S390: Refactor strncpy ifunc handling.

The ifunc handling for strncpy is adjusted in order to omit ifunc
variants if those will never be used as the minimum architecture level
already supports newer CPUs by default.
Glibc internal calls will then also use the "newer" ifunc variant.

Note: The fallback s390-32/s390-64 ifunc variants are now moved to
the strncpy-z900.S files. The s390-32/s390-64 files multiarch/strncpy.c
and strncpy.S are deleted.

ChangeLog:

	* sysdeps/s390/multiarch/Makefile
	(sysdep_routines): Remove strncpy variants.
	* sysdeps/s390/Makefile (sysdep_routines): Add strncpy variants.
	* sysdeps/s390/multiarch/ifunc-impl-list.c
	(__libc_ifunc_impl_list): Refactor ifunc handling for strncpy.
	* sysdeps/s390/multiarch/strncpy-vx.S: Move to ...
	* sysdeps/s390/strncpy-vx.S: ... here and adjust ifunc handling.
	* sysdeps/s390/multiarch/strncpy.c: Move to ...
	* sysdeps/s390/strncpy.c: ... here and adjust ifunc handling.
	* sysdeps/s390/ifunc-strncpy.h: New file.
	* sysdeps/s390/s390-64/strncpy.S: Move to ...
	* sysdeps/s390/s390-64/strncpy-z900.S: ... here
	and adjust ifunc handling.
	* sysdeps/s390/s390-32/strncpy.S: Move to ...
	* sysdeps/s390/s390-32/strncpy-z900.S: ... here
	and adjust ifunc handling.
	* sysdeps/s390/s390-32/multiarch/strncpy.c: Delete file.
	* sysdeps/s390/s390-64/multiarch/strncpy.c: Likewise.

