Ping.
On Thu, Jul 29, 2021 at 4:33 PM Christoph Muellner
<cmuell...@gcc.gnu.org> wrote:
>
> The RISC-V cpymemsi expansion is called, whenever the by-pieces
> infrastructure will not be taking care of the builtin expansion.
> Currently, that's the case for e.g. memcpy() with n <= 24 bytes.
> The code emitted by the by-pieces infrastructure emits code, that
> performs unaligned accesses if the target's
> riscv_slow_unaligned_access_p is false (and n is not 1).
>
> If n > 24, then the RISC-V cpymemsi expansion is called, which is
> implemented in riscv_expand_block_move(). The current implementation
> does not check riscv_slow_unaligned_access_p and never emits unaligned
> accesses.
>
> Since by-pieces emits unaligned accesses, it is reasonable to implement
> the same behaviour in the cpymemsi expansion. And that's what this patch
> is doing.
>
> The patch checks riscv_slow_unaligned_access_p at the entry and sets
> the allowed alignment accordingly. This alignment is then propagated
> down to the routines that emit the actual instructions.
>
> Without the patch a memcpy() with n==25 will be exanded only
> if the given pointers are aligned. With the patch also unaligned
> pointers are accepted if riscv_slow_unaligned_access_p is false.
>
> gcc/ChangeLog:
>
> * config/riscv/riscv.c (riscv_block_move_straight): Add
> parameter align.
> (riscv_adjust_block_mem): Replace parameter length by parameter
> align.
> (riscv_block_move_loop): Add parameter align.
> (riscv_expand_block_move): Set alignment properly if the target
> has fast unaligned access.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/builtins-strict-align.c: New test.
> * gcc.target/riscv/builtins-unaligned-1.c: New test.
> * gcc.target/riscv/builtins-unaligned-2.c: New test.
> * gcc.target/riscv/builtins-unaligned-3.c: New test.
> * gcc.target/riscv/builtins-unaligned-4.c: New test.
> * gcc.target/riscv/builtins.h: New test.
>
> Signed-off-by: Christoph Muellner <cmuell...@gcc.gnu.org>
> ---
> gcc/config/riscv/riscv.c | 53 +++++++++++--------
> .../gcc.target/riscv/builtins-strict-align.c | 13 +++++
> .../gcc.target/riscv/builtins-unaligned-1.c | 15 ++++++
> .../gcc.target/riscv/builtins-unaligned-2.c | 15 ++++++
> .../gcc.target/riscv/builtins-unaligned-3.c | 15 ++++++
> .../gcc.target/riscv/builtins-unaligned-4.c | 15 ++++++
> gcc/testsuite/gcc.target/riscv/builtins.h | 10 ++++
> 7 files changed, 115 insertions(+), 21 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/riscv/builtins-strict-align.c
> create mode 100644 gcc/testsuite/gcc.target/riscv/builtins-unaligned-1.c
> create mode 100644 gcc/testsuite/gcc.target/riscv/builtins-unaligned-2.c
> create mode 100644 gcc/testsuite/gcc.target/riscv/builtins-unaligned-3.c
> create mode 100644 gcc/testsuite/gcc.target/riscv/builtins-unaligned-4.c
> create mode 100644 gcc/testsuite/gcc.target/riscv/builtins.h
>
> diff --git a/gcc/config/riscv/riscv.c b/gcc/config/riscv/riscv.c
> index 576960bb37c..0596a9ff1b6 100644
> --- a/gcc/config/riscv/riscv.c
> +++ b/gcc/config/riscv/riscv.c
> @@ -3173,11 +3173,13 @@ riscv_legitimize_call_address (rtx addr)
> return addr;
> }
>
> -/* Emit straight-line code to move LENGTH bytes from SRC to DEST.
> +/* Emit straight-line code to move LENGTH bytes from SRC to DEST
> + with accesses that are ALIGN bytes aligned.
