[X86][SSE] Combine shuffle nodes with multiple uses if all the users are being combined.

Currently we only combine shuffle nodes if they have a single user to prevent us from causing code bloat by splitting the shuffles into several different combines.

We don't take into account that in some cases we will already have combined all the users during recursively calling up the shuffle tree.

This patch keeps a list of all the shuffle nodes that have been combined so far and permits combining of further shuffle nodes if all its users are in that list.

Differential Revision: https://reviews.llvm.org/D29399

llvm-svn: 294183

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 46dde01970b..dc5c8baaabc 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -7125,6 +7125,21 @@ bool SDNode::isOnlyUserOf(const SDNode *N) const {
   return Seen;
 }
 
+/// Return true if the only users of N are contained in Nodes.
+bool SDNode::areOnlyUsersOf(ArrayRef<const SDNode *> Nodes, const SDNode *N) {
+  bool Seen = false;
+  for (SDNode::use_iterator I = N->use_begin(), E = N->use_end(); I != E; ++I) {
+    SDNode *User = *I;
+    if (llvm::any_of(Nodes,
+                     [&User](const SDNode *Node) { return User == Node; }))
+      Seen = true;
+    else
+      return false;
+  }
+
+  return Seen;
+}
+
 /// isOperand - Return true if this node is an operand of N.
 ///
 bool SDValue::isOperandOf(const SDNode *N) const {