LAPACK test problem dumps core at -O2 - egcs-19981101 g77 - mips-sgi-irix6.2

[Billinghurst, David (RTD)]

I have narrowed this down to one loop, but I can't reduce the size of the
test case ;-<
The problem is with the double loop around a statement function cabs1 in
routine cchkgk
Almost any change to the loop - for example the write statement below -
eliminates the error
 
	*** cchkgk.f    Thu Nov 12 07:57:15 1998
	--- cchkgk2.f   Thu Nov 12 09:00:18 1998
	***************
	*** 148,157 ****
	--- 148,158 ----
	        CALL CGEMM( 'C', 'N', M, M, N, CONE, VLF, LDVL, WORK,
LDWORK,
	       $            CZERO, F, LDF )
	  *
	        VMAX = ZERO
	        DO 70 J = 1, M
	+          write(6,*) 'j = '
	           DO 60 I = 1, M
	              VMAX = MAX( VMAX, CABS1( E( I, J )-F( I, J ) ) )
	     60    CONTINUE
	     70 CONTINUE

> -----Original Message-----
> From:	Billinghurst, David (RTD) 
> Sent:	Friday, November 06, 1998 5:43 PM
> To:	'egcs-bugs@cygnus.com'
> Subject:	 LAPACK test problem dumps core at -O2 - egcs-19981101 g77 -
> mips-sgi-irix6.2
> 
> System: mips-sgi-irix6.2
> Compiler: egcs-19981101 g77
> 
> Problem: LAPACK test problem dumps core at -O2
> 
> 
> The following problem is derived from the LAPACK test suite.
> LAPACK usually compiles and passes without error using egcs g77.
> 
> This case may be of interest since the current egcs snapshot passes
> all the of the testsuite, apart from the usual gcc failures.
> Error is due to optimisation of subroutine cchkgk. -O1 is OK.  -O2 isn't
> 
> Reproduce by:
> 
> # expected behaviour
> /usr/local/tmp/egcs-19981101/bin/g77 -o bug-O1 -g -O1 all.f
> 
> bug-O1 < bug2.in
>  .. test output of CGGBAK .. 
>  value of largest test error                  =   0.000E+00
>  example number where CGGBAL info is not 0    =   0
>  example number where CGGBAK(L) info is not 0 =   0
>  example number where CGGBAK(R) info is not 0 =   0
>  example number having largest error          =   0
>  number of examples where info is not 0       =   0
>  total number of examples tested              =   1 
> 
> # At -O2 get
> /usr/local/tmp/egcs-19981101/bin/g77 -o bug-O2 -g -O2 all.f
> bug-O2  < bug2.in
> Bus error (core dumped)
> 
> dbx bug-O2 core
> dbx version 7.1 Dec  3 1996 17:03:19
> Core from signal SIGBUS: Bus error
> (dbx) where
> >  0 cchkgk_() ["/usr/people/billingd/dev/cgbak/all.f":47, 0x10003650]
>    1 MAIN__() ["/usr/people/billingd/dev/cgbak/all.f":2, 0x10002a9c]
>    2 main(argc = 2147429864, argv = 0x7fff2df0)
> ["/exd2/billingd/obj/egcs-19981101/mips-sgi-irix6.2/libf2c/libF77/../../..
> /../../src/egcs-19981101/libf2c/libF77/main.c":61, 0x10012d80]
>    3 __start()
> ["/vince/6.2-mar09/work/irix/lib/libc/libc_n32_M3/csu/crt1text.s":166,
> 0x10002984]
> (dbx) 
> 
> +++++++++++++++++++++++++++++++++++++++++
> (Mr) David Billinghurst
> Comalco Research and Technical Support
> PO Box 316, Thomastown, Vic, Australia, 3074
> Phone:	+61 3 9469 0642
> FAX:	+61 3 9462 2700
> Email:	David.Billinghurst@riotinto.com.au
> 
>  << File: bug2.in >>  << File: all.f.gz >>