On Wed, Aug 18, 2021 at 4:54 PM lijiang <liji...@redhat.com> wrote:
>
>
> On Wed, Aug 18, 2021 at 2:28 PM lijiang <liji...@redhat.com> wrote:
>
>>
>>
>> On Wed, Aug 18, 2021 at 11:02 AM Dave Young <dyo...@redhat.com> wrote:
>>
>>> Add Kazu in cc list
>>> On Wed, 18 Aug 2021 at 10:45, lijiang <liji...@redhat.com> wrote:
>>> >
>>> > Hi,
>>> >
>>> > In Fedora crash.spec, currently the LTO is disabled as below:
>>> >
>>> > +# This package has an internal copy of GDB which has broken configure
>>> code for
>>> > +# INTDIV0_RAISES_SIGFPE and MUST_REINSTALL_SIGHANDLERS
>>> > +# Updating that code properly seems nontrivial and best left to the
>>> package
>>> > +# maintainer.
>>> > +# Disable LTO
>>>
>>> Hi Lianbo, the above words seem to suggest disable LTO intentionally,
>>>
>>
>> Yes. I copied the above words from the Fedora crash.spec.
>>
>>
>>> I know the upstream crash tool is working on gdb 10.x integration,
>>> maybe the above is eased already with the latest gdb update?
>>>
>>>
After crash is updated to gdb-10.2, the rpm packages have been
successfully built with the LTO flag, so far I have tested it on x86_64 and
ppc64le, they can work well.
Thanks.
Lianbo
>
>> It doesn't enable LTO on upstream by default.
>>
>
>>
>>>
>>> > +%define _lto_cflags %{nil}
>>> >
>>> > commit: c6fc69dae3a2 ("Disable LTO")
>>> >
>>> > I tried to remove the macro "%define _lto_cflags %{nil}" from the
>>> crash.spec, and then build the rpm packages, But I didn't see the lto flag
>>> such as "-flto" or "-ffat-lto-objects" during the whole build stage, and
>>> the build process passed without any error reports.
>>> >
>>>
>>
>> I did the above build test on Fedora rawhide.
>>
>
> So far I have enabled the LTO for Fedora crash, but I got some compilation
> errors on ppc64le as below, and the rpm build has been successfully built
> on other architectures such as x86_64/s390x/aarch64.
>
> ../readline/search.c:55:17: note: code may be misoptimized unless
> '-fno-strict-aliasing' is used
> {standard input}: Assembler messages:
> {standard input}:3623: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:3627: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:3648: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:3652: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:3698: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:3701: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:3908: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:3920: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:4033: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:4054: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:4085: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:4086: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:4120: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:4155: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:4170: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:9811: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:10022: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
> {standard input}:10278: Error: can't resolve `.toc1' {.toc1 section} -
> `.LCTOC1' {*UND* section}
>
>
> Thanks.
>
> Lianbo
>
>
>
>>
>
>>
>>> > I'm wondering if it could rely on the redhat-rpm-config macro or
>>> it(LTO flag) can take effect when the toolchain is clang(not gcc)? Any
>>> thoughts?
>>>
>>> The question seems about how to enable LTO instead of if it is ok to
>>> enable LTO. Maybe Jeff and others can provide some inputs
>>>
>>>
>> Thank you for helping to clarify this, Dave.
>>
>> >
>>> > Thanks.
>>> > Lianbo
>>> >
>>> >
>>> >
>>> > But
>>>
>>> Thanks
>>> Dave
>>>
>>>
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