[v2] hw, target: Prefer fast cpu_env() over slower CPU QOM cast macro

[PATCH v2 02/23] scripts/coccinelle: Add cpu_env.cocci_template script

Philippe Mathieu-Daudé posted 23 patches 10 months ago

Diff against v1 v3
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Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Eduardo Habkost <eduardo@habkost.net>, Stefano Stabellini <sstabellini@kernel.org>, Anthony Perard <anthony.perard@citrix.com>, Paul Durrant <paul@xen.org>, Peter Maydell <peter.maydell@linaro.org>, "Cédric Le Goater" <clg@kaod.org>, Nicholas Piggin <npiggin@gmail.com>, "Frédéric Barrat" <fbarrat@linux.ibm.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Igor Mammedov <imammedo@redhat.com>, Ani Sinha <anisinha@redhat.com>, Laurent Vivier <laurent@vivier.eu>, Alexander Graf <agraf@csgraf.de>, Michael Rolnik <mrolnik@gmail.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Cameron Esfahani <dirty@apple.com>, Roman Bolshakov <rbolshakov@ddn.com>, Marcelo Tosatti <mtosatti@redhat.com>, David Woodhouse <dwmw2@infradead.org>, Reinoud Zandijk <reinoud@netbsd.org>, Sunil Muthuswamy <sunilmut@microsoft.com>, Song Gao <gaosong@loongson.cn>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Aurelien Jarno <aurelien@aurel32.net>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, Huacai Chen <chenhuacai@kernel.org>, Chris Wulff <crwulff@gmail.com>, Marek Vasut <marex@denx.de>, Stafford Horne <shorne@gmail.com>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Bin Meng <bin.meng@windriver.com>, Weiwei Li <liwei1518@gmail.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, Thomas Huth <thuth@redhat.com>, David Hildenbrand <david@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Artyom Tarasenko <atar4qemu@gmail.com>, Bastian Koppelmann <kbastian@mail.uni-paderborn.de>, Max Filippov <jcmvbkbc@gmail.com>

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[PATCH v2 02/23] scripts/coccinelle: Add cpu_env.cocci_template script

Posted by Philippe Mathieu-Daudé 10 months ago

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 | 92 +++++++++++++++++++++++
 2 files changed, 93 insertions(+)
 create mode 100644 scripts/coccinelle/cpu_env.cocci_template

diff --git a/MAINTAINERS b/MAINTAINERS
index dfaca8323e..1d57130ff8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -157,6 +157,7 @@ F: accel/tcg/
 F: accel/stubs/tcg-stub.c
 F: util/cacheinfo.c
 F: util/cacheflush.c
+F: scripts/coccinelle/cpu_env.cocci_template
 F: scripts/decodetree.py
 F: docs/devel/decodetree.rst
 F: docs/devel/tcg*
diff --git a/scripts/coccinelle/cpu_env.cocci_template b/scripts/coccinelle/cpu_env.cocci_template
new file mode 100644
index 0000000000..462ed418bb
--- /dev/null
+++ b/scripts/coccinelle/cpu_env.cocci_template
@@ -0,0 +1,92 @@
+/*
+
+ 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
+
+*/
+
+/* Argument is CPUState* */
+@ CPUState_arg_used @
+CPUState *cs;
+identifier cpu;
+identifier env;
+@@
+-    __ARCHCPU__ *cpu = __ARCH_CPU__(cs);
+-    __CPUArchState__ *env = &cpu->env;
++    __CPUArchState__ *env = cpu_env(cs);
+     ... when != cpu
+
+/*
+ * Argument is not CPUState* but a related QOM object.
+ * CPU() is not a QOM macro but a cast (See commit 0d6d1ab499).
+ */
+@ 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));
+     ... when != cpu
+
+/* Both first_cpu/current_cpu are CPUState* */
+@@
+symbol first_cpu;
+symbol current_cpu;
+@@
+(
+-    CPU(first_cpu)
++    first_cpu
+|
+-    CPU(current_cpu)
++    current_cpu
+)
+
+/* When single use of 'env', call cpu_env() in place */
+@@
+type CPUArchState;
+identifier env;
+expression cs;
+@@
+ {
+-    CPUArchState *env = cpu_env(cs);
+     ... when != env
+-     env
++     cpu_env(cs)
+     ... when != env
+ }
-- 
2.41.0

Re: [PATCH v2 02/23] scripts/coccinelle: Add cpu_env.cocci_template script

Posted by Richard Henderson 10 months ago

On 1/27/24 08:03, 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 | 92 +++++++++++++++++++++++
>   2 files changed, 93 insertions(+)
>   create mode 100644 scripts/coccinelle/cpu_env.cocci_template

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


> +/* Both first_cpu/current_cpu are CPUState* */
> +@@
> +symbol first_cpu;
> +symbol current_cpu;
> +@@
> +(
> +-    CPU(first_cpu)
> ++    first_cpu
> +|
> +-    CPU(current_cpu)
> ++    current_cpu
> +)

I think part of Paolo's query is if there are any new instances of

commit 96449e4a30a56e3303d6d0407aca130c71671754
Author: Philippe Mathieu-Daudé <philmd@linaro.org>
Date:   Tue May 12 09:00:18 2020 +0200

     target: Remove unnecessary CPU() cast
...
       @@
       typedef CPUState;
       CPUState *s;
       @@
       -   CPU(s)
       +   s


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