That got me to the stage of being able to compile v8. However, in runtime,
it crashes with the following error:
#
# Fatal error in v8::HandleScope::CreateHandle()
# Cannot create a handle without a HandleScope
#
zsh: trace trap ~/coding/v8/out/arm64.optdebug/d8 --allow-natives-syntax
I read some more and realized the SealScope wasn't appropriate since the
factory method creates a new Handle. I switched to an EscapableHandleScope.
However, that requires an object of type Local and not Handle.
Am I on the right path? I'm not sure how to get from a Local to Handle or
if I picked the right scope.
RUNTIME_FUNCTION(Runtime_AddressOfArray) {
v8::EscapableHandleScope ehs((v8::Isolate*)isolate);
StdoutStream os;
MaybeObject maybe_object(*args.address_of_arg_at(0));
Object object = maybe_object.GetHeapObjectOrSmi();
void* data_pointer = JSTypedArray::cast(object).DataPtr();
std::ostringstream stream;
stream << data_pointer;
std::string data_pointer_string = stream.str();
data_pointer_string = data_pointer_string.substr(2,
data_pointer_string.size() - 2);
long number = stol(data_pointer_string, nullptr, 16);
Handle<v8::internal::Object> number_handle =
isolate->factory()->NewNumber(number);
return ehs.Escape(number_handle);
}
On Wednesday, February 15, 2023 at 12:34:48 AM UTC-5 jgr...@chromium.org
wrote:
> Hi, something like this should work:
>
> RUNTIME_FUNCTION(...) {
> ...
> return *isolate->factory()->NewNumber(number);
> }
>
> On Tue, Feb 14, 2023 at 8:19 PM Pradyumna Shome <pradyum...@gmail.com>
> wrote:
>
>> Hi all
>>
>> I'm trying to add a new runtime function to return the Data Pointer of an
>> array as a v8::NumberObject, so I can operate upon memory addresses in
>> other JavaScript commands. I'm having trouble constructing and returning an
>> object of type v8::internal::Object, since it seems like every operation
>> always returns a Local/Handle.
>>
>> I reached out to one of the developers (Jakob) separately, and they
>> pointed me to the definition of v8::NumberObject::New
>> <https://source.chromium.org/chromium/chromium/src/+/main:v8/src/api/api.cc;l=7636;drc=e14364652369744ed1a8b9c4a582f11833b35aff>.
>>
>> However, I'm unable to figure out the plumbing required to satisfy the
>> compiler that what I'm returning from the runtime function is indeed a
>> v8::internal::Object. I've shared what I've tried doing to troubleshoot,
>> the error log (bolding the actual errors) and code snippet below.
>>
>> Best
>> Pradyumna
>>
>> *What I've Tried*
>>
>> 1. Constructing v8::StringObjects, v8::NumberObjects, and
>> v8::internal::Numbers,by plumbing together APIs from
>>
>> https://v8docs.nodesource.com/node-0.8/da/d56/classv8_1_1_number_object.html
>> and other sites.
>> 2. Reading the relevant pieces of https://v8.dev/docs/embed to
>> understand what Local/Handle/Persistents are.
>> 3. Searched for call sites of the NumberObject/StringObject/Number
>> APIs on the GitHub, Google, and You search engines to see if others have
>> tried to do something similar. It turns out not a lot of people outside
>> of
>> the v8 developers are editing v8 (at least publicly).
>> 4. Read through numbers StackOverflow questions about construction
>> v8::internal::objects, and manipulating Locals.
>> 5. Searching for related keywords on this forum.
