6cd7a5a73a
The WasmContext struct introduced in this CL is used to store the mem_size and mem_start address of the wasm memory. These variables can be accessed at C++ level at graph build time (e.g., initialized during instance building). When the GrowMemory runtime is invoked, the context variables can be changed in the WasmContext at C++ level so that the generated code will load the correct values. This requires to insert a relocatable pointer only in the JSToWasmWrapper (and in the other wasm entry points), the value is then passed from function to function as an automatically added additional parameter. The WasmContext is then dropped when creating an Interpreter Entry or when invoking a JavaScript function. This removes the need of patching the generated code at runtime (i.e., when the memory grows) with respect to WASM_MEMORY_REFERENCE and WASM_MEMORY_SIZE_REFERENCE. However, we still need to patch the code at instance build time to patch the JSToWasmWrappers; in fact the address of the WasmContext is not known during compilation, but only when the instance is built. The WasmContext address is passed as the first parameter. This has the advantage of not having to move the WasmContext around if the function does not use many registers. This CL also changes the wasm calling convention so that the first parameter register is different from the return value register. The WasmContext is attached to every WasmMemoryObject, to share the same context with multiple instances sharing the same memory. Moreover, the nodes representing the WasmContext variables are cached in the SSA environment, similarly to other local variables that might change during execution. The nodes are created when initializing the SSA environment and refreshed every time a grow_memory or a function call happens, so that we are sure that they always represent the correct mem_size and mem_start variables. This CL also removes the WasmMemorySize runtime (since it's now possible to directly retrieve mem_size from the context) and simplifies the GrowMemory runtime (since every instance now has a memory_object). R=ahaas@chromium.org,clemensh@chromium.org CC=gdeepti@chromium.org Change-Id: I3f058e641284f5a1bbbfc35a64c88da6ff08e240 Reviewed-on: https://chromium-review.googlesource.com/671008 Commit-Queue: Enrico Bacis <enricobacis@google.com> Reviewed-by: Clemens Hammacher <clemensh@chromium.org> Reviewed-by: Andreas Haas <ahaas@chromium.org> Cr-Commit-Position: refs/heads/master@{#48209} |
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| docs | ||
| gni | ||
| gypfiles | ||
| include | ||
| infra | ||
| samples | ||
| src | ||
| test | ||
| testing | ||
| third_party | ||
| tools | ||
| .clang-format | ||
| .editorconfig | ||
| .gitignore | ||
| .gn | ||
| .ycm_extra_conf.py | ||
| AUTHORS | ||
| BUILD.gn | ||
| ChangeLog | ||
| CODE_OF_CONDUCT.md | ||
| codereview.settings | ||
| DEPS | ||
| LICENSE | ||
| LICENSE.fdlibm | ||
| LICENSE.strongtalk | ||
| LICENSE.v8 | ||
| LICENSE.valgrind | ||
| Makefile | ||
| Makefile.android | ||
| OWNERS | ||
| PRESUBMIT.py | ||
| README.md | ||
| snapshot_toolchain.gni | ||
| WATCHLISTS | ||
V8 JavaScript Engine
V8 is Google's open source JavaScript engine.
V8 implements ECMAScript as specified in ECMA-262.
V8 is written in C++ and is used in Google Chrome, the open source browser from Google.
V8 can run standalone, or can be embedded into any C++ application.
V8 Project page: https://github.com/v8/v8/wiki
Getting the Code
Checkout depot tools, and run
fetch v8
This will checkout V8 into the directory v8 and fetch all of its dependencies.
To stay up to date, run
git pull origin
gclient sync
For fetching all branches, add the following into your remote
configuration in .git/config:
fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
fetch = +refs/tags/*:refs/tags/*
Contributing
Please follow the instructions mentioned on the V8 wiki.