tcg: Improve move ops in liveness_pass_2

If the output of the move is dead, then the last use is in
the store. If we propagate the input to the store, then we
can remove the move opcode entirely.

Backports commit 61f15c487fc2aea14f6b0e52c459ae8b7d252a65 from qemu
This commit is contained in:
Richard Henderson 2020-06-14 22:13:02 -04:00 committed by Lioncash
parent 6b91e9bae1
commit 0e68fa345e

View file

@ -2420,34 +2420,68 @@ static bool liveness_pass_2(TCGContext *s)
}
/* Outputs become available. */
for (i = 0; i < nb_oargs; i++) {
arg_ts = arg_temp(op->args[i]);
if (opc == INDEX_op_mov_i32 || opc == INDEX_op_mov_i64) {
arg_ts = arg_temp(op->args[0]);
dir_ts = arg_ts->state_ptr;
if (!dir_ts) {
continue;
if (dir_ts) {
op->args[0] = temp_arg(dir_ts);
changes = true;
/* The output is now live and modified. */
arg_ts->state = 0;
if (NEED_SYNC_ARG(0)) {
TCGOpcode sopc = (arg_ts->type == TCG_TYPE_I32
? INDEX_op_st_i32
: INDEX_op_st_i64);
TCGOp *sop = tcg_op_insert_after(s, op, sopc);
TCGTemp *out_ts = dir_ts;
if (IS_DEAD_ARG(0)) {
out_ts = arg_temp(op->args[1]);
arg_ts->state = TS_DEAD;
tcg_op_remove(s, op);
} else {
arg_ts->state = TS_MEM;
}
sop->args[0] = temp_arg(out_ts);
sop->args[1] = temp_arg(arg_ts->mem_base);
sop->args[2] = arg_ts->mem_offset;
} else {
tcg_debug_assert(!IS_DEAD_ARG(0));
}
}
op->args[i] = temp_arg(dir_ts);
changes = true;
} else {
for (i = 0; i < nb_oargs; i++) {
arg_ts = arg_temp(op->args[i]);
dir_ts = arg_ts->state_ptr;
if (!dir_ts) {
continue;
}
op->args[i] = temp_arg(dir_ts);
changes = true;
/* The output is now live and modified. */
arg_ts->state = 0;
/* The output is now live and modified. */
arg_ts->state = 0;
/* Sync outputs upon their last write. */
if (NEED_SYNC_ARG(i)) {
TCGOpcode sopc = (arg_ts->type == TCG_TYPE_I32
? INDEX_op_st_i32
: INDEX_op_st_i64);
TCGOp *sop = tcg_op_insert_after(s, op, sopc);
/* Sync outputs upon their last write. */
if (NEED_SYNC_ARG(i)) {
TCGOpcode sopc = (arg_ts->type == TCG_TYPE_I32
? INDEX_op_st_i32
: INDEX_op_st_i64);
TCGOp *sop = tcg_op_insert_after(s, op, sopc);
sop->args[0] = temp_arg(dir_ts);
sop->args[1] = temp_arg(arg_ts->mem_base);
sop->args[2] = arg_ts->mem_offset;
sop->args[0] = temp_arg(dir_ts);
sop->args[1] = temp_arg(arg_ts->mem_base);
sop->args[2] = arg_ts->mem_offset;
arg_ts->state = TS_MEM;
}
/* Drop outputs that are dead. */
if (IS_DEAD_ARG(i)) {
arg_ts->state = TS_DEAD;
arg_ts->state = TS_MEM;
}
/* Drop outputs that are dead. */
if (IS_DEAD_ARG(i)) {
arg_ts->state = TS_DEAD;
}
}
}
}