From https://build.chromium.org/p/chromium.fyi/builders/ClangToTLinux/builds/9092

FAILED: obj/third_party/angle/src/tests/angle_end2end_tests/VertexAttributeTest.o 
../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/third_party/angle/src/tests/angle_end2end_tests/VertexAttributeTest.o.d -DV8_DEPRECATION_WARNINGS -DUSE_UDEV -DUSE_AURA=1 -DUSE_PANGO=1 -DUSE_CAIRO=1 -DUSE_GLIB=1 -DUSE_NSS_CERTS=1 -DUSE_X11=1 -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_CLANG_REVISION=\"313352\" -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DCOMPONENT_BUILD -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DGL_GLEXT_PROTOTYPES -DEGL_EGLEXT_PROTOTYPES -DANGLE_X64_CPU -DANGLE_ENABLE_OPENGL -DANGLE_USE_X11 -DANGLE_ENABLE_VULKAN -DANGLE_ENABLE_NULL -DLIBANGLE_IMPLEMENTATION -DGLIB_VERSION_MAX_ALLOWED=GLIB_VERSION_2_32 -DGLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_26 -DGTEST_API_= -DGTEST_HAS_POSIX_RE=0 -DGTEST_LANG_CXX11=1 -DU_USING_ICU_NAMESPACE=0 -DU_ENABLE_DYLOAD=0 -DICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE -DUCHAR_TYPE=uint16_t -DUNIT_TEST -I../../third_party/angle/src/tests/testing/gtest/include -I../../third_party/angle/src/tests -I../../third_party/angle/util -I../.. -Igen -I../../third_party/angle/include -I../../third_party/angle/src -I../../build/linux/debian_jessie_amd64-sysroot/usr/include/glib-2.0 -I../../build/linux/debian_jessie_amd64-sysroot/usr/lib/x86_64-linux-gnu/glib-2.0/include -I../../third_party/googletest/src/googletest/include -I../../third_party/ced/src -I../../third_party/icu/source/common -I../../third_party/icu/source/i18n -I../../third_party/googletest/custom -I../../third_party/googletest/src/googlemock/include -I../../third_party/angle/include -I../../third_party/angle/src -I../../third_party/angle/src/common/third_party/base -Igen/angle -I../../third_party/angle/util -I../../third_party/angle/include -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -funwind-tables -fPIC -pipe -B../../third_party/binutils/Linux_x64/Release/bin -pthread -fcolor-diagnostics -m64 -march=x86-64 -Wall -Werror -Wextra -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -Wno-enum-compare-switch -Wno-tautological-unsigned-zero-compare -O2 -fno-ident -fdata-sections -ffunction-sections -fomit-frame-pointer -g2 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -std=gnu++14 -fno-rtti -nostdinc++ -isystem../../buildtools/third_party/libc++/trunk/include -isystem../../buildtools/third_party/libc++abi/trunk/include --sysroot=../../build/linux/debian_jessie_amd64-sysroot -fno-exceptions -fvisibility-inlines-hidden -c ../../third_party/angle/src/tests/gl_tests/VertexAttributeTest.cpp -o obj/third_party/angle/src/tests/angle_end2end_tests/VertexAttributeTest.o
clang-6.0: /b/c/builder/ClangToTLinux/src/third_party/llvm/lib/CodeGen/MachineRegisterInfo.cpp:366: llvm::MachineInstr* llvm::MachineRegisterInfo::getVRegDef(unsigned int) const: Assertion `(I.atEnd() || std::next(I) == def_instr_end()) && "getVRegDef assumes a single definition or no definition"' failed.
