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target/i386/tcg: merge decode_modrm and decode_modrm_address split

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Unlike the older code in translate.c, mod=11b *is* filtered out earlier
by decode_modrm, and it would have returned bogus code.  Since the register
case is so simple, just inline decode_modrm_address into its caller instead
of removing the "if".

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini
2025-12-23 17:55:59 +01:00
parent 30ebb65f83
commit a1356c5677
1 changed files with 24 additions and 40 deletions
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64
target/i386/tcg/decode-new.c.inc
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@@ -2007,33 +2007,34 @@ static void decode_root(DisasContext *s, CPUX86State *env, X86OpEntry *entry, ui
*entry = opcodes_root[*b];
}
/* Decompose an address. */
static AddressParts decode_modrm_address(CPUX86State *env, DisasContext *s,
int modrm, bool is_vsib)
/* Decode the MODRM and SIB bytes into a register or memory operand. */
static void decode_modrm(DisasContext *s, CPUX86State *env,
X86DecodedInsn *decode, X86DecodedOp *op)
{
int def_seg, base, index, scale, mod, rm;
target_long disp;
bool havesib;
def_seg = R_DS;
index = -1;
scale = 0;
disp = 0;
mod = (modrm >> 6) & 3;
rm = modrm & 7;
base = rm | REX_B(s);
int modrm = get_modrm(s, env);
int mod = (modrm >> 6) & 3;
int rm = modrm & 7;
bool is_vsib = decode->e.vex_class == 12;
bool havesib = false;
if (mod == 3) {
/* Normally filtered out earlier, but including this path
simplifies multi-byte nop, as well as bndcl, bndcu, bndcn. */
goto done;
op->n = rm;
if (op->unit != X86_OP_MMX) {
op->n |= REX_B(s);
}
return;
}
/* Decompose an address. */
int def_seg = R_DS;
int base = rm | REX_B(s);
int index = -1;
int scale = 0;
target_ulong disp = 0;
switch (s->aflag) {
case MO_64:
case MO_32:
havesib = 0;
if (rm == 4) {
int code = x86_ldub_code(env, s);
scale = (code >> 6) & 3;
@@ -2042,7 +2043,7 @@ static AddressParts decode_modrm_address(CPUX86State *env, DisasContext *s,
index = -1; /* no index */
}
base = (code & 7) | REX_B(s);
havesib = 1;
havesib = true;
}
switch (mod) {
@@ -2127,26 +2128,9 @@ static AddressParts decode_modrm_address(CPUX86State *env, DisasContext *s,
g_assert_not_reached();
}
done:
return (AddressParts){ def_seg, base, index, scale, disp };
}
static int decode_modrm(DisasContext *s, CPUX86State *env,
X86DecodedInsn *decode, X86DecodedOp *op)
{
int modrm = get_modrm(s, env);
if ((modrm >> 6) == 3) {
op->n = (modrm & 7);
if (op->unit != X86_OP_MMX) {
op->n |= REX_B(s);
}
} else {
op->has_ea = true;
op->n = -1;
decode->mem = decode_modrm_address(env, s, get_modrm(s, env),
decode->e.vex_class == 12);
}
return modrm;
op->has_ea = true;
op->n = -1;
decode->mem = (AddressParts){ def_seg, base, index, scale, disp };
}
static bool decode_op_size(DisasContext *s, X86OpEntry *e, X86OpSize size, MemOp *ot)