> Assume that the areas do not overlap. */
>
> static void
> -riscv_block_move_straight (rtx dest, rtx src, unsigned HOST_WIDE_INT length)
> +riscv_block_move_straight (rtx dest, rtx src, unsigned HOST_WIDE_INT length,
> + unsigned HOST_WIDE_INT align)
> {
> unsigned HOST_WIDE_INT offset, delta;
> unsigned HOST_WIDE_INT bits;
> @@ -3185,8 +3187,7 @@ riscv_block_move_straight (rtx dest, rtx src, unsigned
> HOST_WIDE_INT length)
> enum machine_mode mode;
> rtx *regs;
>
> - bits = MAX (BITS_PER_UNIT,
> - MIN (BITS_PER_WORD, MIN (MEM_ALIGN (src), MEM_ALIGN (dest))));
> + bits = MAX (BITS_PER_UNIT, MIN (BITS_PER_WORD, align));
>
> mode = mode_for_size (bits, MODE_INT, 0).require ();
> delta = bits / BITS_PER_UNIT;
> @@ -3211,21 +3212,20 @@ riscv_block_move_straight (rtx dest, rtx src,
> unsigned HOST_WIDE_INT length)
> {
> src = adjust_address (src, BLKmode, offset);
> dest = adjust_address (dest, BLKmode, offset);
> - move_by_pieces (dest, src, length - offset,
> - MIN (MEM_ALIGN (src), MEM_ALIGN (dest)), RETURN_BEGIN);
> + move_by_pieces (dest, src, length - offset, align, RETURN_BEGIN);
> }
> }
>
> /* Helper function for doing a loop-based block operation on memory
> - reference MEM. Each iteration of the loop will operate on LENGTH
> - bytes of MEM.
> + reference MEM.
>
> Create a new base register for use within the loop and point it to
> the start of MEM. Create a new memory reference that uses this
> - register. Store them in *LOOP_REG and *LOOP_MEM respectively. */
> + register and has an alignment of ALIGN. Store them in *LOOP_REG
> + and *LOOP_MEM respectively. */
>
> static void
> -riscv_adjust_block_mem (rtx mem, unsigned HOST_WIDE_INT length,
> +riscv_adjust_block_mem (rtx mem, unsigned HOST_WIDE_INT align,
> rtx *loop_reg, rtx *loop_mem)
> {
> *loop_reg = copy_addr_to_reg (XEXP (mem, 0));
> @@ -3233,15 +3233,17 @@ riscv_adjust_block_mem (rtx mem, unsigned
> HOST_WIDE_INT length,
> /* Although the new mem does not refer to a known location,
> it does keep up to LENGTH bytes of alignment. */
> *loop_mem = change_address (mem, BLKmode, *loop_reg);
> - set_mem_align (*loop_mem, MIN (MEM_ALIGN (mem), length * BITS_PER_UNIT));
> + set_mem_align (*loop_mem, align);
> }
>
> /* Move LENGTH bytes from SRC to DEST using a loop that moves BYTES_PER_ITER
> - bytes at a time. LENGTH must be at least BYTES_PER_ITER. Assume that
> - the memory regions do not overlap. */
> + bytes at a time. LENGTH must be at least BYTES_PER_ITER. The alignment
> + of the access can be set by ALIGN. Assume that the memory regions do not
> + overlap. */
>
> static void
> riscv_block_move_loop (rtx dest, rtx src, unsigned HOST_WIDE_INT length,
> + unsigned HOST_WIDE_INT align,
> unsigned HOST_WIDE_INT bytes_per_iter)
> {
> rtx label, src_reg, dest_reg, final_src, test;
> @@ -3251,8 +3253,8 @@ riscv_block_move_loop (rtx dest, rtx src, unsigned
> HOST_WIDE_INT length,
> length -= leftover;
>
> /* Create registers and memory references for use within the loop. */
> - riscv_adjust_block_mem (src, bytes_per_iter, &src_reg, &src);
> - riscv_adjust_block_mem (dest, bytes_per_iter, &dest_reg, &dest);
> + riscv_adjust_block_mem (src, align, &src_reg, &src);
> + riscv_adjust_block_mem (dest, align, &dest_reg, &dest);
>
> /* Calculate the value that SRC_REG should have after the last iteration
> of the loop. */
