[PATCH v10 2/7] ntdll: Don't re-add a module dependency if it already exists.

[Jinoh Kang]

From: Jinoh Kang

Today, calling add_module_dependency() multiple times with the same
arguments results in duplicate edges.

Duplicate edges are harmless, but bloats memory usage.  The number of
duplicate edges does not affect the dependency graph; the graph is
determined by the set of unique edges.

Consciously avoid duplicates by checking for them in
add_module_dependency_after().  This allows us to generate a unique
dependency edge for all imports of export forwarders that belong to the
same DLL.
---
 dlls/ntdll/loader.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/dlls/ntdll/loader.c b/dlls/ntdll/loader.c
index e51ea7197f4..c0cd5d41a05 100644
--- a/dlls/ntdll/loader.c
+++ b/dlls/ntdll/loader.c
@@ -837,6 +837,21 @@ static void remove_single_list_entry( LDRP_CSLIST *list, SINGLE_LIST_ENTRY *entr
     entry->Next = NULL;
 }

+static LDR_DEPENDENCY *find_module_dependency( LDR_DDAG_NODE *from, LDR_DDAG_NODE *to )
+{
+    SINGLE_LIST_ENTRY *entry, *mark = from->Dependencies.Tail;
+
+    if (!mark) return NULL;
+
+    for (entry = mark->Next; entry != mark; entry = entry->Next)
+    {
+        LDR_DEPENDENCY *dep = CONTAINING_RECORD( entry, LDR_DEPENDENCY, dependency_to_entry );
+        if (dep->dependency_from == from && dep->dependency_to == to) return dep;
+    }
+
+    return NULL;
+}
+
 /**********************************************************************
  *	    add_module_dependency_after
  */
@@ -845,6 +860,16 @@ static BOOL add_module_dependency_after( LDR_DDAG_NODE *from, LDR_DDAG_NODE *to,
 {
     LDR_DEPENDENCY *dep;

+    if ((dep = find_module_dependency( from, to )))
+    {
+        /* Dependency already exists; consume the module reference stolen from the caller */
+        LDR_DATA_TABLE_ENTRY *mod = CONTAINING_RECORD( to->Modules.Flink, LDR_DATA_TABLE_ENTRY, NodeModuleLink );
+        WINE_MODREF *wm = CONTAINING_RECORD( mod, WINE_MODREF, ldr );
+        assert( wm->ldr.LoadCount != 1 );
+        if (wm->ldr.LoadCount != -1) wm->ldr.LoadCount--;
+        return TRUE;
+    }
+
     if (!(dep = RtlAllocateHeap( GetProcessHeap(), 0, sizeof(*dep) ))) return FALSE;

dep->dependency_from = from;