[llvm-commits] [llvm] r129763 - /llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

[Eli Friedman]

Author: efriedma
Date: Tue Apr 19 12:01:08 2011
New Revision: 129763

URL: http://llvm.org/viewvc/llvm-project?rev=129763&view=rev
Log:
SelectBasicBlock is rather slow even when it doesn't do anything; skip the
unnecessary work where possible.


Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp?rev=129763&r1=129762&r2=129763&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Tue Apr 19 12:01:08 2011
@@ -1017,11 +1017,13 @@
     else
       ++NumFastIselBlocks;
 
-    // Run SelectionDAG instruction selection on the remainder of the block
-    // not handled by FastISel. If FastISel is not run, this is the entire
-    // block.
-    bool HadTailCall;
-    SelectBasicBlock(Begin, BI, HadTailCall);
+    if (Begin != BI) {
+      // Run SelectionDAG instruction selection on the remainder of the block
+      // not handled by FastISel. If FastISel is not run, this is the entire
+      // block.
+      bool HadTailCall;
+      SelectBasicBlock(Begin, BI, HadTailCall);
+    }
 
     FinishBasicBlock();
     FuncInfo->PHINodesToUpdate.clear();