added 'pure' function attribute - fixed indirect function calls
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4469 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/tcg/tcg.c b/tcg/tcg.c
index aa46bcf..b1d0402 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -946,32 +946,51 @@
def = &tcg_op_defs[op];
switch(op) {
case INDEX_op_call:
- nb_args = args[-1];
- args -= nb_args;
- nb_iargs = args[0] & 0xffff;
- nb_oargs = args[0] >> 16;
- args++;
+ {
+ int call_flags;
- /* output args are dead */
- for(i = 0; i < nb_oargs; i++) {
- arg = args[i];
- dead_temps[arg] = 1;
- }
-
- /* globals are live (they may be used by the call) */
- memset(dead_temps, 0, s->nb_globals);
+ nb_args = args[-1];
+ args -= nb_args;
+ nb_iargs = args[0] & 0xffff;
+ nb_oargs = args[0] >> 16;
+ args++;
+ call_flags = args[nb_oargs + nb_iargs];
- /* input args are live */
- dead_iargs = 0;
- for(i = 0; i < nb_iargs; i++) {
- arg = args[i + nb_oargs];
- if (dead_temps[arg]) {
- dead_iargs |= (1 << i);
+ /* pure functions can be removed if their result is not
+ used */
+ if (call_flags & TCG_CALL_PURE) {
+ for(i = 0; i < nb_oargs; i++) {
+ arg = args[i];
+ if (!dead_temps[arg])
+ goto do_not_remove_call;
+ }
+ tcg_set_nop(s, gen_opc_buf + op_index,
+ args - 1, nb_args);
+ } else {
+ do_not_remove_call:
+
+ /* output args are dead */
+ for(i = 0; i < nb_oargs; i++) {
+ arg = args[i];
+ dead_temps[arg] = 1;
+ }
+
+ /* globals are live (they may be used by the call) */
+ memset(dead_temps, 0, s->nb_globals);
+
+ /* input args are live */
+ dead_iargs = 0;
+ for(i = 0; i < nb_iargs; i++) {
+ arg = args[i + nb_oargs];
+ if (dead_temps[arg]) {
+ dead_iargs |= (1 << i);
+ }
+ dead_temps[arg] = 0;
+ }
+ s->op_dead_iargs[op_index] = dead_iargs;
}
- dead_temps[arg] = 0;
+ args--;
}
- s->op_dead_iargs[op_index] = dead_iargs;
- args--;
break;
case INDEX_op_set_label:
args--;
@@ -1640,7 +1659,7 @@
}
/* mark dead temporaries and free the associated registers */
- for(i = 0; i < nb_params; i++) {
+ for(i = 0; i < nb_iargs; i++) {
arg = args[nb_oargs + i];
if (IS_DEAD_IARG(i)) {
ts = &s->temps[arg];
