Bug#34099162 Add support for mold linker

Add a cmake option -DWITH_LD=mold|lld.
The default is empty, i.e. use the standard linker.
The new option is only visible on Linux.

Remove the cmake option -DUSE_LD_LLD, use -DWITH_LD=lld instead.

Note that for el7/el8/el9 we use compilers from /opt/rh/devtoolset...
and must use the 'ld' linker that comes with that bundle.
Hence alternative linkers like 'lld' and 'mold' cannot be used,
and -DWITH_LD is not available as an option.

Fix a linker warning for 'mysql_ssl_rsa_setup' with lto:
mold: warning: symbol type mismatch: error
>>> defined in /tmp/ccbfnLqs.ltrans0.ltrans.o as STT_OBJECT
>>> defined in /lib64/libc.so.6 as STT_FUNC

Silence -Wno-alloc-size-larger-than warnings for
mysqld and server_unittest_library.
sql/rpl_info_values.cc:45:44: error: argument 1 value
 18446744073709551615
 exceeds maximum object size 9223372036854775807
 [-Werror=alloc-size-larger-than=]

Change-Id: I49bc677194624f944f345ef50b9004575776f736

Author: Tor Didriksen

CMakeLists.txt

@@ -1259,29 +1259,33 @@ IF (ENABLE_GPROF AND NOT WIN32 AND NOT APPLE)
   STRING_APPEND(CMAKE_EXE_LINKER_FLAGS " -pg")
 ENDIF()
 
-# Use lld on Linux if available and not explicitly disabled.
-# You need to install the 'lld' RPM/DEB package.
-# LTO build fails with lld, so turn it off by default.
-IF(LINUX AND NOT ALTERNATIVE_LD AND
-    NOT WITH_LTO AND NOT CMAKE_COMPILER_FLAG_WITH_LTO)
-  OPTION(USE_LD_LLD "Use llvm lld linker" ON)
-ELSE()
-  OPTION(USE_LD_LLD "Use llvm lld linker" OFF)
-ENDIF()
-
-# If ALTERNATIVE_LD is set, we must use it.
-IF(ALTERNATIVE_LD AND USE_LD_LLD)
-  MESSAGE(WARNING
-    "The compiler ${ALTERNATIVE_GPP} is not compatible with lld")
-  SET(USE_LD_LLD 0)
-  SET(USE_LD_LLD 0 CACHE INTERNAL "" FORCE)
-ENDIF()
-
-SET(USING_LD_LLD 0)
-IF(USE_LD_LLD)
-  CHECK_ALTERNATIVE_LINKER("lld" USING_LD_LLD)
+# If LINUX, and not any special build (profiling, devtoolset) then provide
+# -DWITH_LD=mold|lld
+# We restrict the list of known linkers to the ones we have actually tested.
+# LTO builds have failed earlier with "lld", so use this feature with care.
+IF(LINUX AND NOT ALTERNATIVE_LD AND NOT FPROFILE_GENERATE AND NOT FPROFILE_USE)
+  UNSET(USING_LD_LLD)
+  UNSET(USING_LD_LLD CACHE)
+  UNSET(USING_LD_MOLD)
+  UNSET(USING_LD_MOLD CACHE)
+  SET(KNOWN_LINKERS "mold" "lld")
+  IF(WITH_LD)
+    LIST(FIND KNOWN_LINKERS ${WITH_LD} FOUND_LINKER_INDEX)
+    IF(FOUND_LINKER_INDEX EQUAL -1)
+      MESSAGE(FATAL_ERROR "Unknown linker -fuse-ld=${WITH_LD}")
+    ENDIF()
+    UNSET(ALTERNATIVE_LINKER_RESULT)
+    CHECK_ALTERNATIVE_LINKER(${WITH_LD} ALTERNATIVE_LINKER_RESULT)
+    IF(ALTERNATIVE_LINKER_RESULT)
+      STRING(TOUPPER "${WITH_LD}" WITH_LD_UPPER)
+      # See ADD_GDB_INDEX below:
+      SET(USING_LD_${WITH_LD_UPPER} ON)
+      SET(USING_LD_${WITH_LD_UPPER} ON CACHE INTERNAL "")
+    ELSE()
+      MESSAGE(FATAL_ERROR "failed to link using: -fuse-ld=${WITH_LD}")
+    ENDIF()
+  ENDIF()
 ENDIF()
-SET(USING_LD_LLD ${USING_LD_LLD} CACHE INTERNAL "")
 
 IF(LINUX_STANDALONE)
   # ON by default in pushbuild, but only for standalone builds.
@@ -1432,16 +1436,22 @@ IF(LINK_RANDOMIZE)
   SET(CMAKE_C_ARCHIVE_CREATE_APPEND ${CMAKE_CXX_ARCHIVE_CREATE_APPEND})
 ENDIF()
 
-# Gold and LLD support the --gdb-index option, which adds a .gdb_index
+# Mold and LLD support the --gdb-index option, which adds a .gdb_index
 # section to the binaries. It makes loading the binaries in gdb much
-# faster. The overhead of generating the index is small in LLD.
+# faster. The overhead of generating the index is small in.
 OPTION(ADD_GDB_INDEX "Generate a .gdb_index section in the binaries." OFF)
 
