[RFC] Change PCH "checksum"
GCC builds are currently not reproducible because for one the checksum we compute for PCH purposes (by genchecksum) nowaways includes checksums of archives (since we switched from checksumming a dummy executable to checksumming object files). That includes dates (unless built with -D which we don't do). Then later we switched to do thin archives so for example libbackend.a we checksum doesn't contain the actual code anymore... A pragmatic approach to "fix" things would be to just checksum gtype-desc.o which should have enough state to cover PCH dependences if I understand the workings correctly (patch below - a single checksum would suffice so more simplifications are possible). Another solution working on ELF systems with build-id support is simply forgo checksumming anything and rely on the executable build-id instead (pat^whack below as well). Does anybody think that just checksumming gtype-desc.o is a degradation over the current state (which checksums thin archives)? Thanks, Richard. 2019-02-22 Richard Biener c/ * Make-lang.in (cc1-checksum.c): Checksum only gtype-desc.o. cp/ * Make-lang.in (cc1plus-checksum.c): Checksum only gtype-desc.o. objc/ * Make-lang.in (cc1obj-checksum.c): Checksum only gtype-desc.o. objcp/ * Make-lang.in (cc1objplus-checksum.c): Checksum only gtype-desc.o. Index: gcc/c/Make-lang.in === --- gcc/c/Make-lang.in (revision 269111) +++ gcc/c/Make-lang.in (working copy) @@ -70,14 +70,13 @@ endif # compute checksum over all object files and the options # re-use the checksum from the prev-final stage so it passes # the bootstrap comparison and allows comparing of the cc1 binary -cc1-checksum.c : build/genchecksum$(build_exeext) checksum-options \ - $(C_OBJS) $(BACKEND) $(LIBDEPS) +cc1-checksum.c : build/genchecksum$(build_exeext) gtype-desc.o if [ -f ../stage_final ] \ && cmp -s ../stage_current ../stage_final; then \ cp ../prev-gcc/cc1-checksum.c cc1-checksum.c; \ else \ - build/genchecksum$(build_exeext) $(C_OBJS) $(BACKEND) $(LIBDEPS) \ - checksum-options > cc1-checksum.c.tmp && \ + build/genchecksum$(build_exeext) gtype-desc.o \ + > cc1-checksum.c.tmp &&\ $(srcdir)/../move-if-change cc1-checksum.c.tmp cc1-checksum.c; \ fi Index: gcc/cp/Make-lang.in === --- gcc/cp/Make-lang.in (revision 269111) +++ gcc/cp/Make-lang.in (working copy) @@ -105,14 +105,13 @@ cp-warn = $(STRICT_WARN) # compute checksum over all object files and the options # re-use the checksum from the prev-final stage so it passes # the bootstrap comparison and allows comparing of the cc1 binary -cc1plus-checksum.c : build/genchecksum$(build_exeext) checksum-options \ - $(CXX_OBJS) $(BACKEND) $(LIBDEPS) +cc1plus-checksum.c : build/genchecksum$(build_exeext) gtype-desc.o if [ -f ../stage_final ] \ && cmp -s ../stage_current ../stage_final; then \ cp ../prev-gcc/cc1plus-checksum.c cc1plus-checksum.c; \ else \ - build/genchecksum$(build_exeext) $(CXX_OBJS) $(BACKEND) $(LIBDEPS) \ - checksum-options > cc1plus-checksum.c.tmp && \ + build/genchecksum$(build_exeext) gtype-desc.o \ + > cc1plus-checksum.c.tmp && \ $(srcdir)/../move-if-change cc1plus-checksum.c.tmp cc1plus-checksum.c; \ fi Index: gcc/objc/Make-lang.in === --- gcc/objc/Make-lang.in (revision 269111) +++ gcc/objc/Make-lang.in (working copy) @@ -56,10 +56,9 @@ OBJC_OBJS = objc/objc-lang.o objc/objc-a objc_OBJS = $(OBJC_OBJS) cc1obj-checksum.o -cc1obj-checksum.c : build/genchecksum$(build_exeext) checksum-options \ -$(OBJC_OBJS) $(C_AND_OBJC_OBJS) $(BACKEND) $(LIBDEPS) - build/genchecksum$(build_exeext) $(OBJC_OBJS) $(C_AND_OBJC_OBJS) \ -$(BACKEND) $(LIBDEPS) checksum-options > cc1obj-checksum.c.tmp && \ +cc1obj-checksum.c : build/genchecksum$(build_exeext) gtype-desc.o + build/genchecksum$(build_exeext) gtype-desc.o + > cc1obj-checksum.c.tmp && \ $(srcdir)/../move-if-change cc1obj-checksum.c.tmp cc1obj-checksum.c cc1obj$(exeext): $(OBJC_OBJS) $(C_AND_OBJC_OBJS) cc1obj-checksum.o $(BACKEND) $(LIBDEPS) Index: gcc/objcp/Make-lang.in === --- gcc/objcp/Make-lang.in (revision 269111) +++ gcc/objcp/Make-lang.in (working copy) @@ -59,10 +59,9 @@ OBJCXX_OBJS = objcp/objcp-act.o objcp/ob obj-c++_OBJS = $(OBJCXX_OBJS) cc1objplus-checksum.o -cc1objplus-checksum.c : build/genchecksum$(build_exeext) checksum-options \ - $(OBJCXX_OBJS) $(BACKEND) $(LIBDEPS) - build/g
