[libc][cmake] Reduce entrypoint list duplication

[michaelrj-google]

Currently the list of entrypoints defined for a given platform is listed exclusively in the entrypoints.txt for that platform (e.g. for x86_64/linux: https://github.com/llvm/llvm-project/blob/3ccf8ef715574ae9d2fd041cd9b438dd04a7a002/libc/config/linux/x86_64/entrypoints.txt).

Most of these lists for the same OS target should be the same, but they often drift out of sync. We should change the way entrypoints.txt is handle to better match how config.json is handled: There's a top level definition for every linux target (for example) and then each more specific target can include or exclude individual entrypoints.

To implement this there will need to be a significant refactoring in the main CMake file:

llvm-project/libc/CMakeLists.txt

Line 356 in 3ccf8ef

if(EXISTS "${LIBC_CONFIG_PATH}/entrypoints.txt")

.

[llvmbot]

@llvm/issue-subscribers-libc

Author: Michael Jones (michaelrj-google)

Currently the list of entrypoints defined for a given platform is listed exclusively in the `entrypoints.txt` for that platform (e.g. for x86_64/linux: https://github.com/llvm/llvm-project/blob/3ccf8ef715574ae9d2fd041cd9b438dd04a7a002/libc/config/linux/x86_64/entrypoints.txt).

Most of these lists for the same OS target should be the same, but they often drift out of sync. We should change the way entrypoints.txt is handle to better match how config.json is handled: There's a top level definition for every linux target (for example) and then each more specific target can include or exclude individual entrypoints.

To implement this there will need to be a significant refactoring in the main CMake file:

llvm-project/libc/CMakeLists.txt

Line 356 in 3ccf8ef

if(EXISTS "${LIBC_CONFIG_PATH}/entrypoints.txt")

.