Hello all,
I have a custom impl. of V8 here (not node or chromium) and im trying to
use the WebAssembly backend of V8.
Well its all good and working fine.. but i had to manually change the v8
source i have here because theres some
bad allocation policy here pushing a impossible amount of memory to be
allocated by the custom ArrayBufferAllocator.
I dont know if the problem its fixed already, but in case its not, here it
goes:
in wasm-js.cc::WebAssemblyMemory it figures 'int64_t initial' correctly
and then calls wasm::NewArrayBuffer(...)
The 'problem' here is that 'i::FLAG_wasm_guard_pages' evaluates to true
(and my 'fix' was forcing a false here)
on 'NewArrayBuffer'
> enable_guard_regions = enable_guard_regions && kGuardRegionsSupported;
(evaluated to true)
(the real problem was here) -> TryAllocateBackingStore(..
enable_guard_regions ..);
on 'TryAllocateBackingStore'
if (enable_guard_regions && kGuardRegionsSupported) {
...
isolate->array_buffer_allocator()->Reserve(allocation_length); <-- HERE:
'allocation_lenght' asks for a impossible ammount of memory number..
like 18 tb or 180 gb..
} else { // by forcing enable_guard_regions to false it goes here now, and
the ammount to allocate is fine
...
isolate->array_buffer_allocator()->Allocate(size);
// here 'size' is fine.. it evaluated to 16MB in my case with a '256'
memory number on js side
}
Note: im my custom pipeline im using the sync versions wasm::SyncCompile
and wasm::SyncInstantiate on the C side.. not using the js api.
I just hand back to js runtime the handle for the final instance
I dont know if this was already fixed, but i tought it worth warning the
v8-dev team so you guys can handle accordingly.
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