V8 CI build error on ppc

[targos]

@nodejs/platform-ppc

We missed it in the 12.4 upgrade PR.

https://ci.nodejs.org/job/node-test-commit-v8-linux/5914/nodes=rhel8-ppc64le,v8test=v8test/

21:19:30 FAILED: obj/v8_base_without_compiler/turboshaft-graph-interface.o 
21:19:30 ccache g++ -MD -MF obj/v8_base_without_compiler/turboshaft-graph-interface.o.d -DUSE_UDEV -DUSE_AURA=1 -DUSE_GLIB=1 -DUSE_OZONE=1 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_NONE -D_GLIBCXX_ASSERTIONS=1 -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DV8_TYPED_ARRAY_MAX_SIZE_IN_HEAP=64 -DENABLE_GDB_JIT_INTERFACE -DV8_INTL_SUPPORT -DV8_USE_EXTERNAL_STARTUP_DATA -DV8_ATOMIC_OBJECT_FIELD_WRITES -DV8_ENABLE_LAZY_SOURCE_POSITIONS -DV8_SHARED_RO_HEAP -DV8_WIN64_UNWINDING_INFO -DV8_ENABLE_REGEXP_INTERPRETER_THREADED_DISPATCH -DV8_ENABLE_SPARKPLUG -DV8_ENABLE_TURBOFAN -DV8_ENABLE_WEBASSEMBLY -DV8_ENABLE_CONTINUATION_PRESERVED_EMBEDDER_DATA -DV8_ALLOCATION_FOLDING -DV8_ALLOCATION_SITE_TRACKING -DV8_ADVANCED_BIGINT_ALGORITHMS -DV8_USE_ZLIB -DV8_ENABLE_MAGLEV_GRAPH_PRINTER -DV8_ENABLE_EXTENSIBLE_RO_SNAPSHOT -DV8_DEPRECATION_WARNINGS -DV8_IMMINENT_DEPRECATION_WARNINGS -DCPPGC_SLIM_WRITE_BARRIER -DV8_TARGET_ARCH_PPC64 -DV8_TARGET_ARCH_PPC_LE -DV8_HAVE_TARGET_OS -DV8_TARGET_OS_LINUX -DABSL_ALLOCATOR_NOTHROW=1 -DU_USING_ICU_NAMESPACE=0 -DU_ENABLE_DYLOAD=0 -DUSE_CHROMIUM_ICU=1 -DU_ENABLE_TRACING=1 -DU_ENABLE_RESOURCE_TRACING=0 -DU_STATIC_IMPLEMENTATION -DICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE -I../.. -Igen -I../../include -I../../third_party/abseil-cpp -Igen/include -I../../third_party/icu/source/common -I../../third_party/icu/source/i18n -I../../third_party/fp16/src/include -I../../third_party/zlib -Wall -Wno-unused-local-typedefs -Wno-maybe-uninitialized -Wno-deprecated-declarations -Wno-comments -Wno-packed-not-aligned -Wno-missing-field-initializers -Wno-unused-parameter -Wno-psabi -Werror -fno-ident -fno-strict-aliasing -fstack-protector -funwind-tables -fPIC -pipe -pthread -m64 -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fno-omit-frame-pointer -g0 -ffp-contract=off -Wno-invalid-offsetof -Wno-strict-overflow -Wno-return-type -Wno-int-in-bool-context -Wno-deprecated -Wno-stringop-overflow -Wno-stringop-overread -Wno-restrict -Wno-array-bounds -Wno-nonnull -O3 -fdata-sections -ffunction-sections -fno-math-errno -fvisibility=default -Wno-narrowing -Wno-class-memaccess -std=gnu++2a -fno-exceptions -fno-rtti -c ../../src/wasm/turboshaft-graph-interface.cc -o obj/v8_base_without_compiler/turboshaft-graph-interface.o
21:19:30 In file included from ../../src/wasm/turboshaft-graph-interface.h:13,
21:19:30                  from ../../src/wasm/turboshaft-graph-interface.cc:5:
21:19:30 ../../src/compiler/turboshaft/assembler.h: In static member function ‘static _Res std::_Function_handler<_Res(_ArgTypes ...), _Functor>::_M_invoke(const std::_Any_data&, _ArgTypes&& ...) [with _Res = v8::internal::compiler::turboshaft::V<v8::internal::compiler::turboshaft::WordWithBits<32> >; _Functor = v8::internal::wasm::TurboshaftGraphBuildingInterface::ArrayFillImpl(v8::internal::wasm::WasmGraphBuilderBase::V<v8::internal::HeapObject>, v8::internal::wasm::WasmGraphBuilderBase::OpIndex, v8::internal::wasm::WasmGraphBuilderBase::OpIndex, v8::internal::wasm::WasmGraphBuilderBase::OpIndex, const v8::internal::wasm::ArrayType*, bool)::<lambda()>; _ArgTypes = {}]’:
21:19:30 ../../src/compiler/turboshaft/assembler.h:680:16: error: ‘<anonymous>’ is used uninitialized in this function [-Werror=uninitialized]
21:19:30   680 |     return Get();
21:19:30       |                ^
21:19:30 At global scope:
21:19:30 cc1plus: note: unrecognized command-line option ‘-Wno-stringop-overread’ may have been intended to silence earlier diagnostics
21:19:30 cc1plus: all warnings being treated as errors

[miladfarca]

This doesn't happen on our gcc 12 compilers, i'm assuming you are using 10 for ppc? probably related to this bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86465

[richardlau]

Yes, we're currently still using gcc-10 and C++17 (-std=gnu++17. for Node.js). The V8 build is running with -std=gnu++2a (C++20).

FWIW I've been experimenting with gcc-toolset-12 in richardlau-node-test-commit-v8-linux. The build on main from yesterday (today's is still in progress) succeeded with gcc 12: https://ci.nodejs.org/job/richardlau-node-test-commit-v8-linux/nodes=rhel8-ppc64le,v8test=v8test/589/

[richardlau]

I ran some Node.js builds based on main (91dc8c9) plus commits to use C++20 but these still succeed with gcc-toolset-10:

• -std=gnu++20 (ref: build: compile with C++20 support #45427): https://ci.nodejs.org/job/node-test-commit-plinux/53061/
• -std=gnu++2a (same as the V8 CI): https://ci.nodejs.org/job/node-test-commit-plinux/53063/

so there's some other flag difference between the V8 and Node.js builds causing the compilation error to show up in the V8 one but not in the Node.js one when gcc-toolset-10 is used.

[targos]

Isn't the main difference that V8 builds use Clang?

[richardlau]

Isn't the main difference that V8 builds use Clang?

AFAIK not on ppc64le. You can see in the quoted compile failure in #52661 (comment) that it's executed ccache g++ which would be gcc from the gcc-toolset we select in select-compiler.sh.

[richardlau]

The reason the Node.js V8 CI fails with gcc 10 but the Node.js CI does not is because the V8 build passes -Werror and -Wall to enable all warnings (with additional flags to turn some of the warning off) and fail on error while the Node.js build does not. Adding -Wall or just -Wuninitialized to the Node.js compile command line flags the same warning, and adding -Werror causes the build to fail.

[richardlau]

This may be related to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86465. Dropping optimization to a lower level makes the warning go away (i.e. we get the warning with -O3 but not -O2 or -O1).

@miladfarca has submitted https://crrev.com/c/5503350 upstream which also makes the warning go away.
https://ci.nodejs.org/job/node-test-commit-v8-linux/5950/ passed with 2c30d3d.