-IF(ADD_GDB_INDEX AND CMAKE_EXE_LINKER_FLAGS MATCHES "-fuse-ld=lld")
+IF(ADD_GDB_INDEX AND (USING_LD_MOLD OR USING_LD_LLD))
   # -fuse-ld=lld is not enough to ensure that ld.lld will actually be used.
   # On some platforms we need an extra check for -Wl,--gdb-index
+  IF(USING_LD_LLD)
+    SET(FUSE_LD "-fuse-ld=lld")
+  ELSE()
+    SET(FUSE_LD "-fuse-ld=mold")
+  ENDIF()
+
   CMAKE_PUSH_CHECK_STATE()
-  SET(CMAKE_REQUIRED_LIBRARIES "-fuse-ld=lld -Wl,--gdb-index")
+  SET(CMAKE_REQUIRED_LIBRARIES "${FUSE_LD} -Wl,--gdb-index")
   CHECK_CXX_SOURCE_COMPILES("int main() {}" CXX_LD_GDB_INDEX_RESULT)
   CMAKE_POP_CHECK_STATE()
 
@@ -2327,6 +2337,12 @@ IF(NOT WITHOUT_SERVER AND WITH_UNIT_TESTS)
       IF(HAS_WARN_FLAG)
         MY_TARGET_LINK_OPTIONS(server_unittest_library "${HAS_WARN_FLAG}")
       ENDIF()
+      # The mold linker and RelWithDebInfo build complains about
+      # the new expression in Rpl_info_values::init()
+      IF(MY_COMPILER_IS_GNU)
+        MY_TARGET_LINK_OPTIONS(server_unittest_library
+          "-Wno-alloc-size-larger-than")
+      ENDIF()
     ENDIF()
   ELSE()
     SET(DUMMY_SOURCE_FILE ${CMAKE_BINARY_DIR}/server_unittest_library.c)

client/mysql_ssl_rsa_setup.cc

@@ -111,8 +111,10 @@ Sql_string_t ext_files[] = {create_string("cav3.ext"),
 */
 #define MAX_SUFFIX_LEN 17
 
+namespace {
 Log info(cout, "NOTE");
 Log error(cerr, "ERROR");
+}  // namespace
 
 char **defaults_argv = nullptr;
 static char *opt_datadir = nullptr;

cmake/compile_flags.cmake

@@ -138,12 +138,31 @@ ENDFUNCTION(ADD_LINUX_DEB_FLAGS)
 # If compilation/linking succeeds, we extend misc cmake LINKER_FLAGS,
 # and set OUTPUT_RESULT to 1.
 FUNCTION(CHECK_ALTERNATIVE_LINKER LINKER OUTPUT_RESULT)
+  SET(ACCEPTED_VERSION 1)
   CMAKE_PUSH_CHECK_STATE(RESET)
 
   SET(CMAKE_REQUIRED_LIBRARIES "-fuse-ld=${LINKER}")
   CHECK_C_SOURCE_COMPILES("int main() {}" C_LD_${LINKER}_RESULT)
   CHECK_CXX_SOURCE_COMPILES("int main() {}" CXX_LD_${LINKER}_RESULT)
   IF(C_LD_${LINKER}_RESULT AND CXX_LD_${LINKER}_RESULT)
+    IF(${LINKER} STREQUAL "mold")
+      FIND_PROGRAM(MOLD_EXECUTABLE "mold")
+      IF(MOLD_EXECUTABLE)
+        EXECUTE_PROCESS(COMMAND ${MOLD_EXECUTABLE} --version
+          OUTPUT_VARIABLE MOLD_OUTPUT
+          RESULT_VARIABLE MOLD_RESULT
+          OUTPUT_STRIP_TRAILING_WHITESPACE
+          )
+        STRING(REGEX MATCH "^mold ([.0-9]+)" VERSION "${MOLD_OUTPUT}")
+        IF(NOT CMAKE_MATCH_1 OR CMAKE_MATCH_1 VERSION_LESS "2.0.0")
+          MESSAGE(STATUS
+            "This version of mold has an incompatible version: ${MOLD_OUTPUT}")
+          SET(ACCEPTED_VERSION 0)
+        ENDIF()
+      ENDIF()
+    ENDIF()
+  ENDIF()
+  IF(ACCEPTED_VERSION AND C_LD_${LINKER}_RESULT AND CXX_LD_${LINKER}_RESULT)
     FOREACH(flag
         CMAKE_EXE_LINKER_FLAGS
         CMAKE_MODULE_LINKER_FLAGS

cmake/fprofile.cmake

@@ -113,8 +113,6 @@ ENDIF()
 
 IF(FPROFILE_GENERATE OR FPROFILE_USE)
   SET(REPRODUCIBLE_BUILD ON CACHE INTERNAL "")
-  # Build fails with lld, so switch it off.
-  SET(USE_LD_LLD OFF CACHE INTERNAL "")
 ENDIF()
 
