1a0ed6e388
This provides assert_le, assert_lt, and so on, which can print the values of the operands.
47 lines
1.7 KiB
Rust
47 lines
1.7 KiB
Rust
//! Implement a registry of function signatures, for fast indirect call
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//! signature checking.
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use crate::vmcontext::VMSharedSignatureIndex;
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use crate::{hash_map, HashMap};
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use core::convert::TryFrom;
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use cranelift_codegen::ir;
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use more_asserts::{assert_lt, debug_assert_lt};
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/// WebAssembly requires that the caller and callee signatures in an indirect
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/// call must match. To implement this efficiently, keep a registry of all
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/// signatures, shared by all instances, so that call sites can just do an
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/// index comparison.
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#[derive(Debug)]
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pub struct SignatureRegistry {
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signature_hash: HashMap<ir::Signature, VMSharedSignatureIndex>,
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}
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impl SignatureRegistry {
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/// Create a new `SignatureRegistry`.
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pub fn new() -> Self {
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Self {
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signature_hash: HashMap::new(),
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}
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}
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/// Register a signature and return its unique index.
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pub fn register(&mut self, sig: &ir::Signature) -> VMSharedSignatureIndex {
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let len = self.signature_hash.len();
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match self.signature_hash.entry(sig.clone()) {
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hash_map::Entry::Occupied(entry) => *entry.get(),
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hash_map::Entry::Vacant(entry) => {
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// Keep `signature_hash` len under 2**32 -- VMSharedSignatureIndex::new(core::u32::MAX)
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// is reserved for VMSharedSignatureIndex::default().
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debug_assert_lt!(
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len,
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core::u32::MAX as usize,
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"Invariant check: signature_hash.len() < core::u32::MAX"
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);
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let sig_id = VMSharedSignatureIndex::new(u32::try_from(len).unwrap());
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entry.insert(sig_id);
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sig_id
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}
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}
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}
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}
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