> @@ -3264,7 +3266,7 @@ riscv_block_move_loop (rtx dest, rtx src, unsigned
> HOST_WIDE_INT length,
> emit_label (label);
>
> /* Emit the loop body. */
> - riscv_block_move_straight (dest, src, bytes_per_iter);
> + riscv_block_move_straight (dest, src, bytes_per_iter, align);
>
> /* Move on to the next block. */
> riscv_emit_move (src_reg, plus_constant (Pmode, src_reg, bytes_per_iter));
> @@ -3276,7 +3278,7 @@ riscv_block_move_loop (rtx dest, rtx src, unsigned
> HOST_WIDE_INT length,
>
> /* Mop up any left-over bytes. */
> if (leftover)
> - riscv_block_move_straight (dest, src, leftover);
> + riscv_block_move_straight (dest, src, leftover, align);
> else
> emit_insn(gen_nop ());
> }
> @@ -3292,8 +3294,17 @@ riscv_expand_block_move (rtx dest, rtx src, rtx length)
> unsigned HOST_WIDE_INT hwi_length = UINTVAL (length);
> unsigned HOST_WIDE_INT factor, align;
>
> - align = MIN (MIN (MEM_ALIGN (src), MEM_ALIGN (dest)), BITS_PER_WORD);
> - factor = BITS_PER_WORD / align;
> + if (riscv_slow_unaligned_access_p)
> + {
> + align = MIN (MIN (MEM_ALIGN (src), MEM_ALIGN (dest)),
> BITS_PER_WORD);
> + factor = BITS_PER_WORD / align;
> + }
> + else
> + {
> + /* Assume data to be aligned. */
> + align = hwi_length * BITS_PER_UNIT;
> + factor = 1;
> + }
>
> if (optimize_function_for_size_p (cfun)
> && hwi_length * factor * UNITS_PER_WORD > MOVE_RATIO (false))
> @@ -3301,7 +3312,7 @@ riscv_expand_block_move (rtx dest, rtx src, rtx length)
>
> if (hwi_length <= (RISCV_MAX_MOVE_BYTES_STRAIGHT / factor))
> {
> - riscv_block_move_straight (dest, src, INTVAL (length));
> + riscv_block_move_straight (dest, src, hwi_length, align);
> return true;
> }
> else if (optimize && align >= BITS_PER_WORD)
> @@ -3321,7 +3332,7 @@ riscv_expand_block_move (rtx dest, rtx src, rtx length)
> iter_words = i;
> }
>
> - riscv_block_move_loop (dest, src, bytes, iter_words *
> UNITS_PER_WORD);
> + riscv_block_move_loop (dest, src, bytes, align, iter_words *
> UNITS_PER_WORD);
> return true;
> }
> }
> diff --git a/gcc/testsuite/gcc.target/riscv/builtins-strict-align.c
> b/gcc/testsuite/gcc.target/riscv/builtins-strict-align.c
> new file mode 100644
> index 00000000000..6f7b1f324de
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/builtins-strict-align.c
> @@ -0,0 +1,13 @@
> +/* { dg-options "-O2 -mtune=thead-c906 -march=rv64gc -mabi=lp64
> -mstrict-align" } */
> +/* { dg-do compile } */
> +
> +#include "builtins.h"
> +
> +DO_MEMCPY_N(12)
> +
> +/* { dg-final { scan-assembler-times "lbu" 12 } } */
> +/* { dg-final { scan-assembler-times "sb" 12 } } */
> +/* { dg-final { scan-assembler-not "lw" } } */
> +/* { dg-final { scan-assembler-not "sw" } } */
> +/* { dg-final { scan-assembler-not "ld" } } */
> +/* { dg-final { scan-assembler-not "sd" } } */
> diff --git a/gcc/testsuite/gcc.target/riscv/builtins-unaligned-1.c
> b/gcc/testsuite/gcc.target/riscv/builtins-unaligned-1.c
> new file mode 100644
> index 00000000000..f97d60a35d4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/builtins-unaligned-1.c
> @@ -0,0 +1,15 @@
> +/* { dg-options "-O2 -mtune=thead-c906 -march=rv64gc -mabi=lp64" } */
> +/* { dg-do compile } */
> +
> +#include "builtins.h"
> +
> +DO_MEMCPY_N(7)
> +
> +/* { dg-final { scan-assembler-not "ld" } } */
> +/* { dg-final { scan-assembler-not "sd" } } */
> +/* { dg-final { scan-assembler-times "lw" 1 } } */
