[v6,1/7] package/compiler-rt: new package

Message ID 1546552368-50707-1-git-send-email-matthew.weber@rockwellcollins.com
State New
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Series
  • [v6,1/7] package/compiler-rt: new package
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Commit Message

Matthew Weber Jan. 3, 2019, 9:52 p.m.
This patch adds support for the compiler-rt (CLANG runtime) library.
It builds a set of static libraries and installs them into the
CLANG/LLVM toolchain resource folder.

Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Cc: Romain Naour <romain.naour@smile.fr>
Cc: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Valentin Korenblit <valentinkorenblit@gmail.com>
---
Changes
v1 -> v2
[Romain
 - Removed unnecessary host-cmake dependency

v2 -> v3
[Romain
 - Update to use COMPILER_RT_INSTALL_PATH for library install
[Ricardo
 - Fixed check-package extra line
 - Spelling in commit message

v3 -> v4
[Valentin
 - Pointed out that non-glibc libraries won't build. Further
   investigation shows that the lib asan support in compiler-rt
   doesn't have the libc checks yet to support multiple libraries.
   (https://patchwork.ozlabs.org/patch/339938/ was the best example
    I could find and it doesn't look like anything has changed in the
    recent codebase)

v4 -> v5
[Thomas P
 - Revisited staging install step and found a cleaner way to use the
   default and then a hook to setup the runtime library path

v6
 - Bumped to 7.0.1 to match current LLVM/Clang version
---
 DEVELOPERS                           |  1 +
 package/Config.in                    |  1 +
 package/compiler-rt/Config.in        | 14 ++++++++++++++
 package/compiler-rt/compiler-rt.hash |  3 +++
 package/compiler-rt/compiler-rt.mk   | 36 ++++++++++++++++++++++++++++++++++++
 5 files changed, 55 insertions(+)
 create mode 100644 package/compiler-rt/Config.in
 create mode 100644 package/compiler-rt/compiler-rt.hash
 create mode 100644 package/compiler-rt/compiler-rt.mk

