[v1] target/i386: make decoding entirely table based

[PATCH 04/10] target/i386: try not to force EFLAGS computation for CC_OP_ADOX/ADCX

Posted by Paolo Bonzini 5 months, 1 week ago

When computing the "other" flag (CF for CC_OP_ADOX, OF for CC_OP_ADCX),
take into account that it is already in the right position of cpu_cc_src,
just like for CC_OP_EFLAGS.  There is no need to call gen_compute_eflags().

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/tcg/translate.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index 257110ac703..08db40681fa 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -928,6 +928,7 @@ static CCPrepare gen_prepare_eflags_c(DisasContext *s, TCGv reg)
                              .no_setcond = true };
 
     case CC_OP_EFLAGS:
+    case CC_OP_ADOX:
     case CC_OP_SARB ... CC_OP_SARQ:
         /* CC_SRC & 1 */
         return (CCPrepare) { .cond = TCG_COND_TSTNE,
@@ -994,6 +995,9 @@ static CCPrepare gen_prepare_eflags_o(DisasContext *s, TCGv reg)
         return (CCPrepare) { .cond = TCG_COND_NE, .reg = cpu_cc_src };
     default:
         gen_compute_eflags(s);
+        /* fallthrough */
+    case CC_OP_EFLAGS:
+    case CC_OP_ADCX:
         return (CCPrepare) { .cond = TCG_COND_TSTNE, .reg = cpu_cc_src,
                              .imm = CC_O };
     }
-- 
2.45.2

Re: [PATCH 04/10] target/i386: try not to force EFLAGS computation for CC_OP_ADOX/ADCX

Posted by Richard Henderson 5 months, 1 week ago

On 6/20/24 02:54, Paolo Bonzini wrote:
> When computing the "other" flag (CF for CC_OP_ADOX, OF for CC_OP_ADCX),
> take into account that it is already in the right position of cpu_cc_src,
> just like for CC_OP_EFLAGS.  There is no need to call gen_compute_eflags().
> 
> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
> ---
>   target/i386/tcg/translate.c | 4 ++++
>   1 file changed, 4 insertions(+)

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

r~