tcg: Clean up from 'next_tb'

The value returned from tcg_qemu_tb_exec() is the value passed to the
corresponding tcg_gen_exit_tb() at translation time of the last TB
attempted to execute. It is a little confusing to store it in a variable
named 'next_tb'. In fact, it is a combination of 4-byte aligned pointer
and additional information in its two least significant bits. Break it
down right away into two variables named 'last_tb' and 'tb_exit' which
are a pointer to the last TB attempted to execute and the TB exit
reason, correspondingly. This simplifies the code and improves its
readability.

Correct a misleading documentation comment for tcg_qemu_tb_exec() and
fix logging in cpu_tb_exec(). Also rename a misleading 'next_tb' in
another couple of places.

Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com>
Signed-off-by: Sergey Fedorov <sergey.fedorov@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/tci.c b/tci.c
index a8939e6d3c..0fdc4e2c12 100644
--- a/tci.c
+++ b/tci.c
@@ -467,7 +467,7 @@ uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr)
 {
     long tcg_temps[CPU_TEMP_BUF_NLONGS];
     uintptr_t sp_value = (uintptr_t)(tcg_temps + CPU_TEMP_BUF_NLONGS);
-    uintptr_t next_tb = 0;
+    uintptr_t ret = 0;
 
     tci_reg[TCG_AREG0] = (tcg_target_ulong)env;
     tci_reg[TCG_REG_CALL_STACK] = sp_value;
@@ -1085,7 +1085,7 @@ uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr)
             /* QEMU specific operations. */
 
         case INDEX_op_exit_tb:
-            next_tb = *(uint64_t *)tb_ptr;
+            ret = *(uint64_t *)tb_ptr;
             goto exit;
             break;
         case INDEX_op_goto_tb:
@@ -1243,5 +1243,5 @@ uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr)
         tci_assert(tb_ptr == old_code_ptr + op_size);
     }
 exit:
-    return next_tb;
+    return ret;
 }