| Message ID | 20190907094027.9537-5-romain.naour@smile.fr |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Add the support for Clang cross-compiler | expand |
On 07/09/2019 11:40, Romain Naour wrote: > Since host-clang is always build by Buildroot as an internal toolchain, > we have to use a second toolchain-wrapper called toolchain-wrapper-clang > when an external toolchain is used. > Inded, the two wrapper use a different path BR_CROSS_PATH_SUFFIX in this > case. I didn't think this was very clear, so I reworded it as follows: host-clang refers to an existing GCC-based toolchain (internal or external) for libstdc++. However, a Buildroot external toolchain gets a different BR_CROSS_PATH_SUFFIX. Therefore, we can't reuse the toolchain-wrapper that gets built for the GCC-based toolchain, but instead have to compile an additional clang-specific wrapper, called toolchain-wrapper-clang. BTW, I've also fixed small typos in the commit messages here and there, and also some check-package warnings, I'm not going to mention those explicitly. > Use a post install hook to rename the clang-8 binary to clang-8.br_real > and recreate all symlinks: > > # clang -> toolchain-wrapper-clang > # clang++ -> toolchain-wrapper-clang > # clang-8 -> toolchain-wrapper-clang > # clang-8.br_real > # clang++.br_real -> clang-8.br_real Are these *.br_real -> clang-8.br_real symlinks useful for anything? I don't think so, since nobody "knows" that clang++.br_real even exists. > # clang.br_real -> clang-8.br_real > # clang-cl -> toolchain-wrapper-clang > # clang-cl.br_real -> clang-8.br_real > # clang-cpp -> toolchain-wrapper-clang > # clang-cpp.br_real -> clang-8.br_real [snip] > +define HOST_CLANG_INSTALL_WRAPPER_AND_SIMPLE_SYMLINKS > + $(Q)cd $(HOST_DIR)/bin; \ > + for i in clang clang-$(CLANG_VERSION_MAJOR) clang++ clang-cl clang-cpp; do \ > + case "$$i" in \ > + *clang-$(CLANG_VERSION_MAJOR)) \ This loop with cases is not needed here. With gcc and friends, we need it because we loop over a wildcard. Here, however, we know exactly what we loop over. So it's much simpler to move this outside of the loop. > + rm -f $$i.br_real; \ > + mv $$i $$i.br_real; \ > + ln -sf toolchain-wrapper-clang $$i; \ > + ;; \ > + *) \ > + ln -snf toolchain-wrapper-clang $$i; \ > + ln -snf clang-$(CLANG_VERSION_MAJOR).br_real $$i.br_real; \ Given the remark above, I removed this line. Regards, Arnout > + ;; \ > + esac; \ > + done > +endef > + > +define HOST_CLANG_TOOLCHAIN_WRAPPER_BUILD > + $(HOSTCC) $(HOST_CFLAGS) $(TOOLCHAIN_WRAPPER_ARGS) \ > + -s -Wl,--hash-style=$(TOOLCHAIN_WRAPPER_HASH_STYLE) \ > + toolchain/toolchain-wrapper.c \ > + -o $(@D)/toolchain-wrapper-clang > +endef > + > +define HOST_CLANG_TOOLCHAIN_WRAPPER_INSTALL > + $(INSTALL) -D -m 0755 $(@D)/toolchain-wrapper-clang \ > + $(HOST_DIR)/bin/toolchain-wrapper-clang > +endef > + > +HOST_CLANG_TOOLCHAIN_WRAPPER_ARGS += -DBR_CROSS_PATH_SUFFIX='".br_real"' > +HOST_CLANG_POST_BUILD_HOOKS += HOST_CLANG_TOOLCHAIN_WRAPPER_BUILD > +HOST_CLANG_POST_INSTALL_HOOKS += HOST_CLANG_TOOLCHAIN_WRAPPER_INSTALL > +HOST_CLANG_POST_INSTALL_HOOKS += HOST_CLANG_INSTALL_WRAPPER_AND_SIMPLE_SYMLINKS
