diff options
| -rw-r--r-- | Config.in | 27 | ||||
| -rw-r--r-- | docs/manual/ccache-support.txt | 20 | ||||
| -rw-r--r-- | package/gcc/gcc.mk | 4 | ||||
| -rw-r--r-- | toolchain/toolchain-wrapper.c | 11 | ||||
| -rw-r--r-- | toolchain/toolchain-wrapper.mk | 4 |
5 files changed, 65 insertions, 1 deletions
@@ -286,6 +286,33 @@ config BR2_CCACHE_INITIAL_SETUP These initial settings are applied after ccache has been compiled. +config BR2_CCACHE_USE_BASEDIR + bool "Use relative paths" + default y + help + Allow ccache to convert absolute paths within the output + directory into relative paths. + + During the build, many -I include directives are given with + an absolute path. These absolute paths end up in the hashes + that are computed by ccache. Therefore, when you build from a + different directory, the hash will be different and the + cached object will not be used. + + To improve cache performance, set this option to y. This + allows ccache to rewrite absolute paths within the output + directory into relative paths. Note that only paths within + the output directory will be rewritten; therefore, if you + change BR2_HOST_DIR to point outside the output directory and + subsequently move it to a different location, this will lead + to cache misses. + + This option has as a result that the debug information in the + object files also has only relative paths. Therefore, make + sure you cd to the build directory before starting gdb. See + the section "COMPILING IN DIFFERENT DIRECTORIES" in the + ccache manual for more information. + endif config BR2_DEPRECATED diff --git a/docs/manual/ccache-support.txt b/docs/manual/ccache-support.txt index 992471dbf..f6746ad7d 100644 --- a/docs/manual/ccache-support.txt +++ b/docs/manual/ccache-support.txt @@ -33,3 +33,23 @@ make CCACHE_OPTIONS="--max-size=5G" ccache-options # zero statistics counters make CCACHE_OPTIONS="--zero-stats" ccache-options ----------------- + ++ccache+ makes a hash of the source files and of the compiler options. +If a compiler option is different, the cached object file will not be +used. Many compiler options, however, contain an absolute path to the +staging directory. Because of this, building in a different output +directory would lead to many cache misses. + +To avoid this issue, buildroot has the +Use relative paths+ option +(+BR2_CCACHE_USE_BASEDIR+). This will rewrite all absolute paths that +point inside the output directory into relative paths. Thus, changing +the output directory no longer leads to cache misses. + +A disadvantage of the relative paths is that they also end up to be +relative paths in the object file. Therefore, for example, the debugger +will no longer find the file, unless you cd to the output directory +first. + +See https://ccache.samba.org/manual.html#_compiling_in_different_directories[the +ccache manual's section on "Compiling in different directories"] for +more details about this rewriting of absolute paths. diff --git a/package/gcc/gcc.mk b/package/gcc/gcc.mk index 103cbe17b..420c4e9b7 100644 --- a/package/gcc/gcc.mk +++ b/package/gcc/gcc.mk @@ -256,8 +256,10 @@ HOST_GCC_COMMON_CCACHE_HASH_FILES += package/gcc/$(GCC_VERSION)/1000-powerpc-lin endif endif +# _CONF_OPTS contains some references to the absolute path of $(HOST_DIR), +# so substitute those away. HOST_GCC_COMMON_TOOLCHAIN_WRAPPER_ARGS += -DBR_CCACHE_HASH=\"`\ - printf '%s' $($(PKG)_CONF_OPTS) $(GCC_VERSION) \ + printf '%s' $(subst $(HOST_DIR),@HOST_DIR@,$($(PKG)_CONF_OPTS)) \ | sha256sum - $(HOST_GCC_COMMON_CCACHE_HASH_FILES) \ | cut -c -64 | tr -d '\n'`\" endif # BR2_CCACHE diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c index d52115f51..11f93f0fd 100644 --- a/toolchain/toolchain-wrapper.c +++ b/toolchain/toolchain-wrapper.c @@ -268,6 +268,10 @@ int main(int argc, char **argv) fprintf(stderr, "%sCCACHE_COMPILERCHECK='string:" BR_CCACHE_HASH "'", (debug == 2) ? "\n " : " "); #endif +#ifdef BR_CCACHE_BASEDIR + fprintf(stderr, "%sCCACHE_BASEDIR='" BR_CCACHE_BASEDIR "'", + (debug == 2) ? "\n " : " "); +#endif for (i = 0; exec_args[i]; i++) fprintf(stderr, "%s'%s'", (debug == 2) ? "\n " : " ", exec_args[i]); @@ -282,6 +286,13 @@ int main(int argc, char **argv) return 3; } #endif +#ifdef BR_CCACHE_BASEDIR + /* Allow compilercheck to be overridden through the environment */ + if (setenv("CCACHE_BASEDIR", BR_CCACHE_BASEDIR, 0)) { + perror(__FILE__ ": Failed to set CCACHE_BASEDIR"); + return 3; + } +#endif if (execv(exec_args[0], exec_args)) perror(path); diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk index 749afd7a5..c78363a2e 100644 --- a/toolchain/toolchain-wrapper.mk +++ b/toolchain/toolchain-wrapper.mk @@ -20,6 +20,10 @@ ifeq ($(BR2_CCACHE),y) TOOLCHAIN_WRAPPER_ARGS += -DBR_CCACHE endif +ifeq ($(BR2_CCACHE_USE_BASEDIR),y) +TOOLCHAIN_WRAPPER_ARGS += -DBR_CCACHE_BASEDIR='"$(BASE_DIR)"' +endif + # For simplicity, build directly into the install location define TOOLCHAIN_BUILD_WRAPPER $(Q)mkdir -p $(HOST_DIR)/usr/bin |