GCC 8.3 Released
The GNU Compiler Collection version 8.3 has been released. GCC 8.3 is a bug-fix release from the GCC 8 branch containing important fixes for regressions and serious bugs in GCC 8.2 with more than 153 bugs fixed since the previous release. This release is available from the FTP servers listed at: http://www.gnu.org/order/ftp.html Please do not contact me directly regarding questions or comments about this release. Instead, use the resources available from http://gcc.gnu.org. As always, a vast number of people contributed to this GCC release -- far too many to thank them individually!
GCC 8.4 Status Report (2019-02-22)
Status == GCC 8.3 has been released and the branch is again open for regression and documentation fixes. History makes us expect a GCC 8.4 release at the end of this year. Quality Data Priority # Change from last report --- --- P10 P2 209 + 16 P3 34 + 5 P4 162 - 1 P5 24 --- --- Total P1-P3 243 + 21 Total 429 + 20 Previous Report === https://gcc.gnu.org/ml/gcc/2019-02/msg00078.html
Re: [RFC] Change PCH "checksum"
On 2/22/19 4:29 AM, Richard Biener wrote: > > GCC builds are currently not reproducible because for one the checksum > we compute for PCH purposes (by genchecksum) nowaways includes checksums > of archives (since we switched from checksumming a dummy executable > to checksumming object files). That includes dates (unless built with > -D which we don't do). > > Then later we switched to do thin archives so for example libbackend.a > we checksum doesn't contain the actual code anymore... > > A pragmatic approach to "fix" things would be to just checksum > gtype-desc.o which should have enough state to cover PCH dependences > if I understand the workings correctly (patch below - a single > checksum would suffice so more simplifications are possible). > > Another solution working on ELF systems with build-id support is > simply forgo checksumming anything and rely on the executable > build-id instead (pat^whack below as well). > > Does anybody think that just checksumming gtype-desc.o is a > degradation over the current state (which checksums thin archives)? > > Thanks, > Richard. > > 2019-02-22 Richard Biener > > c/ > * Make-lang.in (cc1-checksum.c): Checksum only gtype-desc.o. > > cp/ > * Make-lang.in (cc1plus-checksum.c): Checksum only gtype-desc.o. > > objc/ > * Make-lang.in (cc1obj-checksum.c): Checksum only gtype-desc.o. > > objcp/ > * Make-lang.in (cc1objplus-checksum.c): Checksum only gtype-desc.o. ISTM that gtype-desc effectively describes the structure of all the GC data. Given we're summing the thin-archives, we're already missing things like a change in static data. So I don't think your patch is a degradation over the current state. I'm not 100% sure the current state is correct though :-) jeff
Re: [RFC] Change PCH "checksum"
