Add support for the NonmovingPrunedSegments event

See: https://gitlab.haskell.org/ghc/ghc/-/merge_requests/12152

include/EventLogFormat.h

@@ -213,6 +213,7 @@
 #define EVENT_CONC_SWEEP_END               205
 #define EVENT_CONC_UPD_REM_SET_FLUSH       206
 #define EVENT_NONMOVING_HEAP_CENSUS        207
+#define EVENT_NONMOVING_PRUNED_SEGMENTS    208
 
 #define EVENT_TICKY_COUNTER_DEF            210
 #define EVENT_TICKY_COUNTER_SAMPLE         211

src/GHC/RTS/EventTypes.hs

@@ -462,6 +462,14 @@ data EventInfo
                        , nonmovingCensusFilledSegs :: !Word32
                        , nonmovingCensusLiveBlocks :: !Word32
                        }
+  | NonmovingPrunedSegments
+                       { -- | The number of pruned segments.
+                         nonmovingPrunedSegments :: !Word32
+                       -- | The number of leftover free segments.
+                       -- These could not be pruned as they belong to megablocks
+                       -- with at least one non-free segment.
+                       , nonmovingFreeSegments :: !Word32
+                       }
   | TickyCounterDef
                        { tickyCtrDefId      :: !Word64
                        , tickyCtrDefArity   :: !Word16

src/GHC/RTS/Events.hs

@@ -519,6 +519,10 @@ buildEventInfo spec' =
           <> ": " <> TB.decimal nonmovingCensusActiveSegs <> " active segments"
           <> ", " <> TB.decimal nonmovingCensusFilledSegs <> " filled segments"
           <> ", " <> TB.decimal nonmovingCensusLiveBlocks <> " live blocks"
+        NonmovingPrunedSegments {..} ->
+          "nonmoving segments pruned: "
+           <> TB.decimal nonmovingPrunedSegments <> " pruned segments, "
+           <> TB.decimal nonmovingFreeSegments <> " free segments retained"
         TickyCounterDef {..}  ->
           "ticky counter definition " <> TB.decimal tickyCtrDefId
           <> ", " <>  "arity: " <> TB.decimal tickyCtrDefArity

src/GHC/RTS/Events/Binary.hs

@@ -359,6 +359,11 @@ standardParsers = [
       nonmovingCensusLiveBlocks <- get :: Get Word32
       return NonmovingHeapCensus{..}
     )),
+ (FixedSizeParser EVENT_NONMOVING_PRUNED_SEGMENTS 8 (do -- (pruned_segments, free_segments)
+      nonmovingPrunedSegments <- get :: Get Word32
+      nonmovingFreeSegments <- get :: Get Word32
+      return NonmovingPrunedSegments{..}
+    )),
 
  (FixedSizeParser EVENT_CREATE_THREAD sz_tid (do  -- (thread)
       t <- get
@@ -991,6 +996,7 @@ eventTypeNum e = case e of
     ConcSweepEnd {} -> EVENT_CONC_SWEEP_END
     ConcUpdRemSetFlush {} -> EVENT_CONC_UPD_REM_SET_FLUSH
     NonmovingHeapCensus {} -> EVENT_NONMOVING_HEAP_CENSUS
+    NonmovingPrunedSegments {} -> EVENT_NONMOVING_PRUNED_SEGMENTS
     TickyCounterDef {} -> EVENT_TICKY_COUNTER_DEF
     TickyCounterSample {} -> EVENT_TICKY_COUNTER_SAMPLE
     InfoTableProv {} -> EVENT_IPE
@@ -1446,6 +1452,9 @@ putEventSpec NonmovingHeapCensus {..} = do
     putE nonmovingCensusActiveSegs
     putE nonmovingCensusFilledSegs
     putE nonmovingCensusLiveBlocks
+putEventSpec NonmovingPrunedSegments {..} = do
+    putE nonmovingPrunedSegments
+    putE nonmovingFreeSegments
 putEventSpec TickyCounterDef {..} = do
     putE tickyCtrDefId
     putE tickyCtrDefArity

test/Utils.hs

@@ -5,6 +5,7 @@ files = map ("test/"++)
     [ "nonmoving-gc.eventlog"
     , "nonmoving-gc-census.eventlog"
     , "nonmoving-gc-census-T23340.eventlog"
+    , "nonmoving-gc-pruned-segments.eventlog"
     , "parallelTest.eventlog"
     , "sleep.h.eventlog"
     , "sleep.hC.eventlog"