[Bug target/114717] New: '-fcf-protection' vs. offloading compilation

[Bug target/114717] New: '-fcf-protection' vs. offloading compilation

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114717

            Bug ID: 114717
           Summary: '-fcf-protection' vs. offloading compilation
           Product: gcc
           Version: 14.0
               URL: https://github.com/gcc-mirror/gcc/commit/1bf18629c54ad
                    f4893c8db5227a36e1952ee69a3#commitcomment-140648051
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tschwinge at gcc dot gnu.org
                CC: ams at gcc dot gnu.org, vries at gcc dot gnu.org
  Target Milestone: ---
            Target: GCN, nvptx

If '-fcf-protection' is in effect (as, for example, enabled by default in
certain distributions), that option gets forwarded to the offloading compilers,
but for both GCN and nvptx:

    lto1: error: ‘-fcf-protection=full’ is not supported for this target

Originally reported by Oscar Barenys in
<https://github.com/gcc-mirror/gcc/commit/1bf18629c54adf4893c8db5227a36e1952ee69a3#commitcomment-140648051>.

[Bug driver/114717] '-fcf-protection' vs. offloading compilation

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114717

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|https://github.com/gcc-mirr |
                   |or/gcc/commit/1bf18629c54ad |
                   |f4893c8db5227a36e1952ee69a3 |
                   |#commitcomment-140648051    |
          Component|target                      |driver

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
https://github.com/gcc-mirror/gcc/commit/1bf18629c54adf4893c8db5227a36e1952ee69a3#commitcomment-140648051

This option should be masked off when calling the offload-lto ...

[Bug driver/114717] '-fcf-protection' vs. offloading compilation

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114717

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |lto
   Last reconfirmed|                            |2024-04-15
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, but if offload targets were to support it, not forwarding it would be
wrong.  That said, the way we communicate this is a bit odd.

[Bug driver/114717] '-fcf-protection' vs. offloading compilation

[ams at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114717

--- Comment #3 from Andrew Stubbs <ams at gcc dot gnu.org> ---
Can this be filtered (safely) in mkoffload? That tool is
offload-target-specific, so no problem with "if offload target were to support
it".

[Bug driver/114717] '-fcf-protection' vs. offloading compilation

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114717

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Stubbs from comment #3)
> Can this be filtered (safely) in mkoffload? That tool is
> offload-target-specific, so no problem with "if offload target were to
> support it".

Yes, I think so.

[Bug driver/114717] '-fcf-protection' vs. offloading compilation

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114717

--- Comment #5 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
Distributions injecting some '-fcf-protection' by default could also inject
'-foffload-options=amdgcn-amdhsa=-fno-cf-protection' (or similar) to keep the
default case of offloading compilation working, but then with explicit
user-specified '-fcf-protection', the user would still get an error for
offloading compilation -- which may actually be desirable (for some)?

Alternatively: yes, the 'mkoffload's could filter that out -- but there is a
policy question, whether 'mkoffload's are permitted to silently drop
user-requested '-f[...]' flags?  Probably that's OK if the '-fcf-protection'
documentation is updated accordingly?

I guess I don't have any strong preference.  ;-)