tcg: Drop gen_io_end()

Now we have removed all the uses of gen_io_end() from target frontends,
the only callsite is inside gen_tb_start(). Inline the code there,
and remove the reference to it from the documentation.

While we are inlining the code, switch it to use tcg_constant_i32()
so we don't have to manually create and destroy a TCG temporary.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210724134902.7785-3-peter.maydell@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

diff --git a/docs/devel/tcg-icount.rst b/docs/devel/tcg-icount.rst
index 8d67b6c..50c8e8d 100644 (file)
--- a/docs/devel/tcg-icount.rst
+++ b/docs/devel/tcg-icount.rst
@@ -92,6 +92,3 @@ When the translator is handling an instruction of this kind:
     }
 
 * it must end the TB immediately after this instruction
-
-Note that some older front-ends call a "gen_io_end()" function:
-this is obsolete and should not be used.

diff --git a/include/exec/gen-icount.h b/include/exec/gen-icount.h
index 467529d..610cba5 100644 (file)
--- a/include/exec/gen-icount.h
+++ b/include/exec/gen-icount.h
@@ -17,22 +17,6 @@ static inline void gen_io_start(void)
     tcg_temp_free_i32(tmp);
 }
 
-/*
- * cpu->can_do_io is cleared automatically 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.  Therefore, backends only need to call
- * gen_io_start.
- */
-static inline void gen_io_end(void)
-{
-    TCGv_i32 tmp = tcg_const_i32(0);
-    tcg_gen_st_i32(tmp, cpu_env,
-                   offsetof(ArchCPU, parent_obj.can_do_io) -
-                   offsetof(ArchCPU, env));
-    tcg_temp_free_i32(tmp);
-}
-
 static inline void gen_tb_start(const TranslationBlock *tb)
 {
     TCGv_i32 count;
@@ -64,7 +48,16 @@ static inline void gen_tb_start(const TranslationBlock *tb)
         tcg_gen_st16_i32(count, cpu_env,
                          offsetof(ArchCPU, neg.icount_decr.u16.low) -
                          offsetof(ArchCPU, env));
-        gen_io_end();
+        /*
+         * 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));
     }
 
     tcg_temp_free_i32(count);