Rewrote reference kernels to use #pragma omp simd.

Details:
- Rewrote level-1v, -1f, and -3 reference kernels in terms of simplified
  indexing annotated by the #pragma omp simd directive, which a compiler
  can use to vectorize certain constant-bounded loops. (The new kernels
  actually use _Pragma("omp simd") since the kernels are defined via
  templatizing macros.) Modest speedup was observed in most cases using
  gcc 5.4.0, which may improve with newer versions. Thanks to Devin
  Matthews for suggesting this via issue #286 and #259.
- Updated default blocksizes defined in ref_kernels/bli_cntx_ref.c to
  be 4x16, 4x8, 4x8, and 4x4 for single, double, scomplex and dcomplex,
  respectively, with a default row preference for the gemm ukernel. Also
  updated axpyf, dotxf, and dotxaxpyf fusing factors to 8, 6, and 4,
  respectively, for all datatypes.
- Modified configure to verify that -fopenmp-simd is a valid compiler
  option (via a new detect/omp_simd/omp_simd_detect.c file).
- Added a new header in which prefetch macros are defined according to
  which compiler is detected (via macros such as __GNUC__). These
  prefetch macros are not yet employed anywhere, though.
- Updated the year in copyrights of template license headers in
  build/templates and removed AMD as a default copyright holder.

Author: fgvanzee

build/config.mk.in

@@ -112,6 +112,9 @@ DEBUG_TYPE        := @debug_type@
 # The requested threading model.
 THREADING_MODEL   := @threading_model@
 
+# Whether the compiler supports "#pragma omp simd" via the -fopenmp-simd option.
+PRAGMA_OMP_SIMD   := @pragma_omp_simd@
+
 # The install libdir, includedir, and shareddir values from configure tell
 # us where to install the libraries, header files, and public makefile
 # fragments, respectively. Notice that we support the use of DESTDIR so that

build/detect/omp_simd/omp_simd_detect.c

@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <string.h>
+
+#define ARRAY_LEN  4096
+
+double x[ ARRAY_LEN ];
+double y[ ARRAY_LEN ];
+
+int main( int argc, char **argv )
+{
+	const double alpha = 2.1;
+
+	for ( int i = 0; i < ARRAY_LEN; ++i )
+	{
+		y[ i ] = 0.0;
+		x[ i ] = 1.0;
+	}
+
+	#pragma omp simd
+	for ( int i = 0; i < ARRAY_LEN; ++i )
+	{
+		y[ i ] += alpha * x[ i ];
+	}
+
+#if 0
+	_Pragma( "omp simd" )
+	for ( int i = 0; i < ARRAY_LEN; ++i )
+	{
+		x[ i ] += alpha * y[ i ];
+	}
+#endif
+
+    return 0;
+}
+

build/templates/license.c

@@ -4,8 +4,7 @@
    An object-based framework for developing high-performance BLAS-like
    libraries.
 
-   Copyright (C) 2014, The University of Texas at Austin
-   Copyright (C) 2017, Advanced Micro Devices, Inc.
+   Copyright (C) 2019, The University of Texas at Austin
 
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are

build/templates/license.h

@@ -4,8 +4,7 @@
    An object-based framework for developing high-performance BLAS-like
    libraries.
 
-   Copyright (C) 2014, The University of Texas at Austin
-   Copyright (C) 2017, Advanced Micro Devices, Inc.
+   Copyright (C) 2019, The University of Texas at Austin
 
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are

build/templates/license.sh

@@ -4,8 +4,7 @@
 #  An object-based framework for developing high-performance BLAS-like
 #  libraries.
 #
-#  Copyright (C) 2014, The University of Texas at Austin
-#  Copyright (C) 2017, Advanced Micro Devices, Inc.
+#  Copyright (C) 2019, The University of Texas at Austin
 #
 #  Redistribution and use in source and binary forms, with or without
 #  modification, are permitted provided that the following conditions are

common.mk

@@ -124,6 +124,7 @@ get-refinit-cflags-for   = $(strip $(call load-var-for,COPTFLAGS,$(1)) \
 get-refkern-cflags-for   = $(strip $(call load-var-for,CROPTFLAGS,$(1)) \
                                    $(call load-var-for,CRVECFLAGS,$(1)) \
                                    $(call get-noopt-cflags-for,$(1)) \
+                                   $(COMPSIMDFLAGS) \
                                    -DBLIS_CNAME=$(1) \
                                    $(BUILD_FLAGS) \
                             )
@@ -635,7 +636,6 @@ $(foreach c, $(CONFIG_LIST_FAM), $(eval $(call append-var-for,CXXLANGFLAGS,$(c))
 CPPROCFLAGS := -D_POSIX_C_SOURCE=200112L
 $(foreach c, $(CONFIG_LIST_FAM), $(eval $(call append-var-for,CPPROCFLAGS,$(c))))
 
