Documentation and refactoring in CCS related code

- Remove REGISTER_CC and REGISTER_CCS macros, add functions registerCC
  and registerCCS to Profiling.c.

- Reduce scope of symbols: CC_LIST, CCS_LIST, CC_ID, CCS_ID

- Document CC_LIST and CCS_LIST

2 files changed, 56 insertions, 33 deletions

diff --git a/rts/Profiling.c b/rts/Profiling.c
index 70bf3750e3..3c7f52b6f4 100644
--- a/rts/Profiling.c
+++ b/rts/Profiling.c
@@ -43,8 +43,8 @@ static Arena *prof_arena;
  * closure_cats
  */
 
-unsigned int CC_ID  = 1;
-unsigned int CCS_ID = 1;
+static unsigned int CC_ID  = 1;
+static unsigned int CCS_ID = 1;
 
 /* Globals for opening the profiling log file(s)
  */
@@ -54,11 +54,11 @@ FILE *prof_file;
 static char *hp_filename;       /* heap profile (hp2ps style) log file */
 FILE *hp_file;
 
-/* Linked lists to keep track of CCs and CCSs that haven't
- * been declared in the log file yet
- */
+// List of all cost centres. Used for reporting.
 CostCentre      *CC_LIST  = NULL;
-CostCentreStack *CCS_LIST = NULL;
+// All cost centre stacks temporarily appear here, to be able to make CCS_MAIN a
+// parent of all cost centres stacks (done in initProfiling2()).
+static CostCentreStack *CCS_LIST = NULL;
 
 #if defined(THREADED_RTS)
 static Mutex ccs_mutex;
@@ -125,6 +125,8 @@ static  IndexTable *      addToIndexTable ( IndexTable *, CostCentreStack *,
                                             CostCentre *, bool );
 static  void              ccsSetSelected  ( CostCentreStack *ccs );
 static  void              aggregateCCCosts( CostCentreStack *ccs );
+static  void              registerCC      ( CostCentre *cc );
+static  void              registerCCS     ( CostCentreStack *ccs );
 
 static  void              initTimeProfiling    ( void );
 static  void              initProfilingLogFile ( void );
@@ -158,21 +160,21 @@ void initProfiling (void)
     /* Register all the cost centres / stacks in the program
      * CC_MAIN gets link = 0, all others have non-zero link.
      */
-    REGISTER_CC(CC_MAIN);
-    REGISTER_CC(CC_SYSTEM);
-    REGISTER_CC(CC_GC);
-    REGISTER_CC(CC_OVERHEAD);
-    REGISTER_CC(CC_DONT_CARE);
-    REGISTER_CC(CC_PINNED);
-    REGISTER_CC(CC_IDLE);
-
-    REGISTER_CCS(CCS_SYSTEM);
-    REGISTER_CCS(CCS_GC);
-    REGISTER_CCS(CCS_OVERHEAD);
-    REGISTER_CCS(CCS_DONT_CARE);
-    REGISTER_CCS(CCS_PINNED);
-    REGISTER_CCS(CCS_IDLE);
-    REGISTER_CCS(CCS_MAIN);
+    registerCC(CC_MAIN);
+    registerCC(CC_SYSTEM);
+    registerCC(CC_GC);
+    registerCC(CC_OVERHEAD);
+    registerCC(CC_DONT_CARE);
+    registerCC(CC_PINNED);
+    registerCC(CC_IDLE);
+
+    registerCCS(CCS_SYSTEM);
+    registerCCS(CCS_GC);
+    registerCCS(CCS_OVERHEAD);
+    registerCCS(CCS_DONT_CARE);
+    registerCCS(CCS_PINNED);
+    registerCCS(CCS_IDLE);
+    registerCCS(CCS_MAIN);
 
     /* find all the registered cost centre stacks, and make them
      * children of CCS_MAIN.
@@ -199,10 +201,9 @@ void initProfiling (void)
 //
 void initProfiling2 (void)
 {
-    CostCentreStack *ccs, *next;
-
     // make CCS_MAIN the parent of all the pre-defined CCSs.
-    for (ccs = CCS_LIST; ccs != NULL; ) {
+    CostCentreStack *next;
+    for (CostCentreStack *ccs = CCS_LIST; ccs != NULL; ) {
         next = ccs->prevStack;
         ccs->prevStack = NULL;
         actualPush_(CCS_MAIN,ccs->cc,ccs);
@@ -312,22 +313,47 @@ endProfiling ( void )
     }
 }
 
+/* -----------------------------------------------------------------------------
+   Registering CCs and CCSs
+
+   Registering a CC or CCS consists of
+     - assigning it a unique ID
+     - linking it onto the list of registered CCs/CCSs
+
+   Cost centres are registered at startup by a C constructor function
+   generated by the compiler (ProfInit.hs) in the _stub.c file for each module.
+ -------------------------------------------------------------------------- */
+
+static void
+registerCC(CostCentre *cc)
+{
+    if (cc->link == NULL) {
+        cc->link = CC_LIST;
+        CC_LIST = cc;
+        cc->ccID = CC_ID++;
+    }
+}
+
+static void registerCCS(CostCentreStack *ccs)
+{
+    if (ccs->prevStack == NULL) {
+        ccs->prevStack = CCS_LIST;
+        CCS_LIST = ccs;
+        ccs->ccsID = CCS_ID++;
+    }
+}
 
-/*
-  These are used in the C stubs produced by the code generator
-  to register code.
- */
 void registerCcList(CostCentre **cc_list)
 {
     for (CostCentre **i = cc_list; *i != NULL; i++) {
-        REGISTER_CC(*i);
+        registerCC(*i);
     }
 }
 
 void registerCcsList(CostCentreStack **cc_list)
 {
     for (CostCentreStack **i = cc_list; *i != NULL; i++) {
-        REGISTER_CCS(*i);
+        registerCCS(*i);
     }
 }
 
diff --git a/rts/RtsSymbols.c b/rts/RtsSymbols.c
index 404756e8cd..6966d6deb9 100644
--- a/rts/RtsSymbols.c
+++ b/rts/RtsSymbols.c
@@ -493,9 +493,6 @@
 #define RTS_PROF_SYMBOLS                        \
       SymI_HasProto(CCS_DONT_CARE)              \
       SymI_HasProto(CC_LIST)                    \
-      SymI_HasProto(CC_ID)                      \
-      SymI_HasProto(CCS_LIST)                   \
-      SymI_HasProto(CCS_ID)                     \
       SymI_HasProto(stg_restore_cccs_info)      \
       SymI_HasProto(enterFunCCS)                \
       SymI_HasProto(pushCostCentre)             \