[NFC] Send the closed-world flag to TranslateToFuzzReader (#7136)

This sends --closed-world to wasm-opt from the fuzzer, when we use that
flag (before we just used it on optimizations, but not fuzz generation). And
TranslateToFuzzReader now stores a boolean about whether we are in closed-
world mode or not.

This has no effect so far, and is a refactoring for a later PR, where we must
generate code differently based on whether we are in closed-world mode
or not.

Author: kripken

scripts/fuzz_opt.py

@@ -225,10 +225,12 @@ def randomize_fuzz_settings():
         # optimizations we use to create any other wasm file.
         FUZZ_OPTS += ['--dce']
 
-    # Enclose the world much of the time when fuzzing closed-world, so that many
-    # types are private and hence optimizable.
-    if CLOSED_WORLD and random.random() < 0.5:
-        GEN_ARGS += ['--enclose-world']
+    if CLOSED_WORLD:
+        GEN_ARGS += [CLOSED_WORLD_FLAG]
+        # Enclose the world much of the time when fuzzing closed-world, so that
+        # many types are private and hence optimizable.
+        if random.random() < 0.5:
+            GEN_ARGS += ['--enclose-world']
 
     print('randomized settings (NaNs, OOB, legalize):', NANS, OOB, LEGALIZE)
 

src/tools/fuzzing.h

@@ -65,8 +65,12 @@ struct BinaryArgs {
 
 class TranslateToFuzzReader {
 public:
-  TranslateToFuzzReader(Module& wasm, std::vector<char>&& input);
-  TranslateToFuzzReader(Module& wasm, std::string& filename);
+  TranslateToFuzzReader(Module& wasm,
+                        std::vector<char>&& input,
+                        bool closedWorld = false);
+  TranslateToFuzzReader(Module& wasm,
+                        std::string& filename,
+                        bool closedWorld = false);
 
   void pickPasses(OptimizationOptions& options);
   void setAllowMemory(bool allowMemory_) { allowMemory = allowMemory_; }
@@ -77,6 +81,8 @@ class TranslateToFuzzReader {
   Module& wasm;
 
 private:
+  // Whether the module will be tested in a closed-world environment.
+  bool closedWorld;
   Builder builder;
   Random random;
 

src/tools/fuzzing/fuzzing.cpp

@@ -32,8 +32,10 @@ namespace {
 } // anonymous namespace
 
 TranslateToFuzzReader::TranslateToFuzzReader(Module& wasm,
-                                             std::vector<char>&& input)
-  : wasm(wasm), builder(wasm), random(std::move(input), wasm.features) {
+                                             std::vector<char>&& input,
+                                             bool closedWorld)
+  : wasm(wasm), closedWorld(closedWorld), builder(wasm),
+    random(std::move(input), wasm.features) {
 
   // Half the time add no unreachable code so that we'll execute the most code
   // as possible with no early exits.
@@ -50,9 +52,11 @@ TranslateToFuzzReader::TranslateToFuzzReader(Module& wasm,
 }
 
 TranslateToFuzzReader::TranslateToFuzzReader(Module& wasm,
-                                             std::string& filename)
-  : TranslateToFuzzReader(
-      wasm, read_file<std::vector<char>>(filename, Flags::Binary)) {}
+                                             std::string& filename,
+                                             bool closedWorld)
+  : TranslateToFuzzReader(wasm,
+                          read_file<std::vector<char>>(filename, Flags::Binary),
+                          closedWorld) {}
 
 void TranslateToFuzzReader::pickPasses(OptimizationOptions& options) {
   // Pick random passes to further shape the wasm. This is similar to how we
@@ -197,8 +201,11 @@ void TranslateToFuzzReader::pickPasses(OptimizationOptions& options) {
       case 41:
         // GC specific passes.
         if (wasm.features.hasGC()) {
-          // Most of these depend on closed world, so just set that.
+          // Most of these depend on closed world, so just set that. Set it both
+          // on the global pass options, and in the internal state of this
+          // TranslateToFuzzReader instance.
           options.passOptions.closedWorld = true;
+          closedWorld = true;
 
           switch (upTo(16)) {
             case 0:

src/tools/wasm-opt.cpp

@@ -303,7 +303,8 @@ int main(int argc, const char* argv[]) {
     }
   }
   if (translateToFuzz) {
-    TranslateToFuzzReader reader(wasm, options.extra["infile"]);
+    TranslateToFuzzReader reader(
+      wasm, options.extra["infile"], options.passOptions.closedWorld);
     if (fuzzPasses) {
       reader.pickPasses(options);
     }