[Bug middle-end/90773] Improve piecewise operation

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90773

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by H.J. Lu <hjl@gcc.gnu.org>:

https://gcc.gnu.org/g:985b3a6837dee7001e6b618f073ed74f0edf5787

commit r12-285-g985b3a6837dee7001e6b618f073ed74f0edf5787
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Mon Jun 10 09:57:15 2019 -0700

    Generate offset adjusted operation for op_by_pieces operations

    Add an overlap_op_by_pieces_p target hook for op_by_pieces operations
    between two areas of memory to generate one offset adjusted operation
    in the smallest integer mode for the remaining bytes on the last piece
    operation of a memory region to avoid doing more than one smaller
    operations.

    Pass the RTL information from the previous iteration to m_constfn in
    op_by_pieces operation so that builtin_memset_[read|gen]_str can
    generate the new RTL from the previous RTL.

    Tested on Linux/x86-64.

    gcc/

            PR middle-end/90773
            * builtins.c (builtin_memcpy_read_str): Add a dummy argument.
            (builtin_strncpy_read_str): Likewise.
            (builtin_memset_read_str): Add an argument for the previous RTL
            information and generate the new RTL from the previous RTL info.
            (builtin_memset_gen_str): Likewise.
            * builtins.h (builtin_strncpy_read_str): Update the prototype.
            (builtin_memset_read_str): Likewise.
            * expr.c (by_pieces_ninsns): If targetm.overlap_op_by_pieces_p()
            returns true, round up size and alignment to the widest integer
            mode for maximum size.
            (pieces_addr::adjust): Add a pointer to by_pieces_prev argument
            and pass it to m_constfn.
            (op_by_pieces_d): Add m_push and m_overlap_op_by_pieces.
            (op_by_pieces_d::op_by_pieces_d): Add a bool argument to
            initialize m_push.  Initialize m_overlap_op_by_pieces with
            targetm.overlap_op_by_pieces_p ().
            (op_by_pieces_d::run): Pass the previous RTL information to
            pieces_addr::adjust and generate overlapping operations if
            m_overlap_op_by_pieces is true.
            (PUSHG_P): New.
            (move_by_pieces_d::move_by_pieces_d): Updated for op_by_pieces_d
            change.
            (store_by_pieces_d::store_by_pieces_d): Updated for op_by_pieces_d
            change.
            (can_store_by_pieces): Use by_pieces_constfn on constfun.
            (store_by_pieces): Use by_pieces_constfn on constfun.  Updated
            for op_by_pieces_d change.
            (clear_by_pieces_1): Add a dummy argument.
            (clear_by_pieces): Updated for op_by_pieces_d change.
            (compare_by_pieces_d::compare_by_pieces_d): Likewise.
            (string_cst_read_str): Add a dummy argument.
            * expr.h (by_pieces_constfn): Add a dummy argument.
            (by_pieces_prev): New.
            * target.def (overlap_op_by_pieces_p): New target hook.
            * config/i386/i386.c (TARGET_OVERLAP_OP_BY_PIECES_P): New.
            * doc/tm.texi.in: Add TARGET_OVERLAP_OP_BY_PIECES_P.
            * doc/tm.texi: Regenerated.

    gcc/testsuite/

            PR middle-end/90773
            * g++.dg/pr90773-1.h: New test.
            * g++.dg/pr90773-1a.C: Likewise.
            * g++.dg/pr90773-1b.C: Likewise.
            * g++.dg/pr90773-1c.C: Likewise.
            * g++.dg/pr90773-1d.C: Likewise.
            * gcc.target/i386/pr90773-1.c: Likewise.
            * gcc.target/i386/pr90773-2.c: Likewise.
            * gcc.target/i386/pr90773-3.c: Likewise.
            * gcc.target/i386/pr90773-4.c: Likewise.
            * gcc.target/i386/pr90773-5.c: Likewise.
            * gcc.target/i386/pr90773-6.c: Likewise.
            * gcc.target/i386/pr90773-7.c: Likewise.
            * gcc.target/i386/pr90773-8.c: Likewise.
            * gcc.target/i386/pr90773-9.c: Likewise.
            * gcc.target/i386/pr90773-10.c: Likewise.
            * gcc.target/i386/pr90773-11.c: Likewise.
            * gcc.target/i386/pr90773-12.c: Likewise.
            * gcc.target/i386/pr90773-13.c: Likewise.
            * gcc.target/i386/pr90773-14.c: Likewise.