Andrew Pinski <quic_apin...@quicinc.com> writes:
> After r14-1187-gd6b756447cd58b, simplify_gen_subreg can return
> NULL for "unaligned" memory subreg. Since V8DI has an alignment of 8 bytes,
> using TImode causes simplify_gen_subreg to return NULL.
> This fixes the issue by using DImode instead for the loop. And then we will
> have
> later on the STP/LDP pass combine it back into STP/LDP if needed.
> Since strict align is less important (usually used for firmware and early
> boot only),
> not doing LDP/STP here is ok.
>
> Built and tested for aarch64-linux-gnu with no regressions.
>
> PR target/113657
>
> gcc/ChangeLog:
>
> * config/aarch64/aarch64-simd.md (split for movv8di):
> For strict aligned mode, use DImode instead of TImode.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/aarch64/acle/ls64_strict_align.c: New test.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/config/aarch64/aarch64-simd.md | 16 ++++++++++++----
> .../gcc.target/aarch64/acle/ls64_strict_align.c | 7 +++++++
> 2 files changed, 19 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c
>
> diff --git a/gcc/config/aarch64/aarch64-simd.md
> b/gcc/config/aarch64/aarch64-simd.md
> index 7a6b4430112..0b4b37115d6 100644
> --- a/gcc/config/aarch64/aarch64-simd.md
> +++ b/gcc/config/aarch64/aarch64-simd.md
> @@ -8221,14 +8221,22 @@ (define_split
> || (memory_operand (operands[0], V8DImode)
> && register_operand (operands[1], V8DImode)))
> {
> + int increment = 16;
> + machine_mode mode = TImode;
> + /* For strict alignment, use DImode to avoid "unalign" subreg. */
> + if (STRICT_ALIGNMENT)
> + {
> + mode = DImode;
> + increment = 8;
> + }
Sorry for the trivial change, but I think this would be slightly neater as:
/* V8DI only guarantees 8-byte alignment, whereas TImode requires 16. */
auto mode = STRICT_ALIGNMENT ? DImode : TImode;
int increment = GET_MODE_SIZE (mode);
OK with that change, thanks.
Richard
> std::pair<rtx, rtx> last_pair = {};
> - for (int offset = 0; offset < 64; offset += 16)
> + for (int offset = 0; offset < 64; offset += increment)
> {
> std::pair<rtx, rtx> pair = {
> - simplify_gen_subreg (TImode, operands[0], V8DImode, offset),
> - simplify_gen_subreg (TImode, operands[1], V8DImode, offset)
> + simplify_gen_subreg (mode, operands[0], V8DImode, offset),
> + simplify_gen_subreg (mode, operands[1], V8DImode, offset)
> };
> - if (register_operand (pair.first, TImode)
> + if (register_operand (pair.first, mode)
> && reg_overlap_mentioned_p (pair.first, pair.second))
> last_pair = pair;
> else
> diff --git a/gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c
> b/gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c
> new file mode 100644
> index 00000000000..bf49ac76f78
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/acle/ls64_strict_align.c
> @@ -0,0 +1,7 @@
> +/* { dg-do compile } */
> +/* { dg-options "-mstrict-align" } */
> +/* PR target/113657 */
> +
> +#pragma GCC target "+ls64"
> +#pragma GCC aarch64 "arm_acle.h"
> +__arm_data512_t foo(__arm_data512_t* ptr) { return *ptr; }
