diff.patch

diff --git a/src/gc/debug.h b/src/gc/debug.h
index 1dd4f17bb..6daf4c9ef 100644
--- a/src/gc/debug.h
+++ b/src/gc/debug.h
@@ -3,7 +3,7 @@
  * 1 = Checks on reference assignments and other relatively cheap cases
  * 2 = Checks on every object register access (slow)
  */
-#define MVM_GC_DEBUG 0
+#define MVM_GC_DEBUG 2
 
 #if MVM_GC_DEBUG
 #define MVM_ASSERT_NOT_FROMSPACE(tc, c) do { \
diff --git a/src/gc/worklist.h b/src/gc/worklist.h
index 062f383d8..9725ca934 100644
--- a/src/gc/worklist.h
+++ b/src/gc/worklist.h
@@ -1,3 +1,4 @@
+#include "memdebug.h"
 /* A worklist holds the current set of pointers we have got in the queue
  * to scan. We hide away the details of it behind this abstraction since
  * the order in which we hand things back from it can have a big influence
@@ -48,9 +49,12 @@ struct MVMGCWorklist {
             else if (((*item_to_add)->flags & MVM_CF_STABLE) == 0 && !STABLE(*item_to_add)) \
                 MVM_panic(1, "NULL STable in item added to GC worklist"); \
             if ((char *)*item_to_add >= (char *)tc->nursery_alloc && \
-                    (char *)*item_to_add < (char *)tc->nursery_alloc_limit) \
+                    (char *)*item_to_add < (char *)tc->nursery_alloc_limit) { \
+                char command[128]; snprintf(&command, 128, "who_points_at %p", *item_to_add); VALGRIND_MONITOR_COMMAND(command); \
+                VALGRIND_PRINTF_BACKTRACE("valgrind gc_worklist_add: Adding pointer %p to past fromspace to GC worklist", *item_to_add); \
                 MVM_panic(1, "Adding pointer %p to past fromspace to GC worklist", \
                     *item_to_add); \
+            } \
         } \
         if (*item_to_add && (worklist->include_gen2 || !((*item_to_add)->flags & MVM_CF_SECOND_GEN))) { \
             if (worklist->items == worklist->alloc) \

valgrind.log

[dan@alexandria p6-mqtt]$ MVM_JIT_DISABLE=1 pv6 --profile -I lib/ t/regex.t 
================================================================================================
This is Rakudo Perl 6 running in valgrind, a tool for debugging and profiling programs.
Running a program in valgrind usually takes *a lot* more time than running it directly,
so please be patient.
Valgrind options can be added with MVM_VALGRIND_OPTS environment variable.

