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

[Blue Swirl]

Thanks, applied.

On 4/26/10, Richard Henderson <address@hidden> wrote:
> 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
>
>