From 2e698fba2213fdd193ddd01d145823c73263fbee Mon Sep 17 00:00:00 2001
From: Egor Bogatov <egorbo@gmail.com>
Date: Wed, 5 Oct 2022 17:28:28 +0200
Subject: [PATCH] Don't scan bricks of frozen segments in verify_heap (#76645)

Co-authored-by: Maoni0 <maoni@microsoft.com>
---
 src/coreclr/gc/gc.cpp | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/coreclr/gc/gc.cpp b/src/coreclr/gc/gc.cpp
index d181cfb9ee26f5..c068781f31dce2 100644
--- a/src/coreclr/gc/gc.cpp
+++ b/src/coreclr/gc/gc.cpp
@@ -44422,13 +44422,35 @@ void gc_heap::verify_heap (BOOL begin_gc_p)
             uint8_t*        curr_object = heap_segment_mem (seg);
             uint8_t*        prev_object = 0;
 
+            bool verify_bricks_p = true;
 #ifdef USE_REGIONS
+            if (heap_segment_read_only_p(seg))
+            {
+                dprintf(1, ("seg %Ix is ro! Shouldn't happen with regions", (size_t)seg));
+                FATAL_GC_ERROR();
+            }
             if (heap_segment_gen_num (seg) != heap_segment_plan_gen_num (seg))
             {
                 dprintf (1, ("Seg %Ix, gen num is %d, plan gen num is %d",
                     heap_segment_mem (seg), heap_segment_gen_num (seg), heap_segment_plan_gen_num (seg)));
                 FATAL_GC_ERROR();
             }
+#else //USE_REGIONS
+            if (heap_segment_read_only_p(seg))
+            {
+                size_t current_brick = brick_of(max(heap_segment_mem(seg), lowest_address));
+                size_t end_brick = brick_of(min(heap_segment_reserved(seg), highest_address) - 1);
+                while (current_brick <= end_brick)
+                {
+                    if (brick_table[current_brick] != 0)
+                    {
+                        dprintf(1, ("Verifying Heap: %Ix brick of a frozen segment is not zeroed", current_brick));
+                        FATAL_GC_ERROR();
+                    }
+                    current_brick++;
+                }
+                verify_bricks_p = false;
+            }
 #endif //USE_REGIONS
 
 #ifdef BACKGROUND_GC
@@ -44470,11 +44492,11 @@ void gc_heap::verify_heap (BOOL begin_gc_p)
 #endif //!USE_REGIONS
 
 #ifdef USE_REGIONS
-                if (curr_gen_num != 0)
+                if (verify_bricks_p && curr_gen_num != 0)
 #else
                 // If object is not in the youngest generation, then lets
                 // verify that the brick table is correct....
-                if (((seg != ephemeral_heap_segment) ||
+                if (verify_bricks_p && ((seg != ephemeral_heap_segment) ||
                      (brick_of(curr_object) < brick_of(begin_youngest))))
 #endif //USE_REGIONS
                 {