wasm-emscripten-finalize: Add flags to limit dynCall creation

src/passes/GenerateDynCalls.cpp

@@ -34,19 +34,24 @@
 namespace wasm {
 
 struct GenerateDynCalls : public WalkerPass<PostWalker<GenerateDynCalls>> {
+  GenerateDynCalls(bool onlyI64) : onlyI64(onlyI64) {}
 
   void visitTable(Table* table) {
     if (table->segments.size() > 0) {
       EmscriptenGlueGenerator generator(*getModule());
+      generator.onlyI64DynCalls = onlyI64;
       std::vector<Name> tableSegmentData;
       for (const auto& indirectFunc : table->segments[0].data) {
         generator.generateDynCallThunk(
           getModule()->getFunction(indirectFunc)->sig);
       }
     }
   }
+
+  bool onlyI64;
 };
 
-Pass* createGenerateDynCallsPass() { return new GenerateDynCalls; }
+Pass* createGenerateDynCallsPass() { return new GenerateDynCalls(false); }
+Pass* createGenerateI64DynCallsPass() { return new GenerateDynCalls(true); }
 
 } // namespace wasm

src/passes/pass.cpp

@@ -146,6 +146,11 @@ void PassRegistry::registerPasses() {
   registerPass("generate-dyncalls",
                "generate dynCall fuctions used by emscripten ABI",
                createGenerateDynCallsPass);
+  registerPass("generate-i64-dyncalls",
+               "generate dynCall functions used by emscripten ABI, but only for "
+               "functions with i64 in their signature (which cannot be invoked "
+               "via the wasm table without JavaScript BigInt support).",
+               createGenerateI64DynCallsPass);
   registerPass(
     "generate-stack-ir", "generate Stack IR", createGenerateStackIRPass);
   registerPass(

src/passes/passes.h

@@ -49,6 +49,7 @@ Pass* createFuncCastEmulationPass();
 Pass* createFullPrinterPass();
 Pass* createFunctionMetricsPass();
 Pass* createGenerateDynCallsPass();
+Pass* createGenerateI64DynCallsPass();
 Pass* createGenerateStackIRPass();
 Pass* createI64ToI32LoweringPass();
 Pass* createInlineMainPass();

src/tools/wasm-emscripten-finalize.cpp

@@ -58,6 +58,8 @@ int main(int argc, const char* argv[]) {
   bool standaloneWasm = false;
   // TODO: remove after https://github.com/WebAssembly/binaryen/issues/3043
   bool minimizeWasmChanges = false;
+  bool noDynCalls = false;
+  bool onlyI64DynCalls = false;
 
   ToolOptions options("wasm-emscripten-finalize",
                       "Performs Emscripten-specific transforms on .wasm files");
@@ -174,6 +176,18 @@ int main(int argc, const char* argv[]) {
          [&minimizeWasmChanges](Options* o, const std::string&) {
            minimizeWasmChanges = true;
          })
+    .add("--no-dyncalls",
+         "",
+         "",
+         Options::Arguments::Zero,
+         [&noDynCalls](Options* o, const std::string&) { noDynCalls = true; })
+    .add("--dyncalls-i64",
+         "",
+         "",
+         Options::Arguments::Zero,
+         [&onlyI64DynCalls](Options* o, const std::string&) {
+           onlyI64DynCalls = true;
+         })
     .add_positional("INFILE",
                     Options::Arguments::One,
                     [&infile](Options* o, const std::string& argument) {
@@ -231,9 +245,11 @@ int main(int argc, const char* argv[]) {
   }
 
   EmscriptenGlueGenerator generator(wasm);
-  generator.setStandalone(standaloneWasm);
-  generator.setSideModule(sideModule);
-  generator.setMinimizeWasmChanges(minimizeWasmChanges);
+  generator.standalone = standaloneWasm;
+  generator.sideModule = sideModule;
+  generator.minimizeWasmChanges = minimizeWasmChanges;
+  generator.onlyI64DynCalls = onlyI64DynCalls;
+  generator.noDynCalls = noDynCalls;
 
   generator.fixInvokeFunctionNames();
 
