wasm2js: don't emit obviously unnecessary parens (#2080)

A minifier would probably remove them later anyhow, but they make reading the code annoying and hard.

1 files changed, 26 insertions, 12 deletions

diff --git a/src/emscripten-optimizer/simple_ast.h b/src/emscripten-optimizer/simple_ast.h
index bcfce9712..be5b4fa21 100644
--- a/src/emscripten-optimizer/simple_ast.h
+++ b/src/emscripten-optimizer/simple_ast.h
@@ -1332,6 +1332,10 @@ struct JSPrinter {
     }
   }
 
+  static bool isBlock(Ref node) {
+    return node->isArray() && !node->empty() && node[0] == BLOCK;
+  }
+
   static bool ifHasElse(Ref node) {
     assert(node->isArray() && node[0] == IF);
     return node->size() >= 4 && !!node[3];
@@ -1344,25 +1348,35 @@ struct JSPrinter {
     print(node[1]);
     emit(')');
     space();
-    emit('{');
-    indent++;
-    newline();
-    print(node[2]);
-    indent--;
-    newline();
-    emit('}');
-    if (ifHasElse(node)) {
-      space();
-      emit("else");
-      safeSpace();
+    bool emitsBracesAnyhow = isBlock(node[2]);
+    if (!emitsBracesAnyhow) {
       emit('{');
       indent++;
       newline();
-      print(node[3]);
+    }
+    print(node[2]);
+    if (!emitsBracesAnyhow) {
       indent--;
       newline();
       emit('}');
     }
+    if (ifHasElse(node)) {
+      space();
+      emit("else");
+      safeSpace();
+      bool emitsBracesAnyhow = isBlock(node[3]);
+      if (!emitsBracesAnyhow) {
+        emit('{');
+        indent++;
+        newline();
+      }
+      print(node[3]);
+      if (!emitsBracesAnyhow) {
+        indent--;
+        newline();
+        emit('}');
+      }
+    }
   }
 
   void printDo(Ref node) {