[Bug rtl-optimization/114211] [13 Regression] wrong code with -O -fno-tree-coalesce-vars since r13-1907

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114211

--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:df3994a1be3565ad450d552dc94b696748a7807a

commit r13-8447-gdf3994a1be3565ad450d552dc94b696748a7807a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Mar 5 10:32:38 2024 +0100

    lower-subreg: Fix ROTATE handling [PR114211]

    On the following testcase, we have
    (insn 10 7 11 2 (set (reg/v:TI 106 [ h ])
            (rotate:TI (reg/v:TI 106 [ h ])
                (const_int 64 [0x40]))) "pr114211.c":8:5 1042
{rotl64ti2_doubleword}
         (nil))
    before subreg1 and the pass decides to use
    (reg:DI 127 [ h ]) / (reg:DI 128 [ h+8 ])
    register pair instead of (reg/v:TI 106 [ h ]).
    resolve_operand_for_swap_move_operator implements it by pretending it is
    an assignment from
    (concatn (reg:DI 127 [ h ]) (reg:DI 128 [ h+8 ]))
    to
    (concatn (reg:DI 128 [ h+8 ]) (reg:DI 127 [ h ]))
    The problem is that if the rotate argument is the same as destination or
    if there is even an overlap between the first half of the destination with
    second half of the source we emit incorrect code, because the store to
    (reg:DI 128 [ h+8 ]) overwrites what we need for source of the second
    move.  The following patch detects that case and uses a temporary pseudo
    to hold the original (reg:DI 128 [ h+8 ]) value across the first store.

    2024-03-05  Jakub Jelinek  <jakub@redhat.com>

            PR rtl-optimization/114211
            * lower-subreg.cc (resolve_simple_move): For double-word
            rotates by BITS_PER_WORD if there is overlap between source
            and destination use a temporary.

            * gcc.dg/pr114211.c: New test.

    (cherry picked from commit aed445b0fd0c7ed16124c61e7eb732992426f103)