[CMake] Don't set absolute paths as install runpaths on ELF platforms…

… in llvm_setup_rpath()

If any LLVM subprojects are built separately, the LLVM build directory
LLVM_LIBRARY_DIR is added to both the build and install runpaths in
llvm_setup_rpath(), which is incorrect when installed. Separate the
build and install runpaths on ELF platforms and finally remove the
incorrect call to this function for compiler-rt, as previously attempted
in 21c008d. That prior attempt was reverted in 959dbd1, where it
was said to break the build on macOS and Windows, so I made sure to keep
those platforms the same.

Two examples of incorrect runpaths that are currently added, one from
the latest LLVM 16 toolchain for linux x86_64:

  > readelf -d clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.*so | ag "File:|runpath"
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.asan.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.dyndd.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.hwasan_aliases.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.hwasan.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.memprof.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.scudo_standalone.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.tsan.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.ubsan_minimal.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]
  File: clang+llvm-16.0.0-x86_64-linux-gnu-ubuntu-18.04/lib/clang/16/lib/x86_64-unknown-linux-gnu/libclang_rt.ubsan_standalone.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/tmp/llvm_release/final/Phase3/Release/llvmCore-16.0.0-final.obj/./lib]

Another is in the Swift toolchain, which builds lldb separately:

  > readelf -d swift-5.9-DEVELOPMENT-SNAPSHOT-2023-03-24-a-ubuntu20.04/usr/{bin/lldb*,lib/liblldb.so}|ag "File:|runpath"
  File: swift-5.9-DEVELOPMENT-SNAPSHOT-2023-03-24-a-ubuntu20.04/usr/bin/lldb
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/home/build-user/build/buildbot_linux/llvm-linux-x86_64/./lib]
  File: swift-5.9-DEVELOPMENT-SNAPSHOT-2023-03-24-a-ubuntu20.04/usr/bin/lldb-argdumper
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/home/build-user/build/buildbot_linux/llvm-linux-x86_64/./lib]
  File: swift-5.9-DEVELOPMENT-SNAPSHOT-2023-03-24-a-ubuntu20.04/usr/bin/lldb-server
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/home/build-user/build/buildbot_linux/llvm-linux-x86_64/./lib]
  File: swift-5.9-DEVELOPMENT-SNAPSHOT-2023-03-24-a-ubuntu20.04/usr/lib/liblldb.so
  0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/../lib:/home/build-user/build/buildbot_linux/llvm-linux-x86_64/./lib:/home/build-user/build/buildbot_linux/swift-linux-x86_64/lib/swift/linux:$ORIGIN/../lib/swift/linux]

This patch should fix this problem of absolute paths from the build host
leaking out into the toolchain's runpaths.

Differential revision: https://reviews.llvm.org/D146918

compiler-rt/cmake/Modules/AddCompilerRT.cmake

@@ -392,8 +392,8 @@ function(add_compiler_rt_runtime name type)
       target_link_libraries(${libname} PRIVATE ${builtins_${libname}})
     endif()
     if(${type} STREQUAL "SHARED")
-      if(COMMAND llvm_setup_rpath)
-        llvm_setup_rpath(${libname})
+      if(APPLE OR WIN32)
+        set_property(TARGET ${libname} PROPERTY BUILD_WITH_INSTALL_RPATH ON)
       endif()
       if(WIN32 AND NOT CYGWIN AND NOT MINGW)
         set_target_properties(${libname} PROPERTIES IMPORT_PREFIX "")

llvm/cmake/modules/AddLLVM.cmake

@@ -2336,9 +2336,11 @@ function(llvm_setup_rpath name)
     # Since BUILD_SHARED_LIBS is only recommended for use by developers,
     # hardcode the rpath to build/install lib dir first in this mode.
     # FIXME: update this when there is better solution.
-    set(_install_rpath "${LLVM_LIBRARY_OUTPUT_INTDIR}" "${CMAKE_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
+    set(_build_rpath "${LLVM_LIBRARY_OUTPUT_INTDIR}" ${extra_libdir})
+    set(_install_rpath "${CMAKE_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}")
   elseif(UNIX)
-    set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
+    set(_build_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
+    set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}")
     if(${CMAKE_SYSTEM_NAME} MATCHES "(FreeBSD|DragonFly)")
       set_property(TARGET ${name} APPEND_STRING PROPERTY
                    LINK_FLAGS " -Wl,-z,origin ")
@@ -2352,9 +2354,14 @@ function(llvm_setup_rpath name)
     return()
   endif()
 
-  # Enable BUILD_WITH_INSTALL_RPATH unless CMAKE_BUILD_RPATH is set.
+  # Enable BUILD_WITH_INSTALL_RPATH unless CMAKE_BUILD_RPATH is set and not
+  # building for macOS or Windows, as those two platforms seemingly require it.
   if("${CMAKE_BUILD_RPATH}" STREQUAL "")
-    set_property(TARGET ${name} PROPERTY BUILD_WITH_INSTALL_RPATH ON)
+    if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin|Windows")
+      set_property(TARGET ${name} PROPERTY BUILD_WITH_INSTALL_RPATH ON)
+    else()
+      set_property(TARGET ${name} APPEND PROPERTY BUILD_RPATH "${_build_rpath}")
+    endif()
   endif()
 
   set_target_properties(${name} PROPERTIES