Add patterns for the x86 popcnt instruction.

- Also adds a new POPCNT subtarget feature that is currently enabled if the target
  supports SSE4.2 (nehalem) or SSE4A (barcelona).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120917 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 0bbf990..478bf71 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -285,21 +285,27 @@
   setOperationAction(ISD::FREM             , MVT::f80  , Expand);
   setOperationAction(ISD::FLT_ROUNDS_      , MVT::i32  , Custom);
 
-  setOperationAction(ISD::CTPOP            , MVT::i8   , Expand);
   setOperationAction(ISD::CTTZ             , MVT::i8   , Custom);
   setOperationAction(ISD::CTLZ             , MVT::i8   , Custom);
-  setOperationAction(ISD::CTPOP            , MVT::i16  , Expand);
   setOperationAction(ISD::CTTZ             , MVT::i16  , Custom);
   setOperationAction(ISD::CTLZ             , MVT::i16  , Custom);
-  setOperationAction(ISD::CTPOP            , MVT::i32  , Expand);
   setOperationAction(ISD::CTTZ             , MVT::i32  , Custom);
   setOperationAction(ISD::CTLZ             , MVT::i32  , Custom);
   if (Subtarget->is64Bit()) {
-    setOperationAction(ISD::CTPOP          , MVT::i64  , Expand);
     setOperationAction(ISD::CTTZ           , MVT::i64  , Custom);
     setOperationAction(ISD::CTLZ           , MVT::i64  , Custom);
   }
 
+  if (Subtarget->hasPOPCNT()) {
+    setOperationAction(ISD::CTPOP          , MVT::i8   , Promote);
+  } else {
+    setOperationAction(ISD::CTPOP          , MVT::i8   , Expand);
+    setOperationAction(ISD::CTPOP          , MVT::i16  , Expand);
+    setOperationAction(ISD::CTPOP          , MVT::i32  , Expand);
+    if (Subtarget->is64Bit())
+      setOperationAction(ISD::CTPOP        , MVT::i64  , Expand);
+  }
+
   setOperationAction(ISD::READCYCLECOUNTER , MVT::i64  , Custom);
   setOperationAction(ISD::BSWAP            , MVT::i16  , Expand);