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target/cris: Add DISAS_DBRANCH

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Move delayed branch handling to tb_stop, where we can re-use other
end-of-tb code, e.g. the evaluation of flags.  Honor single stepping.
Validate that we aren't losing state by overwriting is_jmp.

Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Tested-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2021-06-20 13:43:35 -07:00
parent c96747521c
commit 3173715195
1 changed files with 56 additions and 40 deletions
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96
target/cris/translate.c
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@ -61,6 +61,8 @@
#define DISAS_UPDATE DISAS_TARGET_1
/* Cpu state was modified dynamically, excluding pc -- use npc */
#define DISAS_UPDATE_NEXT DISAS_TARGET_2
/* PC update for delayed branch, see cpustate_changed otherwise */
#define DISAS_DBRANCH DISAS_TARGET_3
/* Used by the decoder. */
#define EXTRACT_FIELD(src, start, end) \
@ -3230,50 +3232,22 @@ static void cris_tr_translate_insn(DisasContextBase *dcbase, CPUState *cs)
dc->cpustate_changed |= dc->flags_x != (dc->base.tb->flags & X_FLAG);
/*
* Check for delayed branches here. If we do it before
* actually generating any host code, the simulator will just
* loop doing nothing for on this program location.
* All branches are delayed branches, handled immediately below.
* We don't expect to see odd combinations of exit conditions.
*/
assert(dc->base.is_jmp == DISAS_NEXT || dc->cpustate_changed);
if (dc->delayed_branch && --dc->delayed_branch == 0) {
if (dc->base.tb->flags & 7) {
t_gen_movi_env_TN(dslot, 0);
}
dc->base.is_jmp = DISAS_DBRANCH;
return;
}
if (dc->cpustate_changed) {
cris_store_direct_jmp(dc);
}
if (dc->clear_locked_irq) {
dc->clear_locked_irq = 0;
t_gen_movi_env_TN(locked_irq, 0);
}
if (dc->jmp == JMP_DIRECT_CC) {
TCGLabel *l1 = gen_new_label();
cris_evaluate_flags(dc);
/* Conditional jmp. */
tcg_gen_brcondi_tl(TCG_COND_EQ, env_btaken, 0, l1);
gen_goto_tb(dc, 1, dc->jmp_pc);
gen_set_label(l1);
gen_goto_tb(dc, 0, dc->pc);
dc->base.is_jmp = DISAS_NORETURN;
dc->jmp = JMP_NOJMP;
} else if (dc->jmp == JMP_DIRECT) {
cris_evaluate_flags(dc);
gen_goto_tb(dc, 0, dc->jmp_pc);
dc->base.is_jmp = DISAS_NORETURN;
dc->jmp = JMP_NOJMP;
} else {
TCGv c = tcg_const_tl(dc->pc);
t_gen_cc_jmp(env_btarget, c);
tcg_temp_free(c);
dc->base.is_jmp = DISAS_JUMP;
}
if (dc->base.is_jmp != DISAS_NEXT) {
return;
}
/* Force an update if the per-tb cpu state has changed. */
if (dc->base.is_jmp == DISAS_NEXT && dc->cpustate_changed) {
if (dc->cpustate_changed) {
dc->base.is_jmp = DISAS_UPDATE_NEXT;
return;
}
@ -3283,8 +3257,7 @@ static void cris_tr_translate_insn(DisasContextBase *dcbase, CPUState *cs)
* If we can detect the length of the next insn easily, we should.
* In the meantime, simply stop when we do cross.
*/
if (dc->base.is_jmp == DISAS_NEXT
&& ((dc->pc ^ dc->base.pc_first) & TARGET_PAGE_MASK) != 0) {
if ((dc->pc ^ dc->base.pc_first) & TARGET_PAGE_MASK) {
dc->base.is_jmp = DISAS_TOO_MANY;
}
}
@ -3314,6 +3287,49 @@ static void cris_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
cris_evaluate_flags(dc);
/* Evaluate delayed branch destination and fold to another is_jmp case. */
if (is_jmp == DISAS_DBRANCH) {
if (dc->base.tb->flags & 7) {
t_gen_movi_env_TN(dslot, 0);
}
switch (dc->jmp) {
case JMP_DIRECT:
npc = dc->jmp_pc;
is_jmp = dc->cpustate_changed ? DISAS_UPDATE_NEXT : DISAS_TOO_MANY;
break;
case JMP_DIRECT_CC:
/*
* Use a conditional branch if either taken or not-taken path
* can use goto_tb. If neither can, then treat it as indirect.
*/
if (likely(!dc->base.singlestep_enabled)
&& likely(!dc->cpustate_changed)
&& (use_goto_tb(dc, dc->jmp_pc) || use_goto_tb(dc, npc))) {
TCGLabel *not_taken = gen_new_label();
tcg_gen_brcondi_tl(TCG_COND_EQ, env_btaken, 0, not_taken);
gen_goto_tb(dc, 1, dc->jmp_pc);
gen_set_label(not_taken);
/* not-taken case handled below. */
is_jmp = DISAS_TOO_MANY;
break;
}
tcg_gen_movi_tl(env_btarget, dc->jmp_pc);
/* fall through */
case JMP_INDIRECT:
t_gen_cc_jmp(env_btarget, tcg_constant_tl(npc));
is_jmp = dc->cpustate_changed ? DISAS_UPDATE : DISAS_JUMP;
break;
default:
g_assert_not_reached();
}
}
if (unlikely(dc->base.singlestep_enabled)) {
switch (is_jmp) {
case DISAS_TOO_MANY: