Move the allocation of CAF blackholes into 'newCAF' (#8590)

We now do the allocation of the blackhole indirection closure inside the
RTS procedure 'newCAF' instead of generating the allocation code inline
in the closure body of each CAF.  This slightly decreases code size in
modules with a lot of CAFs.

As a result of this change, for example, the size of DynFlags.o drops by
~60KB and HsExpr.o by ~100KB.

1 files changed, 27 insertions, 13 deletions

diff --git a/rts/sm/Storage.c b/rts/sm/Storage.c
index b5f3202887..755b3d9f00 100644
--- a/rts/sm/Storage.c
+++ b/rts/sm/Storage.c
@@ -333,9 +333,12 @@ freeStorage (rtsBool free_heap)
 
    -------------------------------------------------------------------------- */
 
-STATIC_INLINE StgWord lockCAF (StgIndStatic *caf, StgClosure *bh)
+STATIC_INLINE StgInd *
+lockCAF (StgRegTable *reg, StgIndStatic *caf)
 {
     const StgInfoTable *orig_info;
+    Capability *cap = regTableToCapability(reg);
+    StgInd *bh;
 
     orig_info = caf->header.info;
 
@@ -345,7 +348,7 @@ STATIC_INLINE StgWord lockCAF (StgIndStatic *caf, StgClosure *bh)
     if (orig_info == &stg_IND_STATIC_info ||
         orig_info == &stg_WHITEHOLE_info) {
         // already claimed by another thread; re-enter the CAF
-        return 0;
+        return NULL;
     }
 
     cur_info = (const StgInfoTable *)
@@ -355,7 +358,7 @@ STATIC_INLINE StgWord lockCAF (StgIndStatic *caf, StgClosure *bh)
 
     if (cur_info != orig_info) {
         // already claimed by another thread; re-enter the CAF
-        return 0;
+        return NULL;
     }
 
     // successfully claimed by us; overwrite with IND_STATIC
@@ -364,17 +367,25 @@ STATIC_INLINE StgWord lockCAF (StgIndStatic *caf, StgClosure *bh)
     // For the benefit of revertCAFs(), save the original info pointer
     caf->saved_info = orig_info;
 
-    caf->indirectee = bh;
+    // Allocate the blackhole indirection closure
+    bh = (StgInd *)allocate(cap, sizeofW(*bh));
+    SET_HDR(bh, &stg_CAF_BLACKHOLE_info, caf->header.prof.ccs);
+    bh->indirectee = (StgClosure *)cap->r.rCurrentTSO;
+
+    caf->indirectee = (StgClosure *)bh;
     write_barrier();
     SET_INFO((StgClosure*)caf,&stg_IND_STATIC_info);
 
-    return 1;
+    return bh;
 }
 
-StgWord
-newCAF(StgRegTable *reg, StgIndStatic *caf, StgClosure *bh)
+StgInd *
+newCAF(StgRegTable *reg, StgIndStatic *caf)
 {
-    if (lockCAF(caf,bh) == 0) return 0;
+    StgInd *bh;
+
+    bh = lockCAF(reg, caf);
+    if (!bh) return NULL;
 
     if(keepCAFs)
     {
@@ -418,7 +429,7 @@ newCAF(StgRegTable *reg, StgIndStatic *caf, StgClosure *bh)
 #endif
     }
 
-    return 1;
+    return bh;
 }
 
 // External API for setting the keepCAFs flag. see #3900.
@@ -437,10 +448,13 @@ setKeepCAFs (void)
 //
 // The linker hackily arranges that references to newCaf from dynamic
 // code end up pointing to newDynCAF.
-StgWord
-newDynCAF (StgRegTable *reg STG_UNUSED, StgIndStatic *caf, StgClosure *bh)
+StgInd *
+newDynCAF (StgRegTable *reg, StgIndStatic *caf)
 {
-    if (lockCAF(caf,bh) == 0) return 0;
+    StgInd *bh;
+
+    bh = lockCAF(reg, caf);
+    if (!bh) return NULL;
 
     ACQUIRE_SM_LOCK;
 
@@ -449,7 +463,7 @@ newDynCAF (StgRegTable *reg STG_UNUSED, StgIndStatic *caf, StgClosure *bh)
 
     RELEASE_SM_LOCK;
 
-    return 1;
+    return bh;
 }
 
 /* -----------------------------------------------------------------------------