6

The title says it all! Does clang have an equivalent of GCC's -mno-vzeroupper flag? I use 3.5, perhaps it will be in 3.6 ?

Gábor Buella
  • 1,840
  • 14
  • 22
  • 1
    Funny. One can use `-mllvm -x86-use-vzeroupper` but I don't know how to negate that. There is a pass called `x86-vzeroupper` but I can't find an option to disable a pass... If you are willing to patch the sources and rebuild llvm, it will be trivial. – Marc Glisse Jan 18 '15 at 11:50
  • 1
    I believe it would be a good idea to file a PR in llvm's bugzilla: http://llvm.org/bugs/enter_bug.cgi . They don't seem opposed to adding such a switch: http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-September/065761.html – Marc Glisse Jan 18 '15 at 11:59
  • Two years later... any update on this ? – Paul R Apr 06 '17 at 17:30
  • No, the vzeroupper instructions are still there. – Gábor Buella Sep 15 '17 at 22:54

1 Answers1

1

The following works for me: clang++ -mllvm -x86-use-vzeroupper=0

Wenzel Jakob
  • 555
  • 6
  • 14