[Bug ipa/98237] gcc-dg-lto-modref-3-01.exe etc. FAIL when LTO plugin is not enabled

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98237

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Rainer Orth <ro@gcc.gnu.org>:

https://gcc.gnu.org/g:de658585d6dcc89f1cba71ef5f8f5b55719a7054

commit r14-9024-gde658585d6dcc89f1cba71ef5f8f5b55719a7054
Author: Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
Date:   Fri Feb 16 09:47:35 2024 +0100

    testsuite: Require lto-plugin support in gcc.dg/lto/modref-3 etc. [PR98237]

    gcc.dg/lto/modref-3 etc. FAIL on Solaris with the native linker:

    FAIL: gcc-dg-lto-modref-3-01.exe scan-wpa-ipa-dump modref "parm 1 flags:
no_direct_clobber no_direct_escape"
    FAIL: gcc-dg-lto-modref-4-01.exe scan-wpa-ipa-dump modref "parm 1 flags:
no_direct_clobber no_direct_escape"
    FAIL: gcc.dg/lto/modref-3 c_lto_modref-3_0.o-c_lto_modref-3_1.o execute -O2
-flto-partition=max -fdump-ipa-modref -fno-ipa-sra -fno-ipa-cp -flto
    FAIL: gcc.dg/lto/modref-4 c_lto_modref-4_0.o-c_lto_modref-4_1.o execute -O2
-flto-partition=max -fdump-ipa-modref -fno-ipa-sra -flto

    The issue is that the tests require the linker plugin, which isn't
    available with Solaris ld.  Thus, it also FAILs when gcc is configured
    with --disable-lto-plugin.

    This patch thus declares the requirement.  As it turns out, there's an
    undocumented dg-require-linker-plugin already, but I introduce and use
    the corresponding effective-target keyword and document both.

    Given that the effective-target form is more flexible, I'm tempted to
    remove dg-require-* with an empty arg as already mentioned in
    sourcebuild.texi.  That is not this patch, however.

    Tested on i386-pc-solaris2.11 with ld and gld.

    2024-02-14  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

            gcc/testsuite:
            PR ipa/98237
            * lib/target-supports.exp (is-effective-target): Handle
            linker_plugin.
            * gcc.dg/lto/modref-3_0.c: Require linker_plugin support.
            * gcc.dg/lto/modref-4_0.c: Likewise.

            gcc:
            * doc/sourcebuild.texi (Effective-Target Keywords, Other
            attribugs): Document linker_plugin.
            (Require Support): Document dg-require-linker-plugin.