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Do NOT report bugs when a package is just outdated, or it is in the AUR. Use the 'flag out of date' link on the package page, or the Mailing List.
REPEAT: Do NOT report bugs for outdated packages!
https://wiki.archlinux.org/title/Bug_reporting_guidelines
Do NOT report bugs when a package is just outdated, or it is in the AUR. Use the 'flag out of date' link on the package page, or the Mailing List.
REPEAT: Do NOT report bugs for outdated packages!
FS#54512 - [gcc] "bad codegen for __builtin_clz(unsigned short)"
Attached to Project:
Arch Linux
Opened by Jeff Cook (jeffcookio) - Monday, 19 June 2017, 07:56 GMT
Last edited by Bartłomiej Piotrowski (Barthalion) - Sunday, 25 June 2017, 19:57 GMT
Opened by Jeff Cook (jeffcookio) - Monday, 19 June 2017, 07:56 GMT
Last edited by Bartłomiej Piotrowski (Barthalion) - Sunday, 25 June 2017, 19:57 GMT
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DetailsGCC 7.1 contains a bug that results in invalid code generation when the `-mlzcnt` flag is set. This affects x64 and x86 at any optimization level. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81015 for more details.
This bug has been characterized as "really scary" by Daniel Horn of Dropbox/Stanford. See https://github.com/dropbox/lepton/issues/95 and https://github.com/dropbox/lepton/commit/209463ae36042dbd29864526f739ad851a60757d. The potential consequences of this issue seem far reaching enough to warrant proactive patching. I modified the gcc PKGBUILD locally and it seems to fix the problem. That diff is attached for convenience. |
This task depends upon
Closed by Bartłomiej Piotrowski (Barthalion)
Sunday, 25 June 2017, 19:57 GMT
Reason for closing: Fixed
Sunday, 25 June 2017, 19:57 GMT
Reason for closing: Fixed
Comment by Allan McRae (Allan) -
Monday, 19 June 2017, 09:29 GMT
No need for a backported patch. It is on the gcc-7 branch, so the commit just needs bumped.
0001-Fix-bad-codegen-in-gcc.p...