From 2218b63902cac62e02d9672034fc8d8415945973 Mon Sep 17 00:00:00 2001 From: Thomas Lively Date: Thu, 17 Nov 2022 17:07:21 -0800 Subject: Do not compare reference values across executions (#5276) Since we optimize assuming a closed world, optimizations can change the types and structure of GC data even in externally-visible ways. Because differences are expected, the fuzzer already did not compare reference-typed values from before and after optimizations when running with nominal typing. Update it to not compare these values under any type system. --- src/tools/execution-results.h | 28 ++++++++++------------------ 1 file changed, 10 insertions(+), 18 deletions(-) (limited to 'src') diff --git a/src/tools/execution-results.h b/src/tools/execution-results.h index 723ddffda..925c9b6d8 100644 --- a/src/tools/execution-results.h +++ b/src/tools/execution-results.h @@ -143,25 +143,17 @@ struct ExecutionResults { } bool areEqual(Literal a, Literal b) { - // We allow nulls to have different types (as they compare equal regardless) - // but anything else must have an identical type. - // We cannot do this in nominal typing, however, as different modules will - // have different types in general. We could perhaps compare the entire - // graph structurally TODO - if (getTypeSystem() != TypeSystem::Nominal) { - if (a.type != b.type && !(a.isNull() && b.isNull())) { - std::cout << "types not identical! " << a << " != " << b << '\n'; - return false; - } - } if (a.type.isRef()) { - // Don't compare references - only their types. There are several issues - // here that we can't fully handle, see - // https://github.com/WebAssembly/binaryen/issues/3378, but the core issue - // is that we are comparing results between two separate wasm modules (and - // a separate instance of each) - we can't really identify an identical - // reference between such things. We can only compare things structurally, - // for which we compare the types. + // Don't compare references. There are several issues here that we can't + // fully handle, see https://github.com/WebAssembly/binaryen/issues/3378, + // but the core issue is that since we optimize assuming a closed world, + // the types and structure of GC data can arbitrarily change after + // optimizations, even in ways that are externally visible from outside + // the module. + // + // TODO: Once we support optimizing under some form of open-world + // assumption, we should be able to check that the types and/or structure + // of GC data passed out of the module does not change. return true; } if (a != b) { -- cgit v1.2.3