diff --git a/package/clang/clang.mk b/package/clang/clang.mk index 857ec148ac..148df8e611 100644 --- a/package/clang/clang.mk +++ b/package/clang/clang.mk @@ -110,5 +110,39 @@ ifeq ($(BR2_TOOLCHAIN_EXTERNAL),y) HOST_CLANG_CONF_OPTS += -DGCC_INSTALL_PREFIX:PATH=`realpath --relative-to=$(HOST_DIR)/bin/ $(TOOLCHAIN_EXTERNAL_INSTALL_DIR)` endif +define HOST_CLANG_INSTALL_WRAPPER_AND_SIMPLE_SYMLINKS + $(Q)cd $(HOST_DIR)/bin; \ + for i in clang clang-$(CLANG_VERSION_MAJOR) clang++ clang-cl clang-cpp; do \ + case "$$i" in \ + *clang-$(CLANG_VERSION_MAJOR)) \ + rm -f $$i.br_real; \ + mv $$i $$i.br_real; \ + ln -sf toolchain-wrapper-clang $$i; \ + ;; \ + *) \ + ln -snf toolchain-wrapper-clang $$i; \ + ln -snf clang-$(CLANG_VERSION_MAJOR).br_real $$i.br_real; \ + ;; \ + esac; \ + done +endef + +define HOST_CLANG_TOOLCHAIN_WRAPPER_BUILD + $(HOSTCC) $(HOST_CFLAGS) $(TOOLCHAIN_WRAPPER_ARGS) \ + -s -Wl,--hash-style=$(TOOLCHAIN_WRAPPER_HASH_STYLE) \ + toolchain/toolchain-wrapper.c \ + -o $(@D)/toolchain-wrapper-clang +endef + +define HOST_CLANG_TOOLCHAIN_WRAPPER_INSTALL + $(INSTALL) -D -m 0755 $(@D)/toolchain-wrapper-clang \ + $(HOST_DIR)/bin/toolchain-wrapper-clang +endef + +HOST_CLANG_TOOLCHAIN_WRAPPER_ARGS += -DBR_CROSS_PATH_SUFFIX='".br_real"' +HOST_CLANG_POST_BUILD_HOOKS += HOST_CLANG_TOOLCHAIN_WRAPPER_BUILD +HOST_CLANG_POST_INSTALL_HOOKS += HOST_CLANG_TOOLCHAIN_WRAPPER_INSTALL +HOST_CLANG_POST_INSTALL_HOOKS += HOST_CLANG_INSTALL_WRAPPER_AND_SIMPLE_SYMLINKS + $(eval $(cmake-package)) $(eval $(host-cmake-package))
In order to use clang as a host cross-compiler for Buildroot, we need to provide at least the path to the sysroot (using --sysroot) and some other compiler flags. Hoppefully, we can reuse the toolchain wrapper for gcc since clang support most of the gcc flags used in the Buildroot's toolchain wrapper. Only the flag -mfused-madd (deprecated since gcc 4.6) for mips is not supported by clang. Since Clang require gcc >= 5.x this flag can never be used. Since host-clang is always build by Buildroot as an internal toolchain, we have to use a second toolchain-wrapper called toolchain-wrapper-clang when an external toolchain is used. Inded, the two wrapper use a different path BR_CROSS_PATH_SUFFIX in this case. After building the clang toolchain wrapper, create the symlinks needed to force package infrastructure to use clang througt the wrapper. Initially clang install the clang-8 binary and create all other symlinks: # clang -> clang-8 # clang++ -> clang # clang-8 # clang-cl -> clang # clang-cpp -> clang Use a post install hook to rename the clang-8 binary to clang-8.br_real and recreate all symlinks: # clang -> toolchain-wrapper-clang # clang++ -> toolchain-wrapper-clang # clang-8 -> toolchain-wrapper-clang # clang-8.br_real # clang++.br_real -> clang-8.br_real # clang.br_real -> clang-8.br_real # clang-cl -> toolchain-wrapper-clang # clang-cl.br_real -> clang-8.br_real # clang-cpp -> toolchain-wrapper-clang # clang-cpp.br_real -> clang-8.br_real Use the previously introduced CLANG_VERSION_MAJOR variable to create theses symlinks. Set BR_CROSS_PATH_SUFFIX to ".br_real" as for the Buildroot's internal GCC toolchain backend to find the "real" clang binary installed in $(HOST_DIR)/bin. Borrow TOOLCHAIN_WRAPPER_BUILD and TOOLCHAIN_WRAPPER_INSTALL to build and install the specific clang toolchain wrapper. Signed-off-by: Romain Naour <romain.naour@smile.fr> Cc: Matt Weber <matthew.weber@rockwellcollins.com> Cc: Valentin Korenblit <valentinkorenblit@gmail.com> --- package/clang/clang.mk | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+)