[PATCH 1/4] target/m68k: introduce is_singlestepping() function

[Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>]

The m68k translator currently checks the DisasContextBase singlestep_enabled
boolean directly to determine whether to single-step execution. Soon
single-stepping may also be triggered by setting the appropriate bits in the
SR register so centralise the check into a single is_singlestepping()
function.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 target/m68k/translate.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index 200018ae6a..c774f2e8f0 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -194,6 +194,17 @@ static void do_writebacks(DisasContext *s)
     }
 }
 
+static bool is_singlestepping(DisasContext *s)
+{
+    /*
+     * Return true if we are singlestepping either because of QEMU gdbstub
+     * singlestep. This does not include the command line '-singlestep' mode
+     * which is rather misnamed as it only means "one instruction per TB" and
+     * doesn't affect the code we generate.
+     */
+    return s->base.singlestep_enabled;
+}
+
 /* is_jmp field values */
 #define DISAS_JUMP      DISAS_TARGET_0 /* only pc was modified dynamically */
 #define DISAS_EXIT      DISAS_TARGET_1 /* cpu state was modified dynamically */
@@ -1506,7 +1517,7 @@ static inline bool use_goto_tb(DisasContext *s, uint32_t dest)
 /* Generate a jump to an immediate address.  */
 static void gen_jmp_tb(DisasContext *s, int n, uint32_t dest)
 {
-    if (unlikely(s->base.singlestep_enabled)) {
+    if (unlikely(is_singlestepping(s))) {
         gen_exception(s, dest, EXCP_DEBUG);
     } else if (use_goto_tb(s, dest)) {
         tcg_gen_goto_tb(n);
@@ -6245,7 +6256,7 @@ static void m68k_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         break;
     case DISAS_TOO_MANY:
         update_cc_op(dc);
-        if (dc->base.singlestep_enabled) {
+        if (is_singlestepping(dc)) {
             tcg_gen_movi_i32(QREG_PC, dc->pc);
             gen_raise_exception(EXCP_DEBUG);
         } else {
@@ -6254,7 +6265,7 @@ static void m68k_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         break;
     case DISAS_JUMP:
         /* We updated CC_OP and PC in gen_jmp/gen_jmp_im.  */
-        if (dc->base.singlestep_enabled) {
+        if (is_singlestepping(dc)) {
             gen_raise_exception(EXCP_DEBUG);
         } else {
             tcg_gen_lookup_and_goto_ptr();
@@ -6265,7 +6276,7 @@ static void m68k_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
          * We updated CC_OP and PC in gen_exit_tb, but also modified
          * other state that may require returning to the main loop.
          */
-        if (dc->base.singlestep_enabled) {
+        if (is_singlestepping(dc)) {
             gen_raise_exception(EXCP_DEBUG);
         } else {
             tcg_gen_exit_tb(NULL, 0);
-- 
2.20.1