S390: Add arch13 strstr ifunc variant.

This patch introduces the new arch13 ifunc variant for strstr.
For needles longer than 9 charachters it is relying on the common-code
implementation.  For shorter needles it is using the new vstrs instruction
which is able to search a substring within a vector register.

ChangeLog:

	* sysdeps/s390/Makefile (sysdep_routines): Add strstr-arch13.
	* sysdeps/s390/ifunc-strstr.h (HAVE_STRSTR_ARCH13, STRSTR_ARCH13,
	STRSTR_Z13_ONLY_USED_AS_FALLBACK, HAVE_STRSTR_IFUNC_AND_ARCH13_SUPPORT):
	New defines.
	* sysdeps/s390/multiarch/ifunc-impl-list.c
	(__libc_ifunc_impl_list): Add ifunc variant for arch13 strstr.
	* sysdeps/s390/strstr-arch13.S: New file.
	* sysdeps/s390/strstr-vx.c: Omit GI symbol for z13 strstr ifunc variant
	if it is only used as fallback.
	* sysdeps/s390/strstr.c (strstr): Add arch13 variant in ifunc selector.

7 files changed, 232 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 36af218..cd1453e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,18 @@
 2019-03-22  Stefan Liebler  <stli@linux.ibm.com>
 
+	* sysdeps/s390/Makefile (sysdep_routines): Add strstr-arch13.
+	* sysdeps/s390/ifunc-strstr.h (HAVE_STRSTR_ARCH13, STRSTR_ARCH13,
+	STRSTR_Z13_ONLY_USED_AS_FALLBACK, HAVE_STRSTR_IFUNC_AND_ARCH13_SUPPORT):
+	New defines.
+	* sysdeps/s390/multiarch/ifunc-impl-list.c
+	(__libc_ifunc_impl_list): Add ifunc variant for arch13 strstr.
+	* sysdeps/s390/strstr-arch13.S: New file.
+	* sysdeps/s390/strstr-vx.c: Omit GI symbol for z13 strstr ifunc variant
+	if it is only used as fallback.
+	* sysdeps/s390/strstr.c (strstr): Add arch13 variant in ifunc selector.
+
+2019-03-22  Stefan Liebler  <stli@linux.ibm.com>
+
 	* sysdeps/s390/ifunc-memcpy.h (HAVE_MEMMOVE_ARCH13, MEMMOVE_ARCH13
 	HAVE_MEMMOVE_IFUNC_AND_ARCH13_SUPPORT): New defines.
 	* sysdeps/s390/memcpy-z900.S: Add arch13 memmove implementation.
diff --git a/sysdeps/s390/Makefile b/sysdeps/s390/Makefile
index 35fcf7e..af14344 100644
--- a/sysdeps/s390/Makefile
+++ b/sysdeps/s390/Makefile
@@ -58,7 +58,7 @@ sysdep_routines += bzero memset memset-z900 \
 		   memcmp memcmp-z900 \
 		   mempcpy memcpy memcpy-z900 \
 		   memmove memmove-c \
-		   strstr strstr-vx strstr-c \
+		   strstr strstr-arch13 strstr-vx strstr-c \
 		   memmem memmem-vx memmem-c \
 		   strlen strlen-vx strlen-c \
 		   strnlen strnlen-vx strnlen-c \
diff --git a/sysdeps/s390/ifunc-strstr.h b/sysdeps/s390/ifunc-strstr.h
index 2f67606..2d50d07 100644
--- a/sysdeps/s390/ifunc-strstr.h
+++ b/sysdeps/s390/ifunc-strstr.h
@@ -17,7 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #if defined USE_MULTIARCH && IS_IN (libc)		\
-  && ! defined HAVE_S390_MIN_Z13_ZARCH_ASM_SUPPORT
+  && ! defined HAVE_S390_MIN_ARCH13_ZARCH_ASM_SUPPORT
 # define HAVE_STRSTR_IFUNC	1
 #else
 # define HAVE_STRSTR_IFUNC	0
@@ -29,14 +29,32 @@
 # define HAVE_STRSTR_IFUNC_AND_VX_SUPPORT 0
 #endif
 
