[InstCombine] use 'match' to simplify code

There's probably some vector-with-undef-element pattern
that shows an improvement, so this is probably not quite
'NFC'.

This is the last step towards removing the fake binop 
queries for not/neg. Ie, there are no more uses of those
functions in trunk. Fneg should follow.

llvm-svn: 345050
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 3a18744..a4d7fe8 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -141,7 +141,7 @@
 /// uses of V and only keep uses of ~V.
 static inline bool IsFreeToInvert(Value *V, bool WillInvertAllUses) {
   // ~(~(X)) -> X.
-  if (BinaryOperator::isNot(V))
+  if (match(V, m_Not(m_Value())))
     return true;
 
   // Constants can be considered to be not'ed values.