Hi,
As now it's stage 1, gently ping this:
https://gcc.gnu.org/pipermail/gcc-patches/2024-February/646478.html
Thanks
Gui Haochen
在 2024/2/26 10:25, HAO CHEN GUI 写道:
> Hi,
> This patch enables overlap memory store for block memory clear which
> saves the number of store instructions. The expander calls
> widest_fixed_size_mode_for_block_clear to get the mode for looped block
> clear and calls widest_fixed_size_mode_for_block_clear to get the mode
> for last overlapped clear.
>
> Bootstrapped and tested on x86 and powerpc64-linux BE and LE with no
> regressions. Is it OK for the trunk or next stage 1?
>
> Thanks
> Gui Haochen
>
>
> ChangeLog
> rs6000: Enable overlap memory store for block memory clear
>
> gcc/
> * config/rs6000/rs6000-string.cc
> (widest_fixed_size_mode_for_block_clear): New.
> (smallest_fixed_size_mode_for_block_clear): New.
> (expand_block_clear): Call widest_fixed_size_mode_for_block_clear to
> get the mode for looped memory stores and call
> smallest_fixed_size_mode_for_block_clear to get the mode for the last
> overlapped memory store.
>
> gcc/testsuite
> * gcc.target/powerpc/block-clear-1.c: New.
>
>
> patch.diff
> diff --git a/gcc/config/rs6000/rs6000-string.cc
> b/gcc/config/rs6000/rs6000-string.cc
> index 133e5382af2..c2a6095a586 100644
> --- a/gcc/config/rs6000/rs6000-string.cc
> +++ b/gcc/config/rs6000/rs6000-string.cc
> @@ -38,6 +38,49 @@
> #include "profile-count.h"
> #include "predict.h"
>
> +/* Return the widest mode which mode size is less than or equal to the
> + size. */
> +static fixed_size_mode
> +widest_fixed_size_mode_for_block_clear (unsigned int size, unsigned int
> align,
> + bool unaligned_vsx_ok)
> +{
> + machine_mode mode;
> +
> + if (TARGET_ALTIVEC
> + && size >= 16
> + && (align >= 128
> + || unaligned_vsx_ok))
> + mode = V4SImode;
> + else if (size >= 8
> + && TARGET_POWERPC64
> + && (align >= 64
> + || !STRICT_ALIGNMENT))
> + mode = DImode;
> + else if (size >= 4
> + && (align >= 32
> + || !STRICT_ALIGNMENT))
> + mode = SImode;
> + else if (size >= 2
> + && (align >= 16
> + || !STRICT_ALIGNMENT))
> + mode = HImode;
> + else
> + mode = QImode;
> +
> + return as_a <fixed_size_mode> (mode);
> +}
> +
> +/* Return the smallest mode which mode size is smaller than or eqaul to
> + the size. */
> +static fixed_size_mode
> +smallest_fixed_size_mode_for_block_clear (unsigned int size)
> +{
> + if (size > UNITS_PER_WORD)
> + return as_a <fixed_size_mode> (V4SImode);
> +
> + return smallest_int_mode_for_size (size * BITS_PER_UNIT);
> +}
> +
> /* Expand a block clear operation, and return 1 if successful. Return 0
> if we should let the compiler generate normal code.
>
> @@ -55,7 +98,6 @@ expand_block_clear (rtx operands[])
> HOST_WIDE_INT align;
> HOST_WIDE_INT bytes;
> int offset;
> - int clear_bytes;
> int clear_step;
>
> /* If this is not a fixed size move, just call memcpy */
> @@ -89,62 +131,36 @@ expand_block_clear (rtx operands[])
>
> bool unaligned_vsx_ok = (bytes >= 32 && TARGET_EFFICIENT_UNALIGNED_VSX);
>
> - for (offset = 0; bytes > 0; offset += clear_bytes, bytes -= clear_bytes)
> + auto mode = widest_fixed_size_mode_for_block_clear (bytes, align,
> + unaligned_vsx_ok);
> + offset = 0;
> + rtx dest;
> +
> + do
> {
> - machine_mode mode = BLKmode;
> - rtx dest;
> + unsigned int size = GET_MODE_SIZE (mode);
>
> - if (TARGET_ALTIVEC
> - && (bytes >= 16 && (align >= 128 || unaligned_vsx_ok)))
> + while (bytes >= size)
> {
> - clear_bytes = 16;
> - mode = V4SImode;
> - }
> - else if (bytes >= 8 && TARGET_POWERPC64
> - && (align >= 64 || !STRICT_ALIGNMENT))
> - {
> - clear_bytes = 8;
> - mode = DImode;
> - if (offset == 0 && align < 64)
> - {
> - rtx addr;
> + dest = adjust_address (orig_dest, mode, offset);
> + emit_move_insn (dest, CONST0_RTX (mode));
>
> - /* If the address form is reg+offset with offset not a
> - multiple of four, reload into reg indirect form here
> - rather than waiting for reload. This way we get one
> - reload, not one per store. */
> - addr = XEXP (orig_dest, 0);
> - if ((GET_CODE (addr) == PLUS || GET_CODE (addr) == LO_SUM)
> - && CONST_INT_P (XEXP (addr, 1))
> - && (INTVAL (XEXP (addr, 1)) & 3) != 0)
> - {
> - addr = copy_addr_to_reg (addr);
> - orig_dest = replace_equiv_address (orig_dest, addr);
> - }
> - }
> - }
> - else if (bytes >= 4 && (align >= 32 || !STRICT_ALIGNMENT))
> - { /* move 4 bytes */
> - clear_bytes = 4;
> - mode = SImode;
> - }
> - else if (bytes >= 2 && (align >= 16 || !STRICT_ALIGNMENT))
> - { /* move 2 bytes */
> - clear_bytes = 2;
> - mode = HImode;
> - }
> - else /* move 1 byte at a time */
> - {
> - clear_bytes = 1;
> - mode = QImode;
> + offset += size;
> + bytes -= size;
> }
>
> - dest = adjust_address (orig_dest, mode, offset);
> + if (bytes == 0)
> + return 1;
>
> - emit_move_insn (dest, CONST0_RTX (mode));
> + mode = smallest_fixed_size_mode_for_block_clear (bytes);
> + int gap = GET_MODE_SIZE (mode) - bytes;
> + if (gap > 0)
> + {
> + offset -= gap;
> + bytes += gap;
> + }
> }
> -
> - return 1;
> + while (1);
> }
>
> /* Figure out the correct instructions to generate to load data for
> diff --git a/gcc/testsuite/gcc.target/powerpc/block-clear-1.c
> b/gcc/testsuite/gcc.target/powerpc/block-clear-1.c
> new file mode 100644
> index 00000000000..5e16c44fea3
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/block-clear-1.c
> @@ -0,0 +1,9 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +/* { dg-final { scan-assembler-not {\mst[hb]\M} } } */
> +
> +/* Verify that memclear takes overlap store. */
> +void* foo (char* s1)
> +{
> + __builtin_memset (s1, 0, 31);
> +}
