[Bug target/14563] new/delete much slower than malloc/free because of sjlj exceptions

["kjd at duda dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From kjd at duda dot org  2004-11-10 17:05 -------
(In reply to comment #40)
> Ron, can you please attach your testcase that shows the problem to this PR?
> This PR is a regression on cygwin because the speed is back with 3.2.

Here's a test case for you...
   -Ken

-------------------------------------------------------


// Uncomment one of these defines.
// With the first define uncommented, I get 3.293 usec per "operator new" use.
// With the second define uncommented, I get 1.019 usec per "operator new" use.
// A high price to pay for having one's exceptions properly declared!

//#define THROW throw (std::bad_alloc)
#define THROW


// These definitions are taken straight from libstdc++.


#include "new"
#include <exception_defines.h>

using std::new_handler;
using std::bad_alloc;

extern "C" void *malloc (std::size_t);
extern new_handler __new_handler;

void *
operator new (std::size_t sz) THROW
{
  void *p;

  /* malloc (0) is unpredictable; avoid it.  */
  if (sz == 0)
    sz = 1;
  p = (void *) malloc (sz);
  while (p == 0)
    {
      new_handler handler = __new_handler;
      if (! handler)
#ifdef __EXCEPTIONS
	throw bad_alloc();
#else
        std::abort();
#endif
      handler ();
      p = (void *) malloc (sz);
    }

  return p;
}

void *
operator new[] (std::size_t sz) THROW
{
  return ::operator new(sz);
}




#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <assert.h>

typedef unsigned long long u64;
typedef u64 Usec;

#ifdef WIN32

#include <Windows.h>

inline Usec Now()
{
   DWORD ticks = GetTickCount();
   return ((Usec) ticks) * 1000;
}

#else

#include <sys/types.h>
#include <sys/time.h>

inline Usec Now()
{
   struct timeval tv;
   if( gettimeofday( &tv, 0 ) ) {
      perror( "gettimeofday" );
      exit( 1 );
   }
   return ((Usec) tv.tv_sec) * 1000000 + tv.tv_usec;
}

#endif

using namespace std;



main()
{
  int sizeMin = 4;
  int sizeMax = 100;
  int allocsOutstanding = 1000;
  int reps = 1000;
  int allocsPerRep = 1000;

  int sizeRange = sizeMax - sizeMin;
  char ** ptrs = (char **) malloc( sizeof( char * ) * allocsOutstanding );
  memset( ptrs, 0, sizeof( char * ) * allocsOutstanding );

  Usec start = Now();
  
  int m = reps;
  while( m-- ) {
    int n = allocsPerRep;
    while( n-- ) {
      int r = rand();
      int index = r % allocsOutstanding;
      char * p = ptrs[index];
      delete[] p;
      //      free( p );
      int size = (r % sizeRange) + sizeMin;
      p = new char[ size ];
      //      p = (char *) malloc( size );
      ptrs[index] = p;
    }
  }

  Usec stop = Now();
  double t = ((double) stop - start) / ((double) allocsPerRep * reps);
  printf( "cost of new + delete is about %0.3f usec\n", t );
  fflush( stdout );
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14563