From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Cc: qemu-stable@nongnu.org
Subject: [PATCH] target/i386: fix operand size for DATA16 REX.W POPCNT
Date: Thu, 9 May 2024 17:25:26 +0200 [thread overview]
Message-ID: <20240509152526.141855-1-pbonzini@redhat.com> (raw)
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(-)
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);
--
2.45.0
next reply other threads:[~2024-05-09 15:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-09 15:25 Paolo Bonzini [this message]
2024-05-10 9:20 ` [PATCH] target/i386: fix operand size for DATA16 REX.W POPCNT Richard Henderson
2024-05-10 11:25 ` Zhao Liu
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