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Mail Archives: djgpp/1993/07/07/20:09:40

Date: Wed, 7 Jul 93 18:46:37 -0500
From: rcharif AT math DOT utexas DOT edu
Posted-Date: Wed, 7 Jul 93 18:46:37 -0500
To: grw AT tamu DOT edu
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: djgpp[gcc] vs watcom
Reply-To: rcharif AT math DOT utexas DOT edu

	    Just out of curiosity, does anybody know what the -m486 switch
    does?  I have never found it to speed up anything, but I have found it
    can slow things down.  (Yes, I have a 486.)

It will replace some of the complex 386 instructions by an inline
collection of 486 code which will speed up the program on the 486.
For example :

i386 :
	jcxz	some_label		; 5 clock cycles

i486 :
	or	cx,cx			; 1 clock cycle
	jz	short some_label	; 1 clock cycle

and so on...

Regards,
Rami

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