[systemd-devel] [PATCH] build-sys: add configure option to disable LTO/gold

[Cristian Rodríguez]

LTO may be unreliable, does not work properly in several archs
It may crash or produce wrong code.

Compiler developers also said we should not provide production
RPM packages with LTO enabled.

GOLD also does not work everywhere.
---
 configure.ac | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index 9a2235b..38194ca 100644
--- a/configure.ac
+++ b/configure.ac
@@ -207,10 +207,15 @@ AS_CASE([$CC], [*clang*],
                -Wno-gnu-variable-sized-type-not-at-end \
         ])])
 
-AS_CASE([$CFLAGS], [*-O[[12345\ ]]*],
-        [CC_CHECK_FLAGS_APPEND([with_cflags], [CFLAGS], [\
-               -flto -ffat-lto-objects])],
-        [AC_MSG_RESULT([skipping -flto, optimization not enabled])])
+AC_ARG_ENABLE([lto], AS_HELP_STRING([--disable-lto], [Disable Link time optimization]))
+AS_IF([test "x$enable_lto" != "xno"], [
+AS_CASE([$CFLAGS], [*-O[[12345\ ]]*], [
+        CC_CHECK_FLAGS_APPEND([with_cflags], [CFLAGS], [-flto -ffat-lto-objects])
+        CC_CHECK_FLAGS_APPEND([with_ldflags], [LDFLAGS],[-Wl,-fuse-ld=gold])
+        ],
+[AC_MSG_RESULT([skipping -flto, optimization not enabled])])
+])
+
 AC_SUBST([OUR_CFLAGS], "$with_cflags $sanitizer_cflags")
 
 AS_CASE([$CFLAGS], [*-O[[12345\ ]]*],
@@ -226,7 +231,7 @@ CC_CHECK_FLAGS_APPEND([with_ldflags], [LDFLAGS], [\
         -Wl,-z,relro \
         -Wl,-z,now \
         -pie \
-        -Wl,-fuse-ld=gold])
+        ])
 AC_SUBST([OUR_LDFLAGS], "$with_ldflags $sanitizer_ldflags")
 
 AC_CHECK_SIZEOF(pid_t)
-- 
2.3.0