1 files changed, 208 insertions, 0 deletions

diff --git a/sysdeps/s390/strncpy-vx.S b/sysdeps/s390/strncpy-vx.S
new file mode 100644
index 0000000000..be09ddf092
--- /dev/null
+++ b/sysdeps/s390/strncpy-vx.S
@@ -0,0 +1,208 @@
+/* Vector optimized 32/64 bit S/390 version of strncpy.
+   Copyright (C) 2015-2018 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 <ifunc-strncpy.h>
+#include "sysdep.h"
+#include "asm-syntax.h"
+
+	.text
+
+#if HAVE_STRNCPY_Z13
+/* char * strncpy (const char *dest, const char *src, size_t n)
+   Copy at most n characters of string  src to dest.
+
+   Register usage:
+   -r0=dest pointer for return
+   -r1=tmp, zero byte index
+   -r2=dest
+   -r3=src
+   -r4=n
+   -r5=current_len
+   -r6=tmp, loaded bytes
+   -r7=tmp, border
+   -v16=part of src
+   -v17=index of zero
+   -v18=part of src
+   -v31=register save area for r6, r7
+*/
+ENTRY(STRNCPY_Z13)
+	.machine "z13"
+	.machinemode "zarch_nohighgprs"
+
+# if !defined __s390x__
+	llgfr	%r4,%r4
+# endif /* !defined __s390x__ */
+
+	clgfi	%r4,0
+	ber	%r14		/* Nothing to do, if n == 0.  */
+	lgr	%r0,%r2		/* Save destination pointer for return.  */
+	vlvgp	%v31,%r6,%r7	/* Save registers.  */
+
+	vlbb	%v16,0(%r3),6	/* Load s until next 4k-byte boundary.  */
+	lcbb	%r6,0(%r3),6	/* Get bytes to 4k-byte boundary or 16.  */
+	llgfr	%r6,%r6		/* Convert 32bit to 64bit.  */
+
+	lghi	%r5,0		/* current_len = 0.  */
+
+	clgrjle	%r4,%r6,.Lremaining_v16 /* If n <= loaded-bytes
+					   -> process remaining.  */
+
+	/* n > loaded-byte-count.  */
+	vfenezb	%v17,%v16,%v16	/* Find element not equal with zero search.  */
+	vlgvb	%r1,%v17,7	/* Load zero index or 16 if not found.  */
+	clrjl	%r1,%r6,.Lfound_v16_store /* Found zero within loaded bytes,
+					     copy and return.  */
+
+	/* Align s to 16 byte.  */
+	risbgn	%r7,%r3,60,128+63,0 /* %r3 = bits 60-63 of %r2 'and' 15.  */
+	lghi	%r5,15		/* current_len = 15.  */
+	slr	%r5,%r7		/* Compute highest index to 16byte boundary.  */
+
+	/* Zero not found and n > loaded-byte-count.  */
+	vstl	%v16,%r5,0(%r2)	/* Copy loaded characters - no zero.  */
+	ahi	%r5,1		/* Start loop at next character.  */
+
+	/* Now we are 16byte aligned, so we can load
+	   a full vreg without page fault.  */
+	lgr	%r1,%r5		/* If %r5 + 64 < maxlen? -> loop64.  */
+	aghi	%r1,64
+	clgrjl	%r1,%r4,.Lloop64
+
+	vl	%v16,0(%r5,%r3)	/* Load s.  */
+	clgijl	%r4,17,.Lremaining_v16	/* If n <= 16, process remaining
+					   bytes.  */
+.Llt64:
+	lgr	%r7,%r4
+	slgfi	%r7,16		/* border_len = n - 16.  */
+
+	clgrjhe	%r5,%r7,.Lremaining_v16 /* If current_len >= border
+					   then process remaining bytes.  */
+	vfenezbs %v17,%v16,%v16	/* Find element not equal with zero search.  */
+	je	.Lfound_v16	/* Jump away if zero was found.  */
+	vl	%v18,16(%r5,%r3) /* Load next part of s.  */
+	vst	%v16,0(%r5,%r2)	/* Store previous part without zero to dst.  */
+	aghi	%r5,16
+
+	clgrjhe	%r5,%r7,.Lremaining_v18
+	vfenezbs %v17,%v18,%v18
+	je	.Lfound_v18
+	vl	%v16,16(%r5,%r3)
+	vst	%v18,0(%r5,%r2)
+	aghi	%r5,16
+
+	clgrjhe	%r5,%r7,.Lremaining_v16
+	vfenezbs %v17,%v16,%v16
+	je	.Lfound_v16
+	vl	%v18,16(%r5,%r3)
+	vst	%v16,0(%r5,%r2)
+	aghi	%r5,16
+
+.Lremaining_v18:
+	vlr	%v16,%v18
+.Lremaining_v16:
+	/* v16 contains the remaining bytes [1...16].
+	   Store remaining bytes and append string-termination.  */
+	vfenezb	%v17,%v16,%v16	/* Find element not equal with zero search.  */
+	slgrk	%r7,%r4,%r5	/* Remaining bytes = maxlen - current_len.  */
+	aghi	%r7,-1		/* vstl needs highest index.  */
+	la	%r2,0(%r5,%r2)	/* vstl has no index register.  */
+	vlgvb	%r1,%v17,7	/* Load zero index or 16 if not found.  */
+	/* Zero in remaining bytes? -> jump away (zero-index < max-index)
+	   Do not jump away if zero-index == max-index,
+	   but simply copy zero with vstl below.  */
+	clrjl	%r1,%r7,.Lfound_v16_store
+	vstl	%v16,%r7,0(%r2)	/* Store remaining bytes without null
+				   termination!.  */
+.Lend:
+	/* Restore saved registers.  */
+	vlgvg	%r6,%v31,0
+	vlgvg	%r7,%v31,1
+	lgr	%r2,%r0		/* Load saved dest-ptr.  */
+	br	%r14
+
+
+.Lfound_v16_32:
+	aghi	%r5,32
+	j	.Lfound_v16
+.Lfound_v18_48:
+	aghi	%r5,32
+.Lfound_v18_16:
+	aghi	%r5,16
+.Lfound_v18:
+	vlr	%v16,%v18
+.Lfound_v16:
+	/* v16 contains a zero. Store remaining bytes to zero. current_len
+	   has not reached border, thus checking for n is not needed! */
+	vlgvb	%r1,%v17,7	/* Load byte index of zero.  */
+	la	%r2,0(%r5,%r2)	/* vstl has no support for index-register.  */
+.Lfound_v16_store:
+	vstl	%v16,%r1,0(%r2)	/* Copy characters including zero.  */
+	/* Fill remaining bytes with zero - remaining count always > 0.  */
+	algr	%r5,%r1		/* Remaining bytes (=%r4) = ...  */
+	slgr	%r4,%r5		/* = n - (current_len + zero_index + 1).  */
+	la	%r2,0(%r1,%r2)	/* Pointer to zero. start filling beyond.  */
+	aghi	%r4,-2		/* mvc with exrl needs count - 1.
+				   (additional -1, see remaining bytes above) */
+	srlg	%r6,%r4,8	/* Split into 256 byte blocks.  */
+	ltgr	%r6,%r6
+	je	.Lzero_lt256
+.Lzero_loop256:
+	mvc	1(256,%r2),0(%r2) /* Fill 256 zeros at once.  */
+	la	%r2,256(%r2)
+	brctg	%r6,.Lzero_loop256 /* Loop until all blocks are processed.  */
+.Lzero_lt256:
+	exrl	%r4,.Lmvc_lt256
+	j	.Lend
+.Lmvc_lt256:
+	mvc	1(1,%r2),0(%r2)
+
+.Lloop64:
+	vl	%v16,0(%r5,%r3)	/* Load s.  */
+	vfenezbs %v17,%v16,%v16	/* Find element not equal with zero search.  */
+	je	.Lfound_v16	/* Jump away if zero was found.  */
+	vl	%v18,16(%r5,%r3) /* Load next part of s.  */
+	vst	%v16,0(%r5,%r2)	/* Store previous part without zero to dst.  */
+	vfenezbs %v17,%v18,%v18
+	je	.Lfound_v18_16
+	vl	%v16,32(%r5,%r3)
+	vst	%v18,16(%r5,%r2)
+	vfenezbs %v17,%v16,%v16
+	je	.Lfound_v16_32
+	vl	%v18,48(%r5,%r3)
+	vst	%v16,32(%r5,%r2)
+	vfenezbs %v17,%v18,%v18
+	je	.Lfound_v18_48
+	vst	%v18,48(%r5,%r2)
+
+	aghi	%r5,64
+	lgr	%r1,%r5		/* If %r5 + 64 < maxlen? -> loop64.  */
+	aghi	%r1,64
+	clgrjl	%r1,%r4,.Lloop64
+
+	vl	%v16,0(%r5,%r3)	/* Load s.  */
+	j	.Llt64
+END(STRNCPY_Z13)
+
+# if ! HAVE_STRNCPY_IFUNC
+strong_alias (STRNCPY_Z13, strncpy)
+# endif
+
+# if ! HAVE_STRNCPY_Z900_G5 && defined SHARED && IS_IN (libc)
+strong_alias (STRNCPY_Z13, __GI_strncpy)
+# endif
+#endif