Experiment with one-byte info tableswip/rwbarton-tiny-tables

2 files changed, 28 insertions, 0 deletions

diff --git a/rts/ThreadPaused.c b/rts/ThreadPaused.c
index 1f1d0afe58..e0e616aec4 100644
--- a/rts/ThreadPaused.c
+++ b/rts/ThreadPaused.c
@@ -219,6 +219,14 @@ threadPaused(Capability *cap, StgTSO *tso)
     frame = (StgClosure *)tso->stackobj->sp;
 
     while ((P_)frame < stack_end) {
+        if (*(P_)frame & 1) {
+            nat frame_size = stack_frame_sizeW(frame);
+            weight_pending += frame_size;
+            frame = (StgClosure *)((StgPtr)frame + frame_size);
+            prev_was_update_frame = rtsFalse;
+            continue;
+        }
+
         info = get_ret_itbl(frame);
 
         switch (info->i.type) {
diff --git a/rts/sm/Scav.c b/rts/sm/Scav.c
index 953f055d57..b6783749c5 100644
--- a/rts/sm/Scav.c
+++ b/rts/sm/Scav.c
@@ -174,6 +174,19 @@ static StgPtr scavenge_mut_arr_ptrs_marked (StgMutArrPtrs *a)
 }
 
 STATIC_INLINE StgPtr
+scavenge_tiny_bitmap (StgPtr p, uint8_t layout)
+{
+    while (layout > 1) {
+        if ((layout & 1) == 0) {
+            evacuate((StgClosure **)p);
+        }
+        p++;
+        layout = layout >> 1;
+    }
+    return p;
+}
+
+STATIC_INLINE StgPtr
 scavenge_small_bitmap (StgPtr p, StgWord size, StgWord bitmap)
 {
     while (size > 0) {
@@ -1807,6 +1820,13 @@ scavenge_stack(StgPtr p, StgPtr stack_end)
    */
 
   while (p < stack_end) {
+    if (*p & 1) {
+        // Tiny liveness layout: no SRT
+        uint8_t liveness = *((uint8_t *)(*p) - 1);
+        p = scavenge_tiny_bitmap(p+1, liveness);
+        continue;
+    }
+
     info  = get_ret_itbl((StgClosure *)p);
 
     switch (info->i.type) {