1 unstable release
0.1.0 | Jun 28, 2024 |
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#327 in WebAssembly
15KB
235 lines
Aspect WASM Instrumentation Library
The Aspect WASM Instrumentation Library, utilizing wasm-instrument
from Parity, is designed to instrument Artela Aspect WebAssembly (WASM) files. It seamlessly adds gas metering functionality and ensures corresponding validation, enhancing the execution efficiency and reliability of your WebAssembly applications.
Supported Platforms
The library is currently compatible with multiple operating systems across different architectures:
- Linux: Arm64, x86_64
- MacOS: Arm64, x86_64
- Windows: x86_64
Functionality
This library meticulously parses a given WASM file, injecting a gas counter as a global variable. Additionally, it integrates gas metering code into each designated code section, positioning it at the outset of the section body.
Furthermore, the library facilitates the export of both the gas counter and the start section of the WASM bytecode. These are exported as __gas_counter__
and __aspect_start__
, respectively. It is crucial to initialize the gas counter prior to executing the start section to avoid execution failures.
Before and After Instrumentation
- Original WASM Code Snippet:
# Original wasm code
(func (;67;) (type 1) (param i32) (result i32)
local.get 0
local.get 0
i64.extend_i32_u
i64.const 50862630
i64.mul
call 66
memory.grow
)
- Post-Instrumentation Code Snippet:
(func (;67;) (type 1) (param i32) (result i32)
# Gas consumption for the section
i64.const 11170
# Consuming gas
call 30
# Executing original code
local.get 0
local.get 0
i64.extend_i32_u
i64.const 50862630
i64.mul
call 66
memory.grow
)
# Gas metering logic
(func (;30;) (type 9) (param i64)
global.get 5
local.get 0
i64.ge_u
if
global.get 5
local.get 0
i64.sub
global.set 5
else
i64.const -1
global.set 5
unreachable
end
)
# Global gas counter
(global (;5;) (mut i64) i64.const 0)
# Exported start section
(export "__aspect_start__" (func $~start))
# Gas counter alias
(export "__gas_counter__" (global 5))
Building the Library
To compile for your current platform, run:
make build
For compiling across all supported platforms, ensure the respective cross-compilers are installed:
make all
For a specific platform build, such as Darwin Arm64, execute:
make darwin-aarch64
Build artifacts are located in target/{platform}/release
directory, with a dedicated directory target/release
for the current platform build.
Available Libraries
The build process generates three types of libraries to suit various project requirements:
- Static Library:
libaspect_wasm_instrument.a
- Dynamic Library:
libaspect_wasm_instrument.so
,libaspect_wasm_instrument.dylib
,libaspect_wasm_instrument.dll
- Rust Library:
aspect_wasm_instrument.rlib
Current Limitations
Some features are not yet supported due to the constraints of the underlying wasm-instrument
library, including but not limited to:
- Bulk memory operations
- Reference types
- ...
Stay tuned for future updates as we continue to enhance this library's capabilities and compatibility.
Dependencies
~3MB
~63K SLoC