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Always run incremental_verify_ich when re-computing query results

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Issue #82920 showed that the kind of bugs caught by this flag have
soundness implications.

This causes performance regressions of up to 15.2% during incremental
compilation, but this is necessary to catch miscompilations caused by
bugs in query implementations.
This commit is contained in:
Aaron Hill 2021-03-11 01:12:07 -05:00
parent 066f01d81b
commit 7d7c81a114
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GPG Key ID: B4087E510E98B164
1 changed files with 18 additions and 11 deletions
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29
compiler/rustc_query_system/src/query/plumbing.rs
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@ -533,7 +533,13 @@ where
None
};
let result = if let Some(result) = result {
if let Some(result) = result {
// If `-Zincremental-verify-ich` is specified, re-hash results from
// the cache and make sure that they have the expected fingerprint.
if unlikely!(tcx.dep_context().sess().opts.debugging_opts.incremental_verify_ich) {
incremental_verify_ich(*tcx.dep_context(), &result, dep_node, dep_node_index, query);
}
result
} else {
// We could not load a result from the on-disk cache, so
@ -545,20 +551,21 @@ where
prof_timer.finish_with_query_invocation_id(dep_node_index.into());
result
};
// If `-Zincremental-verify-ich` is specified, re-hash results from
// the cache and make sure that they have the expected fingerprint.
if unlikely!(tcx.dep_context().sess().opts.debugging_opts.incremental_verify_ich) {
// Verify that re-running the query produced a result with the expected hash
// This catches bugs in query implementations, turning them into ICEs.
// For example, a query might sort its result by `DefId` - since `DefId`s are
// not stable across compilation sessions, the result could get up getting sorted
// in a different order when the query is re-run, even though all of the inputs
// (e.g. `DefPathHash` values) were green.
//
// See issue #82920 for an example of a miscompilation that would get turned into
// an ICE by this check
incremental_verify_ich(*tcx.dep_context(), &result, dep_node, dep_node_index, query);
}
result
result
}
}
#[inline(never)]
#[cold]
fn incremental_verify_ich<CTX, K, V: Debug>(
tcx: CTX::DepContext,
result: &V,