Enable SSE4 codegen and pattern matching.
Add some notes to the README.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46949 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/TargetSelectionDAG.td b/lib/Target/TargetSelectionDAG.td
index a38d863..dc9a993 100644
--- a/lib/Target/TargetSelectionDAG.td
+++ b/lib/Target/TargetSelectionDAG.td
@@ -181,8 +181,8 @@
 def SDTVecExtract : SDTypeProfile<1, 2, [ // vector extract
   SDTCisEltOfVec<0, 1>, SDTCisPtrTy<2>
 ]>;
-def SDTVecInsert : SDTypeProfile<1, 2, [  // vector insert
-  SDTCisEltOfVec<1, 0>, SDTCisPtrTy<2>
+def SDTVecInsert : SDTypeProfile<1, 3, [  // vector insert
+  SDTCisEltOfVec<2, 1>, SDTCisSameAs<0, 1>, SDTCisPtrTy<3>
 ]>;
 
 class SDCallSeqStart<list<SDTypeConstraint> constraints> :