[libcxx] r227808 - Reorder a couple of operations in inplace_merge so that we can meet the complexity guidelines mandated by the standard. References PR22427

[Marshall Clow]

Author: marshall
Date: Mon Feb  2 10:44:11 2015
New Revision: 227808

URL: http://llvm.org/viewvc/llvm-project?rev=227808&view=rev
Log:
Reorder a couple of operations in inplace_merge so that we can meet the complexity guidelines mandated by the standard. References PR22427

Modified:
    libcxx/trunk/include/algorithm

Modified: libcxx/trunk/include/algorithm
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/algorithm?rev=227808&r1=227807&r2=227808&view=diff
==============================================================================
--- libcxx/trunk/include/algorithm (original)
+++ libcxx/trunk/include/algorithm Mon Feb  2 10:44:11 2015
@@ -4407,6 +4407,9 @@ __inplace_merge(_BidirectionalIterator _
         // if __middle == __last, we're done
         if (__len2 == 0)
             return;
+        if (__len1 <= __buff_size || __len2 <= __buff_size)
+            return __buffered_inplace_merge<_Compare>
+                   (__first, __middle, __last, __comp, __len1, __len2, __buff);
         // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0
         for (; true; ++__first, (void) --__len1)
         {
@@ -4415,11 +4418,6 @@ __inplace_merge(_BidirectionalIterator _
             if (__comp(*__middle, *__first))
                 break;
         }
-        if (__len1 <= __buff_size || __len2 <= __buff_size)
-        {
-            __buffered_inplace_merge<_Compare>(__first, __middle, __last, __comp, __len1, __len2, __buff);
-            return;
-        }
         // __first < __middle < __last
         // *__first > *__middle
         // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that