optimization/5793: optimisation causes an integer comparison to fail when it shouldn't

[amorris at providence dot org]

>Number:         5793
>Category:       optimization
>Synopsis:       optimisation causes an integer comparison to fail when it shouldn't
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 28 12:06:00 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Adam Morris
>Release:        gcc version 3.0.2
>Organization:
>Environment:
HP-UX11i 64 bit mode on an HP-PA machine.  No environment variables set to modify gcc
>Description:
When compiled with optimisation an if statement fails when it should succeed.  

The if statement looks like...
if (-1 == (pPort->sin_addr.s_addr = inet_addr(pcToHost)))

After the assignment, pPort->sin_addr.s_addr is -1.  If a cast to int is placed in front of the assignment then this works with and without optimisation.  

output from gcc -v -save-temps -O -o bugtest bugtest.c
Reading specs from /usr/local/pa20_64/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/specs
Configured with: ../gcc/configure --prefix=/usr/local/pa20_64 --enable-languages=c,c++ --host=hppa64-hp-hpux11.00 --target=hppa64-hp-hpux11.00 --with-ld=/usr/ccs/bin/ld --with-gnu-as --enable-libstdcxx-v3
Thread model: single
gcc version 3.0.2
 /usr/local/pa20_64/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/cpp0 -lang-c -v -iprefix /usr/local/bin/../lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/ -D__GNUC__=3 -D__GNUC_MINOR__=0 -D__GNUC_PATCHLEVEL__=2 -Dhppa -Dhp9000s800 -D__hp9000s800 -Dhp9k8 -DPWB -Dhpux -Dunix -D__hppa__ -D__hp9000s800__ -D__hp9000s800 -D__hp9k8__ -D__PWB__ -D__hpux__ -D__unix__ -D__hppa -D__hp9000s800 -D__hp9k8 -D__PWB -D__hpux -D__unix -Asystem=unix -Asystem=hpux -Acpu=hppa -Amachine=hppa -D__OPTIMIZE__ -D__STDC_HOSTED__=1 -D_PA_RISC1_1 -D__hp9000s700 -D_PA_RISC2_0 -D__hp9000s800 -D__LP64__ -D__LONG_MAX__=9223372036854775807L -D_HPUX_SOURCE -D_HIUX_SOURCE -D__STDC_EXT__ bugtest.c bugtest.i
GNU CPP version 3.0.2 (cpplib) (hppa)
ignoring nonexistent directory "/usr/local/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/include"
ignoring nonexistent directory "/usr/local/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/../../../../hppa64-hp-hpux11.00/include"
ignoring nonexistent directory "/usr/local/include"
ignoring nonexistent directory "/usr/local/pa20_64/hppa64-hp-hpux11.00/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/pa20_64/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/include
 /usr/include
End of search list.
 /usr/local/pa20_64/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/cc1 -fpreprocessed bugtest.i -quiet -dumpbase bugtest.c -O -version -o bugtest.s
GNU CPP version 3.0.2 (cpplib) (hppa)
GNU C version 3.0.2 (hppa64-hp-hpux11.00)
	compiled by GNU C version 3.0.2.
 /usr/local/pa20_64/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/../../../../hppa64-hp-hpux11.00/bin/as --traditional-format -o bugtest.o bugtest.s
 /usr/local/pa20_64/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/collect2 +Accept TypeMismatch -E -u main -o bugtest /usr/ccs/lib/pa20_64/crt0.o -L/usr/local/pa20_64/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2 -L/usr/ccs/bin -L/usr/ccs/lib/pa20_64 -L/opt/langtools/lib -L/usr/local/pa20_64/lib/gcc-lib/hppa64-hp-hpux11.00/3.0.2/../../.. bugtest.o -lgcc -lc /usr/lib/pa20_64/milli.a -lgcc
>How-To-Repeat:
Compile bugtest.c with -O and it fails.  Without it and it succeeds.  My command line was
gcc [Optional -O in here] -o bugtest bugtest.c
>Fix:
I don't know.  
>Release-Note:
>Audit-Trail:
>Unformatted:
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