[PATCH v3 05/29] scripts/coccinelle: Add cpu_env.cocci script

[Philippe Mathieu-Daudé]

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 | 100 +++++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+)
 create mode 100644 scripts/coccinelle/cpu_env.cocci

diff --git a/MAINTAINERS b/MAINTAINERS
index dfaca8323e..ca3c8c18ab 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
 F: scripts/decodetree.py
 F: docs/devel/decodetree.rst
 F: docs/devel/tcg*
diff --git a/scripts/coccinelle/cpu_env.cocci b/scripts/coccinelle/cpu_env.cocci
new file mode 100644
index 0000000000..5a70c2211a
--- /dev/null
+++ b/scripts/coccinelle/cpu_env.cocci
@@ -0,0 +1,100 @@
+/*
+ * 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.
+ *            CPU() macro is a no-op.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * SPDX-FileCopyrightText: Linaro Ltd 2024
+ * SPDX-FileContributor: Philippe Mathieu-Daudé
+ */
+
+@@
+type ArchCPU =~ "CPU$";
+identifier cpu;
+type CPUArchState =~ "^CPU";
+identifier env;
+@@
+     ArchCPU *cpu;
+     ...
+     CPUArchState *env = &cpu->env;
+     <...
+-    &cpu->env
++    env
+     ...>
+
+
+/*
+ * Due to commit 8ce5c64499 ("semihosting: Return failure from
+ * softmmu-uaccess.h functions"), skip functions using softmmu-uaccess.h
+ * macros (they don't pass 'env' as argument).
+ */
+@ uaccess_api_used exists @
+identifier semihosting_func =~ "^(put|get)_user_[us](al|8|16|32)$";
+@@
+      semihosting_func(...)
+
+
+/*
+ * Argument is CPUState*
+ */
+@ cpustate_arg depends on !uaccess_api_used @
+identifier cpu;
+type ArchCPU =~ "CPU$";
+type CPUArchState;
+identifier ARCH_CPU =~ "CPU$";
+identifier env;
+CPUState *cs;
+@@
+-    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 !uaccess_api_used  && !cpustate_arg @
+identifier cpu;
+type ArchCPU =~ "CPU$";
+type CPUArchState;
+identifier ARCH_CPU =~ "CPU$";
+identifier env;
+expression cs;
+@@
+-    ArchCPU *cpu = ARCH_CPU(cs);
+     ...
+-    CPUArchState *env = &cpu->env;
++    CPUArchState *env = cpu_env(CPU(cs));
+     ... when != cpu
+
+
+/* When single use of 'env', call cpu_env() in place */
+@ depends on !uaccess_api_used @
+type CPUArchState;
+identifier env;
+expression cs;
+@@
+-    CPUArchState *env = cpu_env(cs);
+     ... when != env
+-     env
++     cpu_env(cs)
+     ... when != env
+
+
+/* Both first_cpu/current_cpu are extern CPUState* */
+@@
+symbol first_cpu;
+symbol current_cpu;
+@@
+(
+-    CPU(first_cpu)
++    first_cpu
+|
+-    CPU(current_cpu)
++    current_cpu
+)
-- 
2.41.0