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Date: Tue, 11 Sep 2007 10:06:53 +1200
From: Danny Smith <dannysmith AT clear DOT net DOT nz>
Subject: RE: gcc-dw2? or fast sjlj-exceptions EH
To: matsuoka AT nuce DOT nagoya-u DOT ac DOT jp
Cc: Cygwin <cygwin AT cygwin DOT com>
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At http://www.cygwin.com/ml/cygwin/2007-09/msg00194.html

Tatsuro Matsuoka wrote:

> The best solution, I think, the speed of sjlj-exceptions EH on the 
> cygwin is as fast as that of other platforms.
> 

In the case of octave, I believe that the main cause of slowdown is the
sjlj EH code generated in prologue of new()
Does a no-throw override of libary version of these functions help ?  


Danny
#ifdef __USING_SJLJ_EXCEPTIONS__
#define NEW_THROW_SPEC throw()
#else
#define NEW_THROW_SPEC throw(std::bad_alloc)
#endif 

#include ...

void *
operator new (std::size_t sz) NEW_THROW_SPEC
{
  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 __USING_SJLJ_EXCEPTIONS__
        std::abort();
#else
	  throw bad_alloc();
#endif
      handler ();
      p = (void *) malloc (sz);
    }

  return p;
}

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


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