Fuzzing: Minor execution-results.h fixes (#3747)

    Log out an i64 as two i32s. That keeps the output consistent regardless of
    whether we legalize.

    Do not print a reference result. The printed value cannot be compared, as
    funcref(10) (where 10 is the index of the function) is not guaranteed to be
    the same after opts.

    Trap when trying to call an export with a nondefaultable type (instead of
    asserting when trying to create zeros for it).

3 files changed, 32 insertions, 8 deletions

diff --git a/src/tools/execution-results.h b/src/tools/execution-results.h
index d99826210..a183ad93b 100644
--- a/src/tools/execution-results.h
+++ b/src/tools/execution-results.h
@@ -44,8 +44,20 @@ struct LoggingExternalInterface : public ShellExternalInterface {
       std::cout << "[LoggingExternalInterface logging";
       loggings.push_back(Literal()); // buffer with a None between calls
       for (auto argument : arguments) {
-        std::cout << ' ' << argument;
-        loggings.push_back(argument);
+        if (argument.type == Type::i64) {
+          // To avoid JS legalization changing logging results, treat a logging
+          // of an i64 as two i32s (which is what legalization would turn us
+          // into).
+          auto low = Literal(int32_t(argument.getInteger()));
+          auto high = Literal(int32_t(argument.getInteger() >> int32_t(32)));
+          std::cout << ' ' << low;
+          loggings.push_back(low);
+          std::cout << ' ' << high;
+          loggings.push_back(high);
+        } else {
+          std::cout << ' ' << argument;
+          loggings.push_back(argument);
+        }
       }
       std::cout << "]\n";
       return {};
@@ -97,8 +109,16 @@ struct ExecutionResults {
           results[exp->name] = ret;
           // ignore the result if we hit an unreachable and returned no value
           if (ret.size() > 0) {
-            std::cout << "[fuzz-exec] note result: " << exp->name << " => "
-                      << ret << '\n';
+            std::cout << "[fuzz-exec] note result: " << exp->name << " => ";
+            auto resultType = func->sig.results;
+            if (resultType.isRef()) {
+              // Don't print reference values, as funcref(N) contains an index
+              // for example, which is not guaranteed to remain identical after
+              // optimizations.
+              std::cout << resultType << '\n';
+            } else {
+              std::cout << ret << '\n';
+            }
           }
         } else {
           // no result, run it anyhow (it might modify memory etc.)
@@ -202,6 +222,10 @@ struct ExecutionResults {
       // call the method
       for (const auto& param : func->sig.params) {
         // zeros in arguments TODO: more?
+        if (!param.isDefaultable()) {
+          std::cout << "[trap fuzzer can only send defaultable parameters to "
+                       "exports]\n";
+        }
         arguments.push_back(Literal::makeZero(param));
       }
       return instance.callFunction(func->name, arguments);
diff --git a/test/passes/fuzz-exec_all-features.txt b/test/passes/fuzz-exec_all-features.txt
index 8785d088a..e5687b16a 100644
--- a/test/passes/fuzz-exec_all-features.txt
+++ b/test/passes/fuzz-exec_all-features.txt
@@ -208,7 +208,7 @@
 [fuzz-exec] calling rmw-reads-modifies-and-writes-asymmetrical
 [LoggingExternalInterface logging 214]
 [fuzz-exec] calling func
-[fuzz-exec] note result: func => funcref(func)
+[fuzz-exec] note result: func => funcref
 (module
  (type $none_=>_funcref (func (result funcref)))
  (elem declare func $func)
@@ -218,5 +218,5 @@
  )
 )
 [fuzz-exec] calling func
-[fuzz-exec] note result: func => funcref(func)
+[fuzz-exec] note result: func => funcref
 [fuzz-exec] comparing func
diff --git a/test/passes/simplify-globals_all-features_fuzz-exec.txt b/test/passes/simplify-globals_all-features_fuzz-exec.txt
index 464ef0912..68330b69f 100644
--- a/test/passes/simplify-globals_all-features_fuzz-exec.txt
+++ b/test/passes/simplify-globals_all-features_fuzz-exec.txt
@@ -1,5 +1,5 @@
 [fuzz-exec] calling export
-[fuzz-exec] note result: export => funcref(0)
+[fuzz-exec] note result: export => funcref
 (module
  (type $f32_i31ref_i64_f64_funcref_=>_none (func (param f32 i31ref i64 f64 funcref)))
  (type $none_=>_funcref (func (result funcref)))
@@ -17,5 +17,5 @@
  )
 )
 [fuzz-exec] calling export
-[fuzz-exec] note result: export => funcref(0)
+[fuzz-exec] note result: export => funcref
 [fuzz-exec] comparing export