Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!UUNET.UU.NET!mcvax!ruuinf!piet
From: mcvax!ruuinf!piet@UUNET.UU.NET (Piet van Oostrum)
Newsgroups: gnu.g++.bug
Subject: Bug in g++ 1.32.0 for new.
Message-ID: <8902101647.AA18799@cs.ruu.nl>
Date: 10 Feb 89 16:47:07 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 83

g++ generates incorrect code for new type [i] if type is a class.

The code tests for i being zero, but fails to put a NULL pointer in the
register where the result is delivered. I don't know if i==0 is correct
C++, but the test5[ab] programs from the library (libg++-1.25.0/tests)
actually use this (e.g. to initialize nil_Integer_rep).

The example is on a Sun3 OS3.
------------------------------------------------------------------------
The program:

#include <Integer.h>
extern myfunc(Integer *i);

main()
{
	int i;
	Integer *a = new Integer [i];
	myfunc (a);
}
------------------------------------------------------------------------

g++ -v -S temp1.cc  
g++ version 1.32.0 
 /usr/staff/lib/gcc-cpp -+ -v -undef -D__GNU__ -D__GNUG__ -Dmc68000 -Dsun -Dunix temp1.cc /tmp/cca05970.cpp 
GNU CPP version 1.32 
 /usr/staff/lib/gcc-c++ /tmp/cca05970.cpp -quiet -dumpbase temp1.cc -noreg -version -o temp1.s 
GNU C++ version 1.32.0 (68k, MIT syntax) compiled by CC. 

------------------------------------------------------------------------
the code: (some initial stuff deleted)

_main:
	link a6,#-8
	moveml #0x3c20,sp@-
	movel a6@(-4),d3
	subql #1,d3
	tstl d3				test
	jlt L1074			branch if (i==0)
	movel a6@(-4),d0
	asll #2,d0
	movel d0,sp@-
	jbsr ___builtin_new
	movel d0,d2
	movel d2,d4
	addqw #4,sp
L1075:
	movel d4,a2
	movel a6,d0
	subql #4,d0
	tstl a2
	jne L1079
	pea 4:w
	jbsr ___builtin_new
	movel d0,a2
	addqw #4,sp
L1079:
	movel #__nil_Irep,a2@
	movel a2,d0
	movel d0,d1
	jra L1078
L1078:
	addql #4,d4
L1077:
	subql #1,d3
	moveq #-1,d5
	cmpl d3,d5
	jeq L1076
	jra L1075
L1076:
L1074:
	movel d2,a6@(-8)		<== d2 is not set if i==0
	movel a6@(-8),sp@-
	jbsr _myfunc
	addqw #4,sp
L1073:
	moveml a6@(-28),#0x43c
	unlk a6
	rts

Piet van Oostrum, Dept of Computer Science, University of Utrecht
Padualaan 14, P.O. Box 80.089, 3508 TB Utrecht, The Netherlands
Telephone: +31-30-531806. piet@cs.ruu.nl (mcvax!hp4nl!ruuinf!piet)