Comments

Romain Naour Jan. 16, 2019, 9:59 p.m. | #1
Hi Matt,

Le 03/01/2019 à 22:52, Matt Weber a écrit :
> This patch adds support for the compiler-rt (CLANG runtime) library.
> It builds a set of static libraries and installs them into the
> CLANG/LLVM toolchain resource folder.
> 
> Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
> Cc: Romain Naour <romain.naour@smile.fr>
> Cc: Ricardo Martincoski <ricardo.martincoski@gmail.com>
> Cc: Valentin Korenblit <valentinkorenblit@gmail.com>
> ---
> Changes
> v1 -> v2
> [Romain
>  - Removed unnecessary host-cmake dependency
> 
> v2 -> v3
> [Romain
>  - Update to use COMPILER_RT_INSTALL_PATH for library install
> [Ricardo
>  - Fixed check-package extra line
>  - Spelling in commit message
> 
> v3 -> v4
> [Valentin
>  - Pointed out that non-glibc libraries won't build. Further
>    investigation shows that the lib asan support in compiler-rt
>    doesn't have the libc checks yet to support multiple libraries.
>    (https://patchwork.ozlabs.org/patch/339938/ was the best example
>     I could find and it doesn't look like anything has changed in the
>     recent codebase)
> 
> v4 -> v5
> [Thomas P
>  - Revisited staging install step and found a cleaner way to use the
>    default and then a hook to setup the runtime library path
> 
> v6
>  - Bumped to 7.0.1 to match current LLVM/Clang version
> ---
>  DEVELOPERS                           |  1 +
>  package/Config.in                    |  1 +
>  package/compiler-rt/Config.in        | 14 ++++++++++++++
>  package/compiler-rt/compiler-rt.hash |  3 +++
>  package/compiler-rt/compiler-rt.mk   | 36 ++++++++++++++++++++++++++++++++++++
>  5 files changed, 55 insertions(+)
>  create mode 100644 package/compiler-rt/Config.in
>  create mode 100644 package/compiler-rt/compiler-rt.hash
>  create mode 100644 package/compiler-rt/compiler-rt.mk
> 
> diff --git a/DEVELOPERS b/DEVELOPERS
> index 9654fcf..93d62a3 100644
> --- a/DEVELOPERS
> +++ b/DEVELOPERS
> @@ -1399,6 +1399,7 @@ F:	package/bridge-utils/
>  F:	package/checkpolicy/
>  F:	package/checksec/
>  F:	package/cgroupfs-mount/
> +F:	package/compiler-rt/
>  F:	package/crda/
>  F:	package/cunit/
>  F:	package/devmem2/
> diff --git a/package/Config.in b/package/Config.in
> index a2f3fc6..baabc8a 100644
> --- a/package/Config.in
> +++ b/package/Config.in
> @@ -1629,6 +1629,7 @@ menu "Other"
>  	source "package/clapack/Config.in"
>  	source "package/classpath/Config.in"
>  	source "package/cmocka/Config.in"
> +	source "package/compiler-rt/Config.in"
>  	source "package/cppcms/Config.in"
>  	source "package/cracklib/Config.in"
>  	source "package/dawgdic/Config.in"
> diff --git a/package/compiler-rt/Config.in b/package/compiler-rt/Config.in
> new file mode 100644
> index 0000000..9afc0d9
> --- /dev/null
> +++ b/package/compiler-rt/Config.in
> @@ -0,0 +1,14 @@
> +config BR2_PACKAGE_COMPILER_RT
> +	bool "compiler-rt"
> +	depends on BR2_PACKAGE_LLVM> +	depends on BR2_TOOLCHAIN_USES_GLIBC # asan lib requires
> +	help
> +	  A collection of runtime libraries primarily used by clang and
> +	  llvm to provide builtins, sanitizer runtimes, and profiling
> +	  at runtime.
> +
> +	  https://compiler-rt.llvm.org/
> +
> +comment "compiler-rt requires llvm to be enabled and a glibc toolchain"
> +	depends on !BR2_PACKAGE_LLVM
> +	depends on !BR2_TOOLCHAIN_USES_GLIBC
> diff --git a/package/compiler-rt/compiler-rt.hash b/package/compiler-rt/compiler-rt.hash
> new file mode 100644
> index 0000000..4b6bd1a
> --- /dev/null
> +++ b/package/compiler-rt/compiler-rt.hash
> @@ -0,0 +1,3 @@
> +# Locally computed:
> +sha256 782edfc119ee172f169c91dd79f2c964fb6b248bd9b73523149030ed505bbe18  compiler-rt-7.0.1.src.tar.xz
> +sha256 417541d990edb3f96327ac03cb67e52eac80fc5c3e7afc69213cd04d7c3b9b27  LICENSE.TXT
> diff --git a/package/compiler-rt/compiler-rt.mk b/package/compiler-rt/compiler-rt.mk
> new file mode 100644
> index 0000000..7b5c95a
> --- /dev/null
> +++ b/package/compiler-rt/compiler-rt.mk
> @@ -0,0 +1,36 @@
> +################################################################################
> +#
> +# compiler-rt
> +#
> +################################################################################
> +
> +# Compiler-RT should be bumped together with LLVM and Clang as the run-time is
> +# tied to the version of those tools
> +COMPILER_RT_VERSION = 7.0.1
> +COMPILER_RT_SOURCE = compiler-rt-$(COMPILER_RT_VERSION).src.tar.xz
> +COMPILER_RT_SITE = http://llvm.org/releases/$(COMPILER_RT_VERSION)
> +COMPILER_RT_LICENSE = NCSA MIT
> +COMPILER_RT_LICENSE_FILES = LICENSE.TXT
> +COMPILER_RT_DEPENDENCIES = host-clang llvm
> +
> +COMPILER_RT_INSTALL_STAGING = YES
> +COMPILER_RT_INSTALL_TARGET = NO
> +
> +COMPILER_RT_CONF_OPTS=-DCOMPILER_RT_INCLUDE_TESTS=ON \

Why building the testsuite and tests ?

Otherwise, the patch looks good.
Reviewed-by: Romain Naour <romain.naour@smile.fr>
Build tested on x86_64.

