Add X86 TZCNT instruction and patterns to select it. Also added core-avx2 processor which is gcc's name for Haswell.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141939 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 251064b..f85c201 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -379,11 +379,15 @@
   setOperationAction(ISD::FREM             , MVT::f80  , Expand);
   setOperationAction(ISD::FLT_ROUNDS_      , MVT::i32  , Custom);
 
-  setOperationAction(ISD::CTTZ             , MVT::i8   , Custom);
-  setOperationAction(ISD::CTTZ             , MVT::i16  , Custom);
-  setOperationAction(ISD::CTTZ             , MVT::i32  , Custom);
-  if (Subtarget->is64Bit())
-    setOperationAction(ISD::CTTZ           , MVT::i64  , Custom);
+  if (Subtarget->hasBMI()) {
+    setOperationAction(ISD::CTTZ           , MVT::i8   , Promote);
+  } else {
+    setOperationAction(ISD::CTTZ           , MVT::i8   , Custom);
+    setOperationAction(ISD::CTTZ           , MVT::i16  , Custom);
+    setOperationAction(ISD::CTTZ           , MVT::i32  , Custom);
+    if (Subtarget->is64Bit())
+      setOperationAction(ISD::CTTZ         , MVT::i64  , Custom);
+  }
 
   if (Subtarget->hasLZCNT()) {
     setOperationAction(ISD::CTLZ           , MVT::i8   , Promote);