package/compiler-rt: new package

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. These libraries can then be
used by developers in the SDK for building target applications for
analysis.

What is fuzzing and why libfuzzer?
https://www.moritz.systems/blog/an-introduction-to-llvm-libfuzzer/

The compiler-rt fuzzer and address sanitizer tools require additional
LLVM binary tools installed to allow stack trace decoding actively during
executable analysis.  This patch conditionally enables these tools.
https://github.com/google/sanitizers/wiki/AddressSanitizerCallStack

Signed-off-by: Matt Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Cc: Romain Naour <romain.naour@smile.fr>
Cc: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Valentin Korenblit <valentinkorenblit@gmail.com>
Cc: Michael Drake <michael.drake@codethink.co.uk>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

DEVELOPERS

@@ -1903,6 +1903,7 @@ 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/dacapo/

package/Config.in

@@ -1934,6 +1934,7 @@ menu "Other"
 	source "package/cereal/Config.in"
 	source "package/clang/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"

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

package/compiler-rt/compiler-rt.hash

@@ -0,0 +1,3 @@
+# Locally computed:
+sha256  def1fc00c764cd3abbba925c712ac38860a756a43b696b291f46fee09e453274  compiler-rt-11.1.0.src.tar.xz
+sha256  1a8f1058753f1ba890de984e48f0242a3a5c29a6a8f2ed9fd813f36985387e8d  LICENSE.TXT

package/compiler-rt/compiler-rt.mk

@@ -0,0 +1,37 @@
+################################################################################
+#
+# 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 = 11.1.0
+COMPILER_RT_SOURCE = compiler-rt-$(COMPILER_RT_VERSION).src.tar.xz
+COMPILER_RT_SITE = https://github.com/llvm/llvm-project/releases/download/llvmorg-$(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_STANDALONE_BUILD=OFF \
+	-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
+	ln -sf ../../../../$(GNU_TARGET_NAME)/sysroot/usr/share $(HOST_DIR)/lib/clang/$(HOST_CLANG_VERSION)/share
+endef
+COMPILER_RT_POST_INSTALL_STAGING_HOOKS += COMPILER_RT_SETUP_RUNTIME_LIBS
+
+$(eval $(cmake-package))

package/llvm/llvm.mk

@@ -214,8 +214,7 @@ HOST_LLVM_CONF_OPTS += \
 # We need to activate LLVM_INCLUDE_TOOLS, otherwise it does not generate
 # libLLVM.so
 LLVM_CONF_OPTS += \
-	-DLLVM_INCLUDE_TOOLS=ON \
-	-DLLVM_BUILD_TOOLS=OFF
+	-DLLVM_INCLUDE_TOOLS=ON
 
 ifeq ($(BR2_PACKAGE_LLVM_RTTI),y)
 HOST_LLVM_CONF_OPTS += -DLLVM_ENABLE_RTTI=ON
@@ -278,11 +277,25 @@ LLVM_CONF_OPTS += \
 # directories from STAGING_DIR.
 # output/staging/usr/bin/llvm-config --includedir
 # output/staging/usr/include
-define HOST_LLVM_COPY_LLVM_CONFIG_TO_STAGING_DIR
+define LLVM_COPY_LLVM_CONFIG_TO_STAGING_DIR
 	$(INSTALL) -D -m 0755 $(HOST_DIR)/bin/llvm-config \
 		$(STAGING_DIR)/usr/bin/llvm-config
 endef
-HOST_LLVM_POST_INSTALL_HOOKS = HOST_LLVM_COPY_LLVM_CONFIG_TO_STAGING_DIR
+HOST_LLVM_POST_INSTALL_HOOKS = LLVM_COPY_LLVM_CONFIG_TO_STAGING_DIR
+
+# The llvm-symbolizer binary is used by the Compiler-RT Fuzzer
+# and AddressSanitizer tools on the target for stack traces.
+# If we set -DLLVM_BUILD_TOOLS=ON this will also install the llvm-config
+# target binary to STAGING_DIR, which means we can no longer run it.
+# Therefore, overwrite it again with the host llvm-config.
+ifeq ($(BR2_PACKAGE_COMPILER_RT),y)
+LLVM_CONF_OPTS += \
+	-DLLVM_BUILD_TOOLS=ON
+LLVM_POST_INSTALL_STAGING_HOOKS = LLVM_COPY_LLVM_CONFIG_TO_STAGING_DIR
+else
+LLVM_CONF_OPTS += \
+	-DLLVM_BUILD_TOOLS=OFF
+endif
 
 # By default llvm-tblgen is built and installed on the target but it is
 # not necessary. Also erase LLVMHello.so from /usr/lib