| Message ID | 1282028446-19874-1-git-send-email-andi@firstfloor.org |
|---|---|
| State | New |
| Headers | show |
On Tue, 17 Aug 2010, Andi Kleen wrote: > 2010-08-17 Andi Kleen <ak@linux.intel.com> > > * doc/install.texi (Building a native compiler): Remove > reference to broken BUILD_CONFIG=bootstrap-lto. > Document working method instead. > --- > gcc/doc/install.texi | 12 +++++++----- > 1 files changed, 7 insertions(+), 5 deletions(-) > > diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi > index fc9b988..c952edf 100644 > --- a/gcc/doc/install.texi > +++ b/gcc/doc/install.texi > @@ -2108,6 +2108,13 @@ to work around this, by choosing @code{BOOT_CFLAGS} to avoid the parts > of the stage1 compiler that were miscompiled, or by using @samp{make > bootstrap4} to increase the number of stages of bootstrap. > > +You can also use @code{BOOT_CFLAGS} to force a LTO bootstrap with > +@samp{BOOTCFLAGS='-O2 -fwhopr=jobserver -fuse-linker-plugin -frandom-seed=1'}. BOOT_CFLAGS or BOOTCFLAGS? And "an LTO". > +Configure the compiler with @samp{--enable-stage1-languages=c,lto}. This > +will only work with the @command{gold} linker and if linker plugins are > +corrected configured. The @option{-frandom-seed=1} is needed to avoid > +bootstrap comparison failures. This sounds a bit tricky for our general user installation instructions; any chance to have all this triggered by a configure option or a simple "make bootstrap-lto" or just document it in pure developer documentation? (More a question to Diego et al, I guess.) Oh wait, that's what's there, but broken, right? :-( Gerald
On Mon, Aug 30, 2010 at 1:51 AM, Gerald Pfeifer <gerald@pfeifer.com> wrote: > On Tue, 17 Aug 2010, Andi Kleen wrote: >> 2010-08-17 Andi Kleen <ak@linux.intel.com> >> >> * doc/install.texi (Building a native compiler): Remove >> reference to broken BUILD_CONFIG=bootstrap-lto. >> Document working method instead. >> --- >> gcc/doc/install.texi | 12 +++++++----- >> 1 files changed, 7 insertions(+), 5 deletions(-) >> >> diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi >> index fc9b988..c952edf 100644 >> --- a/gcc/doc/install.texi >> +++ b/gcc/doc/install.texi >> @@ -2108,6 +2108,13 @@ to work around this, by choosing @code{BOOT_CFLAGS} to avoid the parts >> of the stage1 compiler that were miscompiled, or by using @samp{make >> bootstrap4} to increase the number of stages of bootstrap. >> >> +You can also use @code{BOOT_CFLAGS} to force a LTO bootstrap with >> +@samp{BOOTCFLAGS='-O2 -fwhopr=jobserver -fuse-linker-plugin -frandom-seed=1'}. > > BOOT_CFLAGS or BOOTCFLAGS? > > And "an LTO". > >> +Configure the compiler with @samp{--enable-stage1-languages=c,lto}. This >> +will only work with the @command{gold} linker and if linker plugins are >> +corrected configured. The @option{-frandom-seed=1} is needed to avoid >> +bootstrap comparison failures. > > This sounds a bit tricky for our general user installation instructions; > any chance to have all this triggered by a configure option or a simple > "make bootstrap-lto" or just document it in pure developer documentation? > (More a question to Diego et al, I guess.) Oh wait, that's what's there, > but broken, right? :-( The -frandom-seed requirement is indeed very unfortunate. Andi - can't we use sth based on a hash instead that would be stable across bootstrap? Otherwise I'd like us to get rid of --enable-intermodule and its makefile bits and simply fix --with-build-config=bootstrap-lto. Richard. > > Gerald >
On 8/30/2010 8:59 AM, Richard Guenther wrote: > >> BOOT_CFLAGS or BOOTCFLAGS? >> >> And "an LTO". I'll fix the grammar. There was also another mistake noone noticed except me on re-reading :) >>> +Configure the compiler with @samp{--enable-stage1-languages=c,lto}. This >>> +will only work with the @command{gold} linker and if linker plugins are >>> +corrected configured. The @option{-frandom-seed=1} is needed to avoid >>> +bootstrap comparison failures. >> This sounds a bit tricky for our general user installation instructions; >> any chance to have all this triggered by a configure option or a simple >> "make bootstrap-lto" or just document it in pure developer documentation? >> (More a question to Diego et al, I guess.) Oh wait, that's what's there, >> but broken, right? :-( > The -frandom-seed requirement is indeed very unfortunate. Andi - can't we > use sth based on a hash instead that would be stable across bootstrap? In theory could use a hash over the global symbol names, but I'm a bit wary of collisions. For example if you have a set of machine generated files with very similar symbols names there might be problems. Also the random seed issue is only really a problem for bootstraps, but not for other uses of the compiler. > Otherwise I'd like us to get rid of --enable-intermodule and its makefile > bits and simply fix --with-build-config=bootstrap-lto. I'm not very good with Makefiles so I would prefer if someone else does that. -Andi
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi index fc9b988..c952edf 100644 --- a/gcc/doc/install.texi +++ b/gcc/doc/install.texi @@ -2108,6 +2108,13 @@ to work around this, by choosing @code{BOOT_CFLAGS} to avoid the parts of the stage1 compiler that were miscompiled, or by using @samp{make bootstrap4} to increase the number of stages of bootstrap. +You can also use @code{BOOT_CFLAGS} to force a LTO bootstrap with +@samp{BOOTCFLAGS='-O2 -fwhopr=jobserver -fuse-linker-plugin -frandom-seed=1'}. +Configure the compiler with @samp{--enable-stage1-languages=c,lto}. This +will only work with the @command{gold} linker and if linker plugins are +corrected configured. The @option{-frandom-seed=1} is needed to avoid +bootstrap comparison failures. + @code{BOOT_CFLAGS} does not apply to bootstrapped target libraries. Since these are always compiled with the compiler currently being bootstrapped, you can use @code{CFLAGS_FOR_TARGET} to modify their @@ -2155,11 +2162,6 @@ Removes any @option{-O}-started option from @code{BOOT_CFLAGS}, and adds @item @samp{bootstrap-O3} Analogous to @code{bootstrap-O1}. -@item @samp{bootstrap-lto} -Enables Link-Time Optimization for host tools during bootstrapping. -@samp{BUILD_CONFIG=bootstrap-lto} is equivalent to adding -@option{-flto} to @samp{BOOT_CFLAGS}. - @item @samp{bootstrap-debug} Verifies that the compiler generates the same executable code, whether or not it is asked to emit debug information. To this end, this
From: Andi Kleen <ak@linux.intel.com> BUILD_CONFIG=bootstrap-lto does not work currently and causes build failures. Remove a reference to that in the install documentation and instead document a working method using BOOT_CFLAGS. Bootstrapped on x86-64 together with the -fwhopr=jobserver patchkit Ok to commit? 2010-08-17 Andi Kleen <ak@linux.intel.com> * doc/install.texi (Building a native compiler): Remove reference to broken BUILD_CONFIG=bootstrap-lto. Document working method instead. --- gcc/doc/install.texi | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-)