| Message ID | 20230323134628.88073-1-jdek@itanimul.li |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel] configure: add LTO optarg | expand |
| Context | Check | Description |
|---|---|---|
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
On Thu, 23 Mar 2023, J. Dekker wrote: > This allows users to call with './configure --enable-lto' (or more > explicitly './configure --enable-lto=full') for the old functionality or > specify './configure --enable-lto=thin' to use ThinLTO. > > Signed-off-by: J. Dekker <jdek@itanimul.li> > --- > configure | 23 ++++++++++++++--------- > 1 file changed, 14 insertions(+), 9 deletions(-) > > diff --git a/configure b/configure > index 8980cec7ee..b65001d39d 100755 > --- a/configure > +++ b/configure > @@ -412,7 +412,7 @@ Toolchain options: > --build-suffix=SUFFIX library name suffix [] > --enable-pic build position-independent code > --enable-thumb compile for Thumb instruction set > - --enable-lto use link-time optimization > + --enable-lto[=arg] use link-time optimization > --env="ENV=override" override the environment variables > > Advanced options (experts only): > @@ -2524,7 +2524,6 @@ CMDLINE_SELECT=" > debug > extra_warnings > logging > - lto > optimizations > rpath > stripping > @@ -4170,6 +4169,12 @@ for opt do > --enable-sdl) > enable sdl2 > ;; > + --enable-lto) > + lto=full > + ;; > + --enable-lto=*) > + lto="$optval" > + ;; > --enable-*=*|--disable-*=*) > eval $(echo "${opt%%=*}" | sed 's/--/action=/;s/-/ thing=/') > is_in "${thing}s" $COMPONENT_LIST || die_unknown "$opt" > @@ -4639,7 +4644,7 @@ icl_flags(){ > # on Windows, does enable remarks so disable them here. > -Wall) echo $flag -Qdiag-disable:remark ;; > -std=c99) echo -Qstd=c99 ;; > - -flto) echo -ipo ;; > + -flto*) echo -ipo ;; > esac > done > } > @@ -4647,7 +4652,7 @@ icl_flags(){ > icc_flags(){ > for flag; do > case $flag in > - -flto) echo -ipo ;; > + -flto*) echo -ipo ;; > *) echo $flag ;; > esac > done > @@ -7182,17 +7187,17 @@ fi > > check_optflags(){ > check_cflags "$@" > - enabled lto && check_ldflags "$@" > + [ -z "$lto" ] || check_ldflags "$@" With [ -n "$lto" ] you could retain the old logic with && instead of ||, although I don't think it matters much. Also, this extra check when LTO is enabled, mirrors kinda what we've seen that we could need in meson, if LTO would be enabled surprisingly there. > } > > check_optflags $optflags > check_optflags -fno-math-errno > check_optflags -fno-signed-zeros > > -if enabled lto; then > +if [ ! -z "$lto" ]; then This can be [ -n "$lto" ] to avoid the negation. > test "$cc_type" != "$ld_type" && die "LTO requires same compiler and linker" > - check_cflags -flto > - check_ldflags -flto $cpuflags > + check_cflags -flto=$lto > + check_ldflags -flto=$lto $cpuflags Does GCC support -flto=full too, and is that the same thing as just -flto? Or should we stick to just passing -flto to the compiler without any argument if the user configured with plain --enable-lto? > disable inline_asm_direct_symbol_refs > fi > > @@ -7223,7 +7228,7 @@ if enabled icc; then > # icc 11.0 and 11.1 work with ebp_available, but don't pass the test > enable ebp_available > # The test above does not test linking > - enabled lto && disable symver_asm_label > + [ -z "$lto" ] || disable symver_asm_label [ -n "$lto" ] would retain the previous code structure, making the patch even clearer. // Martin
On 23 Mar 2023, at 14:56, Martin Storsjö wrote: [...] >> >> @@ -4647,7 +4652,7 @@ icl_flags(){ >> icc_flags(){ >> for flag; do >> case $flag in >> - -flto) echo -ipo ;; >> + -flto*) echo -ipo ;; >> *) echo $flag ;; >> esac >> done >> @@ -7182,17 +7187,17 @@ fi >> >> check_optflags(){ >> check_cflags "$@" >> - enabled lto && check_ldflags "$@" >> + [ -z "$lto" ] || check_ldflags "$@" > > With [ -n "$lto" ] you could retain the old logic with && instead of ||, although I don't think it matters much. > > Also, this extra check when LTO is enabled, mirrors kinda what we've seen that we could need in meson, if LTO would be enabled surprisingly there. Since not all checks are working with only cflags checks. >> } >> >> check_optflags $optflags >> check_optflags -fno-math-errno >> check_optflags -fno-signed-zeros >> >> -if enabled lto; then >> +if [ ! -z "$lto" ]; then > > This can be [ -n "$lto" ] to avoid the negation. Thanks. >> test "$cc_type" != "$ld_type" && die "LTO requires same compiler and linker" >> - check_cflags -flto >> - check_ldflags -flto $cpuflags >> + check_cflags -flto=$lto >> + check_ldflags -flto=$lto $cpuflags > > Does GCC support -flto=full too, and is that the same thing as just -flto? Or should we stick to just passing -flto to the compiler without any argument if the user configured with plain --enable-lto? No, actually checking it. We might benefit from gcc's -ffat-lto-objects and/or -fwhole-program which is maybe more similar to LLVM's -flto=full. Seems like there is non-trivial mapping between LTO features. >> disable inline_asm_direct_symbol_refs >> fi >> >> @@ -7223,7 +7228,7 @@ if enabled icc; then >> # icc 11.0 and 11.1 work with ebp_available, but don't pass the test >> enable ebp_available >> # The test above does not test linking >> - enabled lto && disable symver_asm_label >> + [ -z "$lto" ] || disable symver_asm_label > > [ -n "$lto" ] would retain the previous code structure, making the patch even clearer. > Will do.
