target/arm: Add DISAS_UPDATE_NOCHAIN

Add an option that writes back the PC, like DISAS_UPDATE_EXIT,
but does not exit back to the main loop.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-7-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index e4795ae..027be7d 100644 (file)
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -14298,6 +14298,9 @@ static void aarch64_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         case DISAS_EXIT:
             tcg_gen_exit_tb(NULL, 0);
             break;
+        case DISAS_UPDATE_NOCHAIN:
+            gen_a64_set_pc_im(dc->base.pc_next);
+            /* fall through */
         case DISAS_JUMP:
             tcg_gen_lookup_and_goto_ptr();
             break;

diff --git a/target/arm/translate.c b/target/arm/translate.c
index 146ff5d..c39a929 100644 (file)
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -8874,6 +8874,7 @@ static void arm_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         case DISAS_NEXT:
         case DISAS_TOO_MANY:
         case DISAS_UPDATE_EXIT:
+        case DISAS_UPDATE_NOCHAIN:
             gen_set_pc_im(dc, dc->base.pc_next);
             /* fall through */
         default:
@@ -8897,6 +8898,9 @@ static void arm_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         case DISAS_TOO_MANY:
             gen_goto_tb(dc, 1, dc->base.pc_next);
             break;
+        case DISAS_UPDATE_NOCHAIN:
+            gen_set_pc_im(dc, dc->base.pc_next);
+            /* fall through */
         case DISAS_JUMP:
             gen_goto_ptr();
             break;

diff --git a/target/arm/translate.h b/target/arm/translate.h
index d5edef2..6dfe24c 100644 (file)
--- a/target/arm/translate.h
+++ b/target/arm/translate.h
@@ -173,6 +173,8 @@ static inline void disas_set_insn_syndrome(DisasContext *s, uint32_t syn)
  * return from cpu_tb_exec.
  */
 #define DISAS_EXIT      DISAS_TARGET_9
+/* CPU state was modified dynamically; no need to exit, but do not chain. */
+#define DISAS_UPDATE_NOCHAIN  DISAS_TARGET_10
 
 #ifdef TARGET_AARCH64
 void a64_translate_init(void);