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target-i386: Fix aflag logic for CODE64 and the 0x67 prefix 

The code reorganization in commit 4a6fd938 broke handling of PREFIX_ADR.
While fixing this, tidy and comment the code so that it's more obvious
what's going on in setting both aflag and dflag.

The TARGET_X86_64 ifdef can be eliminated because CODE64 expands to the
constant zero when TARGET_X86_64 is undefined.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Reported-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1369855851-21400-1-git-send-email-rth@twiddle.net
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Richard Henderson 2013-05-29 12:30:51 -07:00 committed by Anthony Liguori
parent 39c93c67c5
commit dec3fc9657
1 changed files with 15 additions and 15 deletions
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30
target-i386/translate.c
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@ -4677,8 +4677,6 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
}
s->pc = pc_start;
prefixes = 0;
aflag = s->code32;
dflag = s->code32;
s->override = -1;
rex_w = -1;
rex_r = 0;
@ -4801,23 +4799,25 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
}
/* Post-process prefixes. */
if (prefixes & PREFIX_DATA) {
dflag ^= 1;
}
if (prefixes & PREFIX_ADR) {
aflag ^= 1;
}
#ifdef TARGET_X86_64
if (CODE64(s)) {
if (rex_w == 1) {
/* 0x66 is ignored if rex.w is set */
dflag = 2;
/* In 64-bit mode, the default data size is 32-bit. Select 64-bit
data with rex_w, and 16-bit data with 0x66; rex_w takes precedence
over 0x66 if both are present. */
dflag = (rex_w > 0 ? 2 : prefixes & PREFIX_DATA ? 0 : 1);
/* In 64-bit mode, 0x67 selects 32-bit addressing. */
aflag = (prefixes & PREFIX_ADR ? 1 : 2);
} else {
/* In 16/32-bit mode, 0x66 selects the opposite data size. */
dflag = s->code32;
if (prefixes & PREFIX_DATA) {
dflag ^= 1;
}
if (!(prefixes & PREFIX_ADR)) {
aflag = 2;
/* In 16/32-bit mode, 0x67 selects the opposite addressing. */
aflag = s->code32;
if (prefixes & PREFIX_ADR) {
aflag ^= 1;
}
}
#endif
s->prefix = prefixes;
s->aflag = aflag;