| Summary: | Wrong evaluation result | ||
|---|---|---|---|
| Product: | gcc | Reporter: | J. Römmler <jroemmler> |
| Component: | c | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED DUPLICATE | ||
| Severity: | major | CC: | alexey, algorithmus, asokumar, av1474, bala, barnarr, behloul.younes, bmead15, buergel, carpman, chuchunxin, devnull, d_picco, eric.mcvicker, fuchsia.groan, gaurav_har, gcc-bugs, gcc, ggs, jandres, janis, jesser, jompo, krs, lid, lindahlb, lxg8906, mayer, mikaldaz, mike.clarkson, nakkore, nobs, pierre.van.de.laar_at_philips.com, qyang, ramiller, raoulgough, raphael.ribas, rglan, rjvbertin, robc, s9322036, SimonX200, smartmouse714, suan, super.aorta, svetozarmarkov, tczarnecki, vanveghel, vitaly, zshao |
| Priority: | P3 | ||
| Version: | 4.1.0 | ||
| Target Milestone: | --- | ||
| Host: | x86_64-redhat-linux | Target: | x86_64-redhat-linux |
| Build: | x86_64-redhat-linux | Known to work: | |
| Known to fail: | Last reconfirmed: | ||
| Attachments: | Initial test case showing the bug. | ||
Created attachment 13099 [details]
Initial test case showing the bug.
(In reply to comment #0) > The machine is a Fedora Core 6 Linux x86_64 box. Sorry, I meant "Fedora Core release 5 (Bordeaux)" |
The following C program evaluates t.a to a *wrong* value of 5 instead of 9: #include <stdio.h> struct test { int a; }; int func(struct test* tp) { tp->a = 8; /* this update is lost */ return 1; } int main(int ac, char** av) { struct test t; t.a = 4; t.a += func(&t); /* t.a (=4) already loaded into a CPU register? */ printf("t.a=%d ", t.a); if (t.a == 9) { printf("OK\n"); return 0; } else { printf("BAD\n"); return 1; } } # gcc bad_eval.c && ./a.out t.a=5 BAD The machine is a Fedora Core 6 Linux x86_64 box. # uname -a Linux titan 2.6.16-1.2080_FC5 #1 SMP Tue Mar 28 03:38:47 EST 2006 x86_64 x86_64 x86_64 GNU/Linux # gcc -v Using built-in specs. Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=x86_64-redhat-linux Thread model: posix gcc version 4.1.0 20060304 (Red Hat 4.1.0-3)