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optimization of shifts by a constant 

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4524 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
bellard 2008-05-22 12:36:31 +00:00
parent 12e26b75d4
commit c1c379686f
1 changed files with 68 additions and 4 deletions
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72
target-i386/translate.c
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@ -1432,7 +1432,6 @@ static void gen_inc(DisasContext *s1, int ot, int d, int c)
tcg_gen_mov_tl(cpu_cc_dst, cpu_T[0]);
}
/* XXX: add faster immediate case */
static void gen_shift_rm_T1(DisasContext *s, int ot, int op1,
int is_right, int is_arith)
{
@ -1493,6 +1492,57 @@ static void gen_shift_rm_T1(DisasContext *s, int ot, int op1,
s->cc_op = CC_OP_DYNAMIC; /* cannot predict flags after */
}
static void gen_shift_rm_im(DisasContext *s, int ot, int op1, int op2,
int is_right, int is_arith)
{
int mask;
if (ot == OT_QUAD)
mask = 0x3f;
else
mask = 0x1f;
/* load */
if (op1 == OR_TMP0)
gen_op_ld_T0_A0(ot + s->mem_index);
else
gen_op_mov_TN_reg(ot, 0, op1);
op2 &= mask;
if (op2 != 0) {
if (is_right) {
if (is_arith) {
gen_exts(ot, cpu_T[0]);
tcg_gen_sari_tl(cpu_tmp0, cpu_T[0], op2 - 1);
tcg_gen_sari_tl(cpu_T[0], cpu_T[0], op2);
} else {
gen_extu(ot, cpu_T[0]);
tcg_gen_shri_tl(cpu_tmp0, cpu_T[0], op2 - 1);
tcg_gen_shri_tl(cpu_T[0], cpu_T[0], op2);
}
} else {
tcg_gen_shli_tl(cpu_tmp0, cpu_T[0], op2 - 1);
tcg_gen_shli_tl(cpu_T[0], cpu_T[0], op2);
}
}
/* store */
if (op1 == OR_TMP0)
gen_op_st_T0_A0(ot + s->mem_index);
else
gen_op_mov_reg_T0(ot, op1);
/* update eflags if non zero shift */
if (op2 != 0) {
tcg_gen_mov_tl(cpu_cc_src, cpu_tmp0);
tcg_gen_mov_tl(cpu_cc_dst, cpu_T[0]);
if (is_right)
s->cc_op = CC_OP_SARB + ot;
else
s->cc_op = CC_OP_SHLB + ot;
}
}
static inline void tcg_gen_lshift(TCGv ret, TCGv arg1, target_long arg2)
{
if (arg2 >= 0)
@ -1770,9 +1820,23 @@ static void gen_shift(DisasContext *s1, int op, int ot, int d, int s)
static void gen_shifti(DisasContext *s1, int op, int ot, int d, int c)
{
/* currently not optimized */
gen_op_movl_T1_im(c);
gen_shift(s1, op, ot, d, OR_TMP1);
switch(op) {
case OP_SHL:
case OP_SHL1:
gen_shift_rm_im(s1, ot, d, c, 0, 0);
break;
case OP_SHR:
gen_shift_rm_im(s1, ot, d, c, 1, 0);
break;
case OP_SAR:
gen_shift_rm_im(s1, ot, d, c, 1, 1);
break;
default:
/* currently not optimized */
gen_op_movl_T1_im(c);
gen_shift(s1, op, ot, d, OR_TMP1);
break;
}
}
static void gen_lea_modrm(DisasContext *s, int modrm, int *reg_ptr, int *offset_ptr)