Add design_loaded state variable.

This is to decouple the command line flag "--json" and enable other
frontend's.

Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>

common/command.cc

@@ -331,7 +331,7 @@ int CommandHandler::executeMain(std::unique_ptr<Context> ctx)
             execute_python_file(filename.c_str());
     } else
 #endif
-            if (vm.count("json")) {
+            if (ctx->design_loaded) {
         bool do_pack = vm.count("pack-only") != 0 || vm.count("no-pack") == 0;
         bool do_place = vm.count("pack-only") == 0 && vm.count("no-place") == 0;
         bool do_route = vm.count("pack-only") == 0 && vm.count("no-route") == 0;

common/nextpnr.h

@@ -842,6 +842,9 @@ struct BaseCtx
 
     Context *as_ctx = nullptr;
 
+    // Has the frontend loaded a design?
+    bool design_loaded;
+
     BaseCtx()
     {
         idstring_str_to_idx = new std::unordered_map<std::string, int>;
@@ -853,6 +856,8 @@ struct BaseCtx
         wildcard.id.index = 0;
         wildcard.type = TimingConstraintObject::ANYTHING;
         constraintObjects.push_back(wildcard);
+
+        design_loaded = false;
     }
 
     virtual ~BaseCtx()

frontend/frontend_base.h

@@ -135,6 +135,8 @@ template <typename FrontendType> struct GenericFrontend
         ctx->top_module = top;
         // Do the actual import, starting from the top level module
         import_module(m, top.str(ctx), top.str(ctx), mod_refs.at(top));
+
+        ctx->design_loaded = true;
     }
 
     Context *ctx;