| Message ID | 20240509152526.141855-1-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | target/i386: fix operand size for DATA16 REX.W POPCNT | expand |
On 5/9/24 17:25, Paolo Bonzini wrote: > 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-stable@nongnu.org > Signed-off-by: Paolo Bonzini<pbonzini@redhat.com> > --- > target/i386/tcg/translate.c | 17 +---------------- > 1 file changed, 1 insertion(+), 16 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On Thu, May 09, 2024 at 05:25:26PM +0200, Paolo Bonzini wrote: > Date: Thu, 9 May 2024 17:25:26 +0200 > From: Paolo Bonzini <pbonzini@redhat.com> > Subject: [PATCH] target/i386: fix operand size for DATA16 REX.W POPCNT > X-Mailer: git-send-email 2.45.0 > > 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-stable@nongnu.org > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > target/i386/tcg/translate.c | 17 +---------------- > 1 file changed, 1 insertion(+), 16 deletions(-) Awesome! Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index 7d9f6b5c55b..5366dc32dd3 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -411,16 +411,6 @@ static inline MemOp mo_stacksize(DisasContext *s) return CODE64(s) ? MO_64 : SS32(s) ? MO_32 : MO_16; } -/* Select only size 64 else 32. Used for SSE operand sizes. */ -static inline MemOp mo_64_32(MemOp ot) -{ -#ifdef TARGET_X86_64 - return ot == MO_64 ? MO_64 : MO_32; -#else - return MO_32; -#endif -} - /* Select size 8 if lsb of B is clear, else OT. Used for decoding byte vs word opcodes. */ static inline MemOp mo_b_d(int b, MemOp ot) @@ -4545,12 +4535,7 @@ static void disas_insn_old(DisasContext *s, CPUState *cpu, int b) 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);
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-stable@nongnu.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- target/i386/tcg/translate.c | 17 +---------------- 1 file changed, 1 insertion(+), 16 deletions(-)