Revert "rts: Refactor handling of dead threads' stacks"

This reverts commit e09afbf2a998beea7783e3de5dce5dd3c6ff23db.

6 files changed, 9 insertions, 30 deletions

diff --git a/rts/Schedule.c b/rts/Schedule.c
index 9b1e98ea17..fa48bef1a7 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -1315,9 +1315,7 @@ scheduleHandleThreadFinished (Capability *cap, Task *task, StgTSO *t)
           if (t->what_next == ThreadComplete) {
               if (task->incall->ret) {
                   // NOTE: return val is stack->sp[1] (see StgStartup.cmm)
-                  StgDeadThreadFrame *dead = (StgDeadThreadFrame *) &task->incall->tso->stackobj->sp[0];
-                  ASSERT(dead->header.info == &stg_dead_thread_info);
-                  *(task->incall->ret) = (StgClosure *) dead->result;
+                  *(task->incall->ret) = (StgClosure *)task->incall->tso->stackobj->sp[1];
               }
               task->incall->rstat = Success;
           } else {
diff --git a/rts/StgMiscClosures.cmm b/rts/StgMiscClosures.cmm
index dbdd2d71fa..b9aee516d0 100644
--- a/rts/StgMiscClosures.cmm
+++ b/rts/StgMiscClosures.cmm
@@ -414,16 +414,6 @@ INFO_TABLE_RET( stg_apply_interp, RET_BCO )
     jump stg_yield_to_interpreter [];
 }
 
-/*
- * Dummy info table pushed on the top of the stack when the stack's
- * owning thread has finished.
- */
-INFO_TABLE_RET( stg_dead_thread, RET_SMALL,
-                W_ info_ptr,
-                PROF_HDR_FIELDS(W_,p1,p2)
-                P_ result )
-{ foreign "C" barf("stg_dead_thread entered!") never returns; }
-
 /* ----------------------------------------------------------------------------
    Entry code for a BCO
    ------------------------------------------------------------------------- */
diff --git a/rts/StgStartup.cmm b/rts/StgStartup.cmm
index 6d3d47f54f..122eace1f3 100644
--- a/rts/StgStartup.cmm
+++ b/rts/StgStartup.cmm
@@ -51,13 +51,13 @@ INFO_TABLE_RET(stg_stop_thread, STOP_FRAME,
 
        We Leave the stack looking like this:
 
-                +----------------------+
-                |      -----------------------> return value
-                +----------------------+
-                | stg_dead_thread_info |
-                +----------------------+
+                +----------------+
+                |      -------------------> return value
+                +----------------+
+                | stg_enter_info |
+                +----------------+
 
-       The stg_dead_thread_info is just a dummy info table so that the
+       The stg_enter_info is just a dummy info table so that the
        garbage collector can understand the stack (there must always
        be an info table on top of the stack).
     */
@@ -70,9 +70,9 @@ INFO_TABLE_RET(stg_stop_thread, STOP_FRAME,
     unwind UnwindReturnReg = return;
 #endif
 
-    Sp = Sp + SIZEOF_StgStopFrame - SIZEOF_StgDeadThreadFrame;
-    Sp(0) = stg_dead_thread_info;
+    Sp = Sp + SIZEOF_StgStopFrame - WDS(2);
     Sp(1) = R1;
+    Sp(0) = stg_enter_info;
 
     StgTSO_what_next(CurrentTSO) = ThreadComplete::I16;
 
diff --git a/rts/include/rts/storage/Closures.h b/rts/include/rts/storage/Closures.h
index 09c7bfdb88..bfc8308c29 100644
--- a/rts/include/rts/storage/Closures.h
+++ b/rts/include/rts/storage/Closures.h
@@ -285,13 +285,6 @@ typedef struct {
     StgHeader  header;
 } StgStopFrame;
 
-// Stack frame indicating that the stack's owning thread has finished.
-//
-// Closure types: RET_SMALL
-typedef struct {
-    StgHeader  header;
-    StgClosure *result;
-} StgDeadThreadFrame;
 
 // A function return stack frame: used when saving the state for a
 // garbage collection at a function entry point.  The function
diff --git a/rts/include/stg/MiscClosures.h b/rts/include/stg/MiscClosures.h
index b5efd9636b..e87eba0931 100644
--- a/rts/include/stg/MiscClosures.h
+++ b/rts/include/stg/MiscClosures.h
@@ -159,7 +159,6 @@ RTS_RET(stg_ctoi_t61);
 RTS_RET(stg_ctoi_t62);
 
 RTS_RET(stg_apply_interp);
-RTS_RET(stg_dead_thread);
 
 RTS_ENTRY(stg_IND);
 RTS_ENTRY(stg_IND_STATIC);
diff --git a/utils/deriveConstants/Main.hs b/utils/deriveConstants/Main.hs
index 1619f5588c..9a57ecf682 100644
--- a/utils/deriveConstants/Main.hs
+++ b/utils/deriveConstants/Main.hs
@@ -421,7 +421,6 @@ wanteds os = concat
           ,closureSize Both "StgUpdateFrame"
           ,closureSize C    "StgCatchFrame"
           ,closureSize C    "StgStopFrame"
-          ,closureSize C    "StgDeadThreadFrame"
 
           ,closureSize  Both "StgMutArrPtrs"
           ,closureField Both "StgMutArrPtrs" "ptrs"