Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watmath!clyde!rutgers!seismo!mcvax!unido!stollco!bernd
From: bernd@stollco.UUCP
Newsgroups: comp.bugs.sys5,comp.lang.c
Subject: Bug in portable C-compiler SYS V.2
Message-ID: <134@stollco.UUCP>
Date: Fri, 12-Jun-87 11:47:47 EDT
Article-I.D.: stollco.134
Posted: Fri Jun 12 11:47:47 1987
Date-Received: Sun, 14-Jun-87 21:42:26 EDT
Organization: Stollmann Gmbh, D 2000 Hamburg 50
Lines: 60
Xref: utgpu comp.bugs.sys5:125 comp.lang.c:2347


After debugging an application we found that our
C-Compiler generates wrong inline code for 68881.
We used the portable C-compiler from Motorola
coming along with SYS V.2.
We are going to fix the bug, so I'm looking for help.
Maybe someone has encountered the same problem.
Any hint is welcome which part of the compiler sources is
responsible for the error.
 
The problem occurs in conditional expressions combined
with float convertion. Here comes a short example:
The false branch evaluates wrong. 
With or without explicit typecast changes nothing.

test (l)
long l;
{
float f;
f= (l<0) ? -2.0 * l : (float) l;
}

Compiles to:

	file	"fperr.c"
	data	1
	text
	global	test
test:
	link.l	%fp,&F%1
	movm.l	&M%1,(4,%sp)
	fmovm	&FPM%1,(FPO%1,%sp)
	tst.l	(8,%fp)
	bge	L%_11
	fmov.d	&0xc000000000000000,%fp0
	fmul.l	(8,%fp),%fp0
	fmov.x	%fp0,%fp0
	br	L%_12
L%_11:
	fmov.x	%fp0,%fp0		<--- ?????
L%_12:
	fmov.x	%fp0,%fp0
	fmov.s	%fp0,((S%1-4).w,%fp)
L%12:
	movm.l	(4,%sp),&M%1
	fmovm	(FPO%1,%sp),&FPM%1
	unlk	%fp
	rts
	set	S%1,0
	set	T%1,0
	set	F%1,-8
	set	FPO%1,4
	set	FPM%1,0x0000
	set	M%1,0x0000
	data	1

-- 
	Bernd Rennhak
TELE:	+49 40 38900329
UUCP:	...{seismo}!unido!stollco!bernd