add cmake rvv support (#10411)

ggml/CMakeLists.txt

@@ -109,6 +109,7 @@ if (NOT MSVC)
 endif()
 option(GGML_LASX        "ggml: enable lasx"             ON)
 option(GGML_LSX         "ggml: enable lsx"              ON)
+option(GGML_RVV         "ggml: enable rvv"              ON)
 option(GGML_SVE         "ggml: enable SVE"              OFF)
 
 if (WIN32)

ggml/src/ggml-cpu/CMakeLists.txt

@@ -244,6 +244,11 @@ elseif (${CMAKE_SYSTEM_PROCESSOR} MATCHES "loongarch64")
     if (GGML_LSX)
         list(APPEND ARCH_FLAGS -mlsx)
     endif()
+elseif (${CMAKE_SYSTEM_PROCESSOR} MATCHES "riscv64")
+    message(STATUS "RISC-V detected")
+    if (GGML_RVV)
+        list(APPEND ARCH_FLAGS -march=rv64gcv -mabi=lp64d)
+    endif()
 else()
     message(STATUS "Unknown architecture")
 endif()