build_symbolizer: Set LLVM_DEFAULT_TARGET_TRIPLE in llvm builds

[MatzeB]

Summary

Pass on the default target triple of the host clang to the LLVM builds within the build_symbolizer.sh script.

[MatzeB]

For background: We had failing builds because the host clang was configured for a default triple of x86_64-redhat-linux-gnu but the symbolizer build using x86_64-unknown-linux-gnu. I suspect this started failing in combination with the new LLVM_ENABLE_PER_TARGET_RUNTIME_DIR default in LLVM expecting libcxx headers and libraries in a subdirectory matching the target triple.

[MaskRay]

@vitalybuka told me that zorg/buildbot/builders/sanitizers/buildbot_cmake.sh uses build_symbolizer.sh.

[MaskRay]

BTW: build_symbolizer.sh uses the long obsoleted PROJECTS="-DLLVM_ENABLE_PROJECTS='libcxx;libcxxabi'". We need to migrate to LLVM_ENABLE_RUNTIMES at some point. LLVM_ENABLE_RUNTIMES automatically uses the LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=on file hierarchy.

compiler-rt/lib/sanitizer_common/symbolizer/scripts/build_symbolizer.sh

cmake -GNinja \
     -DCMAKE_CXX_FLAGS_RELEASE="${LIBCXX_FLAGS}" \
     -DLIBCXXABI_ENABLE_ASSERTIONS=OFF \
     -DLIBCXXABI_ENABLE_EXCEPTIONS=OFF \
     -DLIBCXXABI_ENABLE_SHARED=OFF \
     -DLIBCXX_ENABLE_ASSERTIONS=OFF \
     -DLIBCXX_ENABLE_EXCEPTIONS=OFF \
     -DLIBCXX_ENABLE_RTTI=OFF \
     -DLIBCXX_ENABLE_SHARED=OFF \
+    -DLLVM_DEFAULT_TARGET_TRIPLE="${TARGET_TRIPLE}" \
   $LLVM_SRC
 fi
 cd ${LIBCXX_BUILD}
 ninja cxx cxxabi
 
 FLAGS="${FLAGS} -fno-rtti -fno-exceptions"
 LLVM_FLAGS="${FLAGS} -nostdinc++ -I${ZLIB_BUILD} -isystem ${LIBCXX_BUILD}/include/${TARGET_TRIPLE}/c++/v1 -isystem ${LIBCXX_BUILD}/include/c++/v1 -Wno-error=global-constructors"
 
 # Build LLVM.
 if [[ ! -d ${LLVM_BUILD} ]]; then
   mkdir -p ${LLVM_BUILD}
   cd ${LLVM_BUILD}
   cmake -GNinja \
     -DCMAKE_BUILD_TYPE=Release \
     -DCMAKE_C_COMPILER=$CC \
     -DCMAKE_CXX_COMPILER=$CXX \
     -DCMAKE_C_FLAGS_RELEASE="${LLVM_FLAGS}" \
     -DCMAKE_CXX_FLAGS_RELEASE="${LLVM_FLAGS}" \
     -DLLVM_TABLEGEN=$TBLGEN \
+    -DLLVM_DEFAULT_TARGET_TRIPLE="${TARGET_TRIPLE}" \
     -DLLVM_ENABLE_ZLIB=ON \
     -DLLVM_ENABLE_TERMINFO=OFF \
     -DLLVM_ENABLE_THREADS=OFF \
   $LLVM_SRC
 fi
 cd ${LLVM_BUILD}
 ninja LLVMSymbolize LLVMObject LLVMBinaryFormat LLVMDebugInfoDWARF LLVMSupport LLVMDebugInfoPDB LLVMDebuginfod LLVMMC LLVMDemangle LLVMTextAPI