-
 # --- Threading flags ---
 
 ifeq ($(CC_VENDOR),gcc)
@@ -680,6 +680,14 @@ LDFLAGS      += $(LIBPTHREAD)
 endif
 endif
 
+# --- #pragma omp simd flags (used for reference kernels only) ---
+
+ifeq ($(PRAGMA_OMP_SIMD),yes)
+COMPSIMDFLAGS := -fopenmp-simd
+else
+COMPSIMDFLAGS :=
+endif
+
 
 
 #
@@ -948,7 +956,8 @@ BLIS_CONFIG_H   := ./bli_config.h
 VERS_DEF       := -DBLIS_VERSION_STRING=\"$(VERSION)\"
 
 # Define a C preprocessor flag that is *only* defined when BLIS is being
-# compiled.
+# compiled. (In other words, an application that #includes blis.h will not
+# get this cpp macro.)
 BUILD_FLAGS    := -DBLIS_IS_BUILDING_LIBRARY
 
 

configure

@@ -1081,6 +1081,36 @@ has_libmemkind()
 	echo "${rval}"
 }
 
+has_pragma_omp_simd()
+{
+	local main_c main_c_filepath binname rval
+
+	# Path to omp-simd detection source file.
+	main_c="omp_simd_detect.c"
+	main_c_filepath=$(find ${dist_path}/build -name "${main_c}")
+
+	# Binary executable filename.
+	binname="omp_simd-detect.x"
+
+	# Attempt to compile a simple main() program that contains a
+	# #pragma omp simd.
+	${found_cc} -std=c99 -O3 -march=native -fopenmp-simd \
+	            -o ${binname} ${main_c_filepath} 2> /dev/null
+
+	# Depending on the return code from the compile step above, we set
+	# enable_memkind accordingly.
+	if [ "$?" == 0 ]; then
+	    rval='yes'
+	else
+	    rval='no'
+	fi
+
+	# Remove the executable generated above.
+	rm -f ./${binname}
+
+	echo "${rval}"
+}
+
 echoerr()
 {
 	printf "${script_name}: error: %s\n" "$*" #>&2;
@@ -2423,6 +2453,9 @@ main()
 	# --without-memkind.
 	has_memkind=$(has_libmemkind)
 
+	# Try to determine whether the chosen compiler supports #pragma omp simd.
+	pragma_omp_simd=$(has_pragma_omp_simd)
+
 
 	# -- Prepare variables for subsitution into template files -----------------
 
@@ -2633,6 +2666,11 @@ main()
 		enable_memkind="no"
 		enable_memkind_01=0
 	fi
+	if [ "x${pragma_omp_simd}" = "xyes" ]; then
+		echo "${script_name}: compiler appears to support #pragma omp simd."
+	else
+		echo "${script_name}: compiler appears to not support #pragma omp simd."
+	fi
 	if [ "x${enable_blas}" = "xyes" ]; then
 		echo "${script_name}: the BLAS compatibility layer is enabled."
 		enable_blas_01=1
@@ -2842,6 +2880,7 @@ main()
 		| sed -e "s/@enable_blas@/${enable_blas}/g" \
 		| sed -e "s/@enable_cblas@/${enable_cblas}/g" \
 		| sed -e "s/@enable_memkind@/${enable_memkind}/g" \
+		| sed -e "s/@pragma_omp_simd@/${pragma_omp_simd}/g" \
 		| sed -e "s/@sandbox@/${sandbox}/g" \
 		> "${config_mk_out_path}"
 

frame/include/bli_arch_config_pre.h

@@ -49,6 +49,10 @@
 #define BLIS_CNAME_INFIX  PASTECH(_,BLIS_CNAME)
 #endif
 
+// Combine the CNAME and _ref for convenience to the code that defines
+// reference kernels.
+//#define BLIS_CNAME_REF_SUFFIX  PASTECH2(_,BLIS_CNAME,BLIS_REF_SUFFIX)
+
 // -- Prototype-generating macro definitions -----------------------------------
 
 // Prototype-generating macro for bli_cntx_init_<arch>*() functions.

frame/include/bli_builtin_macro_defs.h

@@ -0,0 +1,59 @@
+/*
+
+   BLIS
+   An object-based framework for developing high-performance BLAS-like
+   libraries.
+
+   Copyright (C) 2019, The University of Texas at Austin
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+    - Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    - 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.
+    - Neither the name(s) of the copyright holder(s) nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+   HOLDER 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.
+
+*/
+
+#ifndef BLIS_BUILTIN_MACRO_DEFS_H
+#define BLIS_BUILTIN_MACRO_DEFS_H
+
+#if   defined(__ICC) || defined(__INTEL_COMPILER)
+
+  // icc
+
+  #define bli_prefetch( addr, rw, loc )
+
+#elif defined(__clang__)
+
+  // clang
+
+  #define bli_prefetch( addr, rw, loc )
+
+#elif defined(__GNUC__)
+
+  // gcc
+
+  #define bli_prefetch( addr, rw, loc ) __builtin_prefetch( addr, rw, loc );
+
+#endif
+
+
+#endif

frame/include/bli_macro_defs.h

@@ -128,6 +128,15 @@
 #define PASTEMAC3_(ch1,ch2,ch3,op) bli_ ## ch1 ## ch2 ## ch3 ## op
 #define PASTEMAC3(ch1,ch2,ch3,op)  PASTEMAC3_(ch1,ch2,ch3,op)
 
