Date: Wed, 30 Dec 1998 16:40:28 +0200 (IST) From: Eli Zaretskii X-Sender: eliz AT is To: Christian Hofrichter cc: djgpp AT delorie DOT com Subject: Re: pairable instructions much faster than the string operations on a Pentium and above ?! In-Reply-To: <368A195D.F315167E@gmx.de> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Reply-To: djgpp AT delorie DOT com On Wed, 30 Dec 1998, Christian Hofrichter wrote: > So how about a new optimation-switch in djgpp, called pairable > instructions ? It is not clear what exactly would you want that switch to do, and in which circumstances. If you want the compiler to emit Pentium-optimized code when it sees e.g. a call to memcpy or memset, then this suggestion should go to the maintainers of GCC, since the DJGPP port doesn't change the way GCC generates code. There is already -mpentium and -march= switches which should trigger such code generation. If you want the DJGPP library functions to use the faster method, then a GCC switch cannot be used for that (well, not easily, anyway). Perhaps a specialized library of Pentium-optimized functions is required (provided there are several other cases that can be optimized in this way). > After all it can often double the speed of the program. The ration 3:2 will not double the speed, it will only give you a 50% speed boost. > I can also be used to improve graphic-performence, can't it ? I'm not sure, since the bus speed and constraints are an important factor when you move data to/from the video RAM.