aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorMarcus Shawcroft <marcus.shawcroft@linaro.org>2013-01-16 13:28:03 +0000
committerMarcus Shawcroft <marcus.shawcroft@linaro.org>2013-01-17 10:56:49 +0000
commit857c8d222813f26e5178d3de1f272d1c3d9e24ac (patch)
treed88d80b498ed3a5349d6b0cb2a0a290596152402
parent58faa0874bc55f7520ed2255aaa7c5aa42e26292 (diff)
downloadglibc-857c8d222813f26e5178d3de1f272d1c3d9e24ac.zip
glibc-857c8d222813f26e5178d3de1f272d1c3d9e24ac.tar.gz
glibc-857c8d222813f26e5178d3de1f272d1c3d9e24ac.tar.bz2
AArch64: Implement optimized memcpy.
-rw-r--r--ports/ChangeLog.aarch644
-rw-r--r--ports/sysdeps/aarch64/memcpy.S176
2 files changed, 180 insertions, 0 deletions
diff --git a/ports/ChangeLog.aarch64 b/ports/ChangeLog.aarch64
index 9c7b155..51b51eb 100644
--- a/ports/ChangeLog.aarch64
+++ b/ports/ChangeLog.aarch64
@@ -1,5 +1,9 @@
2013-01-17 Marcus Shawcroft <marcus.shawcroft@linaro.org>
+ * sysdeps/aarch64/memcpy.S: New file.
+
+2013-01-17 Marcus Shawcroft <marcus.shawcroft@linaro.org>
+
* sysdeps/aarch64/memset.S: New file.
2013-01-17 Marcus Shawcroft <marcus.shawcroft@linaro.org>
diff --git a/ports/sysdeps/aarch64/memcpy.S b/ports/sysdeps/aarch64/memcpy.S
new file mode 100644
index 0000000..4f4e36c
--- /dev/null
+++ b/ports/sysdeps/aarch64/memcpy.S
@@ -0,0 +1,176 @@
+/* Copyright (C) 2012-2013 Free Software Foundation, Inc.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* Assumptions:
+ *
+ * ARMv8-a, AArch64
+ * Unaligned accesses
+ *
+ */
+
+#define dstin x0
+#define src x1
+#define count x2
+#define tmp1 x3
+#define tmp1w w3
+#define tmp2 x4
+#define tmp2w w4
+#define tmp3 x5
+#define tmp3w w5
+#define dst x6
+
+#define A_l x7
+#define A_h x8
+#define B_l x9
+#define B_h x10
+#define C_l x11
+#define C_h x12
+#define D_l x13
+#define D_h x14
+
+#include <sysdep.h>
+
+ENTRY_ALIGN (memcpy, 6)
+
+ mov dst, dstin
+ cmp count, #64
+ b.ge L(cpy_not_short)
+ cmp count, #15
+ b.le L(tail15tiny)
+
+ /* Deal with small copies quickly by dropping straight into the
+ * exit block. */
+L(tail63):
+ /* Copy up to 48 bytes of data. At this point we only need the
+ * bottom 6 bits of count to be accurate. */
+ ands tmp1, count, #0x30
+ b.eq L(tail15)
+ add dst, dst, tmp1
+ add src, src, tmp1
+ cmp tmp1w, #0x20
+ b.eq 1f
+ b.lt 2f
+ ldp A_l, A_h, [src, #-48]
+ stp A_l, A_h, [dst, #-48]
+1:
+ ldp A_l, A_h, [src, #-32]
+ stp A_l, A_h, [dst, #-32]
+2:
+ ldp A_l, A_h, [src, #-16]
+ stp A_l, A_h, [dst, #-16]
+
+L(tail15):
+ ands count, count, #15
+ beq 1f
+ add src, src, count
+ ldp A_l, A_h, [src, #-16]
+ add dst, dst, count
+ stp A_l, A_h, [dst, #-16]
+1:
+ RET
+
+L(tail15tiny):
+ /* Copy up to 15 bytes of data. Does not assume additional data
+ being copied. */
+ tbz count, #3, 1f
+ ldr tmp1, [src], #8
+ str tmp1, [dst], #8
+1:
+ tbz count, #2, 1f
+ ldr tmp1w, [src], #4
+ str tmp1w, [dst], #4
+1:
+ tbz count, #1, 1f
+ ldrh tmp1w, [src], #2
+ strh tmp1w, [dst], #2
+1:
+ tbz count, #0, 1f
+ ldrb tmp1w, [src]
+ strb tmp1w, [dst]
+1:
+ RET
+
+L(cpy_not_short):
+ /* We don't much care about the alignment of DST, but we want SRC
+ * to be 128-bit (16 byte) aligned so that we don't cross cache line
+ * boundaries on both loads and stores. */
+ neg tmp2, src
+ ands tmp2, tmp2, #15 /* Bytes to reach alignment. */
+ b.eq 2f
+ sub count, count, tmp2
+ /* Copy more data than needed; it's faster than jumping
+ * around copying sub-Quadword quantities. We know that
+ * it can't overrun. */
+ ldp A_l, A_h, [src]
+ add src, src, tmp2
+ stp A_l, A_h, [dst]
+ add dst, dst, tmp2
+ /* There may be less than 63 bytes to go now. */
+ cmp count, #63
+ b.le L(tail63)
+2:
+ subs count, count, #128
+ b.ge L(cpy_body_large)
+ /* Less than 128 bytes to copy, so handle 64 here and then jump
+ * to the tail. */
+ ldp A_l, A_h, [src]
+ ldp B_l, B_h, [src, #16]
+ ldp C_l, C_h, [src, #32]
+ ldp D_l, D_h, [src, #48]
+ stp A_l, A_h, [dst]
+ stp B_l, B_h, [dst, #16]
+ stp C_l, C_h, [dst, #32]
+ stp D_l, D_h, [dst, #48]
+ tst count, #0x3f
+ add src, src, #64
+ add dst, dst, #64
+ b.ne L(tail63)
+ RET
+
+ /* Critical loop. Start at a new cache line boundary. Assuming
+ * 64 bytes per line this ensures the entire loop is in one line. */
+ .p2align 6
+L(cpy_body_large):
+ /* There are at least 128 bytes to copy. */
+ ldp A_l, A_h, [src, #0]
+ sub dst, dst, #16 /* Pre-bias. */
+ ldp B_l, B_h, [src, #16]
+ ldp C_l, C_h, [src, #32]
+ ldp D_l, D_h, [src, #48]! /* src += 64 - Pre-bias. */
+1:
+ stp A_l, A_h, [dst, #16]
+ ldp A_l, A_h, [src, #16]
+ stp B_l, B_h, [dst, #32]
+ ldp B_l, B_h, [src, #32]
+ stp C_l, C_h, [dst, #48]
+ ldp C_l, C_h, [src, #48]
+ stp D_l, D_h, [dst, #64]!
+ ldp D_l, D_h, [src, #64]!
+ subs count, count, #64
+ b.ge 1b
+ stp A_l, A_h, [dst, #16]
+ stp B_l, B_h, [dst, #32]
+ stp C_l, C_h, [dst, #48]
+ stp D_l, D_h, [dst, #64]
+ add src, src, #16
+ add dst, dst, #64 + 16
+ tst count, #0x3f
+ b.ne L(tail63)
+ RET
+END (memcpy)
+libc_hidden_builtin_def (memcpy)