Bug 19543
| Summary: | G++ Generates incorrect code | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | Need Real Name <oneill> |
| Component: | gcc | Assignee: | Jakub Jelinek <jakub> |
| Status: | CLOSED RAWHIDE | QA Contact: | David Lawrence <dkl> |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | 7.0 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i386 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2000-10-24 13:07:33 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
Reproduced (it works well even with -O2 -fno-schedule-insns2), looking into it. Seems like it is scheduled wrongly after reload. Actually, it was related to sibling call optimization (-fno-optimize-sibling-calls also cured it). I've submitted a fix to gcc-patches, am waiting for peer review. Commited into CVS head, is fixed in gcc-2.96-61. |
(Checked for gcc-2.96-54, gcc-2.96-60 and CVS mainline gcc version 2.97 20001009 (experimental), but not a bug in 2.95.2) The enclosed code (which is little more than a "Hello World" program) generates incorrect code when compiled with -O2. For some reason, g++ is generating code that tramples that function arguments. Because the code doesn't seem to be particularly unusual or arcane, this seems like a very serious bug. rh7% g++ -O -o not-buggy buggy.cc && ./not-buggy * Shouldn't segfault * rh7% g++ -O2 -DAVOID_BUG -o not-buggy buggy.cc && ./not-buggy * Shouldn't segfault * rh7% g++ -O2 -o buggy buggy.cc && ./buggy Segmentation fault I hope this one won't be too hard to find and fix... M.E.O. Enc. #include <iostream> ostream& put (char * str, ostream& out) { #if !AVOID_BUG return out << "* " << str << " *\n"; #else out << "* " << str << " *\n"; return out; #endif } int main () { put("Shouldn't segfault", cout); }