 IF(FPROFILE_USE)

packaging/deb-in/deb_debug.cmake

@@ -38,7 +38,6 @@ SET (DEB_RULES_DEBUG_CMAKE
 		-DCOMPILATION_COMMENT_SERVER=\"MySQL ${DEB_PRODUCTNAMEC} Server - ${DEB_LICENSENAME} - Debug\" \\
 		-DINSTALL_LAYOUT=DEB \\
 		-DREPRODUCIBLE_BUILD=OFF \\
-		-DUSE_LD_LLD=OFF \\
 		-DDEB_PRODUCT=${DEB_PRODUCT} \\
 		${DEB_CMAKE_EXTRAS}
 ")

packaging/deb-in/rules.in

@@ -53,7 +53,6 @@ override_dh_auto_configure:
 		-DCOMPILATION_COMMENT_SERVER="MySQL @DEB_PRODUCTNAMEC@ Server - @DEB_LICENSENAME@" \
 		-DINSTALL_LAYOUT=DEB \
 		-DREPRODUCIBLE_BUILD=OFF \
-		-DUSE_LD_LLD=OFF \
 		-DDEB_PRODUCT=@DEB_PRODUCT@ \
 		@DEB_CMAKE_EXTRAS@
 

packaging/rpm-docker/mysql.spec.in

@@ -196,7 +196,6 @@ mkdir release
 	   -DWITH_BOOST=.. \
            -DCMAKE_C_FLAGS="%{optflags}" \
            -DCMAKE_CXX_FLAGS="%{optflags}" \
-           -DUSE_LD_LLD=0 \
            -DWITH_INNODB_MEMCACHED=1 \
            -DINSTALL_MYSQLTESTDIR="" \
            -DMYSQL_UNIX_ADDR="%{mysqldatadir}/mysql.sock" \

packaging/rpm-fedora/mysql.spec.in

@@ -521,7 +521,6 @@ mkdir debug
            -DWITH_MECAB=system \
            -DCMAKE_C_FLAGS="$optflags" \
            -DCMAKE_CXX_FLAGS="$optflags" \
-           -DUSE_LD_LLD=0 \
            -DWITH_SYSTEMD=1 \
            -DWITH_MEB=%{with_meb} \
            -DWITH_ROUTER=%{with_router} \
@@ -560,7 +559,6 @@ mkdir release
            -DWITH_MECAB=system \
            -DCMAKE_C_FLAGS="%{optflags}" \
            -DCMAKE_CXX_FLAGS="%{optflags}" \
-           -DUSE_LD_LLD=0 \
            -DWITH_SYSTEMD=1 \
            -DWITH_MEB=%{with_meb} \
            -DWITH_ROUTER=%{with_router} \

packaging/rpm-oel/mysql.spec.in

@@ -871,7 +871,6 @@ mkdir debug
            -DWITH_BOOST=.. \
            -DCMAKE_C_FLAGS="$optflags" \
            -DCMAKE_CXX_FLAGS="$optflags" \
-           -DUSE_LD_LLD=0 \
 %if 0%{?ssl_default}
            -DWITH_AUTHENTICATION_CLIENT_PLUGINS=1 \
 %else
@@ -928,7 +927,6 @@ mkdir release
 	   -DWITH_BOOST=.. \
            -DCMAKE_C_FLAGS="%{optflags}" \
            -DCMAKE_CXX_FLAGS="%{optflags}" \
-           -DUSE_LD_LLD=0 \
 %if 0%{?ssl_default}
            -DWITH_AUTHENTICATION_CLIENT_PLUGINS=1 \
 %else

packaging/rpm-sles/mysql.spec.in

@@ -612,7 +612,6 @@ mkdir debug
            -DWITH_BOOST=.. \
            -DCMAKE_C_FLAGS="$optflags" \
            -DCMAKE_CXX_FLAGS="$optflags" \
-           -DUSE_LD_LLD=0 \
            -DWITH_SYSTEMD=1 \
            -DSYSTEMD_SERVICE_NAME="mysql" \
            -DSYSTEMD_PID_DIR="/run/mysql" \
@@ -656,7 +655,6 @@ mkdir release
            -DWITH_BOOST=.. \
            -DCMAKE_C_FLAGS="%{optflags}" \
            -DCMAKE_CXX_FLAGS="%{optflags}" \
-           -DUSE_LD_LLD=0 \
            -DWITH_SYSTEMD=1 \
            -DSYSTEMD_SERVICE_NAME="mysql" \
            -DSYSTEMD_PID_DIR="/run/mysql" \

sql/CMakeLists.txt

@@ -26,7 +26,7 @@ ADD_WSHADOW_WARNING()
 
 # Lots of warnings about -Walloc-size-larger-than= from my_malloc.cc
 # but it is basically impossible to trace the actual origin.
-IF(FPROFILE_GENERATE OR FPROFILE_USE)
+IF(FPROFILE_GENERATE OR FPROFILE_USE OR CMAKE_COMPILER_FLAG_WITH_LTO)
   IF(MY_COMPILER_IS_GNU)
     # -Walloc-size-larger-than=PTRDIFF_MAX is enabled by default.
     STRING_APPEND(CMAKE_EXE_LINKER_FLAGS " -Wno-alloc-size-larger-than")