larryh@techbook.com (Larry Hutchinson) (06/21/91)
Following is the text of yet another bug report for MPW C 3.2 final.
I have decided that 3.2f is too buggy to use and am reverting to
the less buggy 3.2b6. Gack!
***********************************
The following code:
#define CLOSE_DELTA 5
int AbsInt(int);
static int
IsClose(Point p1,Point p2)
{
return !( (AbsInt(p1.h-p2.h) > CLOSE_DELTA) |
(AbsInt(p1.v-p2.v) > CLOSE_DELTA) );
}
Produces the following incorrect code.
LINK A6,#$FFFC
MOVE.L D3,-(A7)
MOVE.W $000A(A6),D0
EXT.L D0
MOVE.W $000E(A6),D1
EXT.L D1
SUB.L D1,D0
MOVE.L D0,-(A7)
JSR AbsInt
MOVEQ #$05,D1
CMP.L D0,D1
SLT D0
NEG.B D0
MOVE.L D0,-$0004(A6)
MOVE.W $0008(A6),D0
EXT.L D0
MOVE.W $000C(A6),D1
EXT.L D1
SUB.L D1,D0
MOVE.L D0,-(A7)
JSR AbsInt
MOVEQ #$05,D1
CMP.L D0,D1
MOVE.L -$0004(A6),D0 <----- ERROR
SLT D1
NEG.B D1
OR.B D0,D1
SEQ D3
NEG.B D3
EXTB.L D3
MOVE.L D3,D0
MOVE.L -$0008(A6),D3
UNLK A6
RTS
OR.W A1,D4
DC.W $7343
BGE.S *+$0071
DC.W $7365
MOVE.W D0,D1
DC.W $0000
Note that the move.l at the indicated line destroys the condition
code value from the cmp.l.
Flags:
-r -elems881 -mc68020 -mbg full
-opt off had no effect
***********************************
Larry Hutchinson
WaveMetrics@AppleLink.Apple.COM
or...
--
larryh@techbook.COM ...!{tektronix!nosun,uunet}techbook!larryh
Public Access UNIX at (503) 644-8135 (1200/2400) Voice: +1 503 646-8257
Public Access User --- Not affiliated with TECHbookskeith@Apple.COM (Keith Rollin) (06/24/91)
In article <1991Jun21.163520.22236@techbook.com> larryh@techbook.com (Larry Hutchinson) writes: > > >Following is the text of yet another bug report for MPW C 3.2 final. >I have decided that 3.2f is too buggy to use and am reverting to >the less buggy 3.2b6. Gack! > > >*********************************** > > >The following code: > >#define CLOSE_DELTA 5 >int AbsInt(int); > >static int >IsClose(Point p1,Point p2) >{ > return !( (AbsInt(p1.h-p2.h) > CLOSE_DELTA) | > (AbsInt(p1.v-p2.v) > CLOSE_DELTA) ); >} > >Produces the following incorrect code. > [ buggy object code delete ] If you use a logical or (||) instead of bitwise (|), it seems to generate correct code. -- ------------------------------------------------------------------------------ Keith Rollin --- Apple Computer, Inc. INTERNET: keith@apple.com UUCP: {decwrl, hoptoad, nsc, sun, amdahl}!apple!keith "But where the senses fail us, reason must step in." - Galileo
amanda@visix.com (Amanda Walker) (06/24/91)
In article <54265@apple.Apple.COM> keith@Apple.COM (Keith Rollin) writes: > return !( (AbsInt(p1.h-p2.h) > CLOSE_DELTA) | > (AbsInt(p1.v-p2.v) > CLOSE_DELTA) ); If you use a logical or (||) instead of bitwise (|), it seems to generate correct code. That's a useful workaround, but it's still a bug... MPW C has had problems with the values of comparison expression ever since 3.0 (the switch from Green Hills C to Apple C). Sigh. And no end in sight... Grumble, grumble :). -- Amanda Walker amanda@visix.com Visix Software Inc. ...!uunet!visix!amanda -- "We are confronted with insurmountable opportunities." --Walt Kelly, "Pogo"