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From: yqwfh <amdeniulari@protonmail.com>
To: qemu-devel@nongnu.org
Cc: yqwfh <amdeniulari@protonmail.com>, Daniele Ahmed <ahmeddan@amazon.com>
Subject: [PATCH] target/i386: cmpxchg should not touch accumulator
Date: Sat, 31 Jul 2021 19:06:07 +0000	[thread overview]
Message-ID: <20210731190507.9007-1-amdeniulari@protonmail.com> (raw)

Signed-off-by: Daniele Ahmed <ahmeddan@amazon.com>
---
 target/i386/tcg/translate.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index aacb605..41386dd 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -5366,7 +5366,6 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
                 gen_lea_modrm(env, s, modrm);
                 tcg_gen_atomic_cmpxchg_tl(oldv, s->A0, cmpv, newv,
                                           s->mem_index, ot | MO_LE);
-                gen_op_mov_reg_v(s, ot, R_EAX, oldv);
             } else {
                 if (mod == 3) {
                     rm = (modrm & 7) | REX_B(s);
@@ -5381,15 +5380,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState *cpu)
                 /* store value = (old == cmp ? new : old);  */
                 tcg_gen_movcond_tl(TCG_COND_EQ, newv, oldv, cmpv, newv, oldv);
                 if (mod == 3) {
-                    gen_op_mov_reg_v(s, ot, R_EAX, oldv);
                     gen_op_mov_reg_v(s, ot, rm, newv);
-                } else {
-                    /* Perform an unconditional store cycle like physical cpu;
-                       must be before changing accumulator to ensure
-                       idempotency if the store faults and the instruction
-                       is restarted */
-                    gen_op_st_v(s, ot, newv, s->A0);
-                    gen_op_mov_reg_v(s, ot, R_EAX, oldv);
                 }
             }
             tcg_gen_mov_tl(cpu_cc_src, oldv);
-- 
2.26.3




             reply	other threads:[~2021-07-31 20:54 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-31 19:06 yqwfh [this message]
2021-08-02 18:46 ` [PATCH] target/i386: cmpxchg should not touch accumulator Richard Henderson

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