diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index e2c494e75ef393a2a214c1263a4cb106cac42ab3..c724e8b6f1076181175b2b8b34a553dea6794ff2 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -720,7 +720,7 @@ static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
&& cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0) {
/* Execute just one insn to trigger exception pending in the log */
cpu->cflags_next_tb = (curr_cflags(cpu) & ~CF_USE_ICOUNT)
- | CF_NOIRQ | 1;
+ | CF_LAST_IO | CF_NOIRQ | 1;
}
#endif
return false;
diff --git a/accel/tcg/tb-maint.c b/accel/tcg/tb-maint.c
index 32ae8af61cdf970666539c89ce88e8fdef77a78a..0c3e227409d5b92446aeb1dde3254c2c0558925b 100644
--- a/accel/tcg/tb-maint.c
+++ b/accel/tcg/tb-maint.c
@@ -1083,7 +1083,8 @@ bool tb_invalidate_phys_page_unwind(tb_page_addr_t addr, uintptr_t pc)
if (current_tb_modified) {
/* Force execution of one insn next time. */
CPUState *cpu = current_cpu;
- cpu->cflags_next_tb = 1 | CF_NOIRQ | curr_cflags(current_cpu);
+ cpu->cflags_next_tb =
+ 1 | CF_LAST_IO | CF_NOIRQ | curr_cflags(current_cpu);
return true;
}
return false;
@@ -1153,7 +1154,8 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages,
if (current_tb_modified) {
page_collection_unlock(pages);
/* Force execution of one insn next time. */
- current_cpu->cflags_next_tb = 1 | CF_NOIRQ | curr_cflags(current_cpu);
+ current_cpu->cflags_next_tb =
+ 1 | CF_LAST_IO | CF_NOIRQ | curr_cflags(current_cpu);
mmap_unlock();
cpu_loop_exit_noexc(current_cpu);
}
diff --git a/accel/tcg/translator.c b/accel/tcg/translator.c
index 1a6a5448c8fb16080cfd90c2c018ad46049d550f..358214d5265ef42f0bdcf39eaace9ca518dfd51b 100644
--- a/accel/tcg/translator.c
+++ b/accel/tcg/translator.c
@@ -16,26 +16,19 @@
#include "tcg/tcg-op-common.h"
#include "internal.h"
-static void gen_io_start(void)
+static void set_can_do_io(DisasContextBase *db, bool val)
{
- tcg_gen_st_i32(tcg_constant_i32(1), cpu_env,
- offsetof(ArchCPU, parent_obj.can_do_io) -
- offsetof(ArchCPU, env));
+ if (db->saved_can_do_io != val) {
+ db->saved_can_do_io = val;
+ tcg_gen_st_i32(tcg_constant_i32(val), cpu_env,
+ offsetof(ArchCPU, parent_obj.can_do_io) -
+ offsetof(ArchCPU, env));
+ }
}
bool translator_io_start(DisasContextBase *db)
{
- uint32_t cflags = tb_cflags(db->tb);
-
- if (!(cflags & CF_USE_ICOUNT)) {
- return false;
- }
- if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
- /* Already started in translator_loop. */
- return true;
- }
-
- gen_io_start();
+ set_can_do_io(db, true);
/*
* Ensure that this instruction will be the last in the TB.
@@ -47,14 +40,17 @@ bool translator_io_start(DisasContextBase *db)
return true;
}
-static TCGOp *gen_tb_start(uint32_t cflags)
+static TCGOp *gen_tb_start(DisasContextBase *db, uint32_t cflags)
{
- TCGv_i32 count = tcg_temp_new_i32();
+ TCGv_i32 count = NULL;
TCGOp *icount_start_insn = NULL;
- tcg_gen_ld_i32(count, cpu_env,
- offsetof(ArchCPU, neg.icount_decr.u32) -
- offsetof(ArchCPU, env));
+ if ((cflags & CF_USE_ICOUNT) || !(cflags & CF_NOIRQ)) {
+ count = tcg_temp_new_i32();
+ tcg_gen_ld_i32(count, cpu_env,
+ offsetof(ArchCPU, neg.icount_decr.u32) -
+ offsetof(ArchCPU, env));
+ }
if (cflags & CF_USE_ICOUNT) {
/*
@@ -84,18 +80,15 @@ static TCGOp *gen_tb_start(uint32_t cflags)
tcg_gen_st16_i32(count, cpu_env,
offsetof(ArchCPU, neg.icount_decr.u16.low) -
offsetof(ArchCPU, env));
- /*
- * cpu->can_do_io is cleared automatically here at the beginning of
- * each translation block. The cost is minimal and only paid for
- * -icount, plus it would be very easy to forget doing it in the
- * translator. Doing it here means we don't need a gen_io_end() to
- * go with gen_io_start().
