Remove the -xt heap profiling optionwip/remove-xt

It should be left to tooling to perform the filtering to remove these
specific closure types from the profile if desired.

Fixes #16795

9 files changed, 7 insertions, 60 deletions

diff --git a/docs/users_guide/9.2.1-notes.rst b/docs/users_guide/9.2.1-notes.rst
index 06134387f3..9812279849 100644
--- a/docs/users_guide/9.2.1-notes.rst
+++ b/docs/users_guide/9.2.1-notes.rst
@@ -114,10 +114,13 @@ Runtime system
   Moreover, we now correctly account for the size of the array, meaning that
   space lost to fragmentation is no longer counted as live data.
 
-
 - The :rts-flag:`-h` flag has been deprecated, use either :rts-flag:`-hc` or
   :rts-flag:`-hT` explicitly, as appropriate.
 
+- The ``-xt`` RTS flag has been removed. Now STACK and TSO closures are always
+  included in heap profiles. Tooling can choose to filter out these closure types
+  if necessary.
+
 ``ghc-prim`` library
 ~~~~~~~~~~~~~~~~~~~~
 
diff --git a/docs/users_guide/profiling.rst b/docs/users_guide/profiling.rst
index 2463654837..1eddcb7160 100644
--- a/docs/users_guide/profiling.rst
+++ b/docs/users_guide/profiling.rst
@@ -886,20 +886,6 @@ There are three more options which relate to heap profiling:
     profiles are always sampled with the frequency of the RTS clock. See
     :ref:`prof-time-options` for changing that.
 
-.. rts-flag:: -xt
-
-    Include the memory occupied by threads in a heap profile. Each
-    thread takes up a small area for its thread state in addition to the
-    space allocated for its stack (stacks normally start small and then
-    grow as necessary).
-
-    This includes the main thread, so using :rts-flag:`-xt` is a good way to see
-    how much stack space the program is using.
-
-    Memory occupied by threads and their stacks is labelled as “TSO” and
-    “STACK” respectively when displaying the profile by closure
-    description or type description.
-
 .. rts-flag:: -L ⟨num⟩
 
     Sets the maximum length of a cost-centre stack name in a heap
@@ -1049,9 +1035,6 @@ reasons for this:
    ⟨factor⟩` option. Also add the size of the allocation area (see :rts-flag:`-A
    ⟨size⟩`).
 
--  The stack isn't counted in the heap profile by default. See the
-   RTS :rts-flag:`-xt` option.
-
 -  The program text itself, the C stack, any non-heap data (e.g. data
    allocated by foreign libraries, and data allocated by the RTS), and
    ``mmap()``\'d memory are not counted in the heap profile.
diff --git a/includes/rts/Flags.h b/includes/rts/Flags.h
index 35b45b0940..36ea11426c 100644
--- a/includes/rts/Flags.h
+++ b/includes/rts/Flags.h
@@ -144,7 +144,6 @@ typedef struct _PROFILING_FLAGS {
 
     Time        heapProfileInterval; /* time between samples */
     uint32_t    heapProfileIntervalTicks; /* ticks between samples (derived) */
-    bool        includeTSOs;
 
 
     bool		showCCSOnException;
diff --git a/libraries/base/GHC/RTS/Flags.hsc b/libraries/base/GHC/RTS/Flags.hsc
index b23ae34165..2130ee1aaa 100644
--- a/libraries/base/GHC/RTS/Flags.hsc
+++ b/libraries/base/GHC/RTS/Flags.hsc
@@ -288,7 +288,6 @@ data ProfFlags = ProfFlags
     { doHeapProfile            :: DoHeapProfile
     , heapProfileInterval      :: RtsTime -- ^ time between samples
     , heapProfileIntervalTicks :: Word    -- ^ ticks between samples (derived)
-    , includeTSOs              :: Bool
     , showCCSOnException       :: Bool
     , maxRetainerSetSize       :: Word
     , ccsLength                :: Word
@@ -585,8 +584,6 @@ getProfFlags = do
             <*> #{peek PROFILING_FLAGS, heapProfileInterval} ptr
             <*> #{peek PROFILING_FLAGS, heapProfileIntervalTicks} ptr
             <*> (toBool <$>
