[OpenMP] Added the support for cache line size 256 for A64FX

Fugaku supercomputer is built with the Fujitsu A64FX microprocessor, whose cache line is 256. In current libomp, we only have cache line size 128 for PPC64 and otherwise 64. This patch added the support of cache line 256 for A64FX. It's worth noting that although A64FX is a variant of AArch64, this property is not shared. As a result, in light of UCX source code (392443ab92/src/ucs/arch/aarch64/cpu.c (L17)), we can only determine by checking whether the CPU is FUJITSU A64FX.

Reviewed By: jdoerfert, Hahnfeld

Differential Revision: https://reviews.llvm.org/D93169

openmp/runtime/CMakeLists.txt

@@ -66,7 +66,18 @@ else() # Part of LLVM build
   endif ()
   set(LIBOMP_ENABLE_ASSERTIONS ${LLVM_ENABLE_ASSERTIONS})
 endif()
-libomp_check_variable(LIBOMP_ARCH 32e x86_64 32 i386 arm ppc64 ppc64le aarch64 mic mips mips64 riscv64)
+
+# FUJITSU A64FX is a special processor because its cache line size is 256.
+# We need to pass this information into kmp_config.h.
+if(LIBOMP_ARCH STREQUAL "aarch64")
+  libomp_is_aarch64_a64fx(LIBOMP_DETECT_AARCH64_A64FX)
+  if (LIBOMP_DETECT_AARCH64_A64FX)
+    set(LIBOMP_ARCH "aarch64_a64fx")
+    set(LIBOMP_ARCH_AARCH64_A64FX TRUE)
+  endif()
+endif()
+
+libomp_check_variable(LIBOMP_ARCH 32e x86_64 32 i386 arm ppc64 ppc64le aarch64 aarch64_a64fx mic mips mips64 riscv64)
 
 set(LIBOMP_LIB_TYPE normal CACHE STRING
   "Performance,Profiling,Stubs library (normal/profile/stubs)")
@@ -136,6 +147,7 @@ set(IA32 FALSE)
 set(INTEL64 FALSE)
 set(ARM FALSE)
 set(AARCH64 FALSE)
+set(AARCH64_A64FX FALSE)
 set(PPC64BE FALSE)
 set(PPC64LE FALSE)
 set(PPC64 FALSE)
@@ -157,6 +169,8 @@ elseif("${LIBOMP_ARCH}" STREQUAL "ppc64le") # PPC64LE architecture
   set(PPC64 TRUE)
 elseif("${LIBOMP_ARCH}" STREQUAL "aarch64") # AARCH64 architecture
   set(AARCH64 TRUE)
+elseif("${LIBOMP_ARCH}" STREQUAL "aarch64_a64fx") # AARCH64_A64FX architecture
+  set(AARCH64_A64FX TRUE)
 elseif("${LIBOMP_ARCH}" STREQUAL "mic") # Intel(R) Many Integrated Core Architecture
   set(MIC TRUE)
 elseif("${LIBOMP_ARCH}" STREQUAL "mips") # MIPS architecture

openmp/runtime/cmake/LibompGetArchitecture.cmake

@@ -69,3 +69,16 @@ function(libomp_get_architecture return_arch)
   # Remove ${detect_arch_src_txt} from cmake/ subdirectory
   file(REMOVE "${CMAKE_CURRENT_BINARY_DIR}/libomp_detect_arch.c")
 endfunction()
+
+function(libomp_is_aarch64_a64fx return_is_aarch64_a64fx)
+  file(READ "/proc/cpuinfo" cpu_info_content)
+  string(REGEX MATCH "CPU implementer[ \t]*: 0x46\n" cpu_implementer ${cpu_info_content})
+  string(REGEX MATCH "CPU architecture[ \t]*: 8\n" cpu_architecture ${cpu_info_content})
+
+  set(is_aarch64_a64fx FALSE)
+  if (cpu_architecture AND cpu_implementer)
+    set(is_aarch64_a64fx TRUE)
+  endif()
+
+  set(${return_is_aarch64_a64fx} "${is_aarch64_a64fx}" PARENT_SCOPE)
+endfunction(libomp_is_aarch64_a64fx)

openmp/runtime/cmake/LibompUtils.cmake

@@ -101,6 +101,8 @@ function(libomp_get_legal_arch return_arch_string)
     set(${return_arch_string} "PPC64LE" PARENT_SCOPE)
   elseif(${AARCH64})
     set(${return_arch_string} "AARCH64" PARENT_SCOPE)
+  elseif(${AARCH64_A64FX})
+    set(${return_arch_string} "AARCH64_A64FX" PARENT_SCOPE)
   elseif(${MIPS})
     set(${return_arch_string} "MIPS" PARENT_SCOPE)
   elseif(${MIPS64})

openmp/runtime/cmake/config-ix.cmake

@@ -291,6 +291,7 @@ else()
       (LIBOMP_ARCH STREQUAL i386) OR
 #      (LIBOMP_ARCH STREQUAL arm) OR
       (LIBOMP_ARCH STREQUAL aarch64) OR
+      (LIBOMP_ARCH STREQUAL aarch64_a64fx) OR
       (LIBOMP_ARCH STREQUAL ppc64le) OR
       (LIBOMP_ARCH STREQUAL ppc64) OR
       (LIBOMP_ARCH STREQUAL riscv64))

openmp/runtime/src/kmp_config.h.cmake

@@ -82,10 +82,14 @@
 #define KMP_HAVE_ATTRIBUTE_WAITPKG LIBOMP_HAVE_ATTRIBUTE_WAITPKG
 #cmakedefine01 LIBOMP_HAVE_ATTRIBUTE_RTM
 #define KMP_HAVE_ATTRIBUTE_RTM LIBOMP_HAVE_ATTRIBUTE_RTM
+#cmakedefine01 LIBOMP_ARCH_AARCH64_A64FX
+#define KMP_ARCH_AARCH64_A64FX LIBOMP_ARCH_AARCH64_A64FX
 
 // Configured cache line based on architecture
 #if KMP_ARCH_PPC64
 # define CACHE_LINE 128
+#elif KMP_ARCH_AARCH64_A64FX
+# define CACHE_LINE 256
 #else
 # define CACHE_LINE 64
 #endif