On 3/1/18 1:14 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Enable link time optimization (LTO) if the builder requests it. The
> extra link optimization results in smaller binaries.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
ok
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
> configure.ac | 12 ++++++++++++
> debian/rules | 4 ++--
> include/builddefs.in | 9 +++++++++
> m4/package_libcdev.m4 | 26 ++++++++++++++++++++++++++
> 4 files changed, 49 insertions(+), 2 deletions(-)
>
>
> diff --git a/configure.ac b/configure.ac
> index 3a0ab18..9cfc661 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -90,6 +90,11 @@ AC_ARG_ENABLE(threadsan,
> enable_threadsan=no)
> AC_SUBST(enable_threadsan)
>
> +AC_ARG_ENABLE(lto,
> +[ --enable-lto=[yes/no] Enable link time optimization (LTO) [default=probe]],,
> + enable_lto=probe)
> +AC_SUBST(enable_lto)
> +
> #
> # If the user specified a libdir ending in lib64 do not append another
> # 64 to the library names.
> @@ -206,6 +211,13 @@ if test "$have_threadsan" = "yes" && test "$have_addrsan" = "yes"; then
> AC_MSG_WARN([ADDRSAN and THREADSAN are not known to work together.])
> fi
>
> +if test "$enable_lto" = "yes" || test "$enable_lto" = "probe"; then
> + AC_PACKAGE_CHECK_LTO
> +fi
> +if test "$enable_lto" = "yes" && test "$have_lto" != "yes"; then
> + AC_MSG_ERROR([LTO not supported by compiler.])
> +fi
> +
> AC_CHECK_SIZEOF([long])
> AC_CHECK_SIZEOF([char *])
> AC_TYPE_UMODE_T
> diff --git a/debian/rules b/debian/rules
> index 4cba165..cb4fa22 100755
> --- a/debian/rules
> +++ b/debian/rules
> @@ -20,9 +20,9 @@ stdenv = @GZIP=-q; export GZIP;
>
> options = export DEBUG=-DNDEBUG DISTRIBUTION=debian \
> INSTALL_USER=root INSTALL_GROUP=root \
> - LOCAL_CONFIGURE_OPTIONS="--enable-readline=yes --enable-blkid=yes --disable-ubsan --disable-addrsan --disable-threadsan" ;
> + LOCAL_CONFIGURE_OPTIONS="--enable-readline=yes --enable-blkid=yes --disable-ubsan --disable-addrsan --disable-threadsan --enable-lto" ;
> diopts = $(options) \
> - export OPTIMIZER=-Os LOCAL_CONFIGURE_OPTIONS="--enable-gettext=no --disable-ubsan --disable-addrsan --disable-threadsan" ;
> + export OPTIMIZER=-Os LOCAL_CONFIGURE_OPTIONS="--enable-gettext=no --disable-ubsan --disable-addrsan --disable-threadsan --enable-lto" ;
> checkdir = test -f debian/rules
>
> build: build-arch build-indep
> diff --git a/include/builddefs.in b/include/builddefs.in
> index df76b2c..b0bf9f1 100644
> --- a/include/builddefs.in
> +++ b/include/builddefs.in
> @@ -176,6 +176,15 @@ endif
> SANITIZER_CFLAGS += @addrsan_cflags@ @threadsan_cflags@ @ubsan_cflags@
> SANITIZER_LDFLAGS += @addrsan_ldflags@ @threadsan_ldflags@ @ubsan_ldflags@
>
> +# Use special ar/ranlib wrappers if we have lto
> +HAVE_LTO = @have_lto@
> +ifeq ($(HAVE_LTO),yes)
> +OPTIMIZER += @lto_cflags@
> +LOADERFLAGS += @lto_ldflags@
> +AR = @gcc_ar@
> +RANLIB = @gcc_ranlib@
> +endif
> +
> GCFLAGS = $(DEBUG) \
> -DVERSION=\"$(PKG_VERSION)\" -DLOCALEDIR=\"$(PKG_LOCALE_DIR)\" \
> -DPACKAGE=\"$(PKG_NAME)\" -I$(TOPDIR)/include -I$(TOPDIR)/libxfs
> diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
> index 9258c27..52ddac2 100644
> --- a/m4/package_libcdev.m4
> +++ b/m4/package_libcdev.m4
> @@ -420,3 +420,29 @@ AC_DEFUN([AC_HAVE_HDIO_GETGEO],
> AC_MSG_RESULT(no))
> AC_SUBST(have_hdio_getgeo)
> ])
> +
> +AC_DEFUN([AC_PACKAGE_CHECK_LTO],
> + [ AC_MSG_CHECKING([if C compiler supports LTO])
> + OLD_CFLAGS="$CFLAGS"
> + OLD_LDFLAGS="$LDFLAGS"
> + LTO_FLAGS="-flto -ffat-lto-objects"
> + CFLAGS="$CFLAGS $LTO_FLAGS"
> + LDFLAGS="$LDFLAGS $LTO_FLAGS"
> + AC_LINK_IFELSE([AC_LANG_PROGRAM([])],
> + [AC_MSG_RESULT([yes])]
> + [lto_cflags=$LTO_FLAGS]
> + [lto_ldflags=$LTO_FLAGS]
> + [AC_PATH_PROG(gcc_ar, gcc-ar,,)]
> + [AC_PATH_PROG(gcc_ranlib, gcc-ranlib,,)],
> + [AC_MSG_RESULT([no])])
> + if test -x "$gcc_ar" && test -x "$gcc_ranlib"; then
> + have_lto=yes
> + fi
> + CFLAGS="${OLD_CFLAGS}"
> + LDFLAGS="${OLD_LDFLAGS}"
> + AC_SUBST(gcc_ar)
> + AC_SUBST(gcc_ranlib)
> + AC_SUBST(have_lto)
> + AC_SUBST(lto_cflags)
> + AC_SUBST(lto_ldflags)
> + ])
>
> --
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