As pointed out in
https://discourse.llvm.org/t/undeterministic-thin-index-file/69985, the
block count added to distributed ThinLTO index files breaks incremental
builds on ThinLTO - if any linked file has a different number of BBs,
then the accumulated sum placed in the index files will change, causing
all ThinLTO backend compiles to be redone.
The block count is only used for scaling of partial sample profiles, and
was added in D80403 for D79831.
This patch simply removes this field from the index files of non partial
sample profile compiles, which is NFC on the output of the compiler.
We subsequently need to see if this can be removed for partial sample
profiles without signficant performance loss, or redesigned in a way
that does not destroy caching.
Differential Revision: https://reviews.llvm.org/D148746
Adds support for the following flags:
* --thinlto-index-only, --thinlto-index-only=
* --thinlto-emit-imports-files
* --thinlto-emit-index-files
* --thinlto-object-suffix-replace=
* --thinlto-prefix-replace=
See https://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html
for some words on --thinlto-index-only.
I don't really need the other flags, but they were in the vicinity
and _someone_ might need them, so I figured I'd add them too.
`-object_path_lto` now sets `c.AlwaysEmitRegularLTOObj` as in the other ports,
which means it can now only point to a filename for non-thin LTO.
I think that was the intent of D129705 anyways, so update
test/MachO/lto-object-path.ll to use a non-thin bitcode file for that test.
Differential Revision: https://reviews.llvm.org/D138451
When the same bitcode object file is given multiple times from the Command-line
as lazy object file, empty index is generated which overwrites the one from thinlink.
This could cause undefined symbols during final link.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D133740
After D79300, we don't rewrite InputFile::mb to an empty buffer.
In thinLTOCreateEmptyIndexFiles(), we should check LazyObjFile::fetched
as well as checking whether mb is a bitcode, otherwise we would overwrite (path + .thinlto.bc) with an empty index.
Summary:
Count the per-module number of basic blocks when the module summary is computed
and sum them up during Thin LTO indexing.
This is used to estimate the working set size under the partial sample PGO.
This is split off of D79831.
Reviewers: davidxl, espindola
Subscribers: emaste, inglorion, hiraditya, MaskRay, steven_wu, dexonsmith, arphaman, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D80403
Summary:
The gold plugin behavior (creating empty index files for lazy bitcode
files) was added in D46034, but it missed the case when there is no
non-lazy bitcode files, e.g.
ld.lld -shared crti.o crtbeginS.o --start-lib bitcode.o --end-lib ...
crti.o crtbeginS.o are not bitcode, but our distributed build system
wants bitcode.o.thinlto.bc to confirm all expected outputs are created
based on all of the modules provided to the linker.
Differential Revision: https://reviews.llvm.org/D61420
llvm-svn: 359788
Test case ensures lld generates an error if unable to
write an empty index file for lazy object file that is not added to link.
This covers the following line with a test:
https://github.com/llvm-mirror/lld/blob/master/ELF/LTO.cpp#L206
llvm-svn: 336340
We have a following comment for createEmptyIndex caller code:
// If LazyObjFile has not been added to link, emit empty index files.
// This is needed because this is what GNU gold plugin does and we have a
// distributed build system that depends on that behavior.
Though createEmptyIndex() itself
(https://github.com/llvm-mirror/lld/blob/master/ELF/LTO.cpp#L202)
is never called in our test cases.
Patch adds a test.
llvm-svn: 336270
This should be correctly implied by the linker.
This also makes the tests slightly easier to maintain and compare
with the equivalent tests under for other platforms.
Differential Revision: https://reviews.llvm.org/D47513
llvm-svn: 333567
