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Optimize wasm calls ever-so-slightly #7084

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merged 4 commits into from
Sep 25, 2023
Merged

Optimize wasm calls ever-so-slightly #7084

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0c63911
Optimize wasm calls ever-so-slightly
alexcrichton Sep 25, 2023
8e9b8ed
Fix riscv64
alexcrichton Sep 25, 2023
44eeb5b
Remove stray comment
alexcrichton Sep 25, 2023
b6f3ffb
Shuffle around where `unsafe` lies
alexcrichton Sep 25, 2023
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1 change: 1 addition & 0 deletions crates/runtime/src/instance.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -404,6 +404,7 @@ impl Instance {
}

/// Return a pointer to the interrupts structure
#[inline]
pub fn runtime_limits(&mut self) -> *mut *const VMRuntimeLimits {
unsafe { self.vmctx_plus_offset_mut(self.offsets().vmctx_runtime_limits()) }
}
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4 changes: 3 additions & 1 deletion crates/wasmtime/Cargo.toml
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Expand Up @@ -41,7 +41,6 @@ serde_json = { workspace = true }
bincode = "1.2.1"
indexmap = { workspace = true }
paste = "1.0.3"
psm = "0.1.11"
once_cell = { workspace = true }
rayon = { version = "1.0", optional = true }
object = { workspace = true }
Expand All @@ -56,6 +55,9 @@ features = [
"Win32_System_Diagnostics_Debug",
]

[target.'cfg(target_arch = "s390x")'.dependencies]
psm = "0.1.11"

[dev-dependencies]
tempfile = "3.0"
wasmtime-wasi = { path = "../wasi", default-features = true }
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39 changes: 38 additions & 1 deletion crates/wasmtime/src/func.rs
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Expand Up @@ -1408,7 +1408,7 @@ fn enter_wasm<T>(store: &mut StoreContextMut<'_, T>) -> Option<usize> {
return None;
}

let stack_pointer = psm::stack_pointer() as usize;
let stack_pointer = stack_pointer();

// Determine the stack pointer where, after which, any wasm code will
// immediately trap. This is checked on the entry to all wasm functions.
Expand All @@ -1435,6 +1435,43 @@ fn enter_wasm<T>(store: &mut StoreContextMut<'_, T>) -> Option<usize> {
Some(prev_stack)
}

#[inline]
fn stack_pointer() -> usize {
let stack_pointer: usize;
cfg_if::cfg_if! {
if #[cfg(target_arch = "x86_64")] {
unsafe {
std::arch::asm!(
"mov {}, rsp",
out(reg) stack_pointer,
options(nostack,nomem),
);
}
} else if #[cfg(target_arch = "aarch64")] {
unsafe {
std::arch::asm!(
"mov {}, sp",
out(reg) stack_pointer,
options(nostack,nomem),
);
}
} else if #[cfg(target_arch = "riscv64")] {
unsafe {
std::arch::asm!(
"mv {}, sp",
out(reg) stack_pointer,
options(nostack,nomem),
);
}
} else if #[cfg(target_arch = "s390x")] {
stack_pointer = psm::stack_pointer() as usize;
} else {
compile_error!("unsupported platform");
}
}
stack_pointer
}

fn exit_wasm<T>(store: &mut StoreContextMut<'_, T>, prev_stack: Option<usize>) {
// If we don't have a previous stack pointer to restore, then there's no
// cleanup we need to perform here.
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