-#if defined HAVE_S390_MIN_Z13_ZARCH_ASM_SUPPORT
+#ifdef HAVE_S390_ARCH13_ASM_SUPPORT
+# define HAVE_STRSTR_IFUNC_AND_ARCH13_SUPPORT HAVE_STRSTR_IFUNC
+#else
+# define HAVE_STRSTR_IFUNC_AND_ARCH13_SUPPORT 0
+#endif
+
+#if defined HAVE_S390_MIN_ARCH13_ZARCH_ASM_SUPPORT
+# define STRSTR_DEFAULT		STRSTR_ARCH13
+# define HAVE_STRSTR_C		0
+# define HAVE_STRSTR_Z13	1
+# define STRSTR_Z13_ONLY_USED_AS_FALLBACK 1
+# define HAVE_STRSTR_ARCH13	1
+#elif defined HAVE_S390_MIN_Z13_ZARCH_ASM_SUPPORT
 # define STRSTR_DEFAULT		STRSTR_Z13
 # define HAVE_STRSTR_C		0
 # define HAVE_STRSTR_Z13	1
+# define HAVE_STRSTR_ARCH13	HAVE_STRSTR_IFUNC_AND_ARCH13_SUPPORT
 #else
 # define STRSTR_DEFAULT		STRSTR_C
 # define HAVE_STRSTR_C		1
 # define HAVE_STRSTR_Z13	HAVE_STRSTR_IFUNC_AND_VX_SUPPORT
+# define HAVE_STRSTR_ARCH13	HAVE_STRSTR_IFUNC_AND_ARCH13_SUPPORT
+#endif
+
+#ifndef STRSTR_Z13_ONLY_USED_AS_FALLBACK
+# define STRSTR_Z13_ONLY_USED_AS_FALLBACK 0
 #endif
 
