public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
* [Bug c/52291] New: __sync_fetch_and_add and friends poorly specified for pointer types @ 2012-02-17 0:37 hstong at ca dot ibm.com 2012-02-17 0:41 ` [Bug c/52291] " redi at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: hstong at ca dot ibm.com @ 2012-02-17 0:37 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52291 Bug #: 52291 Summary: __sync_fetch_and_add and friends poorly specified for pointer types Classification: Unclassified Product: gcc Version: 4.6.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned@gcc.gnu.org ReportedBy: hstong@ca.ibm.com CC: michaelw@ca.ibm.com Host: powerpc64-unknown-linux-gnu Target: powerpc64-unknown-linux-gnu The documentation states, regarding the __sync_fetch_and_X builtins: These builtins perform the operation suggested by the name, and returns the value that had previously been in memory. That is, { tmp = *ptr; *ptr op= value; return tmp; } { tmp = *ptr; *ptr = ~(tmp & value); return tmp; } // nand For pointer types (which GCC accepts for these builtins) the "operation suggested by the name" leans toward pointer arithmetic; however, the pointer types are not suitable for these operations in C/C++. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/52291] __sync_fetch_and_add and friends poorly specified for pointer types 2012-02-17 0:37 [Bug c/52291] New: __sync_fetch_and_add and friends poorly specified for pointer types hstong at ca dot ibm.com @ 2012-02-17 0:41 ` redi at gcc dot gnu.org 2012-02-17 1:00 ` hstong at ca dot ibm.com 2012-02-17 9:03 ` mikpe at it dot uu.se 2 siblings, 0 replies; 4+ messages in thread From: redi at gcc dot gnu.org @ 2012-02-17 0:41 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52291 --- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-02-17 00:38:15 UTC --- N.B. those built-ins are deprecated in favour of http://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/52291] __sync_fetch_and_add and friends poorly specified for pointer types 2012-02-17 0:37 [Bug c/52291] New: __sync_fetch_and_add and friends poorly specified for pointer types hstong at ca dot ibm.com 2012-02-17 0:41 ` [Bug c/52291] " redi at gcc dot gnu.org @ 2012-02-17 1:00 ` hstong at ca dot ibm.com 2012-02-17 9:03 ` mikpe at it dot uu.se 2 siblings, 0 replies; 4+ messages in thread From: hstong at ca dot ibm.com @ 2012-02-17 1:00 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52291 --- Comment #1 from Hubert Tong <hstong at ca dot ibm.com> 2012-02-17 00:37:12 UTC --- I mean that the pseudo-code is not consistent with valid C/C++ when the operands (`*ptr' and `value') are pointer types. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/52291] __sync_fetch_and_add and friends poorly specified for pointer types 2012-02-17 0:37 [Bug c/52291] New: __sync_fetch_and_add and friends poorly specified for pointer types hstong at ca dot ibm.com 2012-02-17 0:41 ` [Bug c/52291] " redi at gcc dot gnu.org 2012-02-17 1:00 ` hstong at ca dot ibm.com @ 2012-02-17 9:03 ` mikpe at it dot uu.se 2 siblings, 0 replies; 4+ messages in thread From: mikpe at it dot uu.se @ 2012-02-17 9:03 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52291 --- Comment #3 from Mikael Pettersson <mikpe at it dot uu.se> 2012-02-17 08:53:28 UTC --- (In reply to comment #1) > I mean that the pseudo-code is not consistent with valid C/C++ when the > operands (`*ptr' and `value') are pointer types. I would think it's implied that the pointer values are automatically converted to uintptr_t and that the bit-twiddling or arithmetic is done on their uintptr_t representations. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-02-17 8:54 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-02-17 0:37 [Bug c/52291] New: __sync_fetch_and_add and friends poorly specified for pointer types hstong at ca dot ibm.com 2012-02-17 0:41 ` [Bug c/52291] " redi at gcc dot gnu.org 2012-02-17 1:00 ` hstong at ca dot ibm.com 2012-02-17 9:03 ` mikpe at it dot uu.se
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).