release/21.x: [CMake][Release] Stop linking against stage1 runtimes (#164017)

[llvmbot]

Backport 1906c3e

Requested by: @tstellar

[llvmbot]

@c-rhodes What do you think about merging this PR to the release branch?

[llvmbot]

@llvm/pr-subscribers-clang

Author: None (llvmbot)

Changes

Backport 1906c3e

Requested by: @tstellar

---

Full diff: https://github.com/llvm/llvm-project/pull/167653.diff

1 Files Affected:

• (modified) clang/cmake/caches/Release.cmake (+30-9)

diff --git a/clang/cmake/caches/Release.cmake b/clang/cmake/caches/Release.cmake
index fb12dfcdcb5a5..9f7e906241106 100644
--- a/clang/cmake/caches/Release.cmake
+++ b/clang/cmake/caches/Release.cmake
@@ -44,6 +44,19 @@ set(LLVM_RELEASE_ENABLE_LTO THIN CACHE STRING "")
 set(LLVM_RELEASE_ENABLE_PGO ON CACHE BOOL "")
 set(LLVM_RELEASE_ENABLE_RUNTIMES ${DEFAULT_RUNTIMES} CACHE STRING "")
 set(LLVM_RELEASE_ENABLE_PROJECTS ${DEFAULT_PROJECTS} CACHE STRING "")
+
+# This option enables linking stage2 clang statically with the runtimes
+# (libc++ and compiler-rt) from stage1.  In theory this will give the
+# binaries better performance and make them more portable.  However,
+# this configuration is not well tested and causes build failures with
+# the flang-rt tests cases, since the -stclib=libc++ flag does not
+# get propagated to the runtimes build.  There is also a separate
+# issue on Darwin where clang will use the local libc++ headers, but
+# link with system libc++ which can cause some incompatibilities.
+# See https://github.com/llvm/llvm-project/issues/77653
+# Because of these problems, this option will default to OFF.
+set(LLVM_RELEASE_ENABLE_LINK_LOCAL_RUNTIMES OFF CACHE BOOL "")
+
 # Note we don't need to add install here, since it is one of the pre-defined
 # steps.
 set(LLVM_RELEASE_FINAL_STAGE_TARGETS "clang;package;check-all;check-llvm;check-clang" CACHE STRING "")
@@ -55,8 +68,12 @@ set(CLANG_ENABLE_BOOTSTRAP ON CACHE BOOL "")
 
 set(STAGE1_PROJECTS "clang")
 
+# Need to build compiler-rt in order to use PGO for later stages.
+set(STAGE1_RUNTIMES "compiler-rt")
 # Build all runtimes so we can statically link them into the stage2 compiler.
-set(STAGE1_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind")
+if(LLVM_RELEASE_ENABLE_LINK_LOCAL_RUNTIMES)
+  list(APPEND STAGE1_RUNTIMES "libcxx;libcxxabi;libunwind")
+endif()
 
 if (LLVM_RELEASE_ENABLE_PGO)
   list(APPEND STAGE1_PROJECTS "lld")
@@ -118,11 +135,13 @@ set_instrument_and_final_stage_var(LLVM_ENABLE_LTO "${LLVM_RELEASE_ENABLE_LTO}"
 if (LLVM_RELEASE_ENABLE_LTO)
   set_instrument_and_final_stage_var(LLVM_ENABLE_LLD "ON" BOOL)
 endif()
-set_instrument_and_final_stage_var(LLVM_ENABLE_LIBCXX "ON" BOOL)
-set_instrument_and_final_stage_var(LLVM_STATIC_LINK_CXX_STDLIB "ON" BOOL)
-set(RELEASE_LINKER_FLAGS "-rtlib=compiler-rt --unwindlib=libunwind")
-if(NOT ${CMAKE_HOST_SYSTEM_NAME} MATCHES "Darwin")
-  set(RELEASE_LINKER_FLAGS "${RELEASE_LINKER_FLAGS} -static-libgcc")
+if(LLVM_RELEASE_ENABLE_LINK_LOCAL_RUNTIMES)
+  set_instrument_and_final_stage_var(LLVM_ENABLE_LIBCXX "ON" BOOL)
+  set_instrument_and_final_stage_var(LLVM_STATIC_LINK_CXX_STDLIB "ON" BOOL)
+  set(RELEASE_LINKER_FLAGS "-rtlib=compiler-rt --unwindlib=libunwind")
+  if(NOT ${CMAKE_HOST_SYSTEM_NAME} MATCHES "Darwin")
+    set(RELEASE_LINKER_FLAGS "${RELEASE_LINKER_FLAGS} -static-libgcc")
+  endif()
 endif()
 
 # Set flags for bolt
@@ -130,9 +149,11 @@ if (${CMAKE_HOST_SYSTEM_NAME} MATCHES "Linux")
   set(RELEASE_LINKER_FLAGS "${RELEASE_LINKER_FLAGS} -Wl,--emit-relocs,-znow")
 endif()
 
-set_instrument_and_final_stage_var(CMAKE_EXE_LINKER_FLAGS ${RELEASE_LINKER_FLAGS} STRING)
-set_instrument_and_final_stage_var(CMAKE_SHARED_LINKER_FLAGS ${RELEASE_LINKER_FLAGS} STRING)
-set_instrument_and_final_stage_var(CMAKE_MODULE_LINKER_FLAGS ${RELEASE_LINKER_FLAGS} STRING)
+if (RELEASE_LINKER_FLAGS)
+  set_instrument_and_final_stage_var(CMAKE_EXE_LINKER_FLAGS ${RELEASE_LINKER_FLAGS} STRING)
+  set_instrument_and_final_stage_var(CMAKE_SHARED_LINKER_FLAGS ${RELEASE_LINKER_FLAGS} STRING)
+  set_instrument_and_final_stage_var(CMAKE_MODULE_LINKER_FLAGS ${RELEASE_LINKER_FLAGS} STRING)
+endif()
 
 # Final Stage Config (stage2)
 set_final_stage_var(LLVM_ENABLE_RUNTIMES "${LLVM_RELEASE_ENABLE_RUNTIMES}" STRING)

[dyung]

@tstellar it looks like the macos builds took too long and timed out, is that okay with you?

[tstellar]

@dyung Yes, I've manually verified that the this patch fixes the build failure that was occurring previously after about an hour of build time. We use more powerful runners when we do the official release builds, so the build should finish there.

[github-actions]

@tstellar (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.