rt: Track backtraces of all allocations with RUSTRT_TRACK_ALLOCATIONS=3

Author: brson

src/rt/memory_region.cpp

@@ -1,6 +1,10 @@
 #include "rust_internal.h"
 #include "memory_region.h"
 
+#if RUSTRT_TRACK_ALLOCATIONS >= 3
+#include <execinfo.h>
+#endif
+
 #if RUSTRT_TRACK_ALLOCATIONS >= 1
 // For some platforms, 16 byte alignment is required.
 #  define PTR_SIZE 16
@@ -148,6 +152,13 @@ memory_region::~memory_region() {
                        header->tag,
                        (uintptr_t) get_data(header));
                 ++leak_count;
+
+#               if RUSTRT_TRACK_ALLOCATIONS >= 3
+                if (_detailed_leaks) {
+                    backtrace_symbols_fd(header->bt + 1,
+                                         header->btframes - 1, 2);
+                }
+#               endif
             }
         }
         assert(leak_count == _live_allocations);
@@ -199,6 +210,12 @@ memory_region::claim_alloc(void *mem) {
     if (_synchronized) { _lock.unlock(); }
 #   endif
 
+#   if RUSTRT_TRACK_ALLOCATIONS >= 3
+    if (_detailed_leaks) {
+        alloc->btframes = ::backtrace(alloc->bt, 32);
+    }
+#   endif
+
     add_alloc();
 }
 

src/rt/memory_region.h

@@ -16,6 +16,7 @@
 // 0 --- no headers, no debugging support
 // 1 --- support poison, but do not track allocations
 // 2 --- track allocations in detail
+// 3 --- record backtraces of every allocation
 //
 // NB: please do not commit code with level 2. It's
 // hugely expensive and should only be used as a last resort.
@@ -31,6 +32,10 @@ class memory_region {
         int index;
         const char *tag;
         uint32_t size;
+#       if RUSTRT_TRACK_ALLOCATIONS >= 3
+        void *bt[32];
+        int btframes;
+#       endif
 #       endif
     };