Add support for synthesis translate meta-comments.

lexor.lex

@@ -134,9 +134,12 @@ TU [munpf]
 \n { yylloc.first_line += 1; }
 
   /* C++ style comments start with / / and run to the end of the
-     current line. These are very easy to handle. */
+     current line. These are very easy to handle. The meta-comments
+     format is a little more tricky to handle, but do what we can. */
 
-"//".* { comment_enter = YY_START; BEGIN(LCOMMENT); }
+"//"{W}*"synthesis"{W}*"translate_on"{W}*\n { return K_MC_TRANSLATE_ON; }
+"//"{W}*"synthesis"{W}*"translate_off"{W}*\n { return K_MC_TRANSLATE_OFF; }
+"//" { comment_enter = YY_START; BEGIN(LCOMMENT); }
 <LCOMMENT>.    { yymore(); }
 <LCOMMENT>\n   { yylloc.first_line += 1; BEGIN(comment_enter); }
 

parse.y

@@ -532,6 +532,8 @@ static void current_function_set_statement(const YYLTYPE&loc, vector<Statement*>
 %token K_resolveto K_sin K_sinh K_slew K_split K_sqrt K_tan K_tanh
 %token K_timer K_transition K_units K_white_noise K_wreal
 %token K_zi_nd K_zi_np K_zi_zd K_zi_zp
+ /* Support some meta-comments as pragmas. */
+%token K_MC_TRANSLATE_ON K_MC_TRANSLATE_OFF
 
 %type <flag>    from_exclude
 %type <number>  number pos_neg_number
@@ -4246,6 +4248,13 @@ module_item
   /* Modules can contain further sub-module definitions. */
   : module
 
+    /* The lexor detects "// synthesis translate_on/off" meta-comments,
+       we handle them here by turning on/off a flag. The pform uses
+       that flag to attach implicit attributes to "initial" and
+       "always" statements. */
+  | K_MC_TRANSLATE_OFF { pform_mc_translate_on(false); }
+  | K_MC_TRANSLATE_ON { pform_mc_translate_on(true); }
+
   | attribute_list_opt net_type data_type_or_implicit delay3_opt net_variable_list ';'
 
       { data_type_t*data_type = $3;

pform.cc

@@ -43,6 +43,15 @@
 # include  "ivl_assert.h"
 # include  "ivl_alloc.h"
 
+/*
+ * The "// synthesis translate_on/off" meta-comments cause this flag
+ * to be turned off or on. The pform_make_behavior and similar
+ * functions look at this flag and may choose to add implicit ivl
+ * synthesis flags.
+ */
+static bool pform_mc_translate_flag = true;
+void pform_mc_translate_on(bool flag) { pform_mc_translate_flag = flag; }
+
 /*
  * The pform_modules is a map of the modules that have been defined in
  * the top level. This should not contain nested modules/programs.
@@ -3197,6 +3206,18 @@ PProcess* pform_make_behavior(ivl_process_type_t type, Statement*st,
 {
       PProcess*pp = new PProcess(type, st);
 
+	// If we are in a part of the code where the meta-comment
+	// synthesis translate_off is in effect, then implicitly add
+	// the ivl_synthesis_off attribute to any behavioral code that
+	// we run into.
+      if (pform_mc_translate_flag == false) {
+	    if (attr == 0) attr = new list<named_pexpr_t>;
+	    named_pexpr_t tmp;
+	    tmp.name = perm_string::literal("ivl_synthesis_off");
+	    tmp.parm = 0;
+	    attr->push_back(tmp);
+      }
+
       pform_bind_attributes(pp->attributes, attr);
 
       pform_put_behavior_in_scope(pp);

pform.h

@@ -406,6 +406,7 @@ extern void pform_module_specify_path(PSpecPath*obj);
  */
 extern PProcess*  pform_make_behavior(ivl_process_type_t, Statement*,
 				      list<named_pexpr_t>*attr);
+extern void pform_mc_translate_on(bool flag);
 
 extern std::vector<PWire*>* pform_make_udp_input_ports(list<perm_string>*);