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target/i386: split eflags computation out of gen_compute_eflags

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The new x86 decoder wants the gen_* functions to compute EFLAGS before
writeback, which can be an issue for instructions with a memory
destination such as ARPL or shifts.

Extract code to compute the EFLAGS without clobbering CC_SRC, in case
the memory write causes a fault.  The flags writeback mechanism will
take care of copying the result to CC_SRC.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2023-10-11 16:20:20 +02:00
parent c0099cd40e
commit 80e55f54ac
1 changed files with 19 additions and 9 deletions
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28
target/i386/tcg/translate.c
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@ -862,22 +862,22 @@ static void gen_op_update_neg_cc(DisasContext *s)
tcg_gen_movi_tl(s->cc_srcT, 0);
}
/* compute all eflags to cc_src */
static void gen_compute_eflags(DisasContext *s)
/* compute all eflags to reg */
static void gen_mov_eflags(DisasContext *s, TCGv reg)
{
TCGv zero, dst, src1, src2;
TCGv dst, src1, src2;
TCGv_i32 cc_op;
int live, dead;
if (s->cc_op == CC_OP_EFLAGS) {
tcg_gen_mov_tl(reg, cpu_cc_src);
return;
}
if (s->cc_op == CC_OP_CLR) {
tcg_gen_movi_tl(cpu_cc_src, CC_Z | CC_P);
set_cc_op(s, CC_OP_EFLAGS);
tcg_gen_movi_tl(reg, CC_Z | CC_P);
return;
}
zero = NULL;
dst = cpu_cc_dst;
src1 = cpu_cc_src;
src2 = cpu_cc_src2;
@ -886,7 +886,7 @@ static void gen_compute_eflags(DisasContext *s)
live = cc_op_live[s->cc_op] & ~USES_CC_SRCT;
dead = live ^ (USES_CC_DST | USES_CC_SRC | USES_CC_SRC2);
if (dead) {
zero = tcg_constant_tl(0);
TCGv zero = tcg_constant_tl(0);
if (dead & USES_CC_DST) {
dst = zero;
}
@ -898,8 +898,18 @@ static void gen_compute_eflags(DisasContext *s)
}
}
gen_update_cc_op(s);
gen_helper_cc_compute_all(cpu_cc_src, dst, src1, src2, cpu_cc_op);
if (s->cc_op != CC_OP_DYNAMIC) {
cc_op = tcg_constant_i32(s->cc_op);
} else {
cc_op = cpu_cc_op;
}
gen_helper_cc_compute_all(reg, dst, src1, src2, cc_op);
}
/* compute all eflags to cc_src */
static void gen_compute_eflags(DisasContext *s)
{
gen_mov_eflags(s, cpu_cc_src);
set_cc_op(s, CC_OP_EFLAGS);
}