Custom edif backend (#2030)

This allows us to use latest yosys. The upstream edif pass introduced
changes which are incompatible with SystemVerilog.

This should unblock #2008

frontends/systemverilog/Build.mk

@@ -12,6 +12,7 @@ ${ts}.sources := \
 	${${ts}.src_dir}uhdm_ast_frontend.cc \
 	${${ts}.src_dir}uhdm_common_frontend.cc \
 	${${ts}.src_dir}uhdm_surelog_ast_frontend.cc \
+	${$(call GetTargetStructName,yosys).mod_dir}edif.cc \
 	${$(call GetTargetStructName,yosys).mod_dir}const2ast.cc \
 	${$(call GetTargetStructName,yosys).mod_dir}simplify.cc
 

frontends/systemverilog/uhdm_common_frontend.cc

@@ -18,6 +18,7 @@
  */
 
 #include "uhdm_common_frontend.h"
+#include "edif.h"
 
 namespace systemverilog_plugin
 {
@@ -30,6 +31,8 @@ static void set_line_num(int) {}
 /* Stub for AST::process */
 static int get_line_num(void) { return 1; }
 
+UhdmCommonFrontend::UhdmCommonFrontend(std::string name, std::string short_help) : Frontend(name, short_help) { register_synlig_edif_backend(); }
+
 void UhdmCommonFrontend::print_read_options()
 {
     log("    -noassert\n");

frontends/systemverilog/uhdm_common_frontend.h

@@ -49,7 +49,7 @@ static inline ObjT *make_new_object_with_optional_extra_true_arg(ArgN &&...arg_n
 struct UhdmCommonFrontend : public ::Yosys::Frontend {
     UhdmAstShared shared;
     std::vector<std::string> args;
-    UhdmCommonFrontend(std::string name, std::string short_help) : Frontend(name, short_help) {}
+    UhdmCommonFrontend(std::string name, std::string short_help);
     virtual void print_read_options();
     virtual void help() = 0;
     virtual ::Yosys::AST::AstNode *parse(std::string filename) = 0;