| Message ID | CAMe9rOpfWdbJ8ZrzyRdFws9XyrJdOJgndOxWiADJMjbDDo2=6w@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Thursday 2014-12-18 11:35, H.J. Lu wrote:
> Updated.
"the RAX register" (i.e., add "the"), and I suggest to make
this a sentence, similar to my previous mail for the other
update.
This is fine with these changes.
Thank you -- and that's a nice hack (in the positive sense)!
Gerald
On Thu, Dec 25, 2014 at 9:07 PM, Gerald Pfeifer <gerald@pfeifer.com> wrote: > On Thursday 2014-12-18 11:35, H.J. Lu wrote: >> Updated. > > "the RAX register" (i.e., add "the"), and I suggest to make > this a sentence, similar to my previous mail for the other > update. > > This is fine with these changes. Done. > Thank you -- and that's a nice hack (in the positive sense)! > It really is a hack :-) and was suggested by Rasmus Villemoes. Thanks.
On Dec 26, 2014, at 7:57 AM, "H.J. Lu" <hjl.tools@gmail.com> wrote: > On Thu, Dec 25, 2014 at 9:07 PM, Gerald Pfeifer <gerald@pfeifer.com> wrote: >> On Thursday 2014-12-18 11:35, H.J. Lu wrote: >>> Updated. >> >> "the RAX register" (i.e., add "the"), and I suggest to make >> this a sentence, similar to my previous mail for the other >> update. >> >> This is fine with these changes. > > Done. > >> Thank you -- and that's a nice hack (in the positive sense)! >> > > It really is a hack :-) and was suggested by Rasmus Villemoes. So, my suggestion is similar, but different. Imagine you find 10 of these things over the years, 10 flags look horrible. I like the -mkernel style flag where all are bundled up under it, essentially it becomes the kernel API flag.
On Sat, Dec 27, 2014 at 8:18 AM, Mike Stump <mrs@mrs.kithrup.com> wrote: > On Dec 26, 2014, at 7:57 AM, "H.J. Lu" <hjl.tools@gmail.com> wrote: >> On Thu, Dec 25, 2014 at 9:07 PM, Gerald Pfeifer <gerald@pfeifer.com> wrote: >>> On Thursday 2014-12-18 11:35, H.J. Lu wrote: >>>> Updated. >>> >>> "the RAX register" (i.e., add "the"), and I suggest to make >>> this a sentence, similar to my previous mail for the other >>> update. >>> >>> This is fine with these changes. >> >> Done. >> >>> Thank you -- and that's a nice hack (in the positive sense)! >>> >> >> It really is a hack :-) and was suggested by Rasmus Villemoes. > > So, my suggestion is similar, but different. Imagine you find 10 of these things over the years, 10 flags look horrible. I like the -mkernel style flag where all are bundled up under it, essentially it becomes the kernel API flag. So far, for Linux x86-64 kernel, we added -mskip-rax-setup and allowed -mpreferred-stack-boundary=3. We will see how far it goes :-).
Index: gcc-5/changes.html =================================================================== RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/changes.html,v retrieving revision 1.52 diff -u -p -r1.52 changes.html --- gcc-5/changes.html 15 Dec 2014 19:55:08 -0000 1.52 +++ gcc-5/changes.html 18 Dec 2014 19:35:28 -0000 @@ -444,6 +444,10 @@ void operator delete[] (void *, std::siz place of the __fentry__ or mcount call, so that a call per function can be later patched in. This can be used for low overhead tracing or hot code patching.</li> + <li>The new <code>-mskip-rax-setup</code> option to skip setting + up RAX register when SSE is disabled and there are no variable + arguments passed in vector registers. This can be used to + optimize the Linux kernel.</li> </ul> <h3 id="sh">SH</h3>