ggml-cpu: Add ARM variant targeting neoverse-v2

Author: ckastner

ggml/src/CMakeLists.txt

@@ -317,9 +317,7 @@ if (GGML_CPU_ALL_VARIANTS)
         endif()
     elseif(GGML_SYSTEM_ARCH STREQUAL "ARM")
         if (CMAKE_SYSTEM_NAME MATCHES "Linux")
-            # Many of these features are optional so we build versions with popular
-            # combinations and name the backends based on the version they were
-            # first released with
+            # Generic ARM builds
             ggml_add_cpu_backend_variant(armv8.0_1)
             ggml_add_cpu_backend_variant(armv8.2_1    DOTPROD)
             ggml_add_cpu_backend_variant(armv8.2_2    DOTPROD FP16_VECTOR_ARITHMETIC)
@@ -328,6 +326,9 @@ if (GGML_CPU_ALL_VARIANTS)
             ggml_add_cpu_backend_variant(armv8.6_2    DOTPROD FP16_VECTOR_ARITHMETIC SVE MATMUL_INT8 SVE2)
             ggml_add_cpu_backend_variant(armv9.2_1    DOTPROD FP16_VECTOR_ARITHMETIC SVE MATMUL_INT8 SME)
             ggml_add_cpu_backend_variant(armv9.2_2    DOTPROD FP16_VECTOR_ARITHMETIC SVE MATMUL_INT8 SVE2 SME)
+            # Builds optimized for specific cores
+            # neoverse-v2: AWS Graviton4, NVIDIA Grace
+            ggml_add_cpu_backend_variant(neoverse-v2  DOTPROD FP16_VECTOR_ARITHMETIC SVE MATMUL_INT8 SVE2)
         elseif (CMAKE_SYSTEM_NAME MATCHES "Android")
             # Android-specific backends with SoC-compatible feature sets
             ggml_add_cpu_backend_variant(android_armv8.0_1)

ggml/src/ggml-cpu/CMakeLists.txt

@@ -157,30 +157,30 @@ function(ggml_add_cpu_backend_variant_impl tag_name)
             elseif (GGML_CPU_ARM_ARCH)
                 list(APPEND ARCH_FLAGS -march=${GGML_CPU_ARM_ARCH})
             elseif(GGML_CPU_ALL_VARIANTS)
-                # Begin with the lowest baseline
-                set(ARM_MCPU "armv8-a")
+                # For the generic builds, begin with the lowest supported baseline
+                set(ARM_GENERIC_ARCH "armv8-a")
                 set(ARCH_TAGS "")
                 set(ARCH_DEFINITIONS "")
 
-                # When a feature is selected, bump the MCPU to the first
-                # version that supported it
+                # When a feature is selected, bump GENERIC_ARCH to the earliest
+                # version which supported that feature
                 if (GGML_INTERNAL_DOTPROD)
-                    set(ARM_MCPU "armv8.2-a")
+                    set(ARM_GENERIC_ARCH "armv8.2-a")
                     set(ARCH_TAGS "${ARCH_TAGS}+dotprod")
                     list(APPEND ARCH_DEFINITIONS GGML_USE_DOTPROD)
                 endif()
                 if (GGML_INTERNAL_FP16_VECTOR_ARITHMETIC)
-                    set(ARM_MCPU "armv8.2-a")
+                    set(ARM_GENERIC_ARCH "armv8.2-a")
                     set(ARCH_TAGS "${ARCH_TAGS}+fp16")
                     list(APPEND ARCH_DEFINITIONS GGML_USE_FP16_VECTOR_ARITHMETIC)
                 endif()
                 if (GGML_INTERNAL_SVE)
-                    set(ARM_MCPU "armv8.2-a")
+                    set(ARM_GENERIC_ARCH "armv8.2-a")
                     set(ARCH_TAGS "${ARCH_TAGS}+sve")
                     list(APPEND ARCH_DEFINITIONS GGML_USE_SVE)
                 endif()
                 if (GGML_INTERNAL_MATMUL_INT8)
-                    set(ARM_MCPU "armv8.6-a")
+                    set(ARM_GENERIC_ARCH "armv8.6-a")
                     set(ARCH_TAGS "${ARCH_TAGS}+i8mm")
                     list(APPEND ARCH_DEFINITIONS GGML_USE_MATMUL_INT8)
                 endif()
@@ -197,7 +197,14 @@ function(ggml_add_cpu_backend_variant_impl tag_name)
                     set(ARCH_TAGS "${ARCH_TAGS}+sme")
                     list(APPEND ARCH_DEFINITIONS GGML_USE_SME)
                 endif()
-                list(APPEND ARCH_FLAGS "-march=${ARM_MCPU}${ARCH_TAGS}")
+
+                # CPU targeted builds first, else do the generic build
+                if (${tag_name} STREQUAL "neoverse-v2")
+                    list(APPEND ARCH_FLAGS "-mcpu=neoverse-v2${ARCH_TAGS}")
+		    list(APPEND ARCH_DEFINITIONS GGML_ARM_MCPU=NEOVERSE_V2)
+                else()
+                    list(APPEND ARCH_FLAGS "-march=${ARM_GENERIC_ARCH}${ARCH_TAGS}")
+                endif()
                 ggml_add_cpu_backend_features(${GGML_CPU_NAME} arm ${ARCH_DEFINITIONS})
             endif()