Added initial version of cmake toolchain for RISC-V architecture.

cmake/OpenCVDetectCXXCompiler.cmake

@@ -98,6 +98,8 @@ elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(powerpc|ppc)64")
   set(PPC64 1)
 elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(mips.*|MIPS.*)")
   set(MIPS 1)
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(riscv.*|RISCV.*)")
+  set(RISCV 1)
 else()
   if(NOT OPENCV_SUPPRESS_MESSAGE_UNRECOGNIZED_SYSTEM_PROCESSOR)
     message(WARNING "OpenCV: unrecognized target processor configuration")

modules/core/src/parallel_impl.cpp

@@ -53,6 +53,12 @@ DECLARE_CV_PAUSE
 #   define CV_PAUSE(v) do { for (int __delay = (v); __delay > 0; --__delay) { asm volatile("pause" ::: "memory"); } } while (0)
 # elif defined __GNUC__ && defined __PPC64__
 #   define CV_PAUSE(v) do { for (int __delay = (v); __delay > 0; --__delay) { asm volatile("or 27,27,27" ::: "memory"); } } while (0)
+# elif defined __GNUC__ && defined __riscv
+// PAUSE HINT is not part of RISC-V ISA yet, but is under discussion now. For details see:
+// https://github.com/riscv/riscv-isa-manual/pull/398
+// https://github.com/riscv/riscv-isa-manual/issues/43
+// #   define CV_PAUSE(v) do { for (int __delay = (v); __delay > 0; --__delay) { asm volatile("pause"); } } while (0)
+#   define CV_PAUSE(v) do { for (int __delay = (v); __delay > 0; --__delay) { asm volatile("nop"); } } while (0)
 # else
 #   warning "Can't detect 'pause' (CPU-yield) instruction on the target platform. Specify CV_PAUSE() definition via compiler flags."
 #   define CV_PAUSE(...) do { /* no-op: works, but not effective */ } while (0)

platforms/linux/riscv.toolchain.cmake

@@ -0,0 +1,62 @@
+cmake_minimum_required(VERSION 2.8)
+
+if(COMMAND toolchain_save_config)
+  return() # prevent recursive call
+endif()
+
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_VERSION 1)
+
+include("${CMAKE_CURRENT_LIST_DIR}/gnu.toolchain.cmake")
+
+MESSAGE(STATUS "Debug: CMAKE_C_COMPILER: ${CMAKE_C_COMPILER}")
+
+if(NOT "x${GCC_COMPILER_VERSION}" STREQUAL "x")
+  set(__GCC_VER_SUFFIX "-${GCC_COMPILER_VERSION}")
+endif()
+
+if(NOT DEFINED CMAKE_C_COMPILER)
+  MESSAGE("Looking for compler.. ${GNU_MACHINE}-gcc${__GCC_VER_SUFFIX}")
+  find_program(CMAKE_C_COMPILER NAMES ${GNU_MACHINE}-gcc${__GCC_VER_SUFFIX})
+else()
+  #message(WARNING "CMAKE_C_COMPILER=${CMAKE_C_COMPILER} is defined")
+endif()
+if(NOT DEFINED CMAKE_CXX_COMPILER)
+  find_program(CMAKE_CXX_COMPILER NAMES ${GNU_MACHINE}-g++${__GCC_VER_SUFFIX})
+else()
+  #message(WARNING "CMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} is defined")
+endif()
+if(NOT DEFINED CMAKE_LINKER)
+  find_program(CMAKE_LINKER NAMES ${GNU_MACHINE}-ld${__GCC_VER_SUFFIX} ${GNU_MACHINE}-ld)
+else()
+  #message(WARNING "CMAKE_LINKER=${CMAKE_LINKER} is defined")
+endif()
+if(NOT DEFINED CMAKE_AR)
+  find_program(CMAKE_AR NAMES ${GNU_MACHINE}-ar${__GCC_VER_SUFFIX} ${GNU_MACHINE}-ar)
+else()
+  #message(WARNING "CMAKE_AR=${CMAKE_AR} is defined")
+endif()
+
+if(NOT DEFINED RISCV_LINUX_SYSROOT AND DEFINED GNU_MACHINE)
+  set(RISCV_LINUX_SYSROOT /usr/${GNU_MACHINE})
+endif()
+
+if(NOT DEFINED CMAKE_CXX_FLAGS)
+  set(CMAKE_CXX_FLAGS           "${CMAKE_CXX_FLAGS} -fdata-sections -Wa,--noexecstack -fsigned-char -Wno-psabi")
+  set(CMAKE_C_FLAGS             "${CMAKE_C_FLAGS} -fdata-sections -Wa,--noexecstack -fsigned-char -Wno-psabi")
+  set(CMAKE_EXE_LINKER_FLAGS    "${CMAKE_EXE_LINKER_FLAGS} -Wl,-z,nocopyreloc")
+
+  set(RISCV_LINKER_FLAGS "-Wl,--no-undefined -Wl,--gc-sections -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now")
+  set(CMAKE_SHARED_LINKER_FLAGS "${RISCV_LINKER_FLAGS} ${CMAKE_SHARED_LINKER_FLAGS}")
+  set(CMAKE_MODULE_LINKER_FLAGS "${RISCV_LINKER_FLAGS} ${CMAKE_MODULE_LINKER_FLAGS}")
+  set(CMAKE_EXE_LINKER_FLAGS    "${RISCV_LINKER_FLAGS} ${CMAKE_EXE_LINKER_FLAGS}")
+else()
+  message(STATUS "User provided flags are used instead of defaults")
+endif()
+
+set(CMAKE_FIND_ROOT_PATH ${CMAKE_FIND_ROOT_PATH} ${RISCV_LINUX_SYSROOT})
+
+set(TOOLCHAIN_CONFIG_VARS ${TOOLCHAIN_CONFIG_VARS}
+    RISCV_LINUX_SYSROOT
+)
+toolchain_save_config()

platforms/linux/riscv64-gnu.toolchain.cmake

@@ -0,0 +1,5 @@
+set(CMAKE_SYSTEM_PROCESSOR riscv64)
+set(GNU_MACHINE riscv64-linux-gnu CACHE STRING "GNU compiler triple")
+set(GCC_COMPILER_VERSION "" CACHE STRING "GCC Compiler version")
+
+include("${CMAKE_CURRENT_LIST_DIR}/riscv.toolchain.cmake")