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From: "rearnsha at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/58621] With -fsection-anchors, a superfluous 'add' is performed
Date: Sun, 06 Oct 2013 22:18:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58621

Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #3 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
No, the LO12 relocations (see the AArch64 ELF bindings in infocenter) are
defined to insert (S + A) & 0xff<n> (n = 0xf, 0xe, 0xc, 0x8 for byte, halfword,
word and dword respectively), so never insert more than 12 bits into the offset
field, even when there is space for more.  Note that the addend is inside the
mask operation

This is needed because the ADRP and LDR have to work as a pair when a symbol
has an offset and the offset could be of arbitrary size.  For example,

    adrp  x0, A+102400
    ldr   w1, [x0, #:lo12:A+102400]

still needs to work.