[PATCH] m68k: Fix regression causing Single-Step via GDB/RSP to not single step

[Laurent Vivier <laurent@vivier.eu>]

A regression that was introduced, with the refactor to TranslatorOps,
drops two lines that update the PC when single-stepping is being performed.

Fixes: 11ab74b01e0a ("target/m68k: Convert to TranslatorOps")
Reported-by: Lucien Murray-Pitts <lucienmp_antispam@yahoo.com>
Suggested-by: Lucien Murray-Pitts <lucienmp_antispam@yahoo.com>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---

Notes:
    v2: update patch from Lucien with changes from Richard
        update subject to prefix it with "m68k:"
        rebase

 target/m68k/translate.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index fcdb7bc8e4..a400c2295f 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -6198,29 +6198,36 @@ static void m68k_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
 {
     DisasContext *dc = container_of(dcbase, DisasContext, base);
 
-    if (dc->base.is_jmp == DISAS_NORETURN) {
-        return;
-    }
-    if (dc->base.singlestep_enabled) {
-        gen_helper_raise_exception(cpu_env, tcg_const_i32(EXCP_DEBUG));
-        return;
-    }
-
     switch (dc->base.is_jmp) {
+    case DISAS_NORETURN:
+        break;
     case DISAS_TOO_MANY:
         update_cc_op(dc);
-        gen_jmp_tb(dc, 0, dc->pc);
+        if (dc->base.singlestep_enabled) {
+            tcg_gen_movi_i32(QREG_PC, dc->pc);
+            gen_helper_raise_exception(cpu_env, tcg_const_i32(EXCP_DEBUG));
+        } else {
+            gen_jmp_tb(dc, 0, dc->pc);
+        }
         break;
     case DISAS_JUMP:
         /* We updated CC_OP and PC in gen_jmp/gen_jmp_im.  */
-        tcg_gen_lookup_and_goto_ptr();
+        if (dc->base.singlestep_enabled) {
+            gen_helper_raise_exception(cpu_env, tcg_const_i32(EXCP_DEBUG));
+        } else {
+            tcg_gen_lookup_and_goto_ptr();
+        }
         break;
     case DISAS_EXIT:
         /*
          * We updated CC_OP and PC in gen_exit_tb, but also modified
          * other state that may require returning to the main loop.
          */
-        tcg_gen_exit_tb(NULL, 0);
+        if (dc->base.singlestep_enabled) {
+            gen_helper_raise_exception(cpu_env, tcg_const_i32(EXCP_DEBUG));
+        } else {
+            tcg_gen_exit_tb(NULL, 0);
+        }
         break;
     default:
         g_assert_not_reached();
-- 
2.24.1