Add interpreter support for intrinsics (#4851)

This can give us some chance to catch bugs like #4839 in the fuzzer.

2 files changed, 17 insertions, 3 deletions

diff --git a/src/ir/intrinsics.cpp b/src/ir/intrinsics.cpp
index c2318cabf..26b624391 100644
--- a/src/ir/intrinsics.cpp
+++ b/src/ir/intrinsics.cpp
@@ -19,11 +19,17 @@
 
 namespace wasm {
 
-static Name BinaryenIntrinsics("binaryen-intrinsics"),
+static Name BinaryenIntrinsicsModule("binaryen-intrinsics"),
   CallWithoutEffects("call.without.effects");
 
 bool Intrinsics::isCallWithoutEffects(Function* func) {
-  return func->module == BinaryenIntrinsics && func->base == CallWithoutEffects;
+  if (func->module != BinaryenIntrinsicsModule) {
+    return false;
+  }
+  if (func->base == CallWithoutEffects) {
+    return true;
+  }
+  Fatal() << "Unrecognized intrinsic";
 }
 
 Call* Intrinsics::isCallWithoutEffects(Expression* curr) {
diff --git a/src/wasm-interpreter.h b/src/wasm-interpreter.h
index 107f38f09..65ffdbade 100644
--- a/src/wasm-interpreter.h
+++ b/src/wasm-interpreter.h
@@ -28,6 +28,7 @@
 #include <sstream>
 #include <variant>
 
+#include "ir/intrinsics.h"
 #include "ir/module-utils.h"
 #include "support/bits.h"
 #include "support/safe_integer.h"
@@ -2757,7 +2758,14 @@ public:
     }
     auto* func = wasm.getFunction(curr->target);
     Flow ret;
-    if (func->imported()) {
+    if (Intrinsics(*self()->getModule()).isCallWithoutEffects(func)) {
+      // The call.without.effects intrinsic is a call to an import that actually
+      // calls the given function reference that is the final argument.
+      auto newArguments = arguments;
+      auto target = newArguments.back();
+      newArguments.pop_back();
+      ret.values = callFunctionInternal(target.getFunc(), newArguments);
+    } else if (func->imported()) {
       ret.values = externalInterface->callImport(func, arguments);
     } else {
       ret.values = callFunctionInternal(curr->target, arguments);