Prepare for radical source tree reorganization. zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 166 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/aarch64/strrchr.S b/REORG.TODO/sysdeps/aarch64/strrchr.S
new file mode 100644
index 0000000000..f8e5e8e036
--- /dev/null
+++ b/REORG.TODO/sysdeps/aarch64/strrchr.S
@@ -0,0 +1,166 @@
+/* strrchr: find the last instance of a character in a string.
+
+   Copyright (C) 2014-2017 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/>.  */
+
+#include <sysdep.h>
+
+/* Assumptions:
+ *
+ * ARMv8-a, AArch64
+ * Neon Available.
+ */
+
+/* Arguments and results.  */
+#define srcin		x0
+#define chrin		w1
+
+#define result		x0
+
+#define src		x2
+#define	tmp1		x3
+#define wtmp2		w4
+#define tmp3		x5
+#define src_match	x6
+#define src_offset	x7
+#define const_m1	x8
+#define tmp4		x9
+#define nul_match	x10
+#define chr_match	x11
+
+#define vrepchr		v0
+#define vdata1		v1
+#define vdata2		v2
+#define vhas_nul1	v3
+#define vhas_nul2	v4
+#define vhas_chr1	v5
+#define vhas_chr2	v6
+#define vrepmask_0	v7
+#define vrepmask_c	v16
+#define vend1		v17
+#define vend2		v18
+
+/* Core algorithm.
+
+   For each 32-byte hunk we calculate a 64-bit syndrome value, with
+   two bits per byte (LSB is always in bits 0 and 1, for both big
+   and little-endian systems).  For each tuple, bit 0 is set iff
+   the relevant byte matched the requested character; bit 1 is set
+   iff the relevant byte matched the NUL end of string (we trigger
+   off bit0 for the special case of looking for NUL).  Since the bits
+   in the syndrome reflect exactly the order in which things occur
+   in the original string a count_trailing_zeros() operation will
+   identify exactly which byte is causing the termination, and why.  */
+
+ENTRY(strrchr)
+	DELOUSE (0)
+	cbz	x1, L(null_search)
+	/* Magic constant 0x40100401 to allow us to identify which lane
+	   matches the requested byte.  Magic constant 0x80200802 used
+	   similarly for NUL termination.  */
+	mov	wtmp2, #0x0401
+	movk	wtmp2, #0x4010, lsl #16
+	dup	vrepchr.16b, chrin
+	bic	src, srcin, #31		/* Work with aligned 32-byte hunks.  */
+	dup	vrepmask_c.4s, wtmp2
+	mov	src_offset, #0
+	ands	tmp1, srcin, #31
+	add	vrepmask_0.4s, vrepmask_c.4s, vrepmask_c.4s /* equiv: lsl #1 */
+	b.eq	L(aligned)
+
+	/* Input string is not 32-byte aligned.  Rather than forcing
+	   the padding bytes to a safe value, we calculate the syndrome
+	   for all the bytes, but then mask off those bits of the
+	   syndrome that are related to the padding.  */
+	ld1	{vdata1.16b, vdata2.16b}, [src], #32
+	neg	tmp1, tmp1
+	cmeq	vhas_nul1.16b, vdata1.16b, #0
+	cmeq	vhas_chr1.16b, vdata1.16b, vrepchr.16b
+	cmeq	vhas_nul2.16b, vdata2.16b, #0
+	cmeq	vhas_chr2.16b, vdata2.16b, vrepchr.16b
+	and	vhas_nul1.16b, vhas_nul1.16b, vrepmask_0.16b
+	and	vhas_chr1.16b, vhas_chr1.16b, vrepmask_c.16b
+	and	vhas_nul2.16b, vhas_nul2.16b, vrepmask_0.16b
+	and	vhas_chr2.16b, vhas_chr2.16b, vrepmask_c.16b
+	addp	vhas_nul1.16b, vhas_nul1.16b, vhas_nul2.16b	// 256->128
+	addp	vhas_chr1.16b, vhas_chr1.16b, vhas_chr2.16b	// 256->128
+	addp	vhas_nul1.16b, vhas_nul1.16b, vhas_nul1.16b	// 128->64
+	addp	vhas_chr1.16b, vhas_chr1.16b, vhas_chr1.16b	// 128->64
+	mov	nul_match, vhas_nul1.2d[0]
+	lsl	tmp1, tmp1, #1
+	mov	const_m1, #~0
+	mov	chr_match, vhas_chr1.2d[0]
+	lsr	tmp3, const_m1, tmp1
+
+	bic	nul_match, nul_match, tmp3	// Mask padding bits.
+	bic	chr_match, chr_match, tmp3	// Mask padding bits.
+	cbnz	nul_match, L(tail)
+
+L(loop):
+	cmp	chr_match, #0
+	csel	src_match, src, src_match, ne
+	csel	src_offset, chr_match, src_offset, ne
+L(aligned):
+	ld1	{vdata1.16b, vdata2.16b}, [src], #32
+	cmeq	vhas_nul1.16b, vdata1.16b, #0
+	cmeq	vhas_chr1.16b, vdata1.16b, vrepchr.16b
+	cmeq	vhas_nul2.16b, vdata2.16b, #0
+	cmeq	vhas_chr2.16b, vdata2.16b, vrepchr.16b
+	addp	vend1.16b, vhas_nul1.16b, vhas_nul2.16b	// 256->128
+	and	vhas_chr1.16b, vhas_chr1.16b, vrepmask_c.16b
+	and	vhas_chr2.16b, vhas_chr2.16b, vrepmask_c.16b
+	addp	vhas_chr1.16b, vhas_chr1.16b, vhas_chr2.16b	// 256->128
+	addp	vend1.16b, vend1.16b, vend1.16b	// 128->64
+	addp	vhas_chr1.16b, vhas_chr1.16b, vhas_chr1.16b	// 128->64
+	mov	nul_match, vend1.2d[0]
+	mov	chr_match, vhas_chr1.2d[0]
+	cbz	nul_match, L(loop)
+
+	and	vhas_nul1.16b, vhas_nul1.16b, vrepmask_0.16b
+	and	vhas_nul2.16b, vhas_nul2.16b, vrepmask_0.16b
+	addp	vhas_nul1.16b, vhas_nul1.16b, vhas_nul2.16b
+	addp	vhas_nul1.16b, vhas_nul1.16b, vhas_nul1.16b
+	mov	nul_match, vhas_nul1.2d[0]
+
+L(tail):
+	/* Work out exactly where the string ends.  */
+	sub	tmp4, nul_match, #1
+	eor	tmp4, tmp4, nul_match
+	ands	chr_match, chr_match, tmp4
+	/* And pick the values corresponding to the last match.  */
+	csel	src_match, src, src_match, ne
+	csel	src_offset, chr_match, src_offset, ne
+
+	/* Count down from the top of the syndrome to find the last match.  */
+	clz	tmp3, src_offset
+	/* Src_match points beyond the word containing the match, so we can
+	   simply subtract half the bit-offset into the syndrome.  Because
+	   we are counting down, we need to go back one more character.  */
+	add	tmp3, tmp3, #2
+	sub	result, src_match, tmp3, lsr #1
+	/* But if the syndrome shows no match was found, then return NULL.  */
+	cmp	src_offset, #0
+	csel	result, result, xzr, ne
+
+	ret
+L(null_search):
+	b	__strchrnul
+
+END(strrchr)
+weak_alias (strrchr, rindex)
+libc_hidden_builtin_def (strrchr)