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pw_build_android: Enable function dynamic alloc

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Set the PW_FUNCTION_ENABLE_DYNAMIC_ALLOCATION define for Android builds.
This allows `pw::Function`s to exceed the inline size.

The motivation for setting this across the board is that components
built with dynamic allocation disabled (i.e.
PW_FUNCTION_ENABLE_DYNAMIC_ALLOCATION unset or set to 0) cannot be
linked against components with dynamic allocation enabled.

Since even the smallest Android environment is not nearly as constrained
as a typical embedded environment, the solution is to always set this
flag on Android.

Bug: 349352849
Test: Built Android locally.
Change-Id: I7209151c2508026258c23f931a5c12c64c733a1e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/218219
Reviewed-by: Eli Lipsitz <elipsitz@google.com>
Reviewed-by: Carlos Chinchilla <cachinchilla@google.com>
Reviewed-by: Jonathon Reinhart <jrreinhart@google.com>
Commit-Queue: Andrew Harper <aharp@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
This commit is contained in:
Andrew Harper 2024-06-26 16:52:08 +00:00 committed by CQ Bot Account
parent e6cbfd477a
commit 51ed6ec520
3 changed files with 28 additions and 1 deletions
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10
pw_build_android/Android.bp
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@ -16,13 +16,21 @@ package {
default_applicable_licenses: ["external_pigweed_license"],
}
// List of Common Android backends used by Pigweed modules.
// List of Common Android backends and build flags used by Pigweed modules.
// Do not modify this to swap a different backend. Instead see the
// pw_build_android documentation for how to use custom backends.
cc_defaults {
name: "pw_android_common_backends",
cpp_std: "c++20",
// Note for maintainers:
// Update the build flags in the documentation when updating this list.
cflags: [
// Allow `pw::Function`s to exceed the inline size. This assumes all
// targets built with this backend can use dynamic allocation.
"-DPW_FUNCTION_ENABLE_DYNAMIC_ALLOCATION=1",
],
// Note for maintainers:
// Update the common backends list in the documentation when updating this
// list.

17
pw_build_android/docs.rst
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@ -376,3 +376,20 @@ Backends are defined the same way as
:ref:`module-pw_build_android-module-libraries`. They must follow the
``pw_<MODULE_NAME>.<FACADE_NAME>_<BACKEND_NAME>`` name format or
``pw_<MODULE_NAME>_<BACKEND_NAME>`` if applicable.
-----------
Build flags
-----------
Some build flags should be set for all Android targets; these flags are
specified in ``pw_android_common_backends``. These flags are as follows:
``PW_FUNCTION_ENABLE_DYNAMIC_ALLOCATION``
-----------------------------------------
As discussed in :ref:`module-pw_function-dynamic-allocation`, this flag enables
dynamic allocation of :cpp:type:`pw::Function`, allowing it to exceed the
inline size limit.
Android targets support dynamic allocation since the Android environment is not
memory constrained. Thus, ``PW_FUNCTION_ENABLE_DYNAMIC_ALLOCATION`` is enabled
in ``pw_android_common_backends``. Components built with dynamic allocation
disabled cannot be linked against components with dynamic allocation enabled.

2
pw_function/docs.rst
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@ -327,6 +327,8 @@ is a compile-time error unless dynamic allocation is enabled.
// Compiler error: sizeof(MyCallable) exceeds function's inline storage size.
pw::Function<int(int)> function((MyCallable()));
.. _module-pw_function-dynamic-allocation:
Dynamic allocation
==================
You can configure the inline allocation size of ``pw::Function`` and whether it