Clean up handling of always-inline functions in the inliner.

This patch moves the isInlineViable function from the InlineAlways pass into
the InlineCostAnalyzer and then changes the InlineCost computation to use that
simple check for always-inline functions. All the special-case checks for
AlwaysInline in the CallAnalyzer can then go away.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168300 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/InlineCost.h

@@ -129,6 +129,9 @@ namespace llvm {
     //  Note: This is used by out-of-tree passes, please do not remove without
     //  adding a replacement API.
     InlineCost getInlineCost(CallSite CS, Function *Callee, int Threshold);
+
+    /// \brief Minimal filter to detect invalid constructs for inlining.
+    bool isInlineViable(Function &Callee);
   };
 }