Re: [PATCH 1/2] scripts/coccinelle: Add cpu_env.cocci_template script

[Paolo Bonzini]

On Fri, Jan 26, 2024 at 11:38 AM Philippe Mathieu-Daudé
<philmd@linaro.org> wrote:
>
> On 25/1/24 17:56, Philippe Mathieu-Daudé wrote:
> > Add a Coccinelle script to convert the following slow path
> > (due to the QOM cast macro):
> >
> >    &ARCH_CPU(..)->env
> >
> > to the following fast path:
> >
> >    cpu_env(..)
> >
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > ---
> >   MAINTAINERS                               |  1 +
> >   scripts/coccinelle/cpu_env.cocci_template | 60 +++++++++++++++++++++++
> >   2 files changed, 61 insertions(+)
> >   create mode 100644 scripts/coccinelle/cpu_env.cocci_template
>
>
> > diff --git a/scripts/coccinelle/cpu_env.cocci_template 
> > b/scripts/coccinelle/cpu_env.cocci_template
> > new file mode 100644
> > index 0000000000..53aa3a1fea
> > --- /dev/null
> > +++ b/scripts/coccinelle/cpu_env.cocci_template
> > @@ -0,0 +1,60 @@
> > +/*
> > +
> > + Convert &ARCH_CPU(..)->env to use cpu_env(..).
> > +
> > + Rationale: ARCH_CPU() might be slow, being a QOM cast macro.
> > +            cpu_env() is its fast equivalent.
> > +
> > + SPDX-License-Identifier: GPL-2.0-or-later
> > + SPDX-FileCopyrightText: Linaro Ltd 2024
> > + SPDX-FileContributor: Philippe Mathieu-Daudé
> > +
> > + Usage as of v8.2.0:
> > +
> > + $ for targetdir in target/*; do test -d $targetdir || continue; \
> > +       export target=${targetdir:7}; \
> > +       sed \
> > +           -e "s/__CPUArchState__/$( \
> > +               git grep -h --no-line-number '@env: #CPU.*State' \
> > +                   target/$target/cpu.h \
> > +               | sed -n -e 's/.*\(CPU.*State\).\?/\1/p')/g" \
> > +           -e "s/__ARCHCPU__/$( \
> > +               git grep -h --no-line-number OBJECT_DECLARE_CPU_TYPE.*CPU \
> > +                   target/$target/cpu-qom.h \
> > +               | sed -n -e 's/.*(\(.*\), .*, .*)/\1/p')/g" \
> > +           -e "s/__ARCH_CPU__/$( \
> > +               git grep -h --no-line-number OBJECT_DECLARE_CPU_TYPE.*CPU \
> > +                   target/$target/cpu-qom.h \
> > +               | sed -n -e 's/.*(.*, .*, \(.*\))/\1/p')/g" \
> > +       < scripts/coccinelle/cpu_env.cocci_template \
> > +       > $TMPDIR/cpu_env_$target.cocci; \
> > +       for dir in hw target/$target; do \
> > +           spatch --macro-file scripts/cocci-macro-file.h \
> > +                  --sp-file $TMPDIR/cpu_env_$target.cocci \
> > +                  --keep-comments \
> > +                  --dir $dir \
> > +                  --in-place; \
> > +       done; \
> > +   done
> > +
> > +*/
> > +
> > +@ CPUState_arg_used @
> > +CPUState *cs;
> > +identifier cpu;
> > +identifier env;
> > +@@
> > +-   __ARCHCPU__ *cpu = __ARCH_CPU__(cs);
>
> Here we remove ARCH_CPU(), ...
>
> > +-   __CPUArchState__ *env = &cpu->env;
> > ++   __CPUArchState__ *env = cpu_env(cs);
> > +    ... when != cpu
> > +
> > +@ depends on never CPUState_arg_used @
> > +identifier obj;
> > +identifier cpu;
> > +identifier env;
> > +@@
> > +-   __ARCHCPU__ *cpu = __ARCH_CPU__(obj);
> > +-   __CPUArchState__ *env = &cpu->env;
> > ++   __CPUArchState__ *env = cpu_env(CPU(obj));
>
> ... but here we just change it by a CPU() QOM call.
> So this 2nd change is just style cleanup.

Can you also add a hunk that is

CPUState *cs;
@@
-  CPU(cs)
+ cs

to clean up on the second?  cpu_env(CPU(current_cpu)) is suboptimal
and also a bit ugly.

paolo