From: Jonas Paulsson <jonas.paulsson@ericsson.com>
Date: Wed, 11 Feb 2015 16:10:31 +0000 (+0000)
Subject: Fix SelectionDAG compile time issue with alias analysis.
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=fc58cf76769d6d9d86f2057104f0a639563268a4

Fix SelectionDAG compile time issue with alias analysis.

Add new token factor node and its users to worklist if alias analysis is
turned on, in DAGCombiner::visitTokenFactor(). Alias analysis may cause
a lot of new token factors to be inserted into the DAG, and they need to
be optimized to avoid significant slow-downs.

Reviewed by Hal Finkel.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228841 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index cc7388b4bb5..c8b723a0de2 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1540,8 +1540,11 @@ SDValue DAGCombiner::visitTokenFactor(SDNode *N) {
       Result = DAG.getNode(ISD::TokenFactor, SDLoc(N), MVT::Other, Ops);
     }
 
-    // Don't add users to work list.
-    return CombineTo(N, Result, false);
+    // Add users to worklist if AA is enabled, since it may introduce
+    // a lot of new chained token factors while removing memory deps.
+    bool UseAA = CombinerAA.getNumOccurrences() > 0 ? CombinerAA
+      : DAG.getSubtarget().useAA();
+    return CombineTo(N, Result, UseAA /*add to worklist*/);
   }
 
   return Result;