https://uberchromegw.corp.google.com/i/internal.bling.fyi/builders/clang-tot-device/builds/1033/steps/compile/logs/stdio

FAILED: obj/base/base/json_parser.o 
export DEVELOPER_DIR=/b/build/slave/clang-tot-device/build/src/build/ios_files/Xcode.app;  ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/base/base/json_parser.o.d -DSYSTEM_NATIVE_UTF8 -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DDISABLE_NACL -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_CLANG_REVISION=\"294769\" -DCR_XCODE_VERSION=0821 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D_FORTIFY_SOURCE=2 -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DBASE_IMPLEMENTATION -I../.. -Igen -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -arch arm64 -Wall -Werror -Wextra -Wundeclared-selector -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-deprecated-register -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-shift-negative-value -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -gdwarf-2 -isysroot /b/build/slave/clang-tot-device/build/src/build/ios_files/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.2.sdk -stdlib=libc++ -miphoneos-version-min=9.0 -fvisibility=hidden -Xclang -load -Xclang ../../third_party/llvm-build/Release+Asserts/lib/libFindBadConstructs.dylib -Xclang -add-plugin -Xclang find-bad-constructs -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Wno-char-subscripts -Wexit-time-destructors -Wexit-time-destructors -O2 -fvisibility-inlines-hidden -std=c++11 -fno-rtti -fno-exceptions -c ../../base/json/json_parser.cc -o obj/base/base/json_parser.o
Assertion failed: (MI.hasOneMemOperand() && "Spill instruction does not have exactly one memory operand?"), function extractSpillBaseRegAndOffset, file /b/build/slave/clang-tot-device/build/src/third_party/llvm/lib/CodeGen/LiveDebugValues.cpp, line 331.
0  clang-5.0                0x0000000108331168 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
1  clang-5.0                0x0000000108331866 llvm::sys::PrintStackTraceOnErrorSignal(llvm::StringRef, bool) + 838
2  libsystem_platform.dylib 0x00007fffb2436bba _sigtramp + 26
3  libsystem_platform.dylib 0x00007fff58fca558 _sigtramp + 2797156792
4  libsystem_c.dylib        0x00007fffb22bd420 abort + 129
5  libsystem_c.dylib        0x00007fffb2284893 basename_r + 0
6  clang-5.0                0x0000000107a810e4 llvm::initializeLiveDebugValuesPass(llvm::PassRegistry&) + 15492
7  clang-5.0                0x0000000107a7f18b llvm::initializeLiveDebugValuesPass(llvm::PassRegistry&) + 7467
8  clang-5.0                0x0000000107b06a46 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) + 310
9  clang-5.0                0x0000000107d85823 llvm::FPPassManager::runOnFunction(llvm::Function&) + 547
10 clang-5.0                0x0000000107d85a83 llvm::FPPassManager::runOnModule(llvm::Module&) + 51
11 clang-5.0                0x0000000107d85fce llvm::legacy::PassManagerImpl::run(llvm::Module&) + 958
12 clang-5.0                0x0000000108563582 clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::DataLayout const&, llvm::Module*, clang::BackendAction, std::__1::unique_ptr<llvm::raw_pwrite_stream, std::__1::default_delete<llvm::raw_pwrite_stream> >) + 11634
13 clang-5.0                0x0000000108788edf clang::EmitObjAction::EmitObjAction(llvm::LLVMContext*) + 2095
14 clang-5.0                0x0000000108a3e1fc clang::MultiplexConsumer::HandleTranslationUnit(clang::ASTContext&) + 44
15 clang-5.0                0x00000001091458f5 clang::ParseAST(clang::Sema&, bool, bool) + 469
16 clang-5.0                0x00000001089fcd0c clang::FrontendAction::Execute() + 76
17 clang-5.0                0x00000001089b9d41 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 1217
18 clang-5.0                0x0000000108a5da92 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 4914
19 clang-5.0                0x0000000106c36d3c cc1_main(llvm::ArrayRef<char const*>, char const*, void*) + 1388
20 clang-5.0                0x0000000106c35403 main + 11795