 #if HAVE_STRSTR_C
@@ -50,3 +68,9 @@
 #else
 # define STRSTR_Z13		NULL
 #endif
+
+#if HAVE_STRSTR_ARCH13
+# define STRSTR_ARCH13		__strstr_arch13
+#else
+# define STRSTR_ARCH13		NULL
+#endif
diff --git a/sysdeps/s390/multiarch/ifunc-impl-list.c b/sysdeps/s390/multiarch/ifunc-impl-list.c
index d742d66..75289b5 100644
--- a/sysdeps/s390/multiarch/ifunc-impl-list.c
+++ b/sysdeps/s390/multiarch/ifunc-impl-list.c
@@ -186,6 +186,10 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
 #if HAVE_STRSTR_IFUNC
     IFUNC_IMPL (i, name, strstr,
+# if HAVE_STRSTR_ARCH13
+		IFUNC_IMPL_ADD (array, i, strstr,
+				dl_hwcap & HWCAP_S390_VXRS_EXT2, STRSTR_ARCH13)
+# endif
 # if HAVE_STRSTR_Z13
 		IFUNC_IMPL_ADD (array, i, strstr,
 				dl_hwcap & HWCAP_S390_VX, STRSTR_Z13)
diff --git a/sysdeps/s390/strstr-arch13.S b/sysdeps/s390/strstr-arch13.S
new file mode 100644
index 0000000..929b026
--- /dev/null
+++ b/sysdeps/s390/strstr-arch13.S
@@ -0,0 +1,179 @@
+/* Vector optimized 32/64 bit S/390 version of strstr.
+   Copyright (C) 2019 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-strstr.h>
+#if HAVE_STRSTR_ARCH13
+# include "sysdep.h"
+# include "asm-syntax.h"
+	.text
+
+/* char *strstr (const char *haystack=r2, const char *needle=r3)
+   Locate a substring.  */
+ENTRY(STRSTR_ARCH13)
+	.machine "arch13"
+	.machinemode "zarch_nohighgprs"
+	lcbb	%r1,0(%r3),6
+	jo	.Lneedle_on_bb	/* Needle on block-boundary?  */
+	vl	%v18,0(%r3),6	/* Load needle.  */
+	vfenezb %v19,%v18,%v18	/* v19[7] contains the length of needle.  */
+.Lneedle_loaded:
+	vlgvb	%r4,%v19,7	/* Get index of zero or 16 if not found.  */
+	lghi	%r5,17		/* See below: min-skip-partial-match-index.  */
+	cgibe	%r4,0,0(%r14)	/* Test if needle is zero and return.  */
+
+	/* The vstrs instruction is able to handle needles up to a length of 16,
+	   but then we may have to load the next part of haystack with a
+	   small offset.  This will be slow - see examples:
+	   haystack =mmmmmmmmmmmmmmmm mmmmmmmmmmmmmmmmmm...mmmmmmmmmmmmmmmmmmma
+	   needle   =  mmmmmmmmmmmmmma0
+	   => needle_len=15; vstrs reports a partial match; haystack+=2
+	   haystack =mmmmmmmmmmmmmmmm mmmmmmmmmmmmmmmmmm...mmmmmmmmmmmmmmmmmmma
+	   needle   =        mmmmmmmma0000000
+	   => needle_len=9; vstrs reports a partial match; haystack+=8  */
+# if ! HAVE_STRSTR_Z13
+#  error The arch13 variant of strstr needs the z13 variant of strstr!
+# endif
+	clgfi	%r4,9
+	jh	STRSTR_Z13
+
+	/* In case of a partial match, the vstrs instruction returns the index
+	   of the partial match in a vector-register.  Then we have to
+	   reload the string at the "current-position plus this index" and run
+	   vstrs again in order to determine if it was a full match or no match.
+	   Transferring this index from vr to gr, compute the haystack-address
+	   and loading with vl is quite slow as all instructions have data
+	   dependencies.  Thus we assume, that a partial match is always at the
+	   first possible index and just load the next part of haystack from
+	   there instead of waiting until the correct index is computed:
+	   min-skip-partial-match-index = (16 - n_len) + 1  */
+	sgr	%r5,%r4
+
+.Lloop:
+	lcbb	%r1,0(%r2),6
+	jo	.Lloop_haystack_on_bb	/* Haystack on block-boundary?  */
+	vl	%v16,0(%r2)		/* Load next part of haystack.  */
+.Lloop_haystack_loaded:
+	/* Vector string search with zero search (cc=0 => no match).  */
+	vstrs	%v20,%v16,%v18,%v19,0,2
+	jne	.Lloop_vstrs_nonzero_cc
+	lcbb	%r1,16(%r2),6		/* Next part of haystack.  */
+	jo	.Lloop_haystack_on_bb16
+	vl	%v16,16(%r2)
+	vstrs	%v20,%v16,%v18,%v19,0,2
+	jne	.Lloop_vstrs_nonzero_cc16
+	lcbb	%r1,32(%r2),6		/* Next part of haystack.  */
+	jo	.Lloop_haystack_on_bb32
+	vl	%v16,32(%r2)
+	vstrs	%v20,%v16,%v18,%v19,0,2
+	jne	.Lloop_vstrs_nonzero_cc32
+	lcbb	%r1,48(%r2),6		/* Next part of haystack.  */
+	jo	.Lloop_haystack_on_bb48
+	vl	%v16,48(%r2)
+	vstrs	%v20,%v16,%v18,%v19,0,2
+	jne	.Lloop_vstrs_nonzero_cc48
+	la	%r2,64(%r2)
+	j	.Lloop
+
+.Lloop_vstrs_nonzero_cc48:
+	la	%r2,16(%r2)
+.Lloop_vstrs_nonzero_cc32:
+	la	%r2,16(%r2)
+.Lloop_vstrs_nonzero_cc16:
+	la	%r2,16(%r2)
+.Lloop_vstrs_nonzero_cc:
+	jh	.Lend_match_found /* cc == 2 (full match)  */
+	jl	.Lend_no_match	/* cc == 1 (no match, end of string)  */
+	/* cc == 3 (partial match) See above: min-skip-partial-match-index!  */
+	lcbb	%r1,0(%r5,%r2),6
+	la	%r2,0(%r5,%r2)
+	jo	.Lloop_haystack_on_bb
+	vl	%v16,0(%r2)
+	vstrs	%v20,%v16,%v18,%v19,0,2
+.Lloop_vstrs_nonzero_cc_loop:
+	jh	.Lend_match_found
+	jl	.Lend_no_match
+	la	%r2,0(%r5,%r2)
+	je	.Lloop
+	lcbb	%r1,0(%r2),6		/* Next part of haystack.  */
+	jo	.Lloop_haystack_on_bb
+	vl	%v16,0(%r2)
+	vstrs	%v20,%v16,%v18,%v19,0,2
+	jh	.Lend_match_found
+	jl	.Lend_no_match
+	la	%r2,0(%r5,%r2)
+	je	.Lloop
+	lcbb	%r1,0(%r2),6		/* Next part of haystack.  */
+	jo	.Lloop_haystack_on_bb
+	vl	%v16,0(%r2)
+	vstrs	%v20,%v16,%v18,%v19,0,2
+	jh	.Lend_match_found
+	jl	.Lend_no_match
+	la	%r2,0(%r5,%r2)
+	je	.Lloop
+	lcbb	%r1,0(%r2),6		/* Next part of haystack.  */
+	jo	.Lloop_haystack_on_bb
+	vl	%v16,0(%r2)
+	vstrs	%v20,%v16,%v18,%v19,0,2
+	j	.Lloop_vstrs_nonzero_cc_loop
+
+.Lend_no_match:
+	lghi	%r2,0
+	br	%r14
+.Lend_match_found:
+	vlgvb	%r4,%v20,7
+	la	%r2,0(%r4,%r2)
+	br	%r14
+
+.Lloop_haystack_on_bb48:
+	la	%r2,16(%r2)
+.Lloop_haystack_on_bb32:
+	la	%r2,16(%r2)
+.Lloop_haystack_on_bb16:
+	la	%r2,16(%r2)
+.Lloop_haystack_on_bb:
+	/* Haystack located on page-boundary.  */
+	ahi	%r1,-1		/* vll needs highest index instead of count.  */
+	vll	%v16,%r1,0(%r2)
+	vlvgb	%v21,%r1,7
+	vfenezb	%v17,%v16,%v16	/* Search zero in loaded haystack bytes.  */
+	veclb	%v17,%v21		/* Zero index <= loaded byte index?  */
+	jle	.Lloop_haystack_loaded	/* -> v16 contains full haystack.  */
+	vl	%v16,0(%r2)	/* Load haystack beyond page boundary.  */
+	j	.Lloop_haystack_loaded
+
+.Lneedle_on_bb:
+	/* Needle located on page-boundary.  */
+	ahi	%r1,-1		/* vll needs highest index instead of count.  */
+	vll	%v18,%r1,0(%r3)
+	vlvgb	%v21,%r1,7
+	vfenezb	%v19,%v18,%v18	/* Search zero in loaded needle bytes.  */
+	veclb	%v19,%v21	/* Zero index <= max loaded byte index?  */
+	jle	.Lneedle_loaded	/* -> v18 contains full needle.  */
+	vl	%v16,0(%r3)	/* Load needle beyond page boundary.  */
+	vfenezb	%v19,%v18,%v18
+	j	.Lneedle_loaded
+END(STRSTR_ARCH13)
+
+# if ! HAVE_STRSTR_IFUNC
+strong_alias (STRSTR_ARCH13, strstr)
+# endif
+
+# if STRSTR_Z13_ONLY_USED_AS_FALLBACK && defined SHARED && IS_IN (libc)
+strong_alias (STRSTR_ARCH13, __GI_strstr)
+# endif
+#endif
diff --git a/sysdeps/s390/strstr-vx.c b/sysdeps/s390/strstr-vx.c
index 2752639..6adffda 100644
--- a/sysdeps/s390/strstr-vx.c
+++ b/sysdeps/s390/strstr-vx.c
@@ -19,11 +19,11 @@
 #include <ifunc-strstr.h>
 
