apinski--- via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> From: Andrew Pinski <apin...@marvell.com>
>
> The problem here is the aarch64_expand_setmem code did not check
> STRICT_ALIGNMENT if it is creating an overlapping store.
> This patch adds that check and the testcase works.
>
> gcc/ChangeLog:
>
> PR target/101934
> * config/aarch64/aarch64.c (aarch64_expand_setmem):
> Check STRICT_ALIGNMENT before creating an overlapping
> store.
>
> gcc/testsuite/ChangeLog:
>
> PR target/101934
> * gcc.target/aarch64/memset-strict-align-1.c: New test.
OK, thanks.
Richard
> ---
> gcc/config/aarch64/aarch64.c | 4 +--
> .../aarch64/memset-strict-align-1.c | 28 +++++++++++++++++++
> 2 files changed, 30 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/aarch64/memset-strict-align-1.c
>
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index 3213585a588..26d59ba1e13 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -23566,8 +23566,8 @@ aarch64_expand_setmem (rtx *operands)
> /* Do certain trailing copies as overlapping if it's going to be
> cheaper. i.e. less instructions to do so. For instance doing a 15
> byte copy it's more efficient to do two overlapping 8 byte copies than
> - 8 + 4 + 2 + 1. */
> - if (n > 0 && n < copy_limit / 2)
> + 8 + 4 + 2 + 1. Only do this when -mstrict-align is not supplied. */
> + if (n > 0 && n < copy_limit / 2 && !STRICT_ALIGNMENT)
> {
> next_mode = smallest_mode_for_size (n, MODE_INT);
> int n_bits = GET_MODE_BITSIZE (next_mode).to_constant ();
> diff --git a/gcc/testsuite/gcc.target/aarch64/memset-strict-align-1.c
> b/gcc/testsuite/gcc.target/aarch64/memset-strict-align-1.c
> new file mode 100644
> index 00000000000..5cdc8a44968
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/memset-strict-align-1.c
> @@ -0,0 +1,28 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Os -mstrict-align" } */
> +
> +struct s { char x[95]; };
> +void foo (struct s *);
> +void bar (void) { struct s s1 = {}; foo (&s1); }
> +
> +/* memset (s1 = {}, sizeof = 95) should be expanded out
> + such that there are no overlap stores when -mstrict-align
> + is in use.
> + so 2 pair 16 bytes stores (64 bytes).
> + 1 16 byte stores
> + 1 8 byte store
> + 1 4 byte store
> + 1 2 byte store
> + 1 1 byte store
> + */
> +
> +/* { dg-final { scan-assembler-times "stp\tq" 2 } } */
> +/* { dg-final { scan-assembler-times "str\tq" 1 } } */
> +/* { dg-final { scan-assembler-times "str\txzr" 1 } } */
> +/* { dg-final { scan-assembler-times "str\twzr" 1 } } */
> +/* { dg-final { scan-assembler-times "strh\twzr" 1 } } */
> +/* { dg-final { scan-assembler-times "strb\twzr" 1 } } */
> +
> +/* Also one store pair for the frame-pointer and the LR. */
> +/* { dg-final { scan-assembler-times "stp\tx" 1 } } */
> +