> +	-DCOMPILER_RT_STANDALONE_BUILD=ON \
> +	-DCOMPILER_RT_DEFAULT_TARGET_TRIPLE=$(GNU_TARGET_NAME) \
> +	-DLLVM_CONFIG_PATH=$(HOST_DIR)/usr/bin/llvm-config
> +
> +# The installation of the target runtime libraries defaults to DESTDIR, however
> +# host-clang resources directory needs a link so Clang can find the runtime
> +# libraries in the same location they would be if built as part of the Clang
> +# build. The "resources" directory is loosely documented and seems to be
> +# assumed, as compiler-rt is usually build at the same time as Clang and not
> +# standalone.
> +define COMPILER_RT_SETUP_RUNTIME_LIBS
> +	mkdir -p $(HOST_DIR)/lib/clang/$(HOST_CLANG_VERSION)/lib
> +	ln -sf ../../../../$(GNU_TARGET_NAME)/sysroot/usr/lib/linux $(HOST_DIR)/lib/clang/$(HOST_CLANG_VERSION)/lib/linux
> +endef
> +COMPILER_RT_POST_INSTALL_STAGING_HOOKS += COMPILER_RT_SETUP_RUNTIME_LIBS
> +
> +$(eval $(cmake-package))
>
Matthew Weber Jan. 16, 2019, 11:36 p.m. | #2
Romain,


On Wed, Jan 16, 2019 at 3:59 PM Romain Naour <romain.naour@smile.fr> wrote:
>
> Hi Matt,
>
> Le 03/01/2019 à 22:52, Matt Weber a écrit :
> > This patch adds support for the compiler-rt (CLANG runtime) library.
> > It builds a set of static libraries and installs them into the
> > CLANG/LLVM toolchain resource folder.
> >
> > Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
> > Cc: Romain Naour <romain.naour@smile.fr>
> > Cc: Ricardo Martincoski <ricardo.martincoski@gmail.com>
> > Cc: Valentin Korenblit <valentinkorenblit@gmail.com>
> > ---
> > Changes
> > v1 -> v2
> > [Romain
> >  - Removed unnecessary host-cmake dependency
> >
> > v2 -> v3
> > [Romain
> >  - Update to use COMPILER_RT_INSTALL_PATH for library install
> > [Ricardo
> >  - Fixed check-package extra line
> >  - Spelling in commit message
> >
> > v3 -> v4
> > [Valentin
> >  - Pointed out that non-glibc libraries won't build. Further
> >    investigation shows that the lib asan support in compiler-rt
> >    doesn't have the libc checks yet to support multiple libraries.
> >    (https://patchwork.ozlabs.org/patch/339938/ was the best example
> >     I could find and it doesn't look like anything has changed in the
> >     recent codebase)
> >
> > v4 -> v5
> > [Thomas P
> >  - Revisited staging install step and found a cleaner way to use the
> >    default and then a hook to setup the runtime library path
> >
> > v6
> >  - Bumped to 7.0.1 to match current LLVM/Clang version
> > ---
> >  DEVELOPERS                           |  1 +
> >  package/Config.in                    |  1 +
> >  package/compiler-rt/Config.in        | 14 ++++++++++++++
> >  package/compiler-rt/compiler-rt.hash |  3 +++
> >  package/compiler-rt/compiler-rt.mk   | 36 ++++++++++++++++++++++++++++++++++++
> >  5 files changed, 55 insertions(+)
> >  create mode 100644 package/compiler-rt/Config.in
> >  create mode 100644 package/compiler-rt/compiler-rt.hash
> >  create mode 100644 package/compiler-rt/compiler-rt.mk
> >
> > diff --git a/DEVELOPERS b/DEVELOPERS
> > index 9654fcf..93d62a3 100644
> > --- a/DEVELOPERS
> > +++ b/DEVELOPERS
> > @@ -1399,6 +1399,7 @@ F:      package/bridge-utils/
> >  F:   package/checkpolicy/
> >  F:   package/checksec/
> >  F:   package/cgroupfs-mount/
> > +F:   package/compiler-rt/
> >  F:   package/crda/
> >  F:   package/cunit/
> >  F:   package/devmem2/
> > diff --git a/package/Config.in b/package/Config.in
> > index a2f3fc6..baabc8a 100644
> > --- a/package/Config.in
> > +++ b/package/Config.in
> > @@ -1629,6 +1629,7 @@ menu "Other"
> >       source "package/clapack/Config.in"
> >       source "package/classpath/Config.in"
> >       source "package/cmocka/Config.in"
> > +     source "package/compiler-rt/Config.in"
> >       source "package/cppcms/Config.in"
> >       source "package/cracklib/Config.in"
> >       source "package/dawgdic/Config.in"
> > diff --git a/package/compiler-rt/Config.in b/package/compiler-rt/Config.in
> > new file mode 100644
> > index 0000000..9afc0d9
> > --- /dev/null
> > +++ b/package/compiler-rt/Config.in
> > @@ -0,0 +1,14 @@
> > +config BR2_PACKAGE_COMPILER_RT
> > +     bool "compiler-rt"
> > +     depends on BR2_PACKAGE_LLVM> +  depends on BR2_TOOLCHAIN_USES_GLIBC # asan lib requires
> > +     help
> > +       A collection of runtime libraries primarily used by clang and
> > +       llvm to provide builtins, sanitizer runtimes, and profiling
> > +       at runtime.
> > +
> > +       https://compiler-rt.llvm.org/
> > +
> > +comment "compiler-rt requires llvm to be enabled and a glibc toolchain"
> > +     depends on !BR2_PACKAGE_LLVM
> > +     depends on !BR2_TOOLCHAIN_USES_GLIBC
> > diff --git a/package/compiler-rt/compiler-rt.hash b/package/compiler-rt/compiler-rt.hash
> > new file mode 100644
> > index 0000000..4b6bd1a
> > --- /dev/null
> > +++ b/package/compiler-rt/compiler-rt.hash
> > @@ -0,0 +1,3 @@
> > +# Locally computed:
> > +sha256 782edfc119ee172f169c91dd79f2c964fb6b248bd9b73523149030ed505bbe18  compiler-rt-7.0.1.src.tar.xz
> > +sha256 417541d990edb3f96327ac03cb67e52eac80fc5c3e7afc69213cd04d7c3b9b27  LICENSE.TXT
> > diff --git a/package/compiler-rt/compiler-rt.mk b/package/compiler-rt/compiler-rt.mk
> > new file mode 100644
> > index 0000000..7b5c95a
> > --- /dev/null
> > +++ b/package/compiler-rt/compiler-rt.mk
> > @@ -0,0 +1,36 @@
> > +################################################################################
> > +#
> > +# compiler-rt
> > +#
> > +################################################################################
> > +
> > +# Compiler-RT should be bumped together with LLVM and Clang as the run-time is
> > +# tied to the version of those tools
> > +COMPILER_RT_VERSION = 7.0.1
> > +COMPILER_RT_SOURCE = compiler-rt-$(COMPILER_RT_VERSION).src.tar.xz
> > +COMPILER_RT_SITE = http://llvm.org/releases/$(COMPILER_RT_VERSION)
> > +COMPILER_RT_LICENSE = NCSA MIT
> > +COMPILER_RT_LICENSE_FILES = LICENSE.TXT
> > +COMPILER_RT_DEPENDENCIES = host-clang llvm
> > +
> > +COMPILER_RT_INSTALL_STAGING = YES
> > +COMPILER_RT_INSTALL_TARGET = NO
> > +
> > +COMPILER_RT_CONF_OPTS=-DCOMPILER_RT_INCLUDE_TESTS=ON \
>
> Why building the testsuite and tests ?

