target/i386/emulate: rework string_rep emulation
Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr> Link: https://lore.kernel.org/r/20260223233950.96076-5-mohamed@unpredictable.fr Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Mohamed Mediouni committed
Feb 24, 2026 at 00:39 UTC
03bd8515a3bc5d2da7d95105e5fbc7ede8e658d3
1 file changed
+10
-3
target/i386/emulate/x86_emu.c
+10
-3
@@ -466,18 +466,25 @@ static inline void string_increment_reg(CPUX86State *env, int reg,
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write_reg(env, reg, val, decode->addressing_size);
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}
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+static inline int get_ZF(CPUX86State *env) {
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+ return env->cc_dst ? 0 : CC_Z;
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+}
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+
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static inline void string_rep(CPUX86State *env, struct x86_decode *decode,
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void (*func)(CPUX86State *env,
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struct x86_decode *ins), int rep)
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{
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target_ulong rcx = read_reg(env, R_ECX, decode->addressing_size);
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- while (rcx--) {
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+
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+ while (rcx != 0) {
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+ bool is_cmps_or_scas = decode->cmd == X86_DECODE_CMD_CMPS || decode->cmd == X86_DECODE_CMD_SCAS;
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func(env, decode);
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+ rcx--;
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write_reg(env, R_ECX, rcx, decode->addressing_size);
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- if ((PREFIX_REP == rep) && !env->cc_dst) {
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+ if ((PREFIX_REP == rep) && !get_ZF(env) && is_cmps_or_scas) {
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break;
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}
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- if ((PREFIX_REPN == rep) && env->cc_dst) {
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+ if ((PREFIX_REPN == rep) && get_ZF(env)&& is_cmps_or_scas) {
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break;
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}
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}