[Buildroot] [git commit] pkg-cmake.mk: enable ccache for cmake packages

[Peter Korsgaard]

commit: http://git.buildroot.net/buildroot/commit/?id=c8f2d248f65067979f9b7da25ee2469ae020ec1b
branch: http://git.buildroot.net/buildroot/commit/?id=refs/heads/master

This patch updates the generated toolchainfile.cmake to use ccache.

When toolchainfile.cmake is used inside Buildroot, using ccache during
the build is driven by a CMake knob: USE_CCACHE, automatically set by
the cmake-package infrastructure and reflecting the BR2_CCACHE value.

Since this toolchainefile.cmake file can be used outside Buildroot, and
this file also set a couple of things (among these: the sysroot cflag,
some pkg-config environment variables), it is important to set the
compiler variables as well to keep the consistency of the
cross-compilation configuration.
So, when it is used outside Buildroot, using ccache for the build is
driven by the ccache program availability.

Note that using ccache for the build is achieved by setting the *_ARG1
CMake variables to let CMake use ccache without failing in detecting
the compiler.

Signed-off-by: Luca Ceresoli <luca at lucaceresoli.net>
Signed-off-by: Samuel Martin <s.martin49 at gmail.com>
Cc: Luca Ceresoli <luca at lucaceresoli.net>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout at mind.be>
Reviewed-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 package/pkg-cmake.mk                |    2 ++
 support/misc/toolchainfile.cmake.in |   33 +++++++++++++++++++++++++++++++--
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/package/pkg-cmake.mk b/package/pkg-cmake.mk
index a84aa0b..56a93c7 100644
--- a/package/pkg-cmake.mk
+++ b/package/pkg-cmake.mk
@@ -66,6 +66,7 @@ define $(2)_CONFIGURE_CMDS
 		-DCMAKE_INSTALL_PREFIX="/usr" \
 		-DCMAKE_COLOR_MAKEFILE=OFF \
 		-DBUILD_SHARED_LIBS=$(if $(BR2_PREFER_STATIC_LIB),OFF,ON) \
+		-DUSE_CCACHE=$(if $(BR2_CCACHE),ON,OFF) \
 		$$($$(PKG)_CONF_OPT) \
 	)
 endef
@@ -83,6 +84,7 @@ define $(2)_CONFIGURE_CMDS
 		-DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY="BOTH" \
 		-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE="BOTH" \
 		-DCMAKE_INSTALL_PREFIX="$$(HOST_DIR)/usr" \
+		-DUSE_CCACHE=$(if $(BR2_CCACHE),ON,OFF) \
 		$$($$(PKG)_CONF_OPT) \
 	)
 endef
diff --git a/support/misc/toolchainfile.cmake.in b/support/misc/toolchainfile.cmake.in
index 27a0af1..46ed932 100644
--- a/support/misc/toolchainfile.cmake.in
+++ b/support/misc/toolchainfile.cmake.in
@@ -23,5 +23,34 @@ set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
 set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
 set(ENV{PKG_CONFIG_SYSROOT_DIR} "${RELOCATED_HOST_DIR}/@@STAGING_SUBDIR@@")
 
-set(CMAKE_C_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CC_NOCCACHE@@")
-set(CMAKE_CXX_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CXX_NOCCACHE@@")
+# This toolchain file can be used both inside and outside Buildroot.
+# * When used inside Buildroot, ccache support is explicitly driven using the
+#   USE_CCACHE variable.
+# * When used outside Buildroot (i.e. when USE_CCACHE is not defined), ccache
+#   support is automatically enabled if the ccache program is available.
+if(DEFINED USE_CCACHE)
+	if(USE_CCACHE)
+		set(CMAKE_ASM_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CC_NOCCACHE@@")
+		set(CMAKE_C_COMPILER "${RELOCATED_HOST_DIR}/usr/bin/ccache")
+		set(CMAKE_CXX_COMPILER "${RELOCATED_HOST_DIR}/usr/bin/ccache")
+		set(CMAKE_C_COMPILER_ARG1 "${RELOCATED_HOST_DIR}/@@TARGET_CC_NOCCACHE@@")
+		set(CMAKE_CXX_COMPILER_ARG1 "${RELOCATED_HOST_DIR}/@@TARGET_CXX_NOCCACHE@@")
+	else()
+		set(CMAKE_C_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CC_NOCCACHE@@")
+		set(CMAKE_CXX_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CXX_NOCCACHE@@")
+	endif()
+else()
+	find_program(CCACHE ccache HINTS "${RELOCATED_HOST_DIR}/usr/bin")
+	if(CCACHE)
+		set(CMAKE_ASM_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CC_NOCCACHE@@")
+		set(CMAKE_C_COMPILER "${CCACHE}")
+		set(CMAKE_CXX_COMPILER "${CCACHE}")
+		set(CMAKE_C_COMPILER_ARG1 "${RELOCATED_HOST_DIR}/@@TARGET_CC_NOCCACHE@@")
+		set(CMAKE_CXX_COMPILER_ARG1 "${RELOCATED_HOST_DIR}/@@TARGET_CXX_NOCCACHE@@")
+		message(STATUS "ccache program has been found and will be used for the build.")
+		message(STATUS "  To disable ccache, add -DUSE_CCACHE=OFF on the cmake command line.")
+	else()
+		set(CMAKE_C_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CC_NOCCACHE@@")
+		set(CMAKE_CXX_COMPILER "${RELOCATED_HOST_DIR}/@@TARGET_CXX_NOCCACHE@@")
+	endif()
+endif()