File size: 2,665 Bytes
dabfdaa | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 | use std::sync::OnceLock;
/// Controls whether V8 may generate executable code at runtime.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub enum V8JitMode {
#[default]
Enabled,
Disabled,
}
struct V8Initialization {
_platform: v8::SharedRef<v8::Platform>,
jit_mode: V8JitMode,
}
static V8_INITIALIZATION: OnceLock<Result<V8Initialization, String>> = OnceLock::new();
/// Initializes the process-wide V8 platform with the requested JIT mode.
///
/// Call this before executing any code-mode cells when JIT must be disabled.
/// V8 cannot change JIT mode after initialization, so a later call requesting
/// a different mode returns an error. Code mode initializes V8 with JIT enabled
/// by default when this function has not been called explicitly.
pub fn initialize_v8(jit_mode: V8JitMode) -> Result<(), String> {
match V8_INITIALIZATION.get_or_init(|| initialize_v8_with_mode(jit_mode)) {
Ok(initialization) if initialization.jit_mode == jit_mode => Ok(()),
Ok(initialization) => Err(format!(
"V8 was already initialized with JIT {}",
initialization.jit_mode.description()
)),
Err(error_text) => Err(error_text.clone()),
}
}
pub(crate) fn ensure_v8_initialized() -> Result<(), String> {
match V8_INITIALIZATION.get_or_init(|| initialize_v8_with_mode(V8JitMode::Enabled)) {
Ok(_) => Ok(()),
Err(error_text) => Err(error_text.clone()),
}
}
fn initialize_v8_with_mode(jit_mode: V8JitMode) -> Result<V8Initialization, String> {
v8::icu::set_common_data_77(deno_core_icudata::ICU_DATA)
.map_err(|error_code| format!("failed to initialize ICU data: {error_code}"))?;
// The pinned V8 can inline Array.prototype.sort with incompatible element kinds.
// Disable the affected paths in TurboFan and the Maglev/Turbolev frontend until
// our V8 artifacts include the upstream fix for mixed-element sorting:
// https://github.com/v8/v8/commit/e0562d87ad9c17042b581582c99237d798572e67
v8::V8::set_flags_from_string("--no-maglev --no-turbolev --no-turbo-inline-array-builtins");
match jit_mode {
V8JitMode::Enabled => {}
V8JitMode::Disabled => v8::V8::set_flags_from_string("--jitless"),
}
let platform = v8::new_default_platform(0, false).make_shared();
v8::V8::initialize_platform(platform.clone());
v8::V8::initialize();
Ok(V8Initialization {
_platform: platform,
jit_mode,
})
}
impl V8JitMode {
fn description(self) -> &'static str {
match self {
Self::Enabled => "enabled",
Self::Disabled => "disabled",
}
}
}
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