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, 218 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/arm/armv6/strcpy.S b/REORG.TODO/sysdeps/arm/armv6/strcpy.S
new file mode 100644
index 0000000000..1b98dbce30
--- /dev/null
+++ b/REORG.TODO/sysdeps/arm/armv6/strcpy.S
@@ -0,0 +1,218 @@
+/* strcpy -- copy a nul-terminated string.
+   Copyright (C) 2013-2017 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>
+
+/* Endian independent macros for shifting bytes within registers.  */
+#ifdef __ARMEB__
+#define lsh_gt		lsr
+#define lsh_ls		lsl
+#else
+#define lsh_gt		lsl
+#define lsh_ls		lsr
+#endif
+
+	.syntax unified
+	.text
+
+ENTRY (__stpcpy)
+	@ Signal stpcpy with NULL in IP.
+	mov	ip, #0
+	b	0f
+END (__stpcpy)
+
+weak_alias (__stpcpy, stpcpy)
+libc_hidden_def (__stpcpy)
+libc_hidden_builtin_def (stpcpy)
+
+ENTRY (strcpy)
+	@ Signal strcpy with DEST in IP.
+	mov	ip, r0
+0:
+	pld	[r0, #0]
+	pld	[r1, #0]
+
+	@ To cater to long strings, we want 8 byte alignment in the source.
+	@ To cater to small strings, we don't want to start that right away.
+	@ Loop up to 16 times, less whatever it takes to reach alignment.
+	and	r3, r1, #7
+	rsb	r3, r3, #16
+
+	@ Loop until we find ...
+1:	ldrb	r2, [r1], #1
+	subs	r3, r3, #1		@ ... the alignment point
+	strb	r2, [r0], #1
+	it	ne
+	cmpne	r2, #0			@ ... or EOS
+	bne	1b
+
+	@ Disambiguate the exit possibilites above
+	cmp	r2, #0			@ Found EOS
+	beq	.Lreturn
+
+	@ Load the next two words asap
+	ldrd	r2, r3, [r1], #8
+	pld	[r0, #64]
+	pld	[r1, #64]
+
+	@ For longer strings, we actaully need a stack frame.
+	push	{ r4, r5, r6, r7 }
+	cfi_adjust_cfa_offset (16)
+	cfi_rel_offset (r4, 0)
+	cfi_rel_offset (r5, 4)
+	cfi_rel_offset (r6, 8)
+	cfi_rel_offset (r7, 12)
+
+	@ Subtracting (unsigned saturating) from 1 for any byte means result
+	@ of 1 for any byte that was originally zero and 0 otherwise.
+	@ Therefore we consider the lsb of each byte the "found" bit.
+#ifdef ARCH_HAS_T2
+	movw	r7, #0x0101
+	tst	r0, #3			@ Test alignment of DEST
+	movt	r7, #0x0101
+#else
+	ldr	r7, =0x01010101
+	tst	r0, #3
+#endif
+	bne	.Lunaligned
+
+	@ So now source (r1) is aligned to 8, and dest (r0) is aligned to 4.
+	@ Loop, reading 8 bytes at a time, searching for EOS.
+	.balign	16
+2:	uqsub8	r4, r7, r2		@ Find EOS
+	uqsub8	r5, r7, r3
+	pld	[r1, #128]
+	cmp	r4, #0			@ EOS in first word?
+	pld	[r0, #128]
+	bne	3f
+	str	r2, [r0], #4
+	cmp	r5, #0			@ EOS in second word?
+	bne	4f
+	str	r3, [r0], #4
+	ldrd	r2, r3, [r1], #8
+	b	2b
+
+3:	sub	r1, r1, #4		@ backup to first word
+4:	sub	r1, r1, #4		@ backup to second word
+
+	@ ... then finish up any tail a byte at a time.
+	@ Note that we generally back up and re-read source bytes,
+	@ but we'll not re-write dest bytes.
+.Lbyte_loop:
+	ldrb	r2, [r1], #1
+	cmp	r2, #0
+	strb	r2, [r0], #1
+	bne	.Lbyte_loop
+
+	pop	{ r4, r5, r6, r7 }
+	cfi_remember_state
+	cfi_adjust_cfa_offset (-16)
+	cfi_restore (r4)
+	cfi_restore (r5)
+	cfi_restore (r6)
+	cfi_restore (r7)
+
+.Lreturn:
+	cmp	ip, #0			@ Was this strcpy or stpcpy?
+	ite	eq
+	subeq	r0, r0, #1		@ stpcpy: undo post-inc from store
+	movne	r0, ip			@ strcpy: return original dest
+	bx	lr
+
+.Lunaligned:
+	cfi_restore_state
+	@ Here, source is aligned to 8, but the destination is not word
+	@ aligned.  Therefore we have to shift the data in order to be
+	@ able to perform aligned word stores.
+
+	@ Find out which misalignment we're dealing with.
+	tst	r0, #1
+	beq	.Lunaligned2
+	tst	r0, #2
+	bne	.Lunaligned3
+	@ Fallthru to .Lunaligned1.
+
+.macro unaligned_copy	unalign
+	@ Prologue to unaligned loop.  Seed shifted non-zero bytes.
+	uqsub8	r4, r7, r2		@ Find EOS
+	uqsub8	r5, r7, r3
+	cmp	r4, #0			@ EOS in first word?
+	it	ne
+	subne	r1, r1, #8
+	bne	.Lbyte_loop
+#ifdef __ARMEB__
+	rev	r2, r2			@ Byte stores below need LE data
+#endif
+	@ Store a few bytes from the first word.
+	@ At the same time we align r0 and shift out bytes from r2.
+.rept	4-\unalign
+	strb	r2, [r0], #1
+	lsr	r2, r2, #8
+.endr
+#ifdef __ARMEB__
+	rev	r2, r2			@ Undo previous rev
+#endif
+	@ Rotated unaligned copy loop.  The tail of the prologue is
+	@ shared with the loop itself.
+	.balign 8
+1:	cmp	r5, #0			@ EOS in second word?
+	bne	4f
+	@ Combine first and second words
+	orr	r2, r2, r3, lsh_gt #(\unalign*8)
+	@ Save leftover bytes from the two words
+	lsh_ls	r6, r3, #((4-\unalign)*8)
+	str	r2, [r0], #4
+	@ The "real" start of the unaligned copy loop.
+	ldrd	r2, r3, [r1], #8	@ Load 8 more bytes
+	uqsub8	r4, r7, r2		@ Find EOS
+	pld	[r1, #128]
+	uqsub8	r5, r7, r3
+	pld	[r0, #128]
+	cmp	r4, #0			@ EOS in first word?
+	bne	3f
+	@ Combine the leftover and the first word
+	orr	r6, r6, r2, lsh_gt #(\unalign*8)
+	@ Discard used bytes from the first word.
+	lsh_ls	r2, r2, #((4-\unalign)*8)
+	str	r6, [r0], #4
+	b	1b
+	@ Found EOS in one of the words; adjust backward
+3:	sub	r1, r1, #4
+	mov	r2, r6
+4:	sub	r1, r1, #4
+	@ And store the remaining bytes from the leftover
+#ifdef __ARMEB__
+	rev	r2, r2
+#endif
+.rept	\unalign
+	strb	r2, [r0], #1
+	lsr	r2, r2, #8
+.endr
+	b	.Lbyte_loop
+.endm
+
+.Lunaligned1:
+	unaligned_copy	1
+.Lunaligned2:
+	unaligned_copy	2
+.Lunaligned3:
+	unaligned_copy	3
+
+END (strcpy)
+
+libc_hidden_builtin_def (strcpy)