mem-ruby: Appease compiler with return values

Add default values for the cases where gem5 panics to
appease the compiler.

Change-Id: Ib15a63abfb6f1ffed6ce628f52a57388d2173c44
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/46320
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/mem/ruby/slicc_interface/AbstractCacheEntry.hh

@@ -50,10 +50,9 @@
 #include "base/logging.hh"
 #include "mem/cache/replacement_policies/replaceable_entry.hh"
 #include "mem/ruby/common/Address.hh"
+#include "mem/ruby/common/DataBlock.hh"
 #include "mem/ruby/protocol/AccessPermission.hh"
 
-class DataBlock;
-
 class AbstractCacheEntry : public ReplaceableEntry
 {
   private:
@@ -73,8 +72,15 @@ class AbstractCacheEntry : public ReplaceableEntry
 
     // The methods below are those called by ruby runtime, add when it
     // is absolutely necessary and should all be virtual function.
-    virtual DataBlock& getDataBlk()
-    { panic("getDataBlk() not implemented!"); }
+    virtual DataBlock&
+    getDataBlk()
+    {
+        panic("getDataBlk() not implemented!");
+
+        // Dummy return to appease the compiler
+        static DataBlock b;
+        return b;
+    }
 
     int validBlocks;
     virtual int& getNumValidBlocks()

src/mem/slicc/symbols/Type.py

@@ -586,6 +586,8 @@ AccessPermission ${{self.c_ident}}_to_permission(const ${{self.c_ident}}& obj)
       default:
         panic("Unknown state access permission converstion for ${{self.c_ident}}");
     }
+    // Appease the compiler since this function has a return value
+    return AccessPermission_Invalid;
 }
 
 ''')
@@ -626,6 +628,8 @@ ${{self.c_ident}}_to_string(const ${{self.c_ident}}& obj)
       default:
         panic("Invalid range for type ${{self.c_ident}}");
     }
+    // Appease the compiler since this function has a return value
+    return "";
 }
 
 // Code to convert from a string to the enumeration
@@ -689,6 +693,8 @@ ${{self.c_ident}}_base_level(const ${{self.c_ident}}& obj)
       default:
         panic("Invalid range for type ${{self.c_ident}}");
     }
+    // Appease the compiler since this function has a return value
+    return -1;
 }
 
 /** \\brief returns the machine type for each base vector index used by NetDest
@@ -772,6 +778,8 @@ ${{self.c_ident}}_base_count(const ${{self.c_ident}}& obj)
       default:
         panic("Invalid range for type ${{self.c_ident}}");
     }
+    // Appease the compiler since this function has a return value
+    return -1;
 }
 ''')