1 files changed, 18 insertions, 16 deletions

diff --git a/src/passes/FuncCastEmulation.cpp b/src/passes/FuncCastEmulation.cpp
index ba6d1d583..9d232c9eb 100644
--- a/src/passes/FuncCastEmulation.cpp
+++ b/src/passes/FuncCastEmulation.cpp
@@ -28,6 +28,8 @@
 // params must be identical, i.e., the "ABI" must match.
 //
 
+#include <string>
+
 #include <ir/literal-utils.h>
 #include <pass.h>
 #include <wasm-builder.h>
@@ -35,11 +37,6 @@
 
 namespace wasm {
 
-// This should be enough for everybody. (As described above, we need this
-// to match when dynamically linking, and also dynamic linking is why we
-// can't just detect this automatically in the module we see.)
-static const int NUM_PARAMS = 16;
-
 // Converts a value to the ABI type of i64.
 static Expression* toABI(Expression* value, Module* module) {
   Builder builder(*module);
@@ -133,20 +130,23 @@ struct ParallelFuncCastEmulation
   : public WalkerPass<PostWalker<ParallelFuncCastEmulation>> {
   bool isFunctionParallel() override { return true; }
 
-  Pass* create() override { return new ParallelFuncCastEmulation(ABIType); }
+  Pass* create() override {
+    return new ParallelFuncCastEmulation(ABIType, numParams);
+  }
 
-  ParallelFuncCastEmulation(Signature ABIType) : ABIType(ABIType) {}
+  ParallelFuncCastEmulation(Signature ABIType, Index numParams)
+    : ABIType(ABIType), numParams(numParams) {}
 
   void visitCallIndirect(CallIndirect* curr) {
-    if (curr->operands.size() > NUM_PARAMS) {
-      Fatal() << "FuncCastEmulation::NUM_PARAMS needs to be at least "
+    if (curr->operands.size() > numParams) {
+      Fatal() << "max-func-params needs to be at least "
               << curr->operands.size();
     }
     for (Expression*& operand : curr->operands) {
       operand = toABI(operand, getModule());
     }
     // Add extra operands as needed.
-    while (curr->operands.size() < NUM_PARAMS) {
+    while (curr->operands.size() < numParams) {
       curr->operands.push_back(LiteralUtils::makeZero(Type::i64, *getModule()));
     }
     // Set the new types
@@ -161,20 +161,22 @@ struct ParallelFuncCastEmulation
 private:
   // The signature of a call with the right params and return
   Signature ABIType;
+  Index numParams;
 };
 
 struct FuncCastEmulation : public Pass {
   void run(PassRunner* runner, Module* module) override {
+    Index numParams =
+      std::stoul(runner->options.getArgumentOrDefault("max-func-params", "16"));
     // we just need the one ABI function type for all indirect calls
-    Signature ABIType(Type(std::vector<Type>(NUM_PARAMS, Type::i64)),
-                      Type::i64);
+    Signature ABIType(Type(std::vector<Type>(numParams, Type::i64)), Type::i64);
     // Add a thunk for each function in the table, and do the call through it.
     std::unordered_map<Name, Name> funcThunks;
     for (auto& segment : module->table.segments) {
       for (auto& name : segment.data) {
         auto iter = funcThunks.find(name);
         if (iter == funcThunks.end()) {
-          auto thunk = makeThunk(name, module);
+          auto thunk = makeThunk(name, module, numParams);
           funcThunks[name] = thunk;
           name = thunk;
         } else {
@@ -183,12 +185,12 @@ struct FuncCastEmulation : public Pass {
       }
     }
     // update call_indirects
-    ParallelFuncCastEmulation(ABIType).run(runner, module);
+    ParallelFuncCastEmulation(ABIType, numParams).run(runner, module);
   }
 
 private:
   // Creates a thunk for a function, casting args and return value as needed.
-  Name makeThunk(Name name, Module* module) {
+  Name makeThunk(Name name, Module* module, Index numParams) {
     Name thunk = std::string("byn$fpcast-emu$") + name.str;
     if (module->getFunctionOrNull(thunk)) {
       Fatal() << "FuncCastEmulation::makeThunk seems a thunk name already in "
@@ -206,7 +208,7 @@ private:
     }
     auto* call = builder.makeCall(name, callOperands, type);
     std::vector<Type> thunkParams;
-    for (Index i = 0; i < NUM_PARAMS; i++) {
+    for (Index i = 0; i < numParams; i++) {
       thunkParams.push_back(Type::i64);
     }
     auto thunkFunc =