#0 0x00000000020da83a llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x20da83a)
#1 0x00000000020d891e llvm::sys::RunSignalHandlers() (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x20d891e)
#2 0x00000000020d8a82 (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x20d8a82)
#3 0x00007f4e998aa330 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x10330)
#4 0x00007f4e9849ac37 gsignal /build/eglibc-SvCtMH/eglibc-2.19/signal/../nptl/sysdeps/unix/sysv/linux/raise.c:56:0
#5 0x00007f4e9849e028 abort /build/eglibc-SvCtMH/eglibc-2.19/stdlib/abort.c:91:0
#6 0x00007f4e98493bf6 __assert_fail_base /build/eglibc-SvCtMH/eglibc-2.19/assert/assert.c:92:0
#7 0x00007f4e98493ca2 (/lib/x86_64-linux-gnu/libc.so.6+0x2fca2)
#8 0x00000000019e9cd1 llvm::MachineRegisterInfo::getVRegDef(unsigned int) const (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x19e9cd1)
#9 0x000000000165eaaf (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x165eaaf)
#10 0x0000000001662569 (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1662569)
#11 0x00000000016629b7 (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x16629b7)
#12 0x0000000001662c58 (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1662c58)
#13 0x0000000001663dcc (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1663dcc)
#14 0x0000000001663dbf (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1663dbf)
#15 0x0000000001663dbf (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1663dbf)
#16 0x0000000001663dbf (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1663dbf)
#17 0x0000000001663dbf (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1663dbf)
#18 0x0000000001663dbf (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1663dbf)
#19 0x0000000001663dbf (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1663dbf)
#20 0x00000000016649ec (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x16649ec)
#21 0x0000000001990205 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1990205)
#22 0x0000000001c8c773 llvm::FPPassManager::runOnFunction(llvm::Function&) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1c8c773)
#23 0x0000000001c8c81c llvm::FPPassManager::runOnModule(llvm::Module&) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1c8c81c)
#24 0x0000000001c8d09f llvm::legacy::PassManagerImpl::run(llvm::Module&) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x1c8d09f)
#25 0x00000000022622f8 (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x22622f8)
#26 0x0000000002263592 clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::DataLayout const&, llvm::Module*, clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream> >) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x2263592)
#27 0x0000000002941c6b (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x2941c6b)
#28 0x0000000002d40cf2 clang::ParseAST(clang::Sema&, bool, bool) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x2d40cf2)
#29 0x000000000294130f clang::CodeGenAction::ExecuteAction() (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x294130f)
#30 0x00000000025f88b6 clang::FrontendAction::Execute() (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x25f88b6)
#31 0x00000000025d010e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x25d010e)
#32 0x0000000002688fbb clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0x2688fbb)
#33 0x0000000000bbe678 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0xbbe678)
#34 0x0000000000b55c5e main (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0xb55c5e)
#35 0x00007f4e98485f45 __libc_start_main /build/eglibc-SvCtMH/eglibc-2.19/csu/libc-start.c:321:0
#36 0x0000000000bb9d79 _start (/b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0+0xbb9d79)
Stack dump:
0.	Program arguments: /b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/bin/clang-6.0 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -disable-free -main-file-name VertexAttributeTest.cpp -mrelocation-model pic -pic-level 2 -mthread-model posix -relaxed-aliasing -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debug-info-kind=limited -dwarf-version=4 -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -coverage-notes-file /b/c/builder/ClangToTLinux/src/out/Release/obj/third_party/angle/src/tests/angle_end2end_tests/VertexAttributeTest.gcno -nostdinc++ -resource-dir /b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/lib/clang/6.0.0 -dependency-file obj/third_party/angle/src/tests/angle_end2end_tests/VertexAttributeTest.o.d -MT obj/third_party/angle/src/tests/angle_end2end_tests/VertexAttributeTest.o -isystem ../../buildtools/third_party/libc++/trunk/include -isystem ../../buildtools/third_party/libc++abi/trunk/include -D V8_DEPRECATION_WARNINGS -D USE_UDEV -D USE_AURA=1 -D USE_PANGO=1 -D USE_CAIRO=1 -D USE_GLIB=1 -D USE_NSS_CERTS=1 -D USE_X11=1 -D FULL_SAFE_BROWSING -D SAFE_BROWSING_CSD -D SAFE_BROWSING_DB_LOCAL -D CHROMIUM_BUILD -D FIELDTRIAL_TESTING_ENABLED -D CR_CLANG_REVISION="313352" -D _FILE_OFFSET_BITS=64 -D _LARGEFILE_SOURCE -D _LARGEFILE64_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D COMPONENT_BUILD -D NDEBUG -D NVALGRIND -D DYNAMIC_ANNOTATIONS_ENABLED=0 -D GL_GLEXT_PROTOTYPES -D EGL_EGLEXT_PROTOTYPES -D ANGLE_X64_CPU -D ANGLE_ENABLE_OPENGL -D ANGLE_USE_X11 -D ANGLE_ENABLE_VULKAN -D ANGLE_ENABLE_NULL -D LIBANGLE_IMPLEMENTATION -D GLIB_VERSION_MAX_ALLOWED=GLIB_VERSION_2_32 -D GLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_26 -D GTEST_API_= -D GTEST_HAS_POSIX_RE=0 -D GTEST_LANG_CXX11=1 -D U_USING_ICU_NAMESPACE=0 -D U_ENABLE_DYLOAD=0 -D ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE -D UCHAR_TYPE=uint16_t -D UNIT_TEST -I ../../third_party/angle/src/tests/testing/gtest/include -I ../../third_party/angle/src/tests -I ../../third_party/angle/util -I ../.. -I gen -I ../../third_party/angle/include -I ../../third_party/angle/src -I ../../build/linux/debian_jessie_amd64-sysroot/usr/include/glib-2.0 -I ../../build/linux/debian_jessie_amd64-sysroot/usr/lib/x86_64-linux-gnu/glib-2.0/include -I ../../third_party/googletest/src/googletest/include -I ../../third_party/ced/src -I ../../third_party/icu/source/common -I ../../third_party/icu/source/i18n -I ../../third_party/googletest/custom -I ../../third_party/googletest/src/googlemock/include -I ../../third_party/angle/include -I ../../third_party/angle/src -I ../../third_party/angle/src/common/third_party/base -I gen/angle -I ../../third_party/angle/util -I ../../third_party/angle/include -D __DATE__= -D __TIME__= -D __TIMESTAMP__= -isysroot ../../build/linux/debian_jessie_amd64-sysroot -internal-isystem ../../build/linux/debian_jessie_amd64-sysroot/usr/local/include -internal-isystem /b/c/builder/ClangToTLinux/src/third_party/llvm-build/Release+Asserts/lib/clang/6.0.0/include -internal-externc-isystem ../../build/linux/debian_jessie_amd64-sysroot/usr/include/x86_64-linux-gnu -internal-externc-isystem ../../build/linux/debian_jessie_amd64-sysroot/include -internal-externc-isystem ../../build/linux/debian_jessie_amd64-sysroot/usr/include -O2 -Wno-builtin-macro-redefined -Wall -Werror -Wextra -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -Wno-enum-compare-switch -Wno-tautological-unsigned-zero-compare -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -std=gnu++14 -fdeprecated-macro -fdebug-compilation-dir /b/c/builder/ClangToTLinux/src/out/Release -ferror-limit 19 -fmessage-length 0 -fvisibility hidden -fvisibility-inlines-hidden -pthread -stack-protector 1 -stack-protector-buffer-size 4 -fno-rtti -fobjc-runtime=gcc -fdiagnostics-show-option -fcolor-diagnostics -vectorize-loops -vectorize-slp -o obj/third_party/angle/src/tests/angle_end2end_tests/VertexAttributeTest.o -x c++ ../../third_party/angle/src/tests/gl_tests/VertexAttributeTest.cpp 
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module '../../third_party/angle/src/tests/gl_tests/VertexAttributeTest.cpp'.
4.	Running pass 'X86 LEA Optimize' on function '@_ZN12_GLOBAL__N_154VertexAttributeTestES31_DrawArraysWithLargeStride_Test8TestBodyEv'
clang-6.0: error: unable to execute command: Aborted (core dumped)
clang-6.0: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 6.0.0 (trunk 313352)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /b/c/builder/ClangToTLinux/src/out/Release/../../third_party/llvm-build/Release+Asserts/bin
clang-6.0: note: diagnostic msg: PLEASE submit a bug report to http://llvm.org/bugs/ and include the crash backtrace, preprocessed source, and associated run script.
clang-6.0: note: diagnostic msg: 
********************
PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-6.0: note: diagnostic msg: /b/rr/tmp1Jg17m/t/VertexAttributeTest-0ad698.cpp
clang-6.0: note: diagnostic msg: /b/rr/tmp1Jg17m/t/VertexAttributeTest-0ad698.sh
clang-6.0: note: diagnostic msg: 
********************