add an optimized form of OPC_EmitMergeInputChains for the 1, 0 and

1, 1 cases which are by-far the most frequent.  This shrinks the X86
isel table from 77014 -> 74657 bytes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99740 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 38 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/SelectionDAGISel.h b/include/llvm/CodeGen/SelectionDAGISel.h
index a1576be..def09c7 100644
--- a/include/llvm/CodeGen/SelectionDAGISel.h
+++ b/include/llvm/CodeGen/SelectionDAGISel.h
@@ -136,6 +136,8 @@ public:
     OPC_EmitRegister,
     OPC_EmitConvertToTarget,
     OPC_EmitMergeInputChains,
+    OPC_EmitMergeInputChains1_0,
+    OPC_EmitMergeInputChains1_1,
     OPC_EmitCopyToReg,
     OPC_EmitNodeXForm,
     OPC_EmitNode,
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 3981826..6e5a6ad 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2440,6 +2440,35 @@ SelectCodeCommon(SDNode *NodeToMatch, const unsigned char *MatcherTable,
       continue;
     }
         
+    case OPC_EmitMergeInputChains1_0:    // OPC_EmitMergeInputChains, 1, 0
+    case OPC_EmitMergeInputChains1_1: {  // OPC_EmitMergeInputChains, 1, 1
+      // These are space-optimized forms of OPC_EmitMergeInputChains.
+      assert(InputChain.getNode() == 0 &&
+             "EmitMergeInputChains should be the first chain producing node");
+      assert(ChainNodesMatched.empty() &&
+             "Should only have one EmitMergeInputChains per match");
+      
+      // Read all of the chained nodes.
+      unsigned RecNo = Opcode == OPC_EmitMergeInputChains1_1;
+      assert(RecNo < RecordedNodes.size() && "Invalid CheckSame");
+      ChainNodesMatched.push_back(RecordedNodes[RecNo].getNode());
+        
+      // FIXME: What if other value results of the node have uses not matched
+      // by this pattern?
+      if (ChainNodesMatched.back() != NodeToMatch &&
+          !RecordedNodes[RecNo].hasOneUse()) {
+        ChainNodesMatched.clear();
+        break;
+      }
+      
+      // Merge the input chains if they are not intra-pattern references.
+      InputChain = HandleMergeInputChains(ChainNodesMatched, CurDAG);
+      
+      if (InputChain.getNode() == 0)
+        break;  // Failed to merge.
+      continue;
+    }
+        
     case OPC_EmitMergeInputChains: {
       assert(InputChain.getNode() == 0 &&
              "EmitMergeInputChains should be the first chain producing node");
diff --git a/utils/TableGen/DAGISelMatcherEmitter.cpp b/utils/TableGen/DAGISelMatcherEmitter.cpp
index 8855034..25b7a2f 100644
--- a/utils/TableGen/DAGISelMatcherEmitter.cpp
+++ b/utils/TableGen/DAGISelMatcherEmitter.cpp
@@ -449,6 +449,13 @@ EmitMatcher(const Matcher *N, unsigned Indent, unsigned CurrentIdx,
   case Matcher::EmitMergeInputChains: {
     const EmitMergeInputChainsMatcher *MN =
       cast<EmitMergeInputChainsMatcher>(N);
+    
+    // Handle the specialized forms OPC_EmitMergeInputChains1_0 and 1_1.
+    if (MN->getNumNodes() == 1 && MN->getNode(0) < 2) {
+      OS << "OPC_EmitMergeInputChains1_" << MN->getNode(0) << ",\n";
+      return 1;
+    }
+    
     OS << "OPC_EmitMergeInputChains, " << MN->getNumNodes() << ", ";
     for (unsigned i = 0, e = MN->getNumNodes(); i != e; ++i)
       OS << MN->getNode(i) << ", ";