Shrink-to-fit our std::vector<DWARFDebugInfoEntry> collections and save 20%

to 30% of memory. The size doubling was killing us and we ended up with up to
just under 50% of empty capacity. Cleaning this up saves us a ton of memory.

llvm-svn: 145086

3 files changed, 16 insertions, 8 deletions

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
index aa8699f0ad2..096710cd258 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
@@ -271,7 +271,17 @@ DWARFCompileUnit::ExtractDIEsIfNeeded (bool cu_die_only)
         }
         fprintf (stderr, "warning: DWARF compile unit extends beyond its bounds cu 0x%8.8x at 0x%8.8x in '%s'\n", GetOffset(), offset, path);
     }
+
+    // Since std::vector objects will double their size, we really need to
+    // make a new array with the perfect size so we don't end up wasting
+    // space. So here we copy and swap to make sure we don't have any extra
+    // memory taken up.
     
+    if (m_die_array.size () < m_die_array.capacity())
+    {
+        DWARFDebugInfoEntry::collection exact_size_die_array (m_die_array.begin(), m_die_array.end());
+        exact_size_die_array.swap (m_die_array);
+    }
     LogSP log (LogChannelDWARF::GetLogIfAll (DWARF_LOG_DEBUG_INFO));
     if (log)
     {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.h b/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.h
index 49b05d14473..fc3dd3bbb01 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.h
@@ -74,13 +74,11 @@ public:
     }
 
     void
-    AddDIE(DWARFDebugInfoEntry& die)
+    AddDIE (DWARFDebugInfoEntry& die)
     {
         // The average bytes per DIE entry has been seen to be
-        // around 14-20 so lets pre-reserve the needed memory for
-        // our DIE entries accordingly. Search forward for "Compute
-        // average bytes per DIE" to see #if'ed out code that does
-        // that determination.
+        // around 14-20 so lets pre-reserve half of that since
+        // we are now stripping the NULL tags. 
 
         // Only reserve the memory if we are adding children of
         // the main compile unit DIE. The compile unit DIE is always
@@ -88,7 +86,7 @@ public:
         // the first compile unit child DIE and should reserve
         // the memory.
         if (m_die_array.empty())
-            m_die_array.reserve(GetDebugInfoSize() / 14);
+            m_die_array.reserve(GetDebugInfoSize() / 24);
         m_die_array.push_back(die);
     }
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
index 0d2adb05cf9..20bac6b7423 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
@@ -1926,8 +1926,8 @@ DWARFDebugInfoEntry::DumpDIECollection (Stream &strm, DWARFDebugInfoEntry::colle
 {
     DWARFDebugInfoEntry::const_iterator pos;
     DWARFDebugInfoEntry::const_iterator end = die_collection.end();
-    puts("offset    parent   sibling  child");
-    puts("--------  -------- -------- --------");
+    strm.PutCString("\noffset    parent   sibling  child\n");
+    strm.PutCString("--------  -------- -------- --------\n");
     for (pos = die_collection.begin(); pos != end; ++pos)
     {
         const DWARFDebugInfoEntry& die_ref = *pos;