On Thu Mar 23, 2023 at 3:16 PM CET, J. Dekker wrote: > On 23 Mar 2023, at 14:56, Martin Storsjö wrote: > >> test "$cc_type" != "$ld_type" && die "LTO requires same compiler and linker" > >> - check_cflags -flto > >> - check_ldflags -flto $cpuflags > >> + check_cflags -flto=$lto > >> + check_ldflags -flto=$lto $cpuflags > > > > Does GCC support -flto=full too, and is that the same thing as just -flto? Or should we stick to just passing -flto to the compiler without any argument if the user configured with plain --enable-lto? > > No, actually checking it. We might benefit from gcc's -ffat-lto-objects and/or -fwhole-program which is maybe more similar to LLVM's -flto=full. Seems like there is non-trivial mapping between LTO features. -ffat-lto-objects is only about keeping non-lto object code as well as the intermediate (lto) code in the .o objects. this is 'required' if one wants to then later link the resulting .a's *without* using lto, as having only the 'intermediate' output forces using lto during the link step. by default for gcc, the only difference between -flto and -flto=[n]/auto is the amount of threads used during linking. =auto is generally preferred, since under the gnu make jobserver it controls the jobs instead (or defaults to nproc). the existing `-flto` forces 1-thread link under gcc, and it prints a warning for this: lto-wrapper: warning: using serial compilation of 12 LTRANS jobs lto-wrapper: note: see the '-flto' option documentation for more information (the gcc(1) manpage documents this quite well.) however, i'd say the existing behaviour here is fine. there are indeed a lot of toolchain-specifics between all this- and people building that care about this would usually know better than a 'magic' configure script that tries to learn all of it. simply respecting -flto[=arg] with a user-supplied arg is all that is generally needed. as for -fwhole-program, i'm not sure it has any use: With -flto this option has a limited use. In most cases the precise list of symbols used or exported from the binary is known the resolution info passed to the link-time optimizer by the linker plugin. It is still useful if no linker plugin is used or during incremental link step when final code is produced (with -flto -flinker-output=nolto-rel). (by default, the linker plugin is automatically used for modern-ish gcc (since maybe 4.9?))
diff --git a/configure b/configure index 8980cec7ee..b65001d39d 100755 --- a/configure +++ b/configure @@ -412,7 +412,7 @@ Toolchain options: --build-suffix=SUFFIX library name suffix [] --enable-pic build position-independent code --enable-thumb compile for Thumb instruction set - --enable-lto use link-time optimization + --enable-lto[=arg] use link-time optimization --env="ENV=override" override the environment variables Advanced options (experts only): @@ -2524,7 +2524,6 @@ CMDLINE_SELECT=" debug extra_warnings logging - lto optimizations rpath stripping @@ -4170,6 +4169,12 @@ for opt do --enable-sdl) enable sdl2 ;; + --enable-lto) + lto=full + ;; + --enable-lto=*) + lto="$optval" + ;; --enable-*=*|--disable-*=*) eval $(echo "${opt%%=*}" | sed 's/--/action=/;s/-/ thing=/') is_in "${thing}s" $COMPONENT_LIST || die_unknown "$opt" @@ -4639,7 +4644,7 @@ icl_flags(){ # on Windows, does enable remarks so disable them here. -Wall) echo $flag -Qdiag-disable:remark ;; -std=c99) echo -Qstd=c99 ;; - -flto) echo -ipo ;; + -flto*) echo -ipo ;; esac done } @@ -4647,7 +4652,7 @@ icl_flags(){ icc_flags(){ for flag; do case $flag in - -flto) echo -ipo ;; + -flto*) echo -ipo ;; *) echo $flag ;; esac done @@ -7182,17 +7187,17 @@ fi check_optflags(){ check_cflags "$@" - enabled lto && check_ldflags "$@" + [ -z "$lto" ] || check_ldflags "$@" } check_optflags $optflags check_optflags -fno-math-errno check_optflags -fno-signed-zeros -if enabled lto; then +if [ ! -z "$lto" ]; then test "$cc_type" != "$ld_type" && die "LTO requires same compiler and linker" - check_cflags -flto - check_ldflags -flto $cpuflags + check_cflags -flto=$lto + check_ldflags -flto=$lto $cpuflags disable inline_asm_direct_symbol_refs fi @@ -7223,7 +7228,7 @@ if enabled icc; then # icc 11.0 and 11.1 work with ebp_available, but don't pass the test enable ebp_available # The test above does not test linking - enabled lto && disable symver_asm_label + [ -z "$lto" ] || disable symver_asm_label if enabled x86_32; then icc_version=$($cc -dumpversion) test ${icc_version%%.*} -ge 11 &&
This allows users to call with './configure --enable-lto' (or more explicitly './configure --enable-lto=full') for the old functionality or specify './configure --enable-lto=thin' to use ThinLTO. Signed-off-by: J. Dekker <jdek@itanimul.li> --- configure | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-)