+#define PASTEMAC4_(ch1,ch2,ch3,ch4,op) bli_ ## ch1 ## ch2 ## ch3 ## ch4 ## op
+#define PASTEMAC4(ch1,ch2,ch3,ch4,op)  PASTEMAC4_(ch1,ch2,ch3,ch4,op)
+
+#define PASTEMAC5_(ch1,ch2,ch3,ch4,ch5,op) bli_ ## ch1 ## ch2 ## ch3 ## ch4 ## ch5 ## op
+#define PASTEMAC5(ch1,ch2,ch3,ch4,ch5,op)  PASTEMAC5_(ch1,ch2,ch3,ch4,ch5,op)
+
+#define PASTEMAC6_(ch1,ch2,ch3,ch4,ch5,ch6,op) bli_ ## ch1 ## ch2 ## ch3 ## ch4 ## ch5 ## ch6 ## op
+#define PASTEMAC6(ch1,ch2,ch3,ch4,ch5,ch6,op)  PASTEMAC6_(ch1,ch2,ch3,ch4,ch5,ch6,op)
+
 #define PASTEBLACHK_(op)           bla_ ## op ## _check
 #define PASTEBLACHK(op)            PASTEBLACHK_(op)
 
@@ -163,6 +172,7 @@
 #include "bli_scalar_macro_defs.h"
 #include "bli_error_macro_defs.h"
 #include "bli_blas_macro_defs.h"
+#include "bli_builtin_macro_defs.h"
 
 #include "bli_oapi_macro_defs.h"
 #include "bli_tapi_macro_defs.h"

frame/include/bli_system.h

@@ -45,36 +45,46 @@
 #include <errno.h>
 #include <ctype.h>
 
+// Determine the compiler (hopefully) and define conveniently named macros
+// accordingly.
+#if   defined(__ICC) || defined(__INTEL_COMPILER)
+  #define BLIS_ICC
+#elif defined(__clang__)
+  #define BLIS_CLANG
+#elif defined(__GNUC__)
+  #define BLIS_GCC
+#endif
+
 // Determine if we are on a 64-bit or 32-bit architecture.
 #if defined(_M_X64) || defined(__x86_64) || defined(__aarch64__) || \
     defined(_ARCH_PPC64)
-#define BLIS_ARCH_64
+  #define BLIS_ARCH_64
 #else
-#define BLIS_ARCH_32
+  #define BLIS_ARCH_32
 #endif
 
 // Determine the target operating system.
 #if defined(_WIN32) || defined(__CYGWIN__)
-#define BLIS_OS_WINDOWS 1
+  #define BLIS_OS_WINDOWS 1
 #elif defined(__gnu_hurd__)
-#define BLIS_OS_GNU 1
+  #define BLIS_OS_GNU 1
 #elif defined(__APPLE__) || defined(__MACH__)
-#define BLIS_OS_OSX 1
+  #define BLIS_OS_OSX 1
 #elif defined(__ANDROID__)
-#define BLIS_OS_ANDROID 1
+  #define BLIS_OS_ANDROID 1
 #elif defined(__linux__)
-#define BLIS_OS_LINUX 1
+  #define BLIS_OS_LINUX 1
 #elif defined(__bgq__)
-#define BLIS_OS_BGQ 1
+  #define BLIS_OS_BGQ 1
 #elif defined(__bg__)
-#define BLIS_OS_BGP 1
+  #define BLIS_OS_BGP 1
 #elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || \
       defined(__bsdi__) || defined(__DragonFly__)
-#define BLIS_OS_BSD 1
+  #define BLIS_OS_BSD 1
 #elif defined(EMSCRIPTEN)
-#define BLIS_OS_EMSCRIPTEN
+  #define BLIS_OS_EMSCRIPTEN
 #else
-#error "Cannot determine operating system"
+  #error "Cannot determine operating system"
 #endif
 
 // A few changes that may be necessary in Windows environments.
@@ -86,11 +96,11 @@
   #include <windows.h>
 
   #if !defined(__clang__) && !defined(__GNUC__)
-     // Undefine attribute specifiers in Windows.
-     #define __attribute__(x)
+    // Undefine attribute specifiers in Windows.
+    #define __attribute__(x)
 
-     // Undefine restrict.
-     #define restrict
+    // Undefine restrict.
+    #define restrict
   #endif
 
 #endif