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* [Bug tree-optimization/61493] New: Bug exposed by speculative devirtualizing @ 2014-06-13 6:42 wmi at google dot com 2014-06-13 6:43 ` [Bug tree-optimization/61493] " wmi at google dot com ` (4 more replies) 0 siblings, 5 replies; 6+ messages in thread From: wmi at google dot com @ 2014-06-13 6:42 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61493 Bug ID: 61493 Summary: Bug exposed by speculative devirtualizing Product: gcc Version: 4.10.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: wmi at google dot com 1.cxx is attached. $~/workarea/gcc-r211604/build/install/bin/g++ -v Using built-in specs. COLLECT_GCC=/usr/local/google/home/wmi/workarea/gcc-r211604/build/install/bin/g++ COLLECT_LTO_WRAPPER=/usr/local/google/home/wmi/workarea/gcc-r211604/build/install/libexec/gcc/x86_64-unknown-linux-gnu/4.10.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../src/configure --enable-languages=c,c++ --disable-bootstrap --prefix=/usr/local/google/home/wmi/workarea/gcc-r211604/build/install Thread model: posix gcc version 4.10.0 20140613 (experimental) (GCC) $~/workarea/gcc-r211604/build/install/bin/g++ -O2 1.cxx $./a.out not equal $~/workarea/gcc-r211604/build/install/bin/g++ -O2 1.cxx $./a.out equal $~/workarea/gcc-r211604/build/install/bin/g++ -O2 -fno-devirtualize-speculatively 1.cxx $./a.out equal Google ref b/15521306 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/61493] Bug exposed by speculative devirtualizing 2014-06-13 6:42 [Bug tree-optimization/61493] New: Bug exposed by speculative devirtualizing wmi at google dot com @ 2014-06-13 6:43 ` wmi at google dot com 2014-06-13 9:41 ` [Bug tree-optimization/61493] [4.10 Regression] " rguenth at gcc dot gnu.org ` (3 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: wmi at google dot com @ 2014-06-13 6:43 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61493 --- Comment #1 from wmi at google dot com --- Created attachment 32931 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32931&action=edit testcase ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/61493] [4.10 Regression] Bug exposed by speculative devirtualizing 2014-06-13 6:42 [Bug tree-optimization/61493] New: Bug exposed by speculative devirtualizing wmi at google dot com 2014-06-13 6:43 ` [Bug tree-optimization/61493] " wmi at google dot com @ 2014-06-13 9:41 ` rguenth at gcc dot gnu.org 2014-06-13 15:22 ` ppluzhnikov at google dot com ` (2 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: rguenth at gcc dot gnu.org @ 2014-06-13 9:41 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61493 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |wrong-code CC| |hubicka at gcc dot gnu.org Target Milestone|--- |4.10.0 Summary|Bug exposed by speculative |[4.10 Regression] Bug |devirtualizing |exposed by speculative | |devirtualizing ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/61493] [4.10 Regression] Bug exposed by speculative devirtualizing 2014-06-13 6:42 [Bug tree-optimization/61493] New: Bug exposed by speculative devirtualizing wmi at google dot com 2014-06-13 6:43 ` [Bug tree-optimization/61493] " wmi at google dot com 2014-06-13 9:41 ` [Bug tree-optimization/61493] [4.10 Regression] " rguenth at gcc dot gnu.org @ 2014-06-13 15:22 ` ppluzhnikov at google dot com 2014-06-13 16:36 ` wmi at google dot com 2014-06-24 16:25 ` wmi at google dot com 4 siblings, 0 replies; 6+ messages in thread From: ppluzhnikov at google dot com @ 2014-06-13 15:22 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61493 Paul Pluzhnikov <ppluzhnikov at google dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ppluzhnikov at google dot com --- Comment #2 from Paul Pluzhnikov <ppluzhnikov at google dot com> --- Also broken in 4.9 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/61493] [4.10 Regression] Bug exposed by speculative devirtualizing 2014-06-13 6:42 [Bug tree-optimization/61493] New: Bug exposed by speculative devirtualizing wmi at google dot com ` (2 preceding siblings ...) 2014-06-13 15:22 ` ppluzhnikov at google dot com @ 2014-06-13 16:36 ` wmi at google dot com 2014-06-24 16:25 ` wmi at google dot com 4 siblings, 0 replies; 6+ messages in thread From: wmi at google dot com @ 2014-06-13 16:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61493 --- Comment #3 from wmi at google dot com --- Fix a typo in the first post. $~/workarea/gcc-r211604/build/install/bin/g++ -O2 1.cxx $./a.out not equal $~/workarea/gcc-r211604/build/install/bin/g++ -O0 1.cxx $./a.out equal $~/workarea/gcc-r211604/build/install/bin/g++ -O2 -fno-devirtualize-speculatively 1.cxx $./a.out equal ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/61493] [4.10 Regression] Bug exposed by speculative devirtualizing 2014-06-13 6:42 [Bug tree-optimization/61493] New: Bug exposed by speculative devirtualizing wmi at google dot com ` (3 preceding siblings ...) 2014-06-13 16:36 ` wmi at google dot com @ 2014-06-24 16:25 ` wmi at google dot com 4 siblings, 0 replies; 6+ messages in thread From: wmi at google dot com @ 2014-06-24 16:25 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61493 wmi at google dot com changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #4 from wmi at google dot com --- This is a source problem. So close the bug. void foo(FST *fst) { const PAIR &final_pair = fst->Final().getpair(); if (final_pair == global_pair) __builtin_printf("equal\n"); else __builtin_printf("not equal\n"); return; } The life time of the temporary object generated by fst->Final() will not be extended after the statement generating it, according to the following rule : a temporary bound to a return value of a function in a return statement is not extended: it is destroyed immediately at the end of the return expression. Such function always returns a dangling reference. (http://en.cppreference.com/w/cpp/language/reference_initialization) So it is meaningless to access final_pair afterwards. ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-06-24 16:25 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-06-13 6:42 [Bug tree-optimization/61493] New: Bug exposed by speculative devirtualizing wmi at google dot com 2014-06-13 6:43 ` [Bug tree-optimization/61493] " wmi at google dot com 2014-06-13 9:41 ` [Bug tree-optimization/61493] [4.10 Regression] " rguenth at gcc dot gnu.org 2014-06-13 15:22 ` ppluzhnikov at google dot com 2014-06-13 16:36 ` wmi at google dot com 2014-06-24 16:25 ` wmi at google dot com
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