How to write compile scripts compatible with arm and x86 (Makefile, cmakelists.txt, shell script)

Compilation compatibility mainly includes 3 In terms of ,1. CMakeLists.txt compatible ,2. Makefile compatible ,3. shell compatible

1. CMakeLists.txt

IF(${CMAKE_SYSTEM_PROCESSOR} MATCHES "x86_64")
    SET(CMAKE_CXX_FLAGS "-fPIC -DLINUX -m64 -Wall -Wno-unused-function -Wno-unused-parameter -std=c++11 ")
ELSEIF(CMAKE_HOST_SYSTEM_PROCESSOR MATCHS "aarch64")
    SET(CMAKE_CXX_FLAGS "-fPIC -DLINUX -march=armv8-a -mabi=lp64 -mtune=tsv110 -fsigned-char -Wall -Wno-unused-function -Wno-unused-parameter -std=c++11 ")
ELSE()
    SET(CMAKE_CXX_FLAGS "-fPIC -DLINUX -Wall -Wno-unused-function -Wno-unused-parameter -std=c++11 ")
ENDIF()

2. Makefile

ifeq ($(shell arc), aarch64)
    CPPFLAGS=-g -O2 -march=armv8-a -mabi=lp64 -mtune=tsv110 -fsigned-char
else
    CPPFLAGS=-g -O2 -m64
endif

3. shell

!/bin/bash
get_arch=`arch`
if [[ $get_arch =~ "x86_64" ]];then
    echo "this is x86_64"
elif [[ $get_arch =~ "aarch64" ]];then
    echo "this is arm64"
elif [[ $get_arch =~ "mips64" ]];then
    echo "this is mips64"
else
    echo "unknown!!"
fi