>>
>>
>> *Error Log (for one of the attempts)*
>>
>> # autoninja -C out/arm64.optdebug d8
>> ninja: Entering directory `out/arm64.optdebug'
>> [1/11] CXX obj/v8_base_without_compiler/runtime-test.o
>> FAILED: obj/v8_base_without_compiler/runtime-test.o
>> ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF
>> obj/v8_base_without_compiler/runtime-test.o.d -D__STDC_CONSTANT_MACROS
>> -D__STDC_FORMAT_MACROS -DCR_XCODE_VERSION=1420
>> -DCR_CLANG_REVISION=\"llvmorg-16-init-17653-g39da55e8-2\" -DCOMPONENT_BUILD
>> -DCR_LIBCXX_REVISION=59bae40d835ae4eabaddbef781f5e3b778dd7907
>> -D_LIBCPP_ENABLE_ASSERTIONS=1 -D_DEBUG -DDYNAMIC_ANNOTATIONS_ENABLED=1
>> -DCPPGC_VERIFY_HEAP -DENABLE_DISASSEMBLER
>> -DV8_TYPED_ARRAY_MAX_SIZE_IN_HEAP=64 -DOBJECT_PRINT -DVERIFY_HEAP
>> -DV8_TRACE_MAPS -DV8_ENABLE_ALLOCATION_TIMEOUT -DV8_ENABLE_FORCE_SLOW_PATH
>> -DV8_ENABLE_DOUBLE_CONST_STORE_CHECK -DV8_INTL_SUPPORT
>> -DENABLE_HANDLE_ZAPPING -DV8_CODE_COMMENTS -DV8_ENABLE_DEBUG_CODE
>> -DV8_ENABLE_HEAP_SNAPSHOT_VERIFY -DV8_SNAPSHOT_NATIVE_CODE_COUNTERS
>> -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_SHORT_BUILTIN_CALLS -DV8_EXTERNAL_CODE_SPACE -DV8_ENABLE_MAGLEV
>> -DV8_ENABLE_TURBOFAN -DV8_ENABLE_SYSTEM_INSTRUMENTATION
>> -DV8_ENABLE_WEBASSEMBLY -DV8_ALLOCATION_FOLDING
>> -DV8_ALLOCATION_SITE_TRACKING -DV8_ADVANCED_BIGINT_ALGORITHMS
>> -DV8_STATIC_ROOTS -DV8_USE_ZLIB -DV8_USE_LIBM_TRIG_FUNCTIONS
>> -DV8_ENABLE_CHECKS -DV8_COMPRESS_POINTERS
>> -DV8_COMPRESS_POINTERS_IN_SHARED_CAGE -DV8_31BIT_SMIS_ON_64BIT_ARCH
>> -DV8_ENABLE_SANDBOX -DV8_DEPRECATION_WARNINGS
>> -DV8_IMMINENT_DEPRECATION_WARNINGS -DCPPGC_CAGED_HEAP
>> -DCPPGC_YOUNG_GENERATION -DCPPGC_POINTER_COMPRESSION
>> -DCPPGC_SLIM_WRITE_BARRIER -DV8_TARGET_ARCH_ARM64 -DV8_HAVE_TARGET_OS
>> -DV8_TARGET_OS_MACOS -DDEBUG -DV8_RUNTIME_CALL_STATS -DBUILDING_V8_SHARED
>> -DUSING_V8_BASE_SHARED -DUSING_V8_PLATFORM_SHARED -DU_USING_ICU_NAMESPACE=0
>> -DU_ENABLE_DYLOAD=0 -DUSE_CHROMIUM_ICU=1 -DU_ENABLE_TRACING=1
>> -DU_ENABLE_RESOURCE_TRACING=0 -DICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE
>> -I../.. -Igen -I../../buildtools/third_party/libc++ -I../../include
>> -Igen/include -I../../third_party/icu/source/common
>> -I../../third_party/icu/source/i18n -I../../third_party/zlib -Wall -Werror
>> -Wextra -Wimplicit-fallthrough -Wextra-semi -Wunreachable-code-aggressive
>> -Wthread-safety -Wunguarded-availability -Wno-missing-field-initializers
>> -Wno-unused-parameter -Wno-psabi -Wloop-analysis
>> -Wno-unneeded-internal-declaration -Wenum-compare-conditional
>> -Wno-ignored-pragma-optimize -Wno-deprecated-builtins
>> -Wno-bitfield-constant-conversion -Wshadow -fno-delete-null-pointer-checks
>> -fno-ident -fno-strict-aliasing -fstack-protector-strong
>> -fcolor-diagnostics -fmerge-all-constants
>> -fcrash-diagnostics-dir=../../tools/clang/crashreports -mllvm
>> -instcombine-lower-dbg-declare=0 -ffp-contract=off
>> -fcomplete-member-pointers -arch arm64 -fno-global-isel -mno-outline
>> -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__=