 #if HAVE_STRSTR_Z13
-# if HAVE_STRSTR_IFUNC
+# if HAVE_STRSTR_IFUNC || STRSTR_Z13_ONLY_USED_AS_FALLBACK
 #  define STRSTR STRSTR_Z13
 #  if defined SHARED && IS_IN (libc)
 #   undef libc_hidden_builtin_def
-#   if HAVE_STRSTR_C
+#   if HAVE_STRSTR_C || STRSTR_Z13_ONLY_USED_AS_FALLBACK
 #    define libc_hidden_builtin_def(name)
 #   else
 #    define libc_hidden_builtin_def(name)		\
diff --git a/sysdeps/s390/strstr.c b/sysdeps/s390/strstr.c
index 045c380..599d20d 100644
--- a/sysdeps/s390/strstr.c
+++ b/sysdeps/s390/strstr.c
@@ -32,8 +32,14 @@ extern __typeof (__redirect_strstr) STRSTR_C attribute_hidden;
 extern __typeof (__redirect_strstr) STRSTR_Z13 attribute_hidden;
 # endif
 
+# if HAVE_STRSTR_ARCH13
+extern __typeof (__redirect_strstr) STRSTR_ARCH13 attribute_hidden;
+# endif
+
 s390_libc_ifunc_expr (__redirect_strstr, strstr,
-		      (HAVE_STRSTR_Z13 && (hwcap & HWCAP_S390_VX))
+		      (HAVE_STRSTR_ARCH13 && (hwcap & HWCAP_S390_VXRS_EXT2))
+		      ? STRSTR_ARCH13
+		      : (HAVE_STRSTR_Z13 && (hwcap & HWCAP_S390_VX))
 		      ? STRSTR_Z13
 		      : STRSTR_DEFAULT
 		      )