src/hotspot/share/gc/g1/g1Allocator.cpp

@@ -1,7 +1,7 @@
  /*
-  * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
+  * Copyright (c) 2014, 2026, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.

@@ -244,16 +244,26 @@
        ShouldNotReachHere();
        return nullptr; // Keep some compilers happy
    }
  }
  
+ #ifdef ASSERT
+ void G1Allocator::assert_not_humongous(size_t word_size) {
+   // With CompactObjectHeaders, objects can expand during copy to accomodate hashcode.
+   // It's possible this expansion crosses the humongous threshold. In this case, we allow
+   // that and just treat it as not humongous.
+   size_t pre_expansion_size = UseCompactObjectHeaders ? word_size - 1 : word_size;
+   assert(!_g1h->is_humongous(pre_expansion_size),
+           "we should not be seeing humongous-size allocations in this path");
+ }
+ #endif
+ 
  HeapWord* G1Allocator::survivor_attempt_allocation(uint node_index,
                                                     size_t min_word_size,
                                                     size_t desired_word_size,
                                                     size_t* actual_word_size) {
-   assert(!_g1h->is_humongous(desired_word_size),
-          "we should not be seeing humongous-size allocations in this path");
+   assert_not_humongous(desired_word_size);
  
    HeapWord* result = survivor_gc_alloc_region(node_index)->attempt_allocation(min_word_size,
                                                                                desired_word_size,
                                                                                actual_word_size);
    if (result == nullptr && !survivor_is_full()) {

@@ -274,12 +284,11 @@
  }
  
  HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
                                                size_t desired_word_size,
                                                size_t* actual_word_size) {
-   assert(!_g1h->is_humongous(desired_word_size),
-          "we should not be seeing humongous-size allocations in this path");
+   assert_not_humongous(desired_word_size);
  
    HeapWord* result = old_gc_alloc_region()->attempt_allocation(min_word_size,
                                                                 desired_word_size,
                                                                 actual_word_size);
    if (result == nullptr && !old_is_full()) {