From: Chris Lattner <sabre@nondot.org>
Date: Thu, 24 Jan 2008 07:18:21 +0000 (+0000)
Subject: The dag combiner is missing revisiting nodes that it really should, and thus leaving
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=20e3d86766a38492b3f6203bf4cf70dd9d187b7b

The dag combiner is missing revisiting nodes that it really should, and thus leaving
dead stuff around.  This gets fed into the isel pass and causes certain foldings from
happening because nodes have extraneous uses floating around.  For example, if we turned
foo(bar(x)) -> baz(x), we sometimes left bar(x) around.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46305 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 5ebda953fbd..788c8c04a82 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -606,6 +606,11 @@ void DAGCombiner::Run(bool RunningAfterLegalize) {
         // Push the new node and any users onto the worklist
         AddToWorkList(RV.Val);
         AddUsersToWorkList(RV.Val);
+        
+        // Add any uses of the old node to the worklist if they have a single
+        // use.  They may be dead after this node is deleted.
+        for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
+          AddToWorkList(N->getOperand(i).Val);
           
         // Nodes can be reintroduced into the worklist.  Make sure we do not
         // process a node that has been replaced.