It has been awhile and I don't remember the specific reason.  After
glancing at the cmake files, I believe I was using the test builds as
a way to verify the libraries could be linked against.  I'll start a
test build with that option removed and see if the runtime test has
any issues.  I would keep the tests enabled though as it allows the
user to see if their llvm setup works for fuzzing without having to
debug a custom application too. (Maybe that should be a comment above
the conf opts :-)

>
> Otherwise, the patch looks good.
> Reviewed-by: Romain Naour <romain.naour@smile.fr>
> Build tested on x86_64.
>
> > +     -DCOMPILER_RT_STANDALONE_BUILD=ON \
> > +     -DCOMPILER_RT_DEFAULT_TARGET_TRIPLE=$(GNU_TARGET_NAME) \
> > +     -DLLVM_CONFIG_PATH=$(HOST_DIR)/usr/bin/llvm-config
> > +
> > +# The installation of the target runtime libraries defaults to DESTDIR, however
> > +# host-clang resources directory needs a link so Clang can find the runtime
> > +# libraries in the same location they would be if built as part of the Clang
> > +# build. The "resources" directory is loosely documented and seems to be
> > +# assumed, as compiler-rt is usually build at the same time as Clang and not
> > +# standalone.
> > +define COMPILER_RT_SETUP_RUNTIME_LIBS
> > +     mkdir -p $(HOST_DIR)/lib/clang/$(HOST_CLANG_VERSION)/lib
> > +     ln -sf ../../../../$(GNU_TARGET_NAME)/sysroot/usr/lib/linux $(HOST_DIR)/lib/clang/$(HOST_CLANG_VERSION)/lib/linux
> > +endef
> > +COMPILER_RT_POST_INSTALL_STAGING_HOOKS += COMPILER_RT_SETUP_RUNTIME_LIBS
> > +
> > +$(eval $(cmake-package))
> >
>
Romain Naour Jan. 17, 2019, 2:07 p.m. | #3
Hi Matt,

Le 17/01/2019 à 00:36, Matthew Weber a écrit :
> Romain,
> 
> 
> On Wed, Jan 16, 2019 at 3:59 PM Romain Naour <romain.naour@smile.fr> wrote:
>>
>> Hi Matt,
>>
>> Le 03/01/2019 à 22:52, Matt Weber a écrit :

[...]

