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Subject: [Bug target/97535] [9/10 Regression] On AArch64 memcpy expansion
 cannot handle length > 32-bit signed int max
Date: Tue, 17 Nov 2020 10:20:15 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97535

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Tamar Christina
<tnfchris@gcc.gnu.org>:

https://gcc.gnu.org/g:886964a78aa89ef3c15e69a7b4b96c55d51ea812

commit r10-9034-g886964a78aa89ef3c15e69a7b4b96c55d51ea812
Author: Tamar Christina <tamar.christina@arm.com>
Date:   Tue Nov 17 10:19:20 2020 +0000

    AArch64: Fix overflow in memcopy expansion on aarch64.

    Currently the inline memcpy expansion code for AArch64 is using a signed
int
    to hold the number of elements to copy.  When you giver give it a value
larger
    than INT_MAX it will overflow.

    The overflow causes the maximum number of instructions we want to expan=
d to
    check to fail since this assumes an unsigned number.

    This patch changes the maximum isns arithmetic to be unsigned.  The type
can
    stay 32-bits since the number of instructions we are allowed to expand =
to
    are at most 8 which is far below what you could fit in an unsigned int.

    note that the calculation *must* remained signed as the memcopy issues
    overlapping unaligned copies.  This means the pointer must be moved back
and
    so you need signed arithmetic.

    gcc/ChangeLog:

            PR target/97535
            * config/aarch64/aarch64.c (aarch64_expand_cpymem): Use unsigned
            arithmetic in check.

    gcc/testsuite/ChangeLog:

            PR target/97535
            * gcc.target/aarch64/pr97535.c: New test.=