This Rakudo version is 2019.03.1.248.g.4.e.677.f.048 built on MoarVM version 2019.03.102.g.423.a.9.cc.7.d,
running on arch (5.0.8.arch.1.1.arch) / linux (1.SMP.PREEMPT.Wed.Mar.27.17.53.10.UTC.2019)
------------------------------------------------------------------------------------------------
==29731== Memcheck, a memory error detector
==29731== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==29731== Using Valgrind-3.14.0 and LibVEX; rerun with -h for copyright info
==29731== Command: /home/dan/Source/perl6/install/bin/perl6-m --profile -I lib/ t/regex.t
==29731== 
ok 1 - 4.7.1.2, 'sport/tennis/player1' should match 'sport/tennis/player1/ \#'
ok 2 - 4.7.1.2, 'sport/tennis/player1/ranking' should match 'sport/tennis/player1/ \#'
ok 3 - 4.7.1.2, 'sport/tennis/player1/wimbledon' should match 'sport/tennis/player1/ \#'
ok 4 - 4.7.1.2, 'sport' should match 'sport/ \#'
ok 5 - 4.7.1.3, 'sport/tennis/player1' should match 'sport/tennis/+'
ok 6 - 4.7.1.3, 'sport/tennis/player2' should match 'sport/tennis/+'
ok 7 - 4.7.1.3, 'sport/tennis/player1/ranking' should not match 'sport/tennis/+'
ok 8 - 4.7.1.3, 'sport' should not match 'sport/+'
ok 9 - 4.7.1.3, 'sport/' should match 'sport/+'
ok 10 - 4.7.2.1, '$SYS/something' should not match ' \#'
ok 11 - 4.7.2.1, '$SYS/monitor/Clients' should not match '+/monitor/Clients'
==29731== Searching for pointers to 0x597e3c8
==29731== *0x597e378 points at 0x597e3c8
==29731==  Address 0x597e378 is 1,307,448 bytes inside a block of size 4,194,304 alloc'd
==29731==    at 0x483AB65: calloc (vg_replace_malloc.c:752)
==29731==    by 0x4A4EB83: MVM_calloc (alloc.h:11)
==29731==    by 0x4A4EB83: MVM_tc_create (threadcontext.c:16)
==29731==    by 0x4B5CFD8: MVM_vm_create_instance (moar.c:89)
==29731==    by 0x109EE0: main (main.c:319)
==29731== *0xce60598 points at 0x597e3c8
==29731==  Address 0xce60598 is 1,608 bytes inside a block of size 2,112 alloc'd
==29731==    at 0x483AD7B: realloc (vg_replace_malloc.c:826)
==29731==    by 0x4B56868: MVM_realloc (alloc.h:20)
==29731==    by 0x4B56868: MVM_profiler_log_gc_deallocate (log.c:320)
==29731==    by 0x4A84050: MVM_gc_collect_free_nursery_uncopied (collect.c:629)
==29731==    by 0x4A7A6CE: finish_gc (orchestrate.c:237)
==29731==    by 0x4A7A6CE: run_gc (orchestrate.c:412)
==29731==    by 0x4A7B1CE: MVM_gc_enter_from_allocator (orchestrate.c:525)
==29731==    by 0x4A7B545: MVM_gc_allocate_nursery (allocation.c:35)
==29731==    by 0x4A7B87E: MVM_gc_allocate_object (allocation.c:89)
==29731==    by 0x4A563AB: MVM_frame_takeclosure (frame.c:1195)
==29731==    by 0x4A40E47: MVM_interp_run (interp.c:1230)
==29731==    by 0x4B5DF24: MVM_vm_run_file (moar.c:444)
==29731==    by 0x109FB8: main (main.c:341)
==29731== tid 1 register R11 pointing at 0x597e3c8
**29731** valgrind gc_worklist_add: Adding pointer 0x597E3C8 to past fromspace to GC worklist   at 0x4B533A5: VALGRIND_PRINTF_BACKTRACE.constprop.6 (valgrind.h:6306)
==29731==    by 0x4B55AC9: mark_gc_entries (instrument.c:807)
==29731==    by 0x4B55AC9: MVM_profile_instrumented_mark_data (instrument.c:830)
==29731==    by 0x4A7E8E7: MVM_gc_root_add_tc_roots_to_worklist (roots.c:191)
==29731==    by 0x4A839B7: MVM_gc_collect (collect.c:122)
==29731==    by 0x4A7A5AE: run_gc (orchestrate.c:408)
==29731==    by 0x4A7B1CE: MVM_gc_enter_from_allocator (orchestrate.c:525)
==29731==    by 0x4A7B545: MVM_gc_allocate_nursery (allocation.c:35)
==29731==    by 0x4A7B87E: MVM_gc_allocate_object (allocation.c:89)
==29731==    by 0x4A1E171: MVM_args_set_result_str (args.c:543)
==29731==    by 0x4A2CED2: MVM_interp_run (interp.c:528)
==29731==    by 0x4B5DF24: MVM_vm_run_file (moar.c:444)
==29731==    by 0x109FB8: main (main.c:341)
MoarVM panic: Adding pointer 0x597e3c8 to past fromspace to GC worklist
==29731== 
==29731== HEAP SUMMARY:
==29731==     in use at exit: 88,994,291 bytes in 300,401 blocks
==29731==   total heap usage: 773,771 allocs, 241,677 frees, 304,705,706 bytes allocated
==29731== 

Memcheck: mc_main.c:5761 (vgMemCheck_is_valid_aligned_word): Assertion 'VG_IS_WORD_ALIGNED(a)' failed.

host stacktrace:
==29731==    at 0x58048114: show_sched_status_wrk (m_libcassert.c:369)
==29731==    by 0x58048227: report_and_quit (m_libcassert.c:440)
==29731==    by 0x580483B9: vgPlain_assert_fail (m_libcassert.c:506)
==29731==    by 0x58012C29: vgMemCheck_is_valid_aligned_word (mc_main.c:5761)
==29731==    by 0x580017A8: heuristic_reachedness.isra.3 (mc_leakcheck.c:782)
==29731==    by 0x58001C77: lc_push_without_clique_if_a_chunk_ptr (mc_leakcheck.c:915)
==29731==    by 0x5800240D: lc_push_if_a_chunk_ptr (mc_leakcheck.c:1000)
==29731==    by 0x5800240D: lc_scan_memory (mc_leakcheck.c:1170)
==29731==    by 0x58002A22: lc_process_markstack (mc_leakcheck.c:1194)
==29731==    by 0x5800487E: vgMemCheck_detect_memory_leaks (mc_leakcheck.c:2183)
==29731==    by 0x58007B0E: mc_fini (mc_main.c:8003)
==29731==    by 0x580B9FE5: shutdown_actions_NORETURN (m_main.c:2149)
==29731==    by 0x580F58E3: run_a_thread_NORETURN (syswrap-linux.c:203)

sched status:
  running_tid=1


Note: see also the FAQ in the source distribution.
It contains workarounds to several common problems.
In particular, if Valgrind aborted or crashed after
identifying problems in your program, there's a good chance
that fixing those problems will prevent Valgrind aborting or
crashing, especially if it happened in m_mallocfree.c.

If that doesn't help, please report this bug to: www.valgrind.org

In the bug report, send all the above text, the valgrind
version, and what OS and version you are using.  Thanks.