[gcc r17-2968] statistics: Fix --enable-gather-detailed-mem-stats for PCH [PR28734]

https://gcc.gnu.org/g:60623805437fc74e8e0e90b92d86f181f5ab5ba2

commit r17-2968-g60623805437fc74e8e0e90b92d86f181f5ab5ba2
Author: Lewis Hyatt <[email protected]>
Date:   Sat Aug 1 09:52:31 2026 -0400

    statistics: Fix --enable-gather-detailed-mem-stats for PCH [PR28734]
    
    When GCC is configured with --enable-gather-detailed-mem-stats, most of the
    pch.exp tests fail, because one function
    (mem_alloc_description::release_object_overhead) does not handle the case
    of being asked to process an unknown object. After PCH restore, there will
    be GGC'ed objects that the statistics gathering infrastructure does not know
    about, so simply ignore them in that case.
    
    gcc/ChangeLog:
    
            PR middle-end/28734
            * mem-stats.h (mem_alloc_description::release_object_overhead):
            Handle the case that PTR was not found in the hash map, which can
            happen after PCH restore.

Diff:
---
 gcc/mem-stats.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gcc/mem-stats.h b/gcc/mem-stats.h
index ab8d5ca4e5a8..2d4de15ccff9 100644
--- a/gcc/mem-stats.h
+++ b/gcc/mem-stats.h
@@ -535,6 +535,8 @@ inline void
 mem_alloc_description<T>::release_object_overhead (void *ptr)
 {
   std::pair <T *, size_t> *entry = m_reverse_object_map->get (ptr);
+  if (!entry)
+    return;
   entry->first->release_overhead (entry->second);
   m_reverse_object_map->remove (ptr);
 }