35 lines
1.7 KiB
Rust
35 lines
1.7 KiB
Rust
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use crate::mir::{function::MirFunction, MirInstruction};
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use crate::mir::verification_types::VerificationError;
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/// Ensure that each Await instruction (or ExternCall(env.future.await)) is immediately
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/// preceded and followed by a checkpoint.
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/// A checkpoint is either MirInstruction::Safepoint or ExternCall("env.runtime", "checkpoint").
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pub fn check_await_checkpoints(function: &MirFunction) -> Result<(), Vec<VerificationError>> {
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let mut errors = Vec::new();
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let is_cp = |inst: &MirInstruction| match inst {
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MirInstruction::Safepoint => true,
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MirInstruction::ExternCall { iface_name, method_name, .. } => iface_name == "env.runtime" && method_name == "checkpoint",
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_ => false,
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};
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for (bid, block) in &function.blocks {
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let instrs = &block.instructions;
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for (idx, inst) in instrs.iter().enumerate() {
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let is_await_like = match inst {
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MirInstruction::Await { .. } => true,
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MirInstruction::ExternCall { iface_name, method_name, .. } => iface_name == "env.future" && method_name == "await",
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_ => false,
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};
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if is_await_like {
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if idx == 0 || !is_cp(&instrs[idx - 1]) {
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errors.push(VerificationError::MissingCheckpointAroundAwait { block: *bid, instruction_index: idx, position: "before" });
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}
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if idx + 1 >= instrs.len() || !is_cp(&instrs[idx + 1]) {
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errors.push(VerificationError::MissingCheckpointAroundAwait { block: *bid, instruction_index: idx, position: "after" });
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}
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}
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}
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}
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if errors.is_empty() { Ok(()) } else { Err(errors) }
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}
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