From: Paolo Bonzini <pbonz...@redhat.com> According to the manual, 32-bit vs 64-bit is governed by REX.W and REX ignores the 0x66 prefix. This can be confirmed with this program:
#include <stdio.h> int main() { int x = 0x12340000; int y; asm("popcntl %1, %0" : "=r" (y) : "r" (x)); printf("%x\n", y); asm("mov $-1, %0; .byte 0x66; popcntl %1, %0" : "+r" (y) : "r" (x)); printf("%x\n", y); asm("mov $-1, %0; .byte 0x66; popcntq %q1, %q0" : "+r" (y) : "r" (x)); printf("%x\n", y); } which prints 5/ffff0000/5 on real hardware and 5/ffff0000/ffff0000 on QEMU. Cc: qemu-sta...@nongnu.org Reviewed-by: Zhao Liu <zhao1....@intel.com> Reviewed-by: Richard Henderson <richard.hender...@linaro.org> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> (cherry picked from commit 41c685dc59bb611096f3bb6a663cfa82e4cba97b) Signed-off-by: Michael Tokarev <m...@tls.msk.ru> (Mjt: drop removal of mo_64_32() helper function in target/i386/tcg/translate.c due to missing-in-9.0 v9.0.0-542-gaef4f4affde2 "target/i386: remove now-converted opcodes from old decoder" which removed other user of it) diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index c84196c00b..ebfee15d77 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -6805,12 +6805,7 @@ static bool disas_insn(DisasContext *s, CPUState *cpu) modrm = x86_ldub_code(env, s); reg = ((modrm >> 3) & 7) | REX_R(s); - if (s->prefix & PREFIX_DATA) { - ot = MO_16; - } else { - ot = mo_64_32(dflag); - } - + ot = dflag; gen_ldst_modrm(env, s, modrm, ot, OR_TMP0, 0); gen_extu(ot, s->T0); tcg_gen_mov_tl(cpu_cc_src, s->T0); -- 2.39.2