On Fri, Dec 10, 2010 at 7:13 AM, H.J. Lu <hjl.to...@gmail.com> wrote: > On Thu, Dec 9, 2010 at 8:55 PM, H.J. Lu <hjl.to...@gmail.com> wrote: >> On Thu, Dec 9, 2010 at 6:29 PM, H.J. Lu <hjl.to...@gmail.com> wrote: >>> On Wed, Dec 8, 2010 at 9:36 AM, H.J. Lu <hjl.to...@gmail.com> wrote: >>>> On Wed, Dec 8, 2010 at 5:54 AM, H.J. Lu <hjl.to...@gmail.com> wrote: >>>>> On Wed, Dec 8, 2010 at 1:19 AM, Andi Kleen <a...@firstfloor.org> wrote: >>>>>>> On 12/07/2010 04:20 PM, Andi Kleen wrote: >>>>>>>> >>>>>>>> The only problem left is mixing of lto and non lto objects. this right >>>>>>>> now is not handled. IMHO still the best way to handle it is to use >>>>>>>> slim lto and then simply separate link the "left overs" after deleting >>>>>>>> the LTO objects. This can be actually done with objcopy (with some >>>>>>>> limitations), doesn't even need linker support. >>>>>>>> >>>>>>> >>>>>>> Quite possibly a better way to deal with that is to provide a mechanism >>>>>>> for encapsulating arbitrary binary code objects inside the LTO IR. >>>>>> >>>>>> Then you would need to teach your assembler and everything >>>>> >>>>> The magic section is generated by linker directly. No changes to >>>>> assembler is required. >>>>> >>>>>> else that may generate ELF objects to generate this magic object. But why >>>>>> not just ELF directly? that is what it is after all. >>>>> >>>>> My proposal isn't specific to ELF. >>>>> >>>>>> >>>>>> To be honest I don't really see the point of all this complexity you >>>>>> guys are proposing just to save fat LTO. Fat LTO is always a bad idea >>>>>> because it's slow and does lots of redundant work. If LTO is to become >>>>>> a more wide spread mode it has to go simply because of the poor >>>>>> performance. >>>>>> >>>>>> With slim LTO passthrough is very straight-forward: simple pass >>>>>> through every section that is not LTO and generate code for the LTO >>>>>> sections. No new magic sections needed at all. >>>>>> >>>>> >>>>> My proposal works on both fat and slim LTO objects. The idea is >>>>> you can use "ld -r" on any combination of inputs and its output >>>>> still works as before "ld -r". >>>>> >>>> >>>> Here is the revised proposal. >>>> >>> >>> The initial implementation of my proposal is available on hjl/lto-mixed >>> branch at >>> >>> http://git.kernel.org/?p=devel/binutils/hjl/x86.git;a=summary >>> >>> Simple case works. More cleanups are needed. Feedbacks >>> are welcome. >>> >> >> I checked in patches to remove temporary files. >> >> > > More fixes are checked in. I will try Linux kernel next. >
I checked in new fixes. "ld -r" works on Linux kernel build. But the final kernel link failed due to unrelated errors. -- H.J.
