[llvm-dev] distributed thinlto usage
David Callahan via llvm-dev
llvm-dev at lists.llvm.org
Tue Jan 8 16:36:30 PST 2019
Thanks Teresa
Yes it is astar, happen to send a tar of the sources but they are just copies from the spec distribution
The ld command is:
GNU ld (GNU Binutils) 2.29.1
Thanks for the guidance on path names. The prefix-replace just effects the string written to the object files right? So we could post-process that file with other tools as well, correct?
Thanks again
--david
From: Teresa Johnson <tejohnson at google.com>
Date: Tuesday, January 8, 2019 at 4:11 PM
To: David Callahan <dcallahan at fb.com>
Cc: LLVM Dev Mailing list <llvm-dev at lists.llvm.org>
Subject: Re: [llvm-dev] distributed thinlto usage
Hi David,
That looks basically right, so I am not sure offhand what is wrong. Looks like this is the astar spec binary, so I will try to repro it tomorrow morning. What linker are you using?
Note that if your link involves archives of .a files, you will want to ensure that the final native link includes only those files selected by the linker. That is output in the file given to the "-Wl,-plugin-opt,thinlto-index-only=files.out" option. What we do is use that in combination with the '-Wl,-plugin-opt,thinlto-prefix-replace=path1;path2' option to simplify the final link invocation. Specifically, if you do something like:
"-Wl,-plugin-opt,thinlto-index-only=files.out -Wl,-plugin-opt,thinlto-prefix-replace=path1;path2"
for the indexing link step, the output files from the thin link will be written to a directory tree with the original path substring "path1" replaced with "path2", and the object names in the file emitted by thinlto-index-only= ("files.out" in the above example), will have their path names adjusted to the new path as well - if your native .o files use the new path then this is a simple way of getting a list of input files for the final link, which can be passed via @files.out to gold (note the gold manpage does not document "@" but the gnu ld manpage does).
I.e. something like:
clang++ -flto=thin -O3 -c -o path1/foo.o foo.cpp
...
clang++ -flto=thin -O3 -Wl,-plugin-opt,thinlto-index-only=files.out -Wl,-plugin-opt,thinlto-prefix-replace=path1;path2" foo.o ...
clang++ -c -x ir path1/foo.o -O3 -o path2/foo.o -fthinlto-index=path2/foo.o.thinlto.bc
...
clang++ -flto=thin -O3 -o a.out @files.out
But again, that should only come into play if you are linking archives of bitcode files...
Teresa
On Tue, Jan 8, 2019 at 2:38 PM David Callahan via llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:
I am trying to work through the usage of thinlto for distributed builds.
Here is the simple thinlto usage, just add -flto=thin everywhere, easy:
clang++ -flto=thin -O3 -c -o CreateWay_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else CreateWay_.cpp
clang++ -flto=thin -O3 -c -o Places_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Places_.cpp
clang++ -flto=thin -O3 -c -o RegBounds_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else RegBounds_.cpp
clang++ -flto=thin -O3 -c -o RegMng_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else RegMng_.cpp
clang++ -flto=thin -O3 -c -o Way2_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Way2_.cpp
clang++ -flto=thin -O3 -c -o WayInit_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else WayInit_.cpp
clang++ -flto=thin -O3 -c -o Library.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Library.cpp
clang++ -flto=thin -O3 -c -o Random.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Random.cpp
clang++ -flto=thin -O3 -c -o Region_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Region_.cpp
clang++ -flto=thin -O3 -c -o RegWay_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else RegWay_.cpp
clang++ -flto=thin -O3 -c -o Way_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Way_.cpp
clang++ -flto=thin -O3 -o astar.thin CreateWay_.o Places_.o RegBounds_.o RegMng_.o Way2_.o WayInit_.o Library.o Random.o Region_.o RegWay_.o Way_.o
My understanding is for the distributed, you need to do the inital compiles as above,
then a special link to get the thinlto index files, then compile again to get
native files, and then a final link. This looks like the following but
it does not work:
clang++ -flto=thin -O3 -c -o CreateWay_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else CreateWay_.cpp
clang++ -flto=thin -O3 -c -o Places_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Places_.cpp
clang++ -flto=thin -O3 -c -o RegBounds_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else RegBounds_.cpp
clang++ -flto=thin -O3 -c -o RegMng_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else RegMng_.cpp
clang++ -flto=thin -O3 -c -o Way2_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Way2_.cpp
clang++ -flto=thin -O3 -c -o WayInit_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else WayInit_.cpp
clang++ -flto=thin -O3 -c -o Library.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Library.cpp
clang++ -flto=thin -O3 -c -o Random.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Random.cpp
clang++ -flto=thin -O3 -c -o Region_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Region_.cpp
clang++ -flto=thin -O3 -c -o RegWay_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else RegWay_.cpp
clang++ -flto=thin -O3 -c -o Way_.o -DSPEC_CPU -DNDEBUG -DSPEC_CPU_LITTLE_ENDIAN -Wno-dangling-else Way_.cpp
clang++ -flto=thin -O3 -o thinlto.objects -Wl,-plugin-opt,thinlto-index-only=thinlto.objects CreateWay_.o Places_.o RegBounds_.o RegMng_.o Way2_.o WayInit_.o Library.o Random.o Region_.o RegWay_.o Way_.o
clang++ -c -x ir CreateWay_.o -O3 -o CreateWay_-native.o -fthinlto-index=CreateWay_.o.thinlto.bc
clang++ -c -x ir Places_.o -O3 -o Places_-native.o -fthinlto-index=Places_.o.thinlto.bc
clang++ -c -x ir RegBounds_.o -O3 -o RegBounds_-native.o -fthinlto-index=RegBounds_.o.thinlto.bc
clang++ -c -x ir RegMng_.o -O3 -o RegMng_-native.o -fthinlto-index=RegMng_.o.thinlto.bc
clang++ -c -x ir Way2_.o -O3 -o Way2_-native.o -fthinlto-index=Way2_.o.thinlto.bc
clang++ -c -x ir WayInit_.o -O3 -o WayInit_-native.o -fthinlto-index=WayInit_.o.thinlto.bc
clang++ -c -x ir Library.o -O3 -o Library-native.o -fthinlto-index=Library.o.thinlto.bc
clang++ -c -x ir Random.o -O3 -o Random-native.o -fthinlto-index=Random.o.thinlto.bc
clang++ -c -x ir Region_.o -O3 -o Region_-native.o -fthinlto-index=Region_.o.thinlto.bc
clang++ -c -x ir RegWay_.o -O3 -o RegWay_-native.o -fthinlto-index=RegWay_.o.thinlto.bc
clang++ -c -x ir Way_.o -O3 -o Way_-native.o -fthinlto-index=Way_.o.thinlto.bc
clang++ -o astar CreateWay_-native.o Places_-native.o RegBounds_-native.o RegMng_-native.o Way2_-native.o WayInit_-native.o Library-native.o Random-native.o Region_-native.o RegWay_-native.o Way_-native.o
Library-native.o:(.data+0x0): undefined reference to `vtable for regwayobj'
clang-8: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [astar] Error 1
Did I miss a step?
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--
Teresa Johnson |
Software Engineer |
tejohnson at google.com<mailto:tejohnson at google.com> |
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