>> -ffile-compilation-dir=. -no-canonical-prefixes
>> -ftrivial-auto-var-init=pattern -fno-omit-frame-pointer -g2 -gdwarf-aranges
>> -Xclang -debug-info-kind=limited -isysroot
>> ../../../../../../Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX13.1.sdk
>>
>> -mmacos-version-min=10.13 -Wheader-hygiene -Wstring-conversion
>> -Wtautological-overlap-compare -Wmissing-field-initializers
>> -Wunreachable-code -Wctad-maybe-unsupported -Wno-shadow -Wshorten-64-to-32
>> -O0 -fvisibility=default -Wexit-time-destructors
>> -Wno-undefined-bool-conversion -Wno-tautological-undefined-compare
>> -std=c++20 -Wno-trigraphs -fno-exceptions -fno-rtti -nostdinc++
>> -isystem../../buildtools/third_party/libc++/trunk/include
>> -isystem../../buildtools/third_party/libc++abi/trunk/include -c
>> ../../src/runtime/runtime-test.cc -o
>> obj/v8_base_without_compiler/runtime-test.o
>>
>> *../../src/runtime/runtime-test.cc:1160:57: error: cannot initialize a
>> parameter of type 'Value *' with an rvalue of type 'Local<NumberObject> *'*
>> return *(v8::internal::Object*)v8::NumberObject::Cast(&numberObjectLocal);
>> ^~~~~~~~~~~~~~~~~~
>>
>> *../../include/v8-primitive-object.h:25:46: note: passing argument to
>> parameter 'value' here* V8_INLINE static NumberObject* Cast(Value*
>> value) {
>> ^
>> In file included from ../../src/runtime/runtime-test.cc:10:
>> In file included from ../../include/v8-function.h:11:
>> In file included from ../../include/v8-function-callback.h:8:
>>
>> *../../include/v8-local-handle.h:166:5: error: static assertion failed
>> due to requirement 'std::is_base_of<v8::NumberObject, v8::Value>::value':
>> type check* static_assert(std::is_base_of<T, S>::value, "type check");
>> ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> *../../src/runtime/runtime-test.cc:1159:43: note: in instantiation of
>> function template specialization
>> 'v8::Local<v8::NumberObject>::Local<v8::Value>' requested here*
>> Local<NumberObject> numberObjectLocal =
>> v8::NumberObject::New((v8::Isolate*)isolate, number);
>> ^
>> 2 errors generated.
>> ninja: build stopped: subcommand failed.
>> Error! - V8 compilation finished with errors.
>>
>> *Code Snippet*
>> RUNTIME_FUNCTION(Runtime_AddressOfArray) {
>> SealHandleScope shs(isolate);
>> StdoutStream os;
>>
>> MaybeObject maybe_object(*args.address_of_arg_at(0));
>> Object object = maybe_object.GetHeapObjectOrSmi();
>>
>> void* data_pointer = JSTypedArray::cast(object).DataPtr();
>> os << "Data Pointer: " << data_pointer << std::endl;
>>
>> std::string data_pointer_string;
>> std::ostringstream stream;
>> stream << data_pointer_string;
>> data_pointer_string = stream.str();
>> int number = stoi(data_pointer_string);
>>
>> *Local<NumberObject> numberObjectLocal =
>> v8::NumberObject::New((v8::Isolate*)isolate, number); return
>> *(v8::internal::Object*)v8::NumberObject::Cast(&numberObjectLocal);*
>> }
>>
>> --
>> --
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>>
>
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