From 7a85ff768385e2f833c575b9825af9be83eb637b Mon Sep 17 00:00:00 2001
From: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Date: Mon, 14 Mar 2022 17:26:18 +0100
Subject: [PATCH] sparse: add sparse support

With this adding "-DSPARSE=y" to the "west build" command line
performs a sparse check of the project build. So far only gcc-based
builds are supported.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
---
 CMakeLists.txt                  |  4 ++++
 cmake/compiler/gcc/target.cmake |  9 ++++++++-
 cmake/linker/ld/target.cmake    |  8 +++++++-
 doc/develop/test/index.rst      |  1 +
 doc/develop/test/sparse.rst     | 25 +++++++++++++++++++++++++
 5 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 doc/develop/test/sparse.rst

diff --git a/CMakeLists.txt b/CMakeLists.txt
index fa66f592ca9..bbb5fd2f573 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -267,6 +267,10 @@ if(CONFIG_COMPILER_COLOR_DIAGNOSTICS)
 zephyr_compile_options($<TARGET_PROPERTY:compiler,diagnostic>)
 endif()
 
+if("${SPARSE}" STREQUAL "y")
+  list(APPEND TOOLCHAIN_C_FLAGS -D__CHECKER__)
+endif()
+
 zephyr_compile_options(
   ${TOOLCHAIN_C_FLAGS}
 )
diff --git a/cmake/compiler/gcc/target.cmake b/cmake/compiler/gcc/target.cmake
index 6c114355ac5..1cb68cd60dc 100644
--- a/cmake/compiler/gcc/target.cmake
+++ b/cmake/compiler/gcc/target.cmake
@@ -5,7 +5,14 @@ set_ifndef(C++ g++)
 # Configures CMake for using GCC, this script is re-used by several
 # GCC-based toolchains
 
-find_program(CMAKE_C_COMPILER ${CROSS_COMPILE}${CC} PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
+if("${SPARSE}" STREQUAL "y")
+  find_program(CMAKE_C_COMPILER cgcc)
+  find_program(REAL_CC ${CROSS_COMPILE}${CC} PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
+  set(ENV{REAL_CC} ${REAL_CC})
+else()
+  find_program(CMAKE_C_COMPILER ${CROSS_COMPILE}${CC} PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
+endif()
+
 if(${CMAKE_C_COMPILER} STREQUAL CMAKE_C_COMPILER-NOTFOUND)
   message(FATAL_ERROR "C compiler ${CROSS_COMPILE}${CC} not found - Please check your toolchain installation")
 endif()
diff --git a/cmake/linker/ld/target.cmake b/cmake/linker/ld/target.cmake
index 9d1d2357915..4957b5fd2e0 100644
--- a/cmake/linker/ld/target.cmake
+++ b/cmake/linker/ld/target.cmake
@@ -66,6 +66,12 @@ macro(configure_linker_script linker_script_gen linker_pass_define)
     zephyr_get_include_directories_for_lang(C current_includes)
     get_property(current_defines GLOBAL PROPERTY PROPERTY_LINKER_SCRIPT_DEFINES)
 
+    if("${SPARSE}" STREQUAL "y")
+      set(ld_command ${REAL_CC})
+    else()
+      set(ld_command ${CMAKE_C_COMPILER})
+    endif()
+
     add_custom_command(
       OUTPUT ${linker_script_gen}
       DEPENDS
@@ -74,7 +80,7 @@ macro(configure_linker_script linker_script_gen linker_pass_define)
       ${extra_dependencies}
       # NB: 'linker_script_dep' will use a keyword that ends 'DEPENDS'
       ${linker_script_dep}
-      COMMAND ${CMAKE_C_COMPILER}
+      COMMAND ${ld_command}
       -x assembler-with-cpp
       ${NOSYSDEF_CFLAG}
       -MD -MF ${linker_script_gen}.dep -MT ${linker_script_gen}
diff --git a/doc/develop/test/index.rst b/doc/develop/test/index.rst
index b7debc460b8..2383832a027 100644
--- a/doc/develop/test/index.rst
+++ b/doc/develop/test/index.rst
@@ -9,3 +9,4 @@ Testing
    ztest
    twister
    coverage
+   sparse
diff --git a/doc/develop/test/sparse.rst b/doc/develop/test/sparse.rst
new file mode 100644
index 00000000000..bf4a138ffaf
--- /dev/null
+++ b/doc/develop/test/sparse.rst
@@ -0,0 +1,25 @@
+.. _sparse:
+
+Sparse support
+##############
+
+`Sparse <https://kernelnewbies.org/Sparse>`__ is a static code analysis tool.
+Apart from performing common code analysis tasks it also supports an
+``address_space`` attribute, which allows introduction of distinct address
+spaces in C code with subsequent verification that pointers to different
+address spaces do not get confused. Additionally it supports a ``force``
+attribute which should be used to cast pointers between different address
+spaces. At the moment Zephyr introduces a single custom address space
+``__cache`` used to identify pointers from the cached address range on the
+Xtensa architecture. This helps identify cases where cached and uncached
+addresses are confused.
+
+Running with sparse
+*******************
+
+To run a sparse verification build :ref:`west build <west-building>` should be
+called with a `-DSPARSE=y` parameter, e.g.
+
+.. code-block:: shell
+
+    west build -d hello -b intel_adsp_cavs25 zephyr/samples/hello_world -- -DSPARSE=y