21 libdyld.dylib            0x00007fffb2229255 start + 1
Stack dump:
0.	Program arguments: /b/build/slave/clang-tot-device/build/src/third_party/llvm-build/Release+Asserts/bin/clang-5.0 -cc1 -triple arm64-apple-ios9.0.0 -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -Werror=implicit-function-declaration -emit-obj -disable-free -main-file-name json_parser.cc -mrelocation-model pic -pic-level 2 -mthread-model posix -mdisable-fp-elim -relaxed-aliasing -masm-verbose -target-cpu cyclone -target-feature +neon -target-feature +crypto -target-feature +zcm -target-feature +zcz -target-abi darwinpcs -target-linker-version 274.2 -dwarf-column-info -debug-info-kind=standalone -dwarf-version=2 -debugger-tuning=lldb -coverage-notes-file /b/build/slave/clang-tot-device/build/src/out/Release-iphoneos/obj/base/base/json_parser.gcno -resource-dir /b/build/slave/clang-tot-device/build/src/third_party/llvm-build/Release+Asserts/bin/../lib/clang/5.0.0 -dependency-file obj/base/base/json_parser.o.d -MT obj/base/base/json_parser.o -isysroot /b/build/slave/clang-tot-device/build/src/build/ios_files/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.2.sdk -D SYSTEM_NATIVE_UTF8 -D V8_DEPRECATION_WARNINGS -D NO_TCMALLOC -D DISABLE_NACL -D CHROMIUM_BUILD -D FIELDTRIAL_TESTING_ENABLED -D CR_CLANG_REVISION="294769" -D CR_XCODE_VERSION=0821 -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D _FORTIFY_SOURCE=2 -D NDEBUG -D NVALGRIND -D DYNAMIC_ANNOTATIONS_ENABLED=0 -D BASE_IMPLEMENTATION -I ../.. -I gen -D __DATE__= -D __TIME__= -D __TIMESTAMP__= -stdlib=libc++ -O2 -Wno-builtin-macro-redefined -Wall -Werror -Wextra -Wundeclared-selector -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-deprecated-register -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-shift-negative-value -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Wno-char-subscripts -Wexit-time-destructors -Wexit-time-destructors -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /b/build/slave/clang-tot-device/build/src/out/Release-iphoneos -ferror-limit 19 -fmessage-length 0 -fvisibility hidden -fvisibility-inlines-hidden -stack-protector 1 -stack-protector-buffer-size 4 -fallow-half-arguments-and-returns -fblocks -fno-rtti -fobjc-runtime=ios-9.0.0 -fencode-extended-block-signature -fmax-type-align=16 -fdiagnostics-show-option -fcolor-diagnostics -vectorize-loops -vectorize-slp -load ../../third_party/llvm-build/Release+Asserts/lib/libFindBadConstructs.dylib -add-plugin find-bad-constructs -o obj/base/base/json_parser.o -x c++ ../../base/json/json_parser.cc 
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module '../../base/json/json_parser.cc'.
4.	Running pass 'Live DEBUG_VALUE analysis' on function '@_ZN4base8internal10JSONParser16ConsumeStringRawEPNS1_13StringBuilderE'
clang-5.0: error: unable to execute command: Abort trap: 6
clang-5.0: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 5.0.0 (trunk 294769)
Target: aarch64-apple-darwin16.3.0
Thread model: posix
InstalledDir: /b/build/slave/clang-tot-device/build/src/out/Release-iphoneos/../../third_party/llvm-build/Release+Asserts/bin
clang-5.0: 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-5.0: note: diagnostic msg: 
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PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-5.0: note: diagnostic msg: /var/folders/p4/py6nlvcx4fs5s3fg51_pzqmc0000gm/T/json_parser-7ef6a7.cpp
clang-5.0: note: diagnostic msg: /var/folders/p4/py6nlvcx4fs5s3fg51_pzqmc0000gm/T/json_parser-7ef6a7.sh
clang-5.0: note: diagnostic msg: Crash backtrace is located in
clang-5.0: note: diagnostic msg: /Users/chrome-bot/Library/Logs/DiagnosticReports/clang-5.0_<YYYY-MM-DD-HHMMSS>_<hostname>.crash
clang-5.0: note: diagnostic msg: (choose the .crash file that corresponds to your crash)
clang-5.0: note: diagnostic msg: 

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The bot has been red for a long time for unrelated reasons ( issue 690123  etc), so not clear when this started.