>>> +
>>> +COMPILER_RT_CONF_OPTS=-DCOMPILER_RT_INCLUDE_TESTS=ON \
>>
>> Why building the testsuite and tests ?
> 
> It has been awhile and I don't remember the specific reason.  After
> glancing at the cmake files, I believe I was using the test builds as
> a way to verify the libraries could be linked against.  I'll start a
> test build with that option removed and see if the runtime test has
> any issues.  I would keep the tests enabled though as it allows the
> user to see if their llvm setup works for fuzzing without having to
> debug a custom application too. (Maybe that should be a comment above
> the conf opts :-)
> 

By default, Buildroot packages should disable tests and testsuite when possible
in order to keep rootfs small as possible.

That is why several options are set in the package infra (see pkg-cmake.mk):
   -DBUILD_EXAMPLE=OFF
   -DBUILD_EXAMPLES=OFF
   -DBUILD_TEST=OFF
   -DBUILD_TESTS=OFF
   -DBUILD_TESTING=OFF

But the question is, do we need a global option to enable building packages
tests and testsuite?

Otherwise, I'm fine to keep this option enabled if this is useful.

Best regards,
Romain
Matthew Weber Jan. 17, 2019, 3:11 p.m. | #4
Romain,

On Thu, Jan 17, 2019 at 8:08 AM Romain Naour <romain.naour@smile.fr> wrote:
>
> Hi Matt,
>
> Le 17/01/2019 à 00:36, Matthew Weber a écrit :
> > Romain,
> >
> >
> > On Wed, Jan 16, 2019 at 3:59 PM Romain Naour <romain.naour@smile.fr> wrote:
> >>
> >> Hi Matt,
> >>
> >> Le 03/01/2019 à 22:52, Matt Weber a écrit :
>
> [...]
>
> >>> +
> >>> +COMPILER_RT_CONF_OPTS=-DCOMPILER_RT_INCLUDE_TESTS=ON \
> >>
> >> Why building the testsuite and tests ?
> >
> > It has been awhile and I don't remember the specific reason.  After
> > glancing at the cmake files, I believe I was using the test builds as
> > a way to verify the libraries could be linked against.  I'll start a
> > test build with that option removed and see if the runtime test has
> > any issues.  I would keep the tests enabled though as it allows the
> > user to see if their llvm setup works for fuzzing without having to
> > debug a custom application too. (Maybe that should be a comment above
> > the conf opts :-)
> >
>
> By default, Buildroot packages should disable tests and testsuite when possible
> in order to keep rootfs small as possible.

I've verified we can disable them without impact.  If I respin another
revision I can set that option to OFF.

>
> That is why several options are set in the package infra (see pkg-cmake.mk):
>    -DBUILD_EXAMPLE=OFF
>    -DBUILD_EXAMPLES=OFF
>    -DBUILD_TEST=OFF
>    -DBUILD_TESTS=OFF
>    -DBUILD_TESTING=OFF
>
> But the question is, do we need a global option to enable building packages
> tests and testsuite?
>
> Otherwise, I'm fine to keep this option enabled if this is useful.

My preference is that we leave them enabled as then the run-time test
would catch additional corner cases as versions are bumped.  :-)

