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target-i386: Move CC discards to set_cc_op 

This gets us universal coverage, rather than scattering discards
around at various places.  As a bonus, we do not emit redundant
discards e.g. between sequential logic insns.

Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2013-01-23 13:26:38 -08:00
parent ccfcdd09bf
commit b666265b20
1 changed files with 39 additions and 9 deletions
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42
target-i386/translate.c
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@ -174,15 +174,49 @@ enum {
OR_A0, /* temporary register used when doing address evaluation */
};
enum {
USES_CC_DST = 1,
USES_CC_SRC = 2,
};
/* Bit set if the global variable is live after setting CC_OP to X. */
static const uint8_t cc_op_live[CC_OP_NB] = {
[CC_OP_DYNAMIC] = USES_CC_DST | USES_CC_SRC,
[CC_OP_EFLAGS] = USES_CC_SRC,
[CC_OP_MULB ... CC_OP_MULQ] = USES_CC_DST | USES_CC_SRC,
[CC_OP_ADDB ... CC_OP_ADDQ] = USES_CC_DST | USES_CC_SRC,
[CC_OP_ADCB ... CC_OP_ADCQ] = USES_CC_DST | USES_CC_SRC,
[CC_OP_SUBB ... CC_OP_SUBQ] = USES_CC_DST | USES_CC_SRC,
[CC_OP_SBBB ... CC_OP_SBBQ] = USES_CC_DST | USES_CC_SRC,
[CC_OP_LOGICB ... CC_OP_LOGICQ] = USES_CC_DST,
[CC_OP_INCB ... CC_OP_INCQ] = USES_CC_DST | USES_CC_SRC,
[CC_OP_DECB ... CC_OP_DECQ] = USES_CC_DST | USES_CC_SRC,
[CC_OP_SHLB ... CC_OP_SHLQ] = USES_CC_DST | USES_CC_SRC,
[CC_OP_SARB ... CC_OP_SARQ] = USES_CC_DST | USES_CC_SRC,
};
static void set_cc_op(DisasContext *s, CCOp op)
{
if (s->cc_op != op) {
int dead;
if (s->cc_op == op) {
return;
}
/* Discard CC computation that will no longer be used. */
dead = cc_op_live[s->cc_op] & ~cc_op_live[op];
if (dead & USES_CC_DST) {
tcg_gen_discard_tl(cpu_cc_dst);
}
if (dead & USES_CC_SRC) {
tcg_gen_discard_tl(cpu_cc_src);
}
s->cc_op = op;
/* The DYNAMIC setting is translator only, and should never be
stored. Thus we always consider it clean. */
s->cc_op_dirty = (op != CC_OP_DYNAMIC);
}
}
static void gen_update_cc_op(DisasContext *s)
{
@ -809,7 +843,6 @@ static inline void gen_movs(DisasContext *s, int ot)
static void gen_op_update1_cc(void)
{
tcg_gen_discard_tl(cpu_cc_src);
tcg_gen_mov_tl(cpu_cc_dst, cpu_T[0]);
}
@ -827,7 +860,6 @@ static inline void gen_op_cmpl_T0_T1_cc(void)
static inline void gen_op_testl_T0_T1_cc(void)
{
tcg_gen_discard_tl(cpu_cc_src);
tcg_gen_and_tl(cpu_cc_dst, cpu_T[0], cpu_T[1]);
}
@ -853,7 +885,6 @@ static void gen_compute_eflags(DisasContext *s)
}
gen_update_cc_op(s);
gen_helper_cc_compute_all(cpu_tmp2_i32, cpu_env, cpu_cc_op);
tcg_gen_discard_tl(cpu_cc_dst);
set_cc_op(s, CC_OP_EFLAGS);
tcg_gen_extu_i32_tl(cpu_cc_src, cpu_tmp2_i32);
}
@ -6640,7 +6671,6 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
gen_op_mov_reg_T0(ot, reg);
tcg_gen_movi_tl(cpu_cc_dst, 1);
gen_set_label(label1);
tcg_gen_discard_tl(cpu_cc_src);
set_cc_op(s, CC_OP_LOGICB + ot);
}
tcg_temp_free(t0);