> +/* { dg-final { scan-assembler-times "sw" 1 } } */
> +/* { dg-final { scan-assembler-times "lh" 1 } } */
> +/* { dg-final { scan-assembler-times "sh" 1 } } */
> +/* { dg-final { scan-assembler-times "lbu" 1 } } */
> +/* { dg-final { scan-assembler-times "sb" 1 } } */
> diff --git a/gcc/testsuite/gcc.target/riscv/builtins-unaligned-2.c
> b/gcc/testsuite/gcc.target/riscv/builtins-unaligned-2.c
> new file mode 100644
> index 00000000000..b373651d241
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/builtins-unaligned-2.c
> @@ -0,0 +1,15 @@
> +/* { dg-options "-O2 -mtune=thead-c906 -march=rv64gc -mabi=lp64" } */
> +/* { dg-do compile } */
> +
> +#include "builtins.h"
> +
> +DO_MEMCPY_N(8)
> +
> +/* { dg-final { scan-assembler-times "ld" 1 } } */
> +/* { dg-final { scan-assembler-times "sd" 1 } } */
> +/* { dg-final { scan-assembler-not "lw" } } */
> +/* { dg-final { scan-assembler-not "sw" } } */
> +/* { dg-final { scan-assembler-not "lh" } } */
> +/* { dg-final { scan-assembler-not "sh" } } */
> +/* { dg-final { scan-assembler-not "lbu" } } */
> +/* { dg-final { scan-assembler-not "sb" } } */
> diff --git a/gcc/testsuite/gcc.target/riscv/builtins-unaligned-3.c
> b/gcc/testsuite/gcc.target/riscv/builtins-unaligned-3.c
> new file mode 100644
> index 00000000000..3f4a6b9630b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/builtins-unaligned-3.c
> @@ -0,0 +1,15 @@
> +/* { dg-options "-O2 -mtune=thead-c906 -march=rv64gc -mabi=lp64" } */
> +/* { dg-do compile } */
> +
> +#include "builtins.h"
> +
> +DO_MEMCPY_N(31)
> +
> +/* { dg-final { scan-assembler-times "ld" 3 } } */
> +/* { dg-final { scan-assembler-times "sd" 3 } } */
> +/* { dg-final { scan-assembler-times "lw" 1 } } */
> +/* { dg-final { scan-assembler-times "sw" 1 } } */
> +/* { dg-final { scan-assembler-times "lh" 1 } } */
> +/* { dg-final { scan-assembler-times "sh" 1 } } */
> +/* { dg-final { scan-assembler-times "lbu" 1 } } */
> +/* { dg-final { scan-assembler-times "sb" 1 } } */
> diff --git a/gcc/testsuite/gcc.target/riscv/builtins-unaligned-4.c
> b/gcc/testsuite/gcc.target/riscv/builtins-unaligned-4.c
> new file mode 100644
> index 00000000000..26fcb7a71a7
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/builtins-unaligned-4.c
> @@ -0,0 +1,15 @@
> +/* { dg-options "-O2 -mtune=thead-c906 -march=rv64gc -mabi=lp64" } */
> +/* { dg-do compile } */
> +
> +#include "builtins.h"
> +
> +DO_MEMCPY_N(63)
> +
> +/* { dg-final { scan-assembler-times "ld" 7 } } */
> +/* { dg-final { scan-assembler-times "sd" 7 } } */
> +/* { dg-final { scan-assembler-times "lw" 1 } } */
> +/* { dg-final { scan-assembler-times "sw" 1 } } */
> +/* { dg-final { scan-assembler-times "lh" 1 } } */
> +/* { dg-final { scan-assembler-times "sh" 1 } } */
> +/* { dg-final { scan-assembler-times "lbu" 1 } } */
> +/* { dg-final { scan-assembler-times "sb" 1 } } */
> diff --git a/gcc/testsuite/gcc.target/riscv/builtins.h
> b/gcc/testsuite/gcc.target/riscv/builtins.h
> new file mode 100644
> index 00000000000..5cad5fe194b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/builtins.h
> @@ -0,0 +1,10 @@
> +#ifndef BUILTINS_H
> +#define BUILTINS_H
> +
> +#define DO_MEMCPY_N(N) \
> +void do_memcpy_##N (void *d, const void *s) \
> +{ \
> + __builtin_memcpy (d, s, N); \
> +}
> +
> +#endif /* BUILTINS_H */
> --
> 2.31.1
>
