2 files changed, 61 insertions, 8 deletions

diff --git a/src/s2wasm.h b/src/s2wasm.h
index b17ed0702..3a7cf31db 100644
--- a/src/s2wasm.h
+++ b/src/s2wasm.h
@@ -554,7 +554,7 @@ class S2WasmBuilder {
 
   void parseFuncType() {
     auto decl = make_unique<FunctionType>();
-    Name name = getCommaSeparated();
+    Name rawName = getCommaSeparated();
     skipComma();
     if(match("void")) {
       decl->result = none;
@@ -562,9 +562,11 @@ class S2WasmBuilder {
       decl->result = getType();
     }
     while (*s && skipComma()) decl->params.push_back(getType());
-    decl->name = "FUNCSIG$" + getSig(decl.get());
+    std::string sig = getSig(decl.get());
+    decl->name = "FUNCSIG$" + sig;
 
     FunctionType *ty = wasm->checkFunctionType(decl->name);
+    Name name = fixEmExceptionInvoke(rawName, sig);
     if (!ty) {
       // The wasm module takes ownership of the FunctionType if we insert it.
       // Otherwise it's already in the module and ours is freed.
@@ -876,14 +878,9 @@ class S2WasmBuilder {
       } else {
         // non-indirect call
         Name assign = getAssign();
-        Name target = linkerObj->resolveAlias(cleanFunction(getCommaSeparated()), LinkerObject::Relocation::kFunction);
-
+        Name rawTarget = cleanFunction(getCommaSeparated());
         Call* curr = allocator->alloc<Call>();
-        curr->target = target;
         curr->type = type;
-        if (!linkerObj->isFunctionImplemented(target)) {
-          linkerObj->addUndefinedFunctionCall(curr);
-        }
         skipWhitespace();
         if (*s == ',') {
           skipComma();
@@ -893,6 +890,13 @@ class S2WasmBuilder {
             curr->operands.push_back(inputs[i]);
           }
         }
+        Name target = linkerObj->resolveAlias(
+            fixEmExceptionInvoke(rawTarget, curr->type, curr->operands),
+            LinkerObject::Relocation::kFunction);
+        curr->target = target;
+        if (!linkerObj->isFunctionImplemented(target)) {
+          linkerObj->addUndefinedFunctionCall(curr);
+        }
         setOutput(curr, assign);
       }
     };
@@ -1342,6 +1346,42 @@ class S2WasmBuilder {
     }
   }
 
+  // Converts invoke wrapper names generated by LLVM backend to real invoke
+  // wrapper names that are expected by JavaScript glue code.
+  // This is required to support wasm exception handling (asm.js style).
+  //
+  // LLVM backend lowers
+  //   invoke @func(arg1, arg2) to label %invoke.cont unwind label %lpad
+  // into
+  // ... (some code)
+  //   call @invoke_SIG(func, arg1, arg2)
+  // ... (some code)
+  // SIG is a mangled string generated based on the LLVM IR-level function
+  // signature. In LLVM IR, types are not lowered yet, so this mangling scheme
+  // simply takes LLVM's string representtion of parameter types and concatenate
+  // them with '_'. For example, the name of an invoke wrapper for function
+  // void foo(struct mystruct*, int) will be
+  // "__invoke_void_%struct.mystruct*_int".
+  // This function converts the names of invoke wrappers based on their lowered
+  // argument types and a return type. In the example above, the resulting new
+  // wrapper name becomes "invoke_vii".
+  template<typename ListType>
+  Name fixEmExceptionInvoke(const Name &name, WasmType result,
+                        const ListType &operands) {
+    return fixEmExceptionInvoke(name, getSig(result, operands));
+  }
+
+  Name fixEmExceptionInvoke(const Name &name, const std::string &sig) {
+    std::string nameStr = name.c_str();
+    if (nameStr.front() == '"' && nameStr.back() == '"') {
+      nameStr = nameStr.substr(1, nameStr.size() - 2);
+    }
+    if (nameStr.find("__invoke_") != 0) {
+      return name;
+    }
+    std::string sigWoOrigFunc = sig.front() + sig.substr(2, sig.size() - 2);
+    return Name("invoke_" + sigWoOrigFunc);
+  }
 
 };
 
diff --git a/src/wasm-linker.cpp b/src/wasm-linker.cpp
index 45615fd59..d8bae7558 100644
--- a/src/wasm-linker.cpp
+++ b/src/wasm-linker.cpp
@@ -210,6 +210,19 @@ void Linker::layout() {
     auto* func = out.wasm.getFunction(name);
     func->type = ensureFunctionType(getSig(func), &out.wasm)->name;
   }
+
+  // Export malloc and free whenever availble. JavsScript version of malloc has
+  // some issues and it cannot be called once _sbrk() is called.
+  // TODO This should get the list of exported functions from emcc.py - it has
+  // EXPORTED_FUNCTION metadata to keep track of this. Get the list of exported
+  // functions using a command-line argument from emcc.py and export all of
+  // them.
+  if (out.symbolInfo.implementedFunctions.count("malloc")) {
+    exportFunction("malloc", true);
+  }
+  if (out.symbolInfo.implementedFunctions.count("free")) {
+    exportFunction("free", true);
+  }
 }
 
 bool Linker::linkObject(S2WasmBuilder& builder) {