Re: [PATCH 2/6] target/ppc: optimize hreg_compute_pmu_hflags_value

[BALATON Zoltan]

On Mon, 20 May 2024, Harsh Prateek Bora wrote:
> Cache env->spr[SPR_POWER_MMCR0] in a local variable as used in multiple
> conditions to avoid multiple indirect accesses.
>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> ---
> target/ppc/helper_regs.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
> index 945fa1a596..5de0df5795 100644
> --- a/target/ppc/helper_regs.c
> +++ b/target/ppc/helper_regs.c
> @@ -50,15 +50,16 @@ void hreg_swap_gpr_tgpr(CPUPPCState *env)
> static uint32_t hreg_compute_pmu_hflags_value(CPUPPCState *env)
> {
>     uint32_t hflags = 0;
> -
> #if defined(TARGET_PPC64)
> -    if (env->spr[SPR_POWER_MMCR0] & MMCR0_PMCC0) {
> +    target_ulong spr_power_mmcr0 = env->spr[SPR_POWER_MMCR0];

I think this is simple enough so the compiler should be able to find out 
on its own but adding a local is also simple and may make it more readable 
but I'd call it just mmcr0 for readability.

Regards,
BALATON Zoltan

> +
> +    if (spr_power_mmcr0 & MMCR0_PMCC0) {
>         hflags |= 1 << HFLAGS_PMCC0;
>     }
> -    if (env->spr[SPR_POWER_MMCR0] & MMCR0_PMCC1) {
> +    if (spr_power_mmcr0 & MMCR0_PMCC1) {
>         hflags |= 1 << HFLAGS_PMCC1;
>     }
> -    if (env->spr[SPR_POWER_MMCR0] & MMCR0_PMCjCE) {
> +    if (spr_power_mmcr0 & MMCR0_PMCjCE) {
>         hflags |= 1 << HFLAGS_PMCJCE;
>     }