accel/tcg: Refactor gen_io_start() as set_can_do_io()

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20230914174436.1597356-4-richard.henderson@linaro.org>
[PMD: Split patch in 2, extracting set_can_do_io() first]
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

accel/tcg/translator.c

@@ -16,9 +16,9 @@
 #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,
+    tcg_gen_st_i32(tcg_constant_i32(val), cpu_env,
                    offsetof(ArchCPU, parent_obj.can_do_io) -
                    offsetof(ArchCPU, env));
 }
@@ -35,7 +35,7 @@ bool translator_io_start(DisasContextBase *db)
         return true;
     }
 
-    gen_io_start();
+    set_can_do_io(db, true);
 
     /*
      * Ensure that this instruction will be the last in the TB.
@@ -47,7 +47,7 @@ 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 = NULL;
     TCGOp *icount_start_insn = NULL;
@@ -91,12 +91,9 @@ static TCGOp *gen_tb_start(uint32_t cflags)
          * 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().
+         * translator.
          */
-        tcg_gen_st_i32(tcg_constant_i32(0), cpu_env,
-                       offsetof(ArchCPU, parent_obj.can_do_io) -
-                       offsetof(ArchCPU, env));
+        set_can_do_io(db, false);
     }
 
     return icount_start_insn;
@@ -154,7 +151,7 @@ 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 */
 
@@ -181,7 +178,7 @@ 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();
+            set_can_do_io(db, true);
         }
         ops->translate_insn(db, cpu);