Add MIPS64 to GitHub workflows.

GitOrigin-RevId: 5fe0c3a01f69574b4ff1a5112f63a91d53a88324
Change-Id: Ia2b9b0732b38e6bf67d2611e09864240782eb1cd
diff --git a/.github/workflows/cmake.yml b/.github/workflows/cmake.yml
index 36f138f..f16ab99 100644
--- a/.github/workflows/cmake.yml
+++ b/.github/workflows/cmake.yml
@@ -198,6 +198,12 @@
             packages: qemu qemu-user gcc-mips-linux-gnu g++-mips-linux-gnu libc-dev-mips-cross
             codecov: ubuntu_gcc_mips
 
+          - name: Ubuntu GCC MIPS64
+            os: ubuntu-latest
+            cmake-args: -DCMAKE_TOOLCHAIN_FILE=cmake/toolchain-mips64.cmake
+            packages: qemu qemu-user gcc-mips64-linux-gnuabi64 g++-mips64-linux-gnuabi64 libc-dev-mips64-cross
+            codecov: ubuntu_gcc_mips64
+
           - name: Ubuntu GCC PPC
             os: ubuntu-latest
             cmake-args: -DCMAKE_TOOLCHAIN_FILE=cmake/toolchain-powerpc.cmake
diff --git a/.github/workflows/configure.yml b/.github/workflows/configure.yml
index 4b83191..02a3600 100644
--- a/.github/workflows/configure.yml
+++ b/.github/workflows/configure.yml
@@ -107,6 +107,13 @@
             chost: mips-linux-gnu
             packages: qemu qemu-user gcc-mips-linux-gnu libc-dev-mips-cross
 
+          - name: Ubuntu GCC MIPS64
+            os: ubuntu-latest
+            compiler: mips64-linux-gnuabi64-gcc
+            configure-args: --warn
+            chost: mips64-linux-gnuabi64
+            packages: qemu qemu-user gcc-mips64-linux-gnuabi64 libc-dev-mips64-cross
+
           - name: Ubuntu GCC PPC
             os: ubuntu-latest
             compiler: powerpc-linux-gnu-gcc
diff --git a/cmake/toolchain-mips64.cmake b/cmake/toolchain-mips64.cmake
new file mode 100644
index 0000000..8ef3b6b
--- /dev/null
+++ b/cmake/toolchain-mips64.cmake
@@ -0,0 +1,29 @@
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR mips64)
+set(CMAKE_SYSTEM_VERSION 1)
+
+if(NOT DEFINED CMAKE_C_COMPILER_TARGET)
+    set(CMAKE_C_COMPILER_TARGET mips64-linux-gnuabi64)
+endif()
+if(NOT DEFINED CMAKE_CXX_COMPILER_TARGET)
+    set(CMAKE_CXX_COMPILER_TARGET mips64-linux-gnuabi64)
+endif()
+
+set(CMAKE_CROSSCOMPILING TRUE)
+set(CMAKE_CROSSCOMPILING_EMULATOR qemu-mips64 -L /usr/${CMAKE_C_COMPILER_TARGET}/)
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+find_program(C_COMPILER_FULL_PATH NAMES ${CMAKE_C_COMPILER_TARGET}-gcc)
+if(NOT C_COMPILER_FULL_PATH)
+    message(FATAL_ERROR "Cross-compiler for ${CMAKE_C_COMPILER_TARGET} not found")
+endif()
+set(CMAKE_C_COMPILER ${C_COMPILER_FULL_PATH})
+
+find_program(CXX_COMPILER_FULL_PATH NAMES g++-${CMAKE_CXX_COMPILER_TARGET} ${CMAKE_CXX_COMPILER_TARGET}-g++)
+if(CXX_COMPILER_FULL_PATH)
+    set(CMAKE_CXX_COMPILER ${CXX_COMPILER_FULL_PATH})
+endif()