reg, reg, 0); > + return; This one's questionable. Whether it's an improvement really depends on the host cpu isa. It's probably more of a benefit if we can avoid the setcond completely. See the comments for the next patch. That said, the patch produces correct code. Reviewed-by: Richard Henderson <rth@twiddle.net> r~
diff --git a/target-i386/translate.c b/target-i386/translate.c index fb44839..342b9ec 100644 --- a/target-i386/translate.c +++ b/target-i386/translate.c @@ -1031,10 +1031,9 @@ static inline void gen_setcc_slow(DisasContext *s, int jcc_op, TCGv reg, bool in return; case JCC_BE: gen_compute_eflags(s); - tcg_gen_shri_tl(reg, cpu_cc_src, 6); - tcg_gen_or_tl(reg, reg, cpu_cc_src); - tcg_gen_andi_tl(reg, reg, 1); - break; + tcg_gen_andi_tl(reg, cpu_cc_src, 0x41); + tcg_gen_setcondi_tl(inv ? TCG_COND_EQ : TCG_COND_NE, reg, reg, 0); + return; case JCC_S: gen_compute_eflags_s(s, reg, inv); return;
This is looking at EFLAGS, but it can do so more efficiently with setcond. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- target-i386/translate.c | 7 +++---- 1 file modificato, 3 inserzioni(+), 4 rimozioni(-)