ARM: Optimize IEEE-754 sqrt implementation

Use the vsqrt.f64 and vsqrt.f32 instructions if available.

newlib/libm/machine/arm/Makefile.am

@@ -6,6 +6,8 @@ INCLUDES = -I $(newlib_basedir)/../newlib/libm/common $(NEWLIB_CFLAGS) \
 	$(CROSS_CFLAGS) $(TARGET_CFLAGS)
 
 LIB_SOURCES = \
+	e_sqrt.c \
+	ef_sqrt.c \
 	s_ceil.c \
 	s_floor.c \
 	s_nearbyint.c \

newlib/libm/machine/arm/Makefile.in

@@ -70,7 +70,8 @@ LIBRARIES = $(noinst_LIBRARIES)
 ARFLAGS = cru
 lib_a_AR = $(AR) $(ARFLAGS)
 lib_a_LIBADD =
-am__objects_1 = lib_a-s_ceil.$(OBJEXT) lib_a-s_floor.$(OBJEXT) \
+am__objects_1 = lib_a-e_sqrt.$(OBJEXT) lib_a-ef_sqrt.$(OBJEXT) \
+	lib_a-s_ceil.$(OBJEXT) lib_a-s_floor.$(OBJEXT) \
 	lib_a-s_nearbyint.$(OBJEXT) lib_a-s_rint.$(OBJEXT) \
 	lib_a-s_round.$(OBJEXT) lib_a-s_trunc.$(OBJEXT) \
 	lib_a-sf_ceil.$(OBJEXT) lib_a-sf_floor.$(OBJEXT) \
@@ -202,6 +203,8 @@ INCLUDES = -I $(newlib_basedir)/../newlib/libm/common $(NEWLIB_CFLAGS) \
 	$(CROSS_CFLAGS) $(TARGET_CFLAGS)
 
 LIB_SOURCES = \
+	e_sqrt.c \
+	ef_sqrt.c \
 	s_ceil.c \
 	s_floor.c \
 	s_nearbyint.c \
@@ -291,6 +294,18 @@ distclean-compile:
 .c.obj:
 	$(COMPILE) -c `$(CYGPATH_W) '$<'`
 
+lib_a-e_sqrt.o: e_sqrt.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-e_sqrt.o `test -f 'e_sqrt.c' || echo '$(srcdir)/'`e_sqrt.c
+
+lib_a-e_sqrt.obj: e_sqrt.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-e_sqrt.obj `if test -f 'e_sqrt.c'; then $(CYGPATH_W) 'e_sqrt.c'; else $(CYGPATH_W) '$(srcdir)/e_sqrt.c'; fi`
+
+lib_a-ef_sqrt.o: ef_sqrt.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-ef_sqrt.o `test -f 'ef_sqrt.c' || echo '$(srcdir)/'`ef_sqrt.c
+
+lib_a-ef_sqrt.obj: ef_sqrt.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-ef_sqrt.obj `if test -f 'ef_sqrt.c'; then $(CYGPATH_W) 'ef_sqrt.c'; else $(CYGPATH_W) '$(srcdir)/ef_sqrt.c'; fi`
+
 lib_a-s_ceil.o: s_ceil.c
 	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-s_ceil.o `test -f 's_ceil.c' || echo '$(srcdir)/'`s_ceil.c
 

newlib/libm/machine/arm/e_sqrt.c

@@ -0,0 +1,45 @@
+/*-
+ * Copyright (c) 2017 embedded brains GmbH
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if __ARM_FP & 0x8
+#include <math.h>
+
+double
+__ieee754_sqrt(double x)
+{
+	double result;
+#if __ARM_ARCH >= 6
+	asm ("vsqrt.f64 %P0, %P1" : "=w" (result) : "w" (x));
+#else
+	/* VFP9 Erratum 760019, see GCC sources "gcc/config/arm/vfp.md" */
+	asm ("vsqrt.f64 %P0, %P1" : "=&w" (result) : "w" (x));
+#endif
+	return result;
+}
+
+#else
+#include "../../math/e_sqrt.c"
+#endif

newlib/libm/machine/arm/ef_sqrt.c

@@ -0,0 +1,45 @@
+/*-
+ * Copyright (c) 2017 embedded brains GmbH
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if __ARM_FP & 0x4
+#include <math.h>
+
+float
+__ieee754_sqrtf(float x)
+{
+	float result;
+#if __ARM_ARCH >= 6
+	asm ("vsqrt.f32 %0, %1" : "=w" (result) : "w" (x));
+#else
+	/* VFP9 Erratum 760019, see GCC sources "gcc/config/arm/vfp.md" */
+	asm ("vsqrt.f32 %0, %1" : "=&w" (result) : "w" (x));
+#endif
+	return result;
+}
+
+#else
+#include "../../math/ef_sqrt.c"
+#endif