[libc] Fix startup utilities failing to install in full build mode

[jhuber6]

Summary:
Currently, doing ninja install will fail in fullbuild mode due to the
startup utilities not being built by default. This was hidden previously
by the fact that if tests were run, it would build the startup utilities
and thus they would be present.

This patch solves this issue by making the libc-startup target a
dependncy on the final library. Furthermore we simply factor out the
library install directory into the base CMake directory next to the
include directory handling. This change makes the crt files get
installed in lib/x86_64-unknown-linu-gnu instead of just lib.

This fixes an error I had where doing a runtimes failed to install its
libraries because the install step always errored.

[llvmbot]

@llvm/pr-subscribers-libc

Author: Joseph Huber (jhuber6)

Changes

Summary:
Currently, doing ninja install will fail in fullbuild mode due to the
startup utilities not being built by default. This was hidden previously
by the fact that if tests were run, it would build the startup utilities
and thus they would be present.

This patch solves this issue by making the libc-startup target a
dependncy on the final library. Furthermore we simply factor out the
library install directory into the base CMake directory next to the
include directory handling. This change makes the crt files get
installed in lib/x86_64-unknown-linu-gnu instead of just lib.

This fixes an error I had where doing a runtimes failed to install its
libraries because the install step always errored.

---

Full diff: https://github.com/llvm/llvm-project/pull/82522.diff

3 Files Affected:

• (modified) libc/CMakeLists.txt (+9)
• (modified) libc/lib/CMakeLists.txt (+1-9)
• (modified) libc/startup/linux/CMakeLists.txt (+1-1)

diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
index 3d775736616745..616beae13d9aaa 100644
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -225,6 +225,15 @@ else()
   set(LIBC_INSTALL_INCLUDE_DIR ${CMAKE_INSTALL_INCLUDEDIR})
 endif()
 
+if(LIBC_TARGET_TRIPLE)
+  set(LIBC_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LIBC_TARGET_TRIPLE})
+elseif(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT LIBC_GPU_BUILD)
+  set(LIBC_INSTALL_LIBRARY_DIR
+      lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE})
+else()
+  set(LIBC_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX})
+endif()
+
 if(LIBC_TARGET_ARCHITECTURE_IS_GPU)
   include(prepare_libc_gpu_build)
   set(LIBC_ENABLE_UNITTESTS OFF)
diff --git a/libc/lib/CMakeLists.txt b/libc/lib/CMakeLists.txt
index af7ef2de93dd41..99f8c6a8be9da4 100644
--- a/libc/lib/CMakeLists.txt
+++ b/libc/lib/CMakeLists.txt
@@ -35,19 +35,11 @@ foreach(archive IN ZIP_LISTS
   )
   if(LLVM_LIBC_FULL_BUILD)
     target_link_libraries(${archive_1} PUBLIC libc-headers)
+    add_dependencies(${archive_1} libc-startup)
   endif()
   list(APPEND added_archive_targets ${archive_1})
 endforeach()
 
-if(LIBC_TARGET_TRIPLE)
-  set(LIBC_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LIBC_TARGET_TRIPLE})
-elseif(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT LIBC_GPU_BUILD)
-  set(LIBC_INSTALL_LIBRARY_DIR
-      lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE})
-else()
-  set(LIBC_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX})
-endif()
-
 install(
   TARGETS ${added_archive_targets}
   ARCHIVE DESTINATION ${LIBC_INSTALL_LIBRARY_DIR}
diff --git a/libc/startup/linux/CMakeLists.txt b/libc/startup/linux/CMakeLists.txt
index 39bcca9cdba9fe..3837737d478a2a 100644
--- a/libc/startup/linux/CMakeLists.txt
+++ b/libc/startup/linux/CMakeLists.txt
@@ -131,7 +131,7 @@ foreach(target IN LISTS startup_components)
   set(fq_target_name libc.startup.linux.${target})
   add_dependencies(libc-startup ${fq_target_name})
   install(FILES $<TARGET_OBJECTS:${fq_target_name}>
-          DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    DESTINATION ${LIBC_INSTALL_LIBRARY_DIR}
           RENAME $<TARGET_PROPERTY:${fq_target_name},OUTPUT_NAME>
           COMPONENT libc)
 endforeach()

[jhuber6]

Also realized that actually installing the startup utilities breaks compiling with the compiler. I remember we previously hid these behind install-libc or something. So we likely want to move the installation off of the standard target altogether.

[SchrodingerZhu]

Can you comment a bit about the logic where (i.e. why checking TARGET_TRIPLE)

[jhuber6]

That's the existing logic that's been moved, so it's not related to the patch. But LIBC_TARGET_TRIPLE is set whenever building using https://libc.llvm.org/full_cross_build.html#runtimes-cross-build.

[jhuber6]

The intention is to install these things in subdirectories, like libcxx and libc end up in lib/x86_64-unknown-linux-gnu.

[michaelrj-google]

are there any fullbuild targets we support that don't have startup code yet? (E.g. risc-v linux?)

[jhuber6]

I think linux and gpu are the only ones with startup code currently. But good catch, should be if TARGET.

[michaelrj-google]

LGTM, hopefully we can eventually remove this from EXCLUDE_FROM_ALL but that will probably take a while