Explicitly avoid repeat deps loading

Track for each Edge whether depfile information has been loaded using an
explicit flag.  This will allow RecomputeDirty to be repeated for an
edge without loading deps again.

1 files changed, 10 insertions, 6 deletions

diff --git a/src/graph.cc b/src/graph.cc
index 9c2f784..bf9363d 100644
--- a/src/graph.cc
+++ b/src/graph.cc
@@ -75,12 +75,16 @@ bool DependencyScan::RecomputeDirty(Node* node, vector<Node*>* stack,
       return false;
   }
 
-  if (!dep_loader_.LoadDeps(edge, err)) {
-    if (!err->empty())
-      return false;
-    // Failed to load dependency info: rebuild to regenerate it.
-    // LoadDeps() did EXPLAIN() already, no need to do it here.
-    dirty = edge->deps_missing_ = true;
+  if (!edge->deps_loaded_) {
+    // This is our first encounter with this edge.  Load discovered deps.
+    edge->deps_loaded_ = true;
+    if (!dep_loader_.LoadDeps(edge, err)) {
+      if (!err->empty())
+        return false;
+      // Failed to load dependency info: rebuild to regenerate it.
+      // LoadDeps() did EXPLAIN() already, no need to do it here.
+      dirty = edge->deps_missing_ = true;
+    }
   }
 
   // Visit all inputs; we're dirty if any of the inputs are dirty.