[12/15] target/arm: Don't calculate lr in arm_v7m_cpu_do_interrupt() until needed

Move the code in arm_v7m_cpu_do_interrupt() that calculates the
magic LR value down to when we're actually going to use it.
Having the calculation and use so far apart makes the code
a little harder to understand than it needs to be.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/helper.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

On 08/02/2017 01:43 PM, Peter Maydell wrote:
> Move the code in arm_v7m_cpu_do_interrupt() that calculates the
> magic LR value down to when we're actually going to use it.
> Having the calculation and use so far apart makes the code
> a little harder to understand than it needs to be.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

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

> ---
>   target/arm/helper.c | 15 ++++++++-------
>   1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index b64ddb1..0ecc8f1 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -6311,13 +6311,6 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
>   
>       arm_log_exception(cs->exception_index);
>   
> -    lr = 0xfffffff1;
> -    if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) {
> -        lr |= 4;
> -    }
> -    if (env->v7m.exception == 0)
> -        lr |= 8;
> -
>       /* For exceptions we just mark as pending on the NVIC, and let that
>          handle it.  */
>       switch (cs->exception_index) {
> @@ -6408,6 +6401,14 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
>           return; /* Never happens.  Keep compiler happy.  */
>       }
>   
> +    lr = 0xfffffff1;
> +    if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) {
> +        lr |= 4;
> +    }
> +    if (env->v7m.exception == 0) {
> +        lr |= 8;
> +    }
> +
>       v7m_push_stack(cpu);
>       v7m_exception_taken(cpu, lr);
>       qemu_log_mask(CPU_LOG_INT, "... as %d\n", env->v7m.exception);
>

On Wed, Aug 02, 2017 at 05:43:58PM +0100, Peter Maydell wrote:
> Move the code in arm_v7m_cpu_do_interrupt() that calculates the
> magic LR value down to when we're actually going to use it.
> Having the calculation and use so far apart makes the code
> a little harder to understand than it needs to be.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>


> ---
>  target/arm/helper.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index b64ddb1..0ecc8f1 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -6311,13 +6311,6 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
>  
>      arm_log_exception(cs->exception_index);
>  
> -    lr = 0xfffffff1;
> -    if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) {
> -        lr |= 4;
> -    }
> -    if (env->v7m.exception == 0)
> -        lr |= 8;
> -
>      /* For exceptions we just mark as pending on the NVIC, and let that
>         handle it.  */
>      switch (cs->exception_index) {
> @@ -6408,6 +6401,14 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
>          return; /* Never happens.  Keep compiler happy.  */
>      }
>  
> +    lr = 0xfffffff1;
> +    if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) {
> +        lr |= 4;
> +    }
> +    if (env->v7m.exception == 0) {
> +        lr |= 8;
> +    }
> +
>      v7m_push_stack(cpu);
>      v7m_exception_taken(cpu, lr);
>      qemu_log_mask(CPU_LOG_INT, "... as %d\n", env->v7m.exception);
> -- 
> 2.7.4
> 
>

On 08/02/2017 09:43 AM, Peter Maydell wrote:
> Move the code in arm_v7m_cpu_do_interrupt() that calculates the
> magic LR value down to when we're actually going to use it.
> Having the calculation and use so far apart makes the code
> a little harder to understand than it needs to be.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  target/arm/helper.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~