On Fri, Feb 22, 2019 at 08:47:09AM -0700, Jeff Law wrote: > > 2019-02-22 Richard Biener > > > > c/ > > * Make-lang.in (cc1-checksum.c): Checksum only gtype-desc.o. > > > > cp/ > > * Make-lang.in (cc1plus-checksum.c): Checksum only gtype-desc.o. > > > > objc/ > > * Make-lang.in (cc1obj-checksum.c): Checksum only gtype-desc.o. > > > > objcp/ > > * Make-lang.in (cc1objplus-checksum.c): Checksum only gtype-desc.o. > ISTM that gtype-desc effectively describes the structure of all the GC data. > > Given we're summing the thin-archives, we're already missing things like > a change in static data. So I don't think your patch is a degradation > over the current state. I'm not 100% sure the current state is correct > though :-) Does it cover everything though? I believe gtype-desc.c only covers a small portion, the rest is in all the gtype-*.h and gt-*.h headers that are included in the various object files. So, either we need to checksum all the object files that include gt-*.h or gtype-*.h headers in addition to gtype-desc.o, or perhaps checksum gtype.state ? Though, that state wouldn't cover changes in ABI etc. Jakub
Re: [RFC] Change PCH "checksum"
On February 22, 2019 5:03:46 PM GMT+01:00, Jakub Jelinek wrote: >On Fri, Feb 22, 2019 at 08:47:09AM -0700, Jeff Law wrote: >> > 2019-02-22 Richard Biener >> > >> >c/ >> >* Make-lang.in (cc1-checksum.c): Checksum only gtype-desc.o. >> > >> >cp/ >> >* Make-lang.in (cc1plus-checksum.c): Checksum only gtype-desc.o. >> > >> >objc/ >> >* Make-lang.in (cc1obj-checksum.c): Checksum only gtype-desc.o. >> > >> >objcp/ >> >* Make-lang.in (cc1objplus-checksum.c): Checksum only >gtype-desc.o. >> ISTM that gtype-desc effectively describes the structure of all the >GC data. >> >> Given we're summing the thin-archives, we're already missing things >like >> a change in static data. So I don't think your patch is a >degradation >> over the current state. I'm not 100% sure the current state is >correct >> though :-) > >Does it cover everything though? I believe gtype-desc.c only covers a >small >portion, the rest is in all the gtype-*.h and gt-*.h headers that are >included in the various object files. >So, either we need to checksum all the object files that include gt-*.h >or >gtype-*.h headers in addition to gtype-desc.o, or perhaps checksum >gtype.state ? Though, that state wouldn't cover changes in ABI etc. Gtype-desc.o does not cover everything indeed. But the current state doesn't cover Gtype-desc.o... Slightly better would be to Re-include frontend objects. Not sure why we checksummed build flags for example. Isn't it enough to handle gty walking changes? Anyway, for suse I'm probably using the build-id thing. Richard. > Jakub
AVR __progmem__ variable reading
Hi I am using for a while now gcc and especially __progmem__ attribute. I’d like to report a feature request for gcc to handle reading from flash memory variables. Compiler has all the knowledge (target device, availability of LPM, ELPM instructions etc.) in order to properly interpret variable is accessed (eg. by array subscription). This would remove need for any assembly code written to do this. Make user code much cleaner. GCC having all this knowledge can optimize end assembly code. Simple attribute addition will switch from array in memory to array in flash. Can serve as future implementations for other platforms. What do you think ?
gcc-8-20190222 is now available
Snapshot gcc-8-20190222 is now available on ftp://gcc.gnu.org/pub/gcc/snapshots/8-20190222/ and on various mirrors, see http://gcc.gnu.org/mirrors.html for details. This snapshot has been generated from the GCC 8 SVN branch with the following options: svn://gcc.gnu.org/svn/gcc/branches/gcc-8-branch revision 269136 You'll find: gcc-8-20190222.tar.xzComplete GCC SHA256=2dc39abb337369fe43f2fb760d2787a47cc4f934179b9b43f6790bddc5169a56 SHA1=b9259d4c75e37aeb4cd7044a5993a71ff57f5da2 Diffs from 8-20190215 are available in the diffs/ subdirectory. When a particular snapshot is ready for public consumption the LATEST-8 link is updated and a message is sent to the gcc list. Please do not use a snapshot before it has been announced that way.
