[Lldb-commits] [lldb] af96914 - [lldb] Pin the shared cache when iterating over its images

[Jonas Devlieghere via lldb-commits]

Author: Jonas Devlieghere
Date: 2022-02-11T15:26:33-08:00
New Revision: af969141fa285157044e34fb6b27963c3278241b

URL: https://github.com/llvm/llvm-project/commit/af969141fa285157044e34fb6b27963c3278241b
DIFF: https://github.com/llvm/llvm-project/commit/af969141fa285157044e34fb6b27963c3278241b.diff

LOG: [lldb] Pin the shared cache when iterating over its images

Use the dyld_shared_cache_(un)pin_mapping SPI to map the whole shared
cache in memory (if possible) to avoid repeated calls to mmap.

rdar://81189015

Added: 
    

Modified: 
    lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index 10137e714861d..131d1932fe142 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -2711,7 +2711,7 @@ void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
         if (process_shared_cache_uuid.IsValid() &&
           process_shared_cache_uuid != UUID::fromOptionalData(&cache_uuid, 16))
         return;
-
+      const bool pinned = dyld_shared_cache_pin_mapping(shared_cache);
       dyld_shared_cache_for_each_image(shared_cache, ^(dyld_image_t image) {
         uuid_t dsc_image_uuid;
         if (found_image)
@@ -2768,6 +2768,8 @@ void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
               nlist_count = nlistCount;
             });
       });
+      if (pinned)
+        dyld_shared_cache_unpin_mapping(shared_cache);
     });
     if (nlist_buffer) {
       DataExtractor dsc_local_symbols_data(nlist_buffer,