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target/i386: Fix calculation of LOCK NEG eflags

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After:

        lock negl -0x14(%rbp)
        pushf
        pop    %rax

%rax will contain the wrong value because the "lock neg" calculates the
wrong eflags.  Simple test:

        #include <assert.h>

        int main()
        {
          __volatile__ unsigned test = 0x2363a;
          __volatile__ char cond = 0;
          asm(
              "lock negl %0 \n\t"
              "sets %1"
              : "=m"(test), "=r"(cond));
          assert(cond & 1);
          return 0;
        }

Reported-by: Jinyang Shen <shenjinyang@loongson.cn>
Co-Developed-by: Xuehai Chen <chenxuehai@loongson.cn>
Signed-off-by: Xuehai Chen <chenxuehai@loongson.cn>
Signed-off-by: Qi Hu <huqi@loongson.cn>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Qi Hu 2022-10-24 10:41:55 +02:00 committed by Paolo Bonzini
parent 75d30fde55
commit 1215317510
1 changed files with 1 additions and 1 deletions
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2
target/i386/tcg/translate.c
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@ -3300,7 +3300,7 @@ static bool disas_insn(DisasContext *s, CPUState *cpu)
tcg_temp_free(t2);
tcg_temp_free(a0);
tcg_gen_mov_tl(s->T0, t0);
tcg_gen_neg_tl(s->T0, t0);
tcg_temp_free(t0);
} else {
tcg_gen_neg_tl(s->T0, s->T0);