First round of target/i386/tcg patches for QEMU 11.0

[PATCH 05/18] target/i386/tcg: do not compute all flags for SAHF

Posted by Paolo Bonzini 6 days, 14 hours ago

Only OF is needed, the others are overwritten.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/tcg/emit.c.inc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/i386/tcg/emit.c.inc b/target/i386/tcg/emit.c.inc
index 22e53f5b000..131aefce53c 100644
--- a/target/i386/tcg/emit.c.inc
+++ b/target/i386/tcg/emit.c.inc
@@ -3778,7 +3778,7 @@ static void gen_SAHF(DisasContext *s, X86DecodedInsn *decode)
         return gen_illegal_opcode(s);
     }
     tcg_gen_shri_tl(s->T0, cpu_regs[R_EAX], 8);
-    gen_compute_eflags(s);
+    gen_neg_setcc(s, JCC_O << 1, cpu_cc_src);
     tcg_gen_andi_tl(cpu_cc_src, cpu_cc_src, CC_O);
     tcg_gen_andi_tl(s->T0, s->T0, CC_S | CC_Z | CC_A | CC_P | CC_C);
     tcg_gen_or_tl(cpu_cc_src, cpu_cc_src, s->T0);
-- 
2.52.0

Re: [PATCH 05/18] target/i386/tcg: do not compute all flags for SAHF

Posted by Richard Henderson 5 days, 11 hours ago

On 12/10/25 07:16, Paolo Bonzini wrote:
> Only OF is needed, the others are overwritten.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   target/i386/tcg/emit.c.inc | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/target/i386/tcg/emit.c.inc b/target/i386/tcg/emit.c.inc
> index 22e53f5b000..131aefce53c 100644
> --- a/target/i386/tcg/emit.c.inc
> +++ b/target/i386/tcg/emit.c.inc
> @@ -3778,7 +3778,7 @@ static void gen_SAHF(DisasContext *s, X86DecodedInsn *decode)
>           return gen_illegal_opcode(s);
>       }
>       tcg_gen_shri_tl(s->T0, cpu_regs[R_EAX], 8);
> -    gen_compute_eflags(s);
> +    gen_neg_setcc(s, JCC_O << 1, cpu_cc_src);
>       tcg_gen_andi_tl(cpu_cc_src, cpu_cc_src, CC_O);
>       tcg_gen_andi_tl(s->T0, s->T0, CC_S | CC_Z | CC_A | CC_P | CC_C);
>       tcg_gen_or_tl(cpu_cc_src, cpu_cc_src, s->T0);

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~