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tcg: Assert fixed_reg is read-only

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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.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-03-16 17:48:02 +00:00
parent 53229a7703
commit d63e3b6e69
1 changed files with 40 additions and 47 deletions
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87
tcg/tcg.c
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@ -3274,11 +3274,8 @@ 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) {
@ -3314,6 +3311,9 @@ 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;
@ -3338,7 +3338,7 @@ 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));
@ -3351,7 +3351,7 @@ 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;
@ -3504,6 +3504,10 @@ 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];
@ -3512,29 +3516,21 @@ 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;
}
}
@ -3550,10 +3546,10 @@ 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)) {
@ -3674,26 +3670,23 @@ 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);
}
}
}