Implement stack chunks and separate TSO/STACK objects
[ghc.git] / rts / StgStdThunks.cmm
index db9c254..be85999 100644 (file)
 #define RET_PARAMS
 #endif
 
-#define SELECTOR_CODE_UPD(offset) \
+/*
+ * TODO: On return, we can use a more efficient
+ *       untagging (we know the constructor tag).
+ * 
+ * When entering stg_sel_#_upd, we know R1 points to its closure,
+ * so it's untagged.
+ * The payload might be a thunk or a constructor,
+ * so we enter it.
+ *
+ * When returning, we know for sure it is a constructor,
+ * so we untag it before accessing the field.
+ *
+ */
+#ifdef PROFILING
+// When profiling, we cannot shortcut by checking the tag,
+// because LDV profiling relies on entering closures to mark them as
+// "used".
+#define SEL_ENTER(offset)                       \
+      R1 = UNTAG(R1);                           \
+      jump %GET_ENTRY(R1);
+#else
+#define SEL_ENTER(offset)                               \
+      if (GETTAG(R1) != 0) {                            \
+          jump RET_LBL(stg_sel_ret_##offset##_upd);     \
+      }                                                 \
+      jump %GET_ENTRY(R1);
+#endif
+
+#define SELECTOR_CODE_UPD(offset)                                       \
   INFO_TABLE_RET(stg_sel_ret_##offset##_upd, RET_SMALL, RET_PARAMS)    \
   {                                                                    \
-      R1 = StgClosure_payload(R1,offset);                              \
+      R1 = StgClosure_payload(UNTAG(R1),offset);                       \
       GET_SAVED_CCCS;                                                  \
       Sp = Sp + SIZEOF_StgHeader;                                      \
       ENTER();                                                         \
@@ -58,9 +86,9 @@
       ENTER_CCS_THUNK(R1);                                             \
       SAVE_CCCS(WITHUPD_FRAME_SIZE);                                   \
       W_[Sp-WITHUPD_FRAME_SIZE] = stg_sel_ret_##offset##_upd_info;     \
-      R1 = StgThunk_payload(R1,0);                                     \
       Sp = Sp - WITHUPD_FRAME_SIZE;                                    \
-      jump %GET_ENTRY(R1);                                             \
+      R1 = StgThunk_payload(R1,0);                                     \
+      SEL_ENTER(offset);                                                \
   }
   /* NOTE: no need to ENTER() here, we know the closure cannot evaluate to a function,
      because we're going to do a field selection on the result. */
@@ -85,10 +113,10 @@ SELECTOR_CODE_UPD(15)
 #define SELECTOR_CODE_NOUPD(offset) \
   INFO_TABLE_RET(stg_sel_ret_##offset##_noupd, RET_SMALL, RET_PARAMS)  \
   {                                                                    \
-      R1 = StgClosure_payload(R1,offset);                              \
+      R1 = StgClosure_payload(UNTAG(R1),offset);                       \
       GET_SAVED_CCCS;                                                  \
       Sp = Sp + SIZEOF_StgHeader;                                      \
-      jump %GET_ENTRY(R1);                                             \
+      ENTER();                                                         \
   }                                                                    \
                                                                        \
   INFO_TABLE_SELECTOR(stg_sel_##offset##_noupd, offset, THUNK_SELECTOR, "stg_sel_noupd", "stg_sel_noupd")\
@@ -101,8 +129,11 @@ SELECTOR_CODE_UPD(15)
       ENTER_CCS_THUNK(R1);                                             \
       SAVE_CCCS(NOUPD_FRAME_SIZE);                                     \
       W_[Sp-NOUPD_FRAME_SIZE] = stg_sel_ret_##offset##_noupd_info;     \
-      R1 = StgThunk_payload(R1,0);                                     \
       Sp = Sp - NOUPD_FRAME_SIZE;                                      \
+      R1 = StgThunk_payload(R1,0);                                     \
+      if (GETTAG(R1) != 0) {                                            \
+          jump RET_LBL(stg_sel_ret_##offset##_noupd);                  \
+      }                                                                 \
       jump %GET_ENTRY(R1);                                             \
   }
 
@@ -141,7 +172,7 @@ SELECTOR_CODE_NOUPD(15)
  * in the compiler that means stg_ap_1 is generated occasionally (ToDo)
  */
 
-INFO_TABLE(stg_ap_1_upd,1,1,THUNK_1_0,"stg_ap_1_upd_info","stg_ap_1_upd_info")
+INFO_TABLE(stg_ap_1_upd,1,0,THUNK_1_0,"stg_ap_1_upd_info","stg_ap_1_upd_info")
 {
   TICK_ENT_DYN_THK();
   STK_CHK_NP(SIZEOF_StgUpdateFrame+WDS(1));