systemc: Implement sc_gen_unique_name.

The Accellera implementation statically allocates the buffer it uses to
build the unique names and only allocates the name generator if it's
going to be used for a particular module. I assume that's to avoid
allocating a large buffer if it's not going to be used.

In this implementation, I use an std::string which manages its own
memory and so shouldn't need to be selectively allocated. I also use a
string stream to construct the name instead of sprintf.

Change-Id: If92c68586a85b5d27c067a75a6e9ebbf00d8c785
Reviewed-on: https://gem5-review.googlesource.com/12066
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/core/module.hh

@@ -31,7 +31,10 @@
 #define __SYSTEMC_CORE_MODULE_HH__
 
 #include <cassert>
+#include <map>
 #include <set>
+#include <sstream>
+#include <string>
 
 #include "systemc/core/object.hh"
 #include "systemc/ext/core/sc_module.hh"
@@ -39,6 +42,23 @@
 namespace sc_gem5
 {
 
+class UniqueNameGen
+{
+  private:
+    std::map<std::string, int> counts;
+    std::string buf;
+
+  public:
+    const char *
+    gen(std::string seed)
+    {
+        std::ostringstream os;
+        os << seed << "_" << counts[seed]++;
+        buf = os.str();
+        return buf.c_str();
+    }
+};
+
 class Module
 {
   private:
@@ -46,6 +66,8 @@ class Module
     sc_core::sc_module *_sc_mod;
     Object *_obj;
 
+    UniqueNameGen nameGen;
+
   public:
 
     Module(const char *name);
@@ -77,6 +99,8 @@ class Module
     }
 
     void pop();
+
+    const char *uniqueName(const char *seed) { return nameGen.gen(seed); }
 };
 
 Module *currentModule();

src/systemc/core/sc_module.cc

@@ -64,6 +64,8 @@ newCThreadProcess(const char *name, ProcessFuncWrapper *func)
     return p;
 }
 
+UniqueNameGen nameGen;
+
 } // namespace sc_gem5
 
 namespace sc_core
@@ -643,10 +645,11 @@ at_negedge(const sc_signal_in_if<sc_dt::sc_logic> &)
 }
 
 const char *
-sc_gen_unique_name(const char *)
+sc_gen_unique_name(const char *seed)
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
-    return "";
+    ::sc_gem5::Module *mod = ::sc_gem5::currentModule();
+    return mod ? mod->uniqueName(seed) :
+        ::sc_gem5::nameGen.gen(seed);
 }
 
 bool