From 0e68fa345e6f318663bdb773352aa891f77d60ed Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Sun, 14 Jun 2020 22:13:02 -0400 Subject: [PATCH] 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 --- qemu/tcg/tcg.c | 78 ++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 56 insertions(+), 22 deletions(-) diff --git a/qemu/tcg/tcg.c b/qemu/tcg/tcg.c index e79f8182..7807659f 100644 --- a/qemu/tcg/tcg.c +++ b/qemu/tcg/tcg.c @@ -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; + } } } }