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tcg: Sink def, nb_iargs, nb_oargs loads in liveness_pass_1

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Sink the sets of the def, nb_iargs, nb_oargs variables to
the default and do_not_remove labels.  They're not really
needed beforehand, and it avoids preceding code from having
to keep them up-to-date.  Note that def had *not* been kept
up-to-date; thankfully only def->flags had been used and
those bits were constant between opcode changes.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2025-01-14 13:12:35 -08:00
parent 7d10d8e076
commit 3e3689df4e
1 changed files with 7 additions and 13 deletions
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20
tcg/tcg.c
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@ -4071,8 +4071,6 @@ liveness_pass_1(TCGContext *s)
case INDEX_op_sub2_i64:
opc_new = INDEX_op_sub;
do_addsub2:
nb_iargs = 4;
nb_oargs = 2;
/* Test if the high part of the operation is dead, but not
the low part. The result can be optimized to a simple
add or sub. This happens often for x86_64 guest when the
@ -4087,8 +4085,6 @@ liveness_pass_1(TCGContext *s)
op->args[1] = op->args[2];
op->args[2] = op->args[4];
/* Fall through and mark the single-word operation live. */
nb_iargs = 2;
nb_oargs = 1;
}
goto do_not_remove;
@ -4100,8 +4096,6 @@ liveness_pass_1(TCGContext *s)
opc_new = INDEX_op_mul;
opc_new2 = INDEX_op_muluh;
do_mul2:
nb_iargs = 2;
nb_oargs = 2;
if (arg_temp(op->args[1])->state == TS_DEAD) {
if (arg_temp(op->args[0])->state == TS_DEAD) {
/* Both parts of the operation are dead. */
@ -4122,19 +4116,15 @@ liveness_pass_1(TCGContext *s)
goto do_not_remove;
}
/* Mark the single-word operation live. */
nb_oargs = 1;
goto do_not_remove;
default:
/* XXX: optimize by hardcoding common cases (e.g. triadic ops) */
nb_iargs = def->nb_iargs;
nb_oargs = def->nb_oargs;
/* Test if the operation can be removed because all
its outputs are dead. We assume that nb_oargs == 0
implies side effects */
if (!(def->flags & TCG_OPF_SIDE_EFFECTS) && nb_oargs != 0) {
for (int i = 0; i < nb_oargs; i++) {
def = &tcg_op_defs[opc];
if (!(def->flags & TCG_OPF_SIDE_EFFECTS) && def->nb_oargs != 0) {
for (int i = def->nb_oargs - 1; i >= 0; i--) {
if (arg_temp(op->args[i])->state != TS_DEAD) {
goto do_not_remove;
}
@ -4148,6 +4138,10 @@ liveness_pass_1(TCGContext *s)
break;
do_not_remove:
def = &tcg_op_defs[opc];
nb_iargs = def->nb_iargs;
nb_oargs = def->nb_oargs;
for (int i = 0; i < nb_oargs; i++) {
ts = arg_temp(op->args[i]);