introduce a new helper to SILBuilder that emits a StrongRelease operation,

scanning up the local block to see if it immediately cancels a retain 
operation.

Use this in mandatory inlining to zap more retains and release.  Before
this patch, the result LogicValue allocation blocked this optimization,
preventing the partial_apply from being deleted from the case in 
rdar://15328833.




Swift SVN r10447

include/swift/SIL/SILBuilder.h

@@ -764,6 +764,12 @@ public:
   /// generate an explicit one if that fails.
   void emitDestroyAddr(SILLocation Loc, SILValue Operand);
 
+  /// Perform a strong_release instruction at the current location, attempting
+  /// to fold it locally into nearby retain instructions or emitting an explicit
+  /// strong release if necessary.  If this inserts a new instruction, it
+  /// returns it, otherwise it returns null.
+  StrongReleaseInst *emitStrongRelease(SILLocation Loc, SILValue Operand);
+
   /// Convenience function for calling emitRetain on the type lowering
   /// for the non-address value.
   SILValue emitCopyValueOperation(SILLocation loc, SILValue v) {