Move the code to generate the "condition failed" instruction
codepath out of the if (singlestepping) {} else {}. This
will allow adding support for handling a new is_jmp type
which can't be neatly split into "singlestepping case"
versus "not singlestepping case".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/translate.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/target/arm/translate.c b/target/arm/translate.c
index a1a0e73..87fd702 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -11988,9 +11988,9 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
     /* At this stage dc->condjmp will only be set when the skipped
        instruction was a conditional branch or trap, and the PC has
        already been written.  */
+    gen_set_condexec(dc);
     if (unlikely(cs->singlestep_enabled || dc->ss_active)) {
         /* Unconditional and "condition passed" instruction codepath. */
-        gen_set_condexec(dc);
         switch (dc->is_jmp) {
         case DISAS_SWI:
             gen_ss_advance(dc);
@@ -12013,13 +12013,6 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
             /* FIXME: Single stepping a WFI insn will not halt the CPU. */
             gen_singlestep_exception(dc);
         }
-        if (dc->condjmp) {
-            /* "Condition failed" instruction codepath. */
-            gen_set_label(dc->condlabel);
-            gen_set_condexec(dc);
-            gen_set_pc_im(dc, dc->pc);
-            gen_singlestep_exception(dc);
-        }
     } else {
         /* While branches must always occur at the end of an IT block,
            there are a few other things that can cause us to terminate
@@ -12029,7 +12022,6 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
             - Hardware watchpoints.
            Hardware breakpoints have already been handled and skip this code.
          */
-        gen_set_condexec(dc);
         switch(dc->is_jmp) {
         case DISAS_NEXT:
             gen_goto_tb(dc, 1, dc->pc);
@@ -12069,11 +12061,17 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
             gen_exception(EXCP_SMC, syn_aa32_smc(), 3);
             break;
         }
-        if (dc->condjmp) {
-            gen_set_label(dc->condlabel);
-            gen_set_condexec(dc);
+    }
+
+    if (dc->condjmp) {
+        /* "Condition failed" instruction codepath for the branch/trap insn */
+        gen_set_label(dc->condlabel);
+        gen_set_condexec(dc);
+        if (unlikely(cs->singlestep_enabled || dc->ss_active)) {
+            gen_set_pc_im(dc, dc->pc);
+            gen_singlestep_exception(dc);
+        } else {
             gen_goto_tb(dc, 1, dc->pc);
-            dc->condjmp = 0;
         }
     }
 
-- 
2.7.4

Hi Peter,

On 04/10/2017 07:39 AM, Peter Maydell wrote:
> Move the code to generate the "condition failed" instruction
> codepath out of the if (singlestepping) {} else {}. This
> will allow adding support for handling a new is_jmp type
> which can't be neatly split into "singlestepping case"
> versus "not singlestepping case".

This makes also the code more readable :)

>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  target/arm/translate.c | 24 +++++++++++-------------
>  1 file changed, 11 insertions(+), 13 deletions(-)
>
> diff --git a/target/arm/translate.c b/target/arm/translate.c
> index a1a0e73..87fd702 100644
> --- a/target/arm/translate.c
> +++ b/target/arm/translate.c
> @@ -11988,9 +11988,9 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
>      /* At this stage dc->condjmp will only be set when the skipped
>         instruction was a conditional branch or trap, and the PC has
>         already been written.  */
> +    gen_set_condexec(dc);
>      if (unlikely(cs->singlestep_enabled || dc->ss_active)) {
>          /* Unconditional and "condition passed" instruction codepath. */
> -        gen_set_condexec(dc);
>          switch (dc->is_jmp) {
>          case DISAS_SWI:
>              gen_ss_advance(dc);
> @@ -12013,13 +12013,6 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
>              /* FIXME: Single stepping a WFI insn will not halt the CPU. */
>              gen_singlestep_exception(dc);
>          }
> -        if (dc->condjmp) {
> -            /* "Condition failed" instruction codepath. */
> -            gen_set_label(dc->condlabel);
> -            gen_set_condexec(dc);
> -            gen_set_pc_im(dc, dc->pc);
> -            gen_singlestep_exception(dc);
> -        }
>      } else {
>          /* While branches must always occur at the end of an IT block,
>             there are a few other things that can cause us to terminate
> @@ -12029,7 +12022,6 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
>              - Hardware watchpoints.
>             Hardware breakpoints have already been handled and skip this code.
>           */
> -        gen_set_condexec(dc);
>          switch(dc->is_jmp) {
>          case DISAS_NEXT:
>              gen_goto_tb(dc, 1, dc->pc);
> @@ -12069,11 +12061,17 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb)
>              gen_exception(EXCP_SMC, syn_aa32_smc(), 3);
>              break;
>          }
> -        if (dc->condjmp) {
> -            gen_set_label(dc->condlabel);
> -            gen_set_condexec(dc);
> +    }
> +
> +    if (dc->condjmp) {
> +        /* "Condition failed" instruction codepath for the branch/trap insn */
> +        gen_set_label(dc->condlabel);
> +        gen_set_condexec(dc);
> +        if (unlikely(cs->singlestep_enabled || dc->ss_active)) {

I'm custom to think "let's change that and think how to protect the code 
to help the next one who will modify it" and wonder if it isn't safer to 
define:

const bool singlestepping;

singlestepping = cs->singlestep_enabled || dc->ss_active;

Then use:

if unlikely(singlestepping)

At line 11993 and here, what do you think?

Either way:

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

> +            gen_set_pc_im(dc, dc->pc);
> +            gen_singlestep_exception(dc);
> +        } else {
>              gen_goto_tb(dc, 1, dc->pc);
> -            dc->condjmp = 0;
>          }
>      }
>
>

On 10 April 2017 at 14:22, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> I'm custom to think "let's change that and think how to protect the code to
> help the next one who will modify it" and wonder if it isn't safer to
> define:
>
> const bool singlestepping;
>
> singlestepping = cs->singlestep_enabled || dc->ss_active;
>
> Then use:
>
> if unlikely(singlestepping)
>
> At line 11993 and here, what do you think?

I think we could do this with a function (that takes the DisasContext*);
then we can use it in the new gen_bx_excret_final_code() too.

I'll add an extra patch to the set in v2 that does that.

thanks
-- PMM