- */
- tcg_gen_st_i32(tcg_constant_i32(0), cpu_env,
- offsetof(ArchCPU, parent_obj.can_do_io) -
- offsetof(ArchCPU, env));
}
+ /*
+ * cpu->can_do_io is set automatically here at the beginning of
+ * each translation block. The cost is minimal, plus it would be
+ * very easy to forget doing it in the translator.
+ */
+ set_can_do_io(db, db->max_insns == 1 && (cflags & CF_LAST_IO));
+
return icount_start_insn;
}
@@ -144,6 +137,7 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
db->num_insns = 0;
db->max_insns = *max_insns;
db->singlestep_enabled = cflags & CF_SINGLE_STEP;
+ db->saved_can_do_io = -1;
db->host_addr[0] = host_pc;
db->host_addr[1] = NULL;
@@ -151,11 +145,17 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */
/* Start translating. */
- icount_start_insn = gen_tb_start(cflags);
+ icount_start_insn = gen_tb_start(db, cflags);
ops->tb_start(db, cpu);
tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */
- plugin_enabled = plugin_gen_tb_start(cpu, db, cflags & CF_MEMI_ONLY);
+ if (cflags & CF_MEMI_ONLY) {
+ /* We should only see CF_MEMI_ONLY for io_recompile. */
+ assert(cflags & CF_LAST_IO);
+ plugin_enabled = plugin_gen_tb_start(cpu, db, true);
+ } else {
+ plugin_enabled = plugin_gen_tb_start(cpu, db, false);
+ }
while (true) {
*max_insns = ++db->num_insns;
@@ -172,13 +172,9 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
the next instruction. */
if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
/* Accept I/O on the last instruction. */
- gen_io_start();
- ops->translate_insn(db, cpu);
- } else {
- /* we should only see CF_MEMI_ONLY for io_recompile */
- tcg_debug_assert(!(cflags & CF_MEMI_ONLY));
- ops->translate_insn(db, cpu);
+ set_can_do_io(db, true);
}
+ ops->translate_insn(db, cpu);
/*
* We can't instrument after instructions that change control
diff --git a/include/exec/translator.h b/include/exec/translator.h
index 4e17c4f401d6104de3969ddbcbd6bd4f0c26416f..9d9e980819c45c2746456e760095516d4c617a9c 100644
--- a/include/exec/translator.h
+++ b/include/exec/translator.h
@@ -72,6 +72,7 @@ typedef enum DisasJumpType {
* @num_insns: Number of translated instructions (including current).
* @max_insns: Maximum number of instructions to be translated in this TB.
* @singlestep_enabled: "Hardware" single stepping enabled.
+ * @saved_can_do_io: Known value of cpu->neg.can_do_io, or -1 for unknown.
*
* Architecture-agnostic disassembly context.
*/
@@ -83,6 +84,7 @@ typedef struct DisasContextBase {
int num_insns;
int max_insns;
bool singlestep_enabled;
+ int8_t saved_can_do_io;
void *host_addr[2];
} DisasContextBase;
diff --git a/target/mips/tcg/translate.c b/target/mips/tcg/translate.c
index 9bb40f1849d6ebfb165ab7272b47eb5a6900ac82..593fc804588f35e7a683b6f8b1bb59e95729f902 100644
--- a/target/mips/tcg/translate.c
+++ b/target/mips/tcg/translate.c
@@ -11212,7 +11212,6 @@ static void gen_branch(DisasContext *ctx, int insn_bytes)
/* Branches completion */
clear_branch_hflags(ctx);
ctx->base.is_jmp = DISAS_NORETURN;
- /* FIXME: Need to clear can_do_io. */
switch (proc_hflags & MIPS_HFLAG_BMASK_BASE) {
case MIPS_HFLAG_FBNSLOT:
gen_goto_tb(ctx, 0, ctx->base.pc_next + insn_bytes);