[Bug ld/25416] TLSDESC relaxation doesn't work for x32

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=25416

--- Comment #3 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot 
gnu.org> ---
The master branch has been updated by H.J. Lu <address@hidden>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=14470f0755dbc942aa684ed647df978ddfc7cff2

commit 14470f0755dbc942aa684ed647df978ddfc7cff2
Author: H.J. Lu <address@hidden>
Date:   Mon Jan 20 06:58:51 2020 -0800

    x86-64: Fix TLSDESC relaxation for x32

    For x32, we must encode "lea x@TLSDESC(%rip), %reg" with a REX prefix
    even if it isn't required.  Otherwise linker can’t safely perform
    GDesc -> IE/LE optimization.  X32 TLSDESC sequences can be:

    40 8d 05 00 00 00 00        rex lea x@TLSDESC(%rip), %reg
    ...
    67 ff 10            call    *x@TLSCALL(%eax)

    or the same sequence as LP64:

    48 8d 05 00 00 00 00        lea     foo@TLSDESC(%rip), %reg
    ...
    ff 10                       call    *foo@TLSCALL(%rax)

    We need to support both sequences for x32.  For both GDesc -> IE/LE
    transitions,

    67 ff 10            call    *x@TLSCALL(%eax)

    should relaxed to

    0f 1f 00            nopl    (%rax)

    For GDesc -> LE transition,

    40 8d 05 00 00 00 00        rex lea x@TLSDESC(%rip), %reg

    should relaxed to

    40 c7 c0 fc ff ff ff        rex movl $x@tpoff, %reg

    For GDesc -> IE transition,

    40 8d 05 00 00 00 00        rex lea x@TLSDESC(%rip), %reg

    should relaxed to

    40 8b 05 00 00 00 00        rex movl x@gottpoff(%rip), %eax

    bfd/

        PR ld/25416
        * elf64-x86-64.c (elf_x86_64_check_tls_transition): Support
        "rex leal x@tlsdesc(%rip), %reg" and "call *x@tlsdesc(%eax)" in
        X32 mode.
        (elf_x86_64_relocate_section): In x32 mode, for GDesc -> LE
        transition, relax "rex leal x@tlsdesc(%rip), %reg" to
        "rex movl $x@tpoff, %reg", for GDesc -> IE transition, relax
        "rex leal x@tlsdesc(%rip), %reg" to
        "rex movl x@gottpoff(%rip), %eax".  For both transitions, relax
        "call *(%eax)" to "nopl (%rax)".

    gas/

        PR ld/25416
        * config/tc-i386.c (output_insn): Add a dummy REX_OPCODE prefix
        for lea with R_X86_64_GOTPC32_TLSDESC relocation when generating
        x32 object.
        * testsuite/gas/i386/ilp32/x32-tls.d: Updated.
        * testsuite/gas/i386/ilp32/x32-tls.s: Add tests for lea with
        R_X86_64_GOTPC32_TLSDESC relocation.

    ld/

        PR ld/25416
        * testsuite/ld-x86-64/pr25416-1.s: New file
        * testsuite/ld-x86-64/pr25416-1a.d: Likewise.
        * testsuite/ld-x86-64/pr25416-1b.d: Likewise.
        * testsuite/ld-x86-64/pr25416-1.s: Likewise.
        * testsuite/ld-x86-64/pr25416-2.s: Likewise.
        * testsuite/ld-x86-64/pr25416-2a.d: Likewise.
        * testsuite/ld-x86-64/pr25416-2b.d: Likewise.
        * testsuite/ld-x86-64/pr25416-3.d: Likewise.
        * testsuite/ld-x86-64/pr25416-3.s: Likewise.
        * testsuite/ld-x86-64/pr25416-4.d: Likewise.
        * testsuite/ld-x86-64/pr25416-4.s: Likewise.
        * testsuite/ld-x86-64/pr25416-5a.c: Likewise.
        * testsuite/ld-x86-64/pr25416-5b.s: Likewise.
        * testsuite/ld-x86-64/pr25416-5c.s: Likewise.
        * testsuite/ld-x86-64/pr25416-5d.s: Likewise.
        * testsuite/ld-x86-64/pr25416-5e.s: Likewise.
        * testsuite/ld-x86-64/x86-64.exp: Run PR ld/25416 tests.

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