[Qemu-devel] [PATCH] target-sparc: Fix -singlestep.

[Richard Henderson]

Single-stepping was not properly updating npc, resulting in some
instructions being executed twice.  In addition, we were emitting
dead code at the end of the TB.

Fix both by teaching gen_goto_tb to avoid goto_tb for single-step
and removing the special-case code in gen_intermediate_code_internal.

Signed-off-by: Richard Henderson <address@hidden>
---
 target-sparc/translate.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/target-sparc/translate.c b/target-sparc/translate.c
index b54c520..be2a116 100644
--- a/target-sparc/translate.c
+++ b/target-sparc/translate.c
@@ -79,6 +79,7 @@ typedef struct DisasContext {
     int mem_idx;
     int fpu_enabled;
     int address_mask_32bit;
+    int singlestep;
     uint32_t cc_op;  /* current CC operation */
     struct TranslationBlock *tb;
     sparc_def_t *def;
@@ -234,7 +235,8 @@ static inline void gen_goto_tb(DisasContext *s, int tb_num,
 
     tb = s->tb;
     if ((pc & TARGET_PAGE_MASK) == (tb->pc & TARGET_PAGE_MASK) &&
-        (npc & TARGET_PAGE_MASK) == (tb->pc & TARGET_PAGE_MASK))  {
+        (npc & TARGET_PAGE_MASK) == (tb->pc & TARGET_PAGE_MASK) &&
+        !s->singlestep)  {
         /* jump to same page: we can use a direct jump */
         tcg_gen_goto_tb(tb_num);
         tcg_gen_movi_tl(cpu_pc, pc);
@@ -4694,6 +4696,7 @@ static inline void 
gen_intermediate_code_internal(TranslationBlock * tb,
 #ifdef TARGET_SPARC64
     dc->address_mask_32bit = env->pstate & PS_AM;
 #endif
+    dc->singlestep = (env->singlestep_enabled || singlestep);
     gen_opc_end = gen_opc_buf + OPC_MAX_SIZE;
 
     cpu_tmp0 = tcg_temp_new();
@@ -4754,9 +4757,7 @@ static inline void 
gen_intermediate_code_internal(TranslationBlock * tb,
             break;
         /* if single step mode, we generate only one instruction and
            generate an exception */
-        if (env->singlestep_enabled || singlestep) {
-            tcg_gen_movi_tl(cpu_pc, dc->pc);
-            tcg_gen_exit_tb(0);
+        if (dc->singlestep) {
             break;
         }
     } while ((gen_opc_ptr < gen_opc_end) &&
-- 
1.6.6.1