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
This commit is contained in:
Richard Henderson 2019-05-16 15:09:32 -04:00 committed by Lioncash
parent c54b2776f6
commit fef5700c9c
No known key found for this signature in database
GPG key ID: 4E3C3CC1031BA9C7

View file

@ -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);
}
}
}