Add bounds-checked unsafe intrinsics#13597
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fitzgen merged 5 commits intoJun 10, 2026
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Great idea; the bounds-checking logic looks right to me. Just a few comments below.
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| let [_callee_vmctx, _caller_vmctx, base_address, offset, length] = *self.abi_load_params() | ||
| else { | ||
| unreachable!() |
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More descriptive panic message here? Note that the above corresponds to a signature declared elsewhere such that mismatches will be caught earlier?
| .trapz(addr, ir::TrapCode::HEAP_OUT_OF_BOUNDS); | ||
| addr | ||
| } | ||
| // Otherwise, when Specter mitigations are disabled, just conditionally |
| /// | ||
| /// See [`TrampolineCompiler::checked_native_addr`] for details; this is the | ||
| /// equivalent for the inlined translation path. | ||
| fn checked_native_addr( |
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Deja vu -- is there any way to deduplicate the two implementations here? Especially if we add any other kind of logic to bounds-checking in the future, and especially as it's safety-critical code, it's unfortunate it has to be duplicated...
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Deduped. Will send a follow up to dedupe the rest of the methods as well.
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These intrinsics are similar to the unchecked versions, but instead of taking a raw address, take a base, offset, and length. They do a bounds check first, and trap on out-of-bounds accesses or perform the actual in-bounds access. When Spectre mitigations are enabled, their bounds check has Spectre mitigations applied.
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This means we will correctly call the raise-trap libcall when signals-based traps are disabled. However, it also means that `UnsafeIntrinsicCompiler` needed to be refactored a bit to take a `FuncBuilder` rather than a `FuncCursor`, and additionally take a generic `T: TranslateTrap`. This should fix the s390x errors in CI.
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These intrinsics are similar to the unchecked versions, but instead of taking a raw address, take a base, offset, and length. They do a bounds check first, and trap on out-of-bounds accesses or perform the actual in-bounds access. When Spectre mitigations are enabled, their bounds check has Spectre mitigations applied.