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

[Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
 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