On 12/15/24 03:06, Paolo Bonzini wrote:
Explicitly generate a TSTEQ branch (which is optimized to NE x,0 if possible).
This does not make much sense yet, but later we will add more checks and some
will use a temporary to check on the decremented value of CX/ECX/RCX; it will
be clearer for all checks to share the same logic using TSTEQ(reg, cx_mask).
Signed-off-by: Paolo Bonzini <[email protected]>
---
target/i386/tcg/translate.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index 4b53a47000e..8ef938372d5 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -1336,6 +1336,7 @@ static void do_gen_rep(DisasContext *s, MemOp ot,
bool is_repz_nz)
{
TCGLabel *done = gen_new_label();
+ target_ulong cx_mask = MAKE_64BIT_MASK(0, 8 << s->aflag);
bool had_rf = s->flags & HF_RF_MASK;
/*
@@ -1358,7 +1359,7 @@ static void do_gen_rep(DisasContext *s, MemOp ot,
tcg_set_insn_start_param(s->base.insn_start, 1, CC_OP_DYNAMIC);
/* Any iteration at all? */
- gen_op_jz_ecx(s, done);
+ tcg_gen_brcondi_tl(TCG_COND_TSTEQ, cpu_regs[R_ECX], cx_mask, done);
fn(s, ot);
gen_op_add_reg_im(s, s->aflag, R_ECX, -1);
gen_op_jz_ecx should become unused now.
And maybe gen_op_jnz_ecx went unused a few patches ago, when gen_jz_ecx_string
got merged?
Anyway, I think there are some dead inlines which clang would Werror about.
With those fixed,
Reviewed-by: Richard Henderson <[email protected]>
r~