@@ -278,9 +294,13 @@ int main(int argc, const char* argv[]) {
     passRunner.add("emscripten-pic-main-module");
   }
 
-  if (!standaloneWasm) {
+  if (!noDynCalls && !standaloneWasm) {
     // If not standalone wasm then JS is relevant and we need dynCalls.
-    passRunner.add("generate-dyncalls");
+    if (onlyI64DynCalls) {
+      passRunner.add("generate-i64-dyncalls");
+    } else {
+      passRunner.add("generate-dyncalls");
+    }
   }
 
   // Legalize the wasm, if BigInts don't make that moot.

src/wasm-emscripten.h

@@ -33,12 +33,6 @@ class EmscriptenGlueGenerator {
     : wasm(wasm), builder(wasm), stackPointerOffset(stackPointerOffset),
       useStackPointerGlobal(stackPointerOffset == 0) {}
 
-  void setStandalone(bool standalone_) { standalone = standalone_; }
-  void setSideModule(bool sideModule_) { sideModule = sideModule_; }
-  void setMinimizeWasmChanges(bool minimizeWasmChanges_) {
-    minimizeWasmChanges = minimizeWasmChanges_;
-  }
-
   Function* generateMemoryGrowthFunction();
   Function* generateAssignGOTEntriesFunction();
   void generatePostInstantiateFunction();
@@ -67,14 +61,17 @@ class EmscriptenGlueGenerator {
 
   void generateDynCallThunk(Signature sig);
 
+  bool standalone = false;
+  bool sideModule = false;
+  bool minimizeWasmChanges = false;
+  bool noDynCalls = false;
+  bool onlyI64DynCalls = false;
+
 private:
   Module& wasm;
   Builder builder;
   Address stackPointerOffset;
   bool useStackPointerGlobal;
-  bool standalone;
-  bool sideModule;
-  bool minimizeWasmChanges;
   // Used by generateDynCallThunk to track all the dynCall functions created
   // so far.
   std::unordered_set<Signature> sigs;

src/wasm/wasm-emscripten.cpp

@@ -143,7 +143,27 @@ inline void exportFunction(Module& wasm, Name name, bool must_export) {
   wasm.addExport(exp);
 }
 
+static bool hasI64(Signature sig) {
+  // We only generate dynCall functions for signatures that contain
+  // i64.  This is because any other function can be called directly
+  // from JavaScript using the wasm table.
+  for (auto t : sig.results) {
+    if (t.getID() == Type::i64) {
+      return true;
+    }
+  }
+  for (auto t : sig.params) {
+    if (t.getID() == Type::i64) {
+      return true;
+    }
+  }
+  return false;
+}
+
 void EmscriptenGlueGenerator::generateDynCallThunk(Signature sig) {
+  if (noDynCalls || (onlyI64DynCalls && !hasI64(sig))) {
+    return;
+  }
   if (!sigs.insert(sig).second) {
     return; // sig is already in the set
   }

test/passes/generate-i64-dyncalls.txt

@@ -0,0 +1,20 @@
+(module
+ (type $i32_=>_i64 (func (param i32) (result i64)))
+ (type $none_=>_i32 (func (result i32)))
+ (type $i32_i32_=>_i64 (func (param i32 i32) (result i64)))
+ (table $0 2 2 funcref)
+ (elem (i32.const 0) $f1 $f2)
+ (export "dynCall_ji" (func $dynCall_ji))
+ (func $f1 (result i32)
+  (i32.const 1024)
+ )
+ (func $f2 (param $0 i32) (result i64)
+  (i64.const 42)
+ )
+ (func $dynCall_ji (param $fptr i32) (param $0 i32) (result i64)
+  (call_indirect (type $i32_=>_i64)
+   (local.get $0)
+   (local.get $fptr)
+  )
+ )
+)

test/passes/generate-i64-dyncalls.wast

@@ -0,0 +1,10 @@
+(module
+ (func $f1 (result i32)
+  (i32.const 1024)
+ )
+ (func $f2 (param i32) (result i64)
+  (i64.const 42)
+ )
+ (table 2 2 funcref)
+ (elem (i32.const 0) $f1 $f2)
+)