piet@UUNET.UU.NET (Piet van Oostrum) (02/11/89)
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)piet@ruuinf (Piet van Oostrum) (02/16/89)
I tried to mail this to bug-g++, but I have reasons to believe that that
failed. Sorry if you see this twice.
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)