New in version 3.19.

This is a CMake Environment Variable. Its initial value is taken from the calling process environment.

Add default compilation flags to be used when compiling ISPC files.

CMake uses this environment variable value, in combination with its own builtin default flags for the toolchain, to initialize and store the CMAKE_ISPC_FLAGS cache entry. This occurs the first time a build tree is configured for language ISPC. For any configuration run (including the first), the environment variable will be ignored if the CMAKE_ISPC_FLAGS variable is already defined.