Path: utzoo!mnetor!uunet!husc6!bbn!rochester!PT.CS.CMU.EDU!sei!sei.cmu.edu!firth
From: firth@sei.cmu.edu (Robert Firth)
Newsgroups: comp.lang.c
Subject: pcc Codegeneration
Message-ID: <4650@aw.sei.cmu.edu>
Date: 18 Mar 88 16:40:01 GMT
References: <5020@nsc.nsc.com> <10702@mimsy.UUCP>
Sender: netnews@sei.cmu.edu
Reply-To: firth@bd.sei.cmu.edu.UUCP (Robert Firth)
Organization: Carnegie-Mellon University, SEI, Pgh, Pa
Lines: 35
Keywords: conversions

In article <10702@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:

[old pcc versions fail when converting unsigned to float]

] Donn Seeley has fixed this in recent versions of the 4BSD
] compilers.  The 4.3BSD compiler turns
] 
] 	main(){
] 		register unsigned u = 0xf0000000;
] 		register float f = u;
] 		printf("%u %u\n", u, (unsigned)f);
] 	}
] 
] into
] 
] 	movl	$-268435456,r11		# u = 0xf0000000;
] 	movl	r11,r10			# begin f = u:
] 	jbsc	$31,r10,L99999		# was it negative?
] 	cvtlf	r10,r10			# it was not negative; convert
] 	jbr	L99998			# and done
] L99999:
] 	cvtlf	r10,r10			# it was negative but is no longer
] 	addf2	$0f2.147483648e9,r10	# so convert and add 1<<31.
] L99998:
	...


Sigh!  It seems pcc code generation is as sloppy as it ever was.

Wouldn't this be a lot simpler, faster, and easier to generate?

	CVTLF src, reg
	BGEQ  1$
	ADDF2 #2**32,reg
    1$: