build: remove --enable-lto

This has outlived its usefulness, doesn't gel well with
newer compilers & `-flto` related options, i.e thin vs full, or `=auto`,
and having `-flto` as the only option means that sometimes this just
needs to be worked around, i.e in oss-fuzz:
https://github.com/google/oss-fuzz/blob/master/projects/bitcoin-core/build.sh.

While it was convenient when `-flto` was newer, support for `-flto` is now
in all compilers we use, and there's also no-longer any real need
for us to treat `-flto` different to any other optimization option.

Remove it, to remove build complexity, and so there's no need
to port a similar option to CMake.

Note that the LTO option remains in depends, because we still a way to
build packages that have LTO specific patches/options.

If we decide to merge this, I'll follow up downstream in oss-fuzz first,
to make sure we don't break the build.
This commit is contained in:
fanquake
2023-12-06 12:26:02 +00:00
parent c80f57ba57
commit 2d1b1c7dae
11 changed files with 5 additions and 57 deletions

View File

@@ -321,11 +321,6 @@ AC_ARG_ENABLE([external-signer],
[use_external_signer=$enableval],
[use_external_signer=auto])
AC_ARG_ENABLE([lto],
[AS_HELP_STRING([--enable-lto],[build using LTO (default is no)])],
[enable_lto=$enableval],
[enable_lto=no])
AC_LANG_PUSH([C++])
dnl Check for a flag to turn compiler warnings into errors. This is helpful for checks which may
@@ -377,11 +372,6 @@ if test "$enable_debug" = "yes"; then
AX_CHECK_COMPILE_FLAG([-ftrapv], [DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -ftrapv"], [], [$CXXFLAG_WERROR])
fi
if test "$enable_lto" = "yes"; then
AX_CHECK_COMPILE_FLAG([-flto], [LTO_CXXFLAGS="$LTO_CXXFLAGS -flto"], [AC_MSG_ERROR([compile failed with -flto])], [$CXXFLAG_WERROR])
AX_CHECK_LINK_FLAG([-flto], [LTO_LDFLAGS="$LTO_LDFLAGS -flto"], [AC_MSG_ERROR([link failed with -flto])], [$CXXFLAG_WERROR])
fi
if test "$use_sanitizers" != ""; then
dnl First check if the compiler accepts flags. If an incompatible pair like
dnl -fsanitize=address,thread is used here, this check will fail. This will also
@@ -1893,8 +1883,6 @@ AC_SUBST(GPROF_LDFLAGS)
AC_SUBST(HARDENED_CXXFLAGS)
AC_SUBST(HARDENED_CPPFLAGS)
AC_SUBST(HARDENED_LDFLAGS)
AC_SUBST(LTO_CXXFLAGS)
AC_SUBST(LTO_LDFLAGS)
AC_SUBST(PIC_FLAGS)
AC_SUBST(PIE_FLAGS)
AC_SUBST(SANITIZER_CXXFLAGS)
@@ -2002,7 +1990,6 @@ echo " sanitizers = $use_sanitizers"
echo " debug enabled = $enable_debug"
echo " gprof enabled = $enable_gprof"
echo " werror = $enable_werror"
echo " LTO = $enable_lto"
echo
echo " target os = $host_os"
echo " build os = $build_os"
@@ -2011,8 +1998,8 @@ echo " CC = $CC"
echo " CFLAGS = $PTHREAD_CFLAGS $CFLAGS"
echo " CPPFLAGS = $DEBUG_CPPFLAGS $HARDENED_CPPFLAGS $CORE_CPPFLAGS $CPPFLAGS"
echo " CXX = $CXX"
echo " CXXFLAGS = $LTO_CXXFLAGS $DEBUG_CXXFLAGS $HARDENED_CXXFLAGS $WARN_CXXFLAGS $NOWARN_CXXFLAGS $ERROR_CXXFLAGS $GPROF_CXXFLAGS $CORE_CXXFLAGS $CXXFLAGS"
echo " LDFLAGS = $LTO_LDFLAGS $PTHREAD_LIBS $HARDENED_LDFLAGS $GPROF_LDFLAGS $CORE_LDFLAGS $LDFLAGS"
echo " CXXFLAGS = $DEBUG_CXXFLAGS $HARDENED_CXXFLAGS $WARN_CXXFLAGS $NOWARN_CXXFLAGS $ERROR_CXXFLAGS $GPROF_CXXFLAGS $CORE_CXXFLAGS $CXXFLAGS"
echo " LDFLAGS = $PTHREAD_LIBS $HARDENED_LDFLAGS $GPROF_LDFLAGS $CORE_LDFLAGS $LDFLAGS"
echo " AR = $AR"
echo " ARFLAGS = $ARFLAGS"
echo