-                  (#{peek PROFILING_FLAGS, includeTSOs} ptr :: IO CBool))
-            <*> (toBool <$>
                   (#{peek PROFILING_FLAGS, showCCSOnException} ptr :: IO CBool))
             <*> #{peek PROFILING_FLAGS, maxRetainerSetSize} ptr
             <*> #{peek PROFILING_FLAGS, ccsLength} ptr
diff --git a/rts/ProfHeap.c b/rts/ProfHeap.c
index 0bd8423b4c..f880f5f406 100644
--- a/rts/ProfHeap.c
+++ b/rts/ProfHeap.c
@@ -1179,35 +1179,13 @@ heapCensusBlock(Census *census, bdescr *bd)
 
         case TSO:
             prim = true;
-#if defined(PROFILING)
-            if (RtsFlags.ProfFlags.includeTSOs) {
-                size = sizeofW(StgTSO);
-                break;
-            } else {
-                // Skip this TSO and move on to the next object
-                p += sizeofW(StgTSO);
-                continue;
-            }
-#else
             size = sizeofW(StgTSO);
             break;
-#endif
 
         case STACK:
             prim = true;
-#if defined(PROFILING)
-            if (RtsFlags.ProfFlags.includeTSOs) {
-                size = stack_sizeW((StgStack*)p);
-                break;
-            } else {
-                // Skip this TSO and move on to the next object
-                p += stack_sizeW((StgStack*)p);
-                continue;
-            }
-#else
             size = stack_sizeW((StgStack*)p);
             break;
-#endif
 
         case TREC_CHUNK:
             prim = true;
diff --git a/rts/RtsFlags.c b/rts/RtsFlags.c
index 380ccc3afc..f592f246db 100644
--- a/rts/RtsFlags.c
+++ b/rts/RtsFlags.c
@@ -214,7 +214,6 @@ void initRtsFlagsDefaults(void)
     RtsFlags.ProfFlags.heapProfileInterval = USToTime(100000); // 100ms
 
 #if defined(PROFILING)
-    RtsFlags.ProfFlags.includeTSOs        = false;
     RtsFlags.ProfFlags.showCCSOnException = false;
     RtsFlags.ProfFlags.maxRetainerSetSize = 8;
     RtsFlags.ProfFlags.ccsLength          = 25;
@@ -1686,11 +1685,9 @@ error = true;
 
                 case 't':  /* Include memory used by TSOs in a heap profile */
                     OPTION_SAFE;
-                    PROFILING_BUILD_ONLY(
-                        RtsFlags.ProfFlags.includeTSOs = true;
-                        );
-                    unchecked_arg_start++;
-                    goto check_rest;
+                    errorBelch("The -xt option has been removed (#16795)");
+                    error = true;
+                    break;
 
                   /*
                    * The option prefix '-xx' is reserved for future
diff --git a/testsuite/tests/rts/T9839_06.hs b/testsuite/tests/rts/T9839_06.hs
deleted file mode 100755
index d82a4bd93b..0000000000
--- a/testsuite/tests/rts/T9839_06.hs
+++ /dev/null
@@ -1,4 +0,0 @@
-module Main where
-
-main :: IO ()
-main = return ()
diff --git a/testsuite/tests/rts/T9839_06.stderr b/testsuite/tests/rts/T9839_06.stderr
deleted file mode 100644
index 016eed0376..0000000000
--- a/testsuite/tests/rts/T9839_06.stderr
+++ /dev/null
@@ -1 +0,0 @@
-T9839_06: flag -x given an argument when none was expected: -xtx
diff --git a/testsuite/tests/rts/all.T b/testsuite/tests/rts/all.T
index 4d30601e08..a5a57b6a8c 100644
--- a/testsuite/tests/rts/all.T
+++ b/testsuite/tests/rts/all.T
@@ -309,11 +309,6 @@ test('T9839_05',
       grep_stderr('given an argument when none was expected')],
      compile_and_run, [''])
 
-test('T9839_06',
-     [only_ways(prof_ways), extra_run_opts('+RTS -xtx'), no_check_hp,
-      grep_stderr('given an argument when none was expected')],
-     compile_and_run, [''])
-
 # ignore_stderr as RTS reports slightly different error messages
 # in 'epoll' and 'select' backends on reading from EBADF
 # mingw32 skip as UNIX pipe and close(fd) is used to exercise the problem