Matt

Patch

diff --git a/DEVELOPERS b/DEVELOPERS
index 9654fcf..93d62a3 100644
--- a/DEVELOPERS
+++ b/DEVELOPERS
@@ -1399,6 +1399,7 @@  F:	package/bridge-utils/
 F:	package/checkpolicy/
 F:	package/checksec/
 F:	package/cgroupfs-mount/
+F:	package/compiler-rt/
 F:	package/crda/
 F:	package/cunit/
 F:	package/devmem2/
diff --git a/package/Config.in b/package/Config.in
index a2f3fc6..baabc8a 100644
--- a/package/Config.in
+++ b/package/Config.in
@@ -1629,6 +1629,7 @@  menu "Other"
 	source "package/clapack/Config.in"
 	source "package/classpath/Config.in"
 	source "package/cmocka/Config.in"
+	source "package/compiler-rt/Config.in"
 	source "package/cppcms/Config.in"
 	source "package/cracklib/Config.in"
 	source "package/dawgdic/Config.in"
diff --git a/package/compiler-rt/Config.in b/package/compiler-rt/Config.in
new file mode 100644
index 0000000..9afc0d9
--- /dev/null
+++ b/package/compiler-rt/Config.in
@@ -0,0 +1,14 @@ 
+config BR2_PACKAGE_COMPILER_RT
+	bool "compiler-rt"
+	depends on BR2_PACKAGE_LLVM
+	depends on BR2_TOOLCHAIN_USES_GLIBC # asan lib requires
+	help
+	  A collection of runtime libraries primarily used by clang and
+	  llvm to provide builtins, sanitizer runtimes, and profiling
+	  at runtime.
+
+	  https://compiler-rt.llvm.org/
+
+comment "compiler-rt requires llvm to be enabled and a glibc toolchain"
+	depends on !BR2_PACKAGE_LLVM
+	depends on !BR2_TOOLCHAIN_USES_GLIBC
diff --git a/package/compiler-rt/compiler-rt.hash b/package/compiler-rt/compiler-rt.hash
new file mode 100644
index 0000000..4b6bd1a
--- /dev/null
+++ b/package/compiler-rt/compiler-rt.hash
@@ -0,0 +1,3 @@ 
+# Locally computed:
+sha256 782edfc119ee172f169c91dd79f2c964fb6b248bd9b73523149030ed505bbe18  compiler-rt-7.0.1.src.tar.xz
+sha256 417541d990edb3f96327ac03cb67e52eac80fc5c3e7afc69213cd04d7c3b9b27  LICENSE.TXT
diff --git a/package/compiler-rt/compiler-rt.mk b/package/compiler-rt/compiler-rt.mk
new file mode 100644
index 0000000..7b5c95a
--- /dev/null
+++ b/package/compiler-rt/compiler-rt.mk
@@ -0,0 +1,36 @@ 
+################################################################################
+#
+# compiler-rt
+#
+################################################################################
+
+# Compiler-RT should be bumped together with LLVM and Clang as the run-time is
+# tied to the version of those tools
+COMPILER_RT_VERSION = 7.0.1
+COMPILER_RT_SOURCE = compiler-rt-$(COMPILER_RT_VERSION).src.tar.xz
+COMPILER_RT_SITE = http://llvm.org/releases/$(COMPILER_RT_VERSION)
+COMPILER_RT_LICENSE = NCSA MIT
+COMPILER_RT_LICENSE_FILES = LICENSE.TXT
+COMPILER_RT_DEPENDENCIES = host-clang llvm
+
+COMPILER_RT_INSTALL_STAGING = YES
+COMPILER_RT_INSTALL_TARGET = NO
+
+COMPILER_RT_CONF_OPTS=-DCOMPILER_RT_INCLUDE_TESTS=ON \
+	-DCOMPILER_RT_STANDALONE_BUILD=ON \
+	-DCOMPILER_RT_DEFAULT_TARGET_TRIPLE=$(GNU_TARGET_NAME) \
+	-DLLVM_CONFIG_PATH=$(HOST_DIR)/usr/bin/llvm-config
+
+# The installation of the target runtime libraries defaults to DESTDIR, however
+# host-clang resources directory needs a link so Clang can find the runtime
+# libraries in the same location they would be if built as part of the Clang
+# build. The "resources" directory is loosely documented and seems to be
+# assumed, as compiler-rt is usually build at the same time as Clang and not
+# standalone.
+define COMPILER_RT_SETUP_RUNTIME_LIBS
+	mkdir -p $(HOST_DIR)/lib/clang/$(HOST_CLANG_VERSION)/lib
+	ln -sf ../../../../$(GNU_TARGET_NAME)/sysroot/usr/lib/linux $(HOST_DIR)/lib/clang/$(HOST_CLANG_VERSION)/lib/linux
+endef
+COMPILER_RT_POST_INSTALL_STAGING_HOOKS += COMPILER_RT_SETUP_RUNTIME_LIBS
+
+$(eval $(cmake-package))