3 files changed, 31 insertions, 2 deletions
diff --git a/src/wasm-interpreter.h b/src/wasm-interpreter.h
index c4bf21d54..7b8812d69 100644
--- a/src/wasm-interpreter.h
+++ b/src/wasm-interpreter.h
@@ -15,6 +15,8 @@ using namespace cashew;
 // An instance of a WebAssembly module, which can execute it via AST interpretation
 //
 
+IString WASM("wasm");
+
 class ModuleInstance {
 public:
   typedef std::vector<Literal> LiteralList;
@@ -562,7 +564,18 @@ public:
       }
       Flow visitHost(Host *curr) override {
         NOTE_ENTER("Host");
-        abort();
+
+        switch (curr->op) {
+          case PageSize:   return Literal(64*1024);
+          case MemorySize: return Literal(instance.memorySize);
+          case GrowMemory: abort();
+          case HasFeature: {
+            IString id = curr->nameOperand;
+            if (id == WASM) return Literal(1);
+            return Literal(0);
+          }
+          default: abort();
+        }
       }
       Flow visitNop(Nop *curr) override {
         NOTE_ENTER("Nop");
diff --git a/src/wasm-s-parser.h b/src/wasm-s-parser.h
index 2f86fcef2..0e9967128 100644
--- a/src/wasm-s-parser.h
+++ b/src/wasm-s-parser.h
@@ -336,7 +336,7 @@ public:
   #define abort_on(str) { std::cerr << "aborting on " << str << '\n'; onError(); }
 
   Expression* parseExpression(Element& s) {
-    //if (debug) std::cerr << "parse expression " << s << '\n';
+    //std::cerr << "parse expression " << s << '\n';
     IString id = s[0]->str();
     const char *str = id.str;
     const char *dot = strchr(str, '.');
@@ -483,6 +483,10 @@ public:
           if (str[1] == 'e') return makeGetLocal(s);
           abort_on(str);
         }
+        case 'h': {
+          if (str[1] == 'a') return makeHost(s, HostOp::HasFeature);
+          abort_on(str);
+        }
         case 'i': {
           if (str[1] == 'f') return makeIf(s);
           abort_on(str);
@@ -548,6 +552,17 @@ private:
     return ret;
   }
 
+  Expression* makeHost(Element& s, HostOp op) {
+    auto ret = allocator.alloc<Host>();
+    ret->op = op;
+    if (op == HostOp::HasFeature) {
+      ret->nameOperand = s[1]->str();
+    } else {
+      parseCallOperands(s, 1, ret);
+    }
+    return ret;
+  }
+
   Expression* makeSetLocal(Element& s) {
     auto ret = allocator.alloc<SetLocal>();
     ret->name = s[1]->str();
diff --git a/src/wasm.h b/src/wasm.h
index 6d1ac7b83..f2c9b742b 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -748,6 +748,7 @@ public:
   Host() : Expression(HostId) {}
 
   HostOp op;
+  Name nameOperand;
   ExpressionList operands;
 
   std::ostream& doPrint(std::ostream &o, unsigned indent) {