Patch: delete_test1.cpp

[Jeffrey Oldham]

Compiling src/Utilities/tests/delete_test1.cpp showed that the vector
type `Array_t' was declared to store doubles but actually stored
integers.  Also, a call to std::memmove() illegally converted vector
iterators to pointers.  The alternative call to std::copy() is instead
used.

Considerable discussion between Jim Crotinger and Jeffrey D. Oldham on
pooma-dev annoyed other people on the list.  The issue, also present
in some Domain code, is that using std::memmove() requires converting
a vector iterator to a pointer.  Jeffrey Oldham objects to this
violation of the abstraction barrier and was not able to show a
significant speedup using std::memmove() rather than std::copy().  Jim
Crotinger says he measured significant speed-up using std::memmove()
in early 2000.

For the record, one way to obtain a pointer to a vector location that
the gcc 3.0 compiler accepts is
  const Array_t::pointer data_begin_ptr = &(data[0]);

2001 May 25  Jeffrey D. Oldham  <oldham at codesourcery.com>

        * delete_test1.cpp (Array_t): s/vector<double>/vector<int>/
        (delete_shiftup_test2): Remove "optimization" call to memmove.

Tested on       sequential Linux using gcc 3.0 by compiling the program
Approved by     Jim Crotinger

Thanks,
Jeffrey D. Oldham
oldham at codesourcery.com
-------------- next part --------------
Index: delete_test1.cpp
===================================================================
RCS file: /home/pooma/Repository/r2/src/Utilities/tests/delete_test1.cpp,v
retrieving revision 1.7
diff -c -p -r1.7 delete_test1.cpp
*** delete_test1.cpp	2001/03/21 00:56:09	1.7
--- delete_test1.cpp	2001/05/25 20:20:55
*************** int main(int argc, char *argv[])
*** 94,100 ****
  
  
  typedef std::vector<int> KillList_t;
! typedef std::vector<double> Array_t;
  
  void delete_shiftup_orig (Array_t &data, const KillList_t &killList);
  void delete_shiftup_test1(Array_t &data, const KillList_t &killList);
--- 94,100 ----
  
  
  typedef std::vector<int> KillList_t;
! typedef std::vector<int> Array_t;
  
  void delete_shiftup_orig (Array_t &data, const KillList_t &killList);
  void delete_shiftup_test1(Array_t &data, const KillList_t &killList);
*************** void delete_shiftup_test2(Array_t &data,
*** 618,635 ****
  	      if (inext < killed)
  	        copy_end_index = killList[inext];
  	        
!               const int length = copy_end_index - copy_begin_index;
! 
!               if (length < 100)
!   	        std::copy(data_begin + copy_begin_index, 
! 	                  data_begin + copy_end_index,
! 	                  data_begin + insert_index);
! 	      else
! 	        std::memmove(data_begin + insert_index,
! 	                     data_begin + copy_begin_index,
! 	                     sizeof(Array_t::value_type)*length);
! 
! 	      insert_index += length;
  	    }
          }
        
--- 618,627 ----
  	      if (inext < killed)
  	        copy_end_index = killList[inext];
  	        
! 	      std::copy(data_begin + copy_begin_index, 
! 			data_begin + copy_end_index,
! 			data_begin + insert_index);
! 	      insert_index += copy_end_index - copy_begin_index;
  	    }
          }