From fef5700c9cb250c48fd1d26a31b441932887b652 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Thu, 16 May 2019 15:09:32 -0400 Subject: [PATCH] tcg: Assert fixed_reg is read-only The only fixed_reg is cpu_env, and it should not be modified during any TB. Therefore code that tries to special-case moves into a fixed_reg is dead. Remove it. Backports commit d63e3b6e694ad6c887be135dddb9cd4893f1a844 from qemu --- qemu/tcg/tcg.c | 87 +++++++++++++++++++++++--------------------------- 1 file changed, 40 insertions(+), 47 deletions(-) diff --git a/qemu/tcg/tcg.c b/qemu/tcg/tcg.c index 967dcb77..2124f674 100644 --- a/qemu/tcg/tcg.c +++ b/qemu/tcg/tcg.c @@ -2752,11 +2752,8 @@ static void tcg_reg_alloc_do_movi(TCGContext *s, TCGTemp *ots, tcg_target_ulong val, TCGLifeData arg_life, TCGRegSet preferred_regs) { - if (ots->fixed_reg) { - /* For fixed registers, we do not do any constant propagation. */ - tcg_out_movi(s, ots->type, ots->reg, val); - return; - } + /* ENV should not be modified. */ + tcg_debug_assert(!ots->fixed_reg); /* The movi is not explicitly generated here. */ if (ots->val_type == TEMP_VAL_REG) { @@ -2792,6 +2789,9 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOp *op) ots = arg_temp(op->args[0]); ts = arg_temp(op->args[1]); + /* ENV should not be modified. */ + tcg_debug_assert(!ots->fixed_reg); + /* Note that otype != itype for no-op truncation. */ otype = ots->type; itype = ts->type; @@ -2816,7 +2816,7 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOp *op) } tcg_debug_assert(ts->val_type == TEMP_VAL_REG); - if (IS_DEAD_ARG(0) && !ots->fixed_reg) { + if (IS_DEAD_ARG(0)) { /* mov to a non-saved dead register makes no sense (even with liveness analysis disabled). */ tcg_debug_assert(NEED_SYNC_ARG(0)); @@ -2829,7 +2829,7 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOp *op) } temp_dead(s, ots); } else { - if (IS_DEAD_ARG(1) && !ts->fixed_reg && !ots->fixed_reg) { + if (IS_DEAD_ARG(1) && !ts->fixed_reg) { /* the mov can be suppressed */ if (ots->val_type == TEMP_VAL_REG) { s->reg_to_temp[ots->reg] = NULL; @@ -2982,6 +2982,10 @@ static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op) arg = op->args[i]; arg_ct = &def->args_ct[i]; ts = arg_temp(arg); + + /* ENV should not be modified. */ + tcg_debug_assert(!ts->fixed_reg); + if ((arg_ct->ct & TCG_CT_ALIAS) && !const_args[arg_ct->alias_index]) { reg = new_args[arg_ct->alias_index]; @@ -2990,29 +2994,21 @@ static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op) i_allocated_regs | o_allocated_regs, op->output_pref[k], ts->indirect_base); } else { - /* if fixed register, we try to use it */ - reg = ts->reg; - if (ts->fixed_reg && - tcg_regset_test_reg(arg_ct->u.regs, reg)) { - goto oarg_end; - } reg = tcg_reg_alloc(s, arg_ct->u.regs, o_allocated_regs, op->output_pref[k], ts->indirect_base); } tcg_regset_set_reg(o_allocated_regs, reg); - /* if a fixed register is used, then a move will be done afterwards */ - if (!ts->fixed_reg) { - if (ts->val_type == TEMP_VAL_REG) { - s->reg_to_temp[ts->reg] = NULL; - } - ts->val_type = TEMP_VAL_REG; - ts->reg = reg; - /* temp value is modified, so the value kept in memory is - potentially not the same */ - ts->mem_coherent = 0; - s->reg_to_temp[reg] = ts; + if (ts->val_type == TEMP_VAL_REG) { + s->reg_to_temp[ts->reg] = NULL; } - oarg_end: + ts->val_type = TEMP_VAL_REG; + ts->reg = reg; + /* + * Temp value is modified, so the value kept in memory is + * potentially not the same. + */ + ts->mem_coherent = 0; + s->reg_to_temp[reg] = ts; new_args[i] = reg; } } @@ -3028,10 +3024,10 @@ static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op) /* move the outputs in the correct register if needed */ for(i = 0; i < nb_oargs; i++) { ts = arg_temp(op->args[i]); - reg = new_args[i]; - if (ts->fixed_reg && ts->reg != reg) { - tcg_out_mov(s, ts->type, ts->reg, reg); - } + + /* ENV should not be modified. */ + tcg_debug_assert(!ts->fixed_reg); + if (NEED_SYNC_ARG(i)) { temp_sync(s, ts, o_allocated_regs, 0, IS_DEAD_ARG(i)); } else if (IS_DEAD_ARG(i)) { @@ -3152,26 +3148,23 @@ static void tcg_reg_alloc_call(TCGContext *s, TCGOp *op) for(i = 0; i < nb_oargs; i++) { arg = op->args[i]; ts = arg_temp(arg); + + /* ENV should not be modified. */ + tcg_debug_assert(!ts->fixed_reg); + reg = tcg_target_call_oarg_regs[i]; tcg_debug_assert(s->reg_to_temp[reg] == NULL); - - if (ts->fixed_reg) { - if (ts->reg != reg) { - tcg_out_mov(s, ts->type, ts->reg, reg); - } - } else { - if (ts->val_type == TEMP_VAL_REG) { - s->reg_to_temp[ts->reg] = NULL; - } - ts->val_type = TEMP_VAL_REG; - ts->reg = reg; - ts->mem_coherent = 0; - s->reg_to_temp[reg] = ts; - if (NEED_SYNC_ARG(i)) { - temp_sync(s, ts, allocated_regs, 0, IS_DEAD_ARG(i)); - } else if (IS_DEAD_ARG(i)) { - temp_dead(s, ts); - } + if (ts->val_type == TEMP_VAL_REG) { + s->reg_to_temp[ts->reg] = NULL; + } + ts->val_type = TEMP_VAL_REG; + ts->reg = reg; + ts->mem_coherent = 0; + s->reg_to_temp[reg] = ts; + if (NEED_SYNC_ARG(i)) { + temp_sync(s, ts, allocated_regs, 0, IS_DEAD_ARG(i)); + } else if (IS_DEAD_ARG(i)) { + temp_dead(s, ts); } } }