Add functions 'hasPredecessor' and 'hasPredecessorHelper' to SDNode. The

hasPredecessorHelper function allows predecessors to be cached to speed up
repeated invocations. This fixes PR10186.

X.isPredecessorOf(Y) now just calls Y.hasPredecessor(X)

Y.hasPredecessor(X) calls Y.hasPredecessorHelper(X, Visited, Worklist) with
empty Visited and Worklist sets (i.e. no caching over invocations).

Y.hasPredecessorHelper(X, Visited, Worklist) caches search state in Visited
and Worklist to speed up repeated calls. The Visited set is searched for X
before going to the worklist to further search the DAG if necessary.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134592 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 90e0cc7ce4..79e76125bb 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5929,12 +5929,17 @@ bool DAGCombiner::CombineToPreIndexedLoadStore(SDNode *N) {
 
   // Now check for #3 and #4.
   bool RealUse = false;
+
+  // Caches for hasPredecessorHelper
+  SmallPtrSet<const SDNode *, 32> Visited;
+  SmallVector<const SDNode *, 16> Worklist;
+
   for (SDNode::use_iterator I = Ptr.getNode()->use_begin(),
          E = Ptr.getNode()->use_end(); I != E; ++I) {
     SDNode *Use = *I;
     if (Use == N)
       continue;
-    if (Use->isPredecessorOf(N))
+    if (N->hasPredecessorHelper(Use, Visited, Worklist))
       return false;
 
     if (!((Use->getOpcode() == ISD::LOAD &&