tejohnson added inline comments.
================
Comment at: lib/CodeGen/BackendUtil.cpp:1345
Conf.RemarksPasses = CGOpts.OptRecordPasses;
- Conf.DwoPath = CGOpts.SplitDwarfFile;
+ Conf.DwoPath = CGOpts.SplitDwarfOutput;
switch (Action) {
----------------
aaronpuchert wrote:
> tejohnson wrote:
> > aaronpuchert wrote:
> > > aaronpuchert wrote:
> > > > @pcc Your documentation for `DwoPath` suggests that this should be the
> > > > actual output filename. However, the test that you added together with
> > > > this line in rC333677 doesn't fail whatever garbage I write into that
> > > > field here. What can I add to that so that it fails when we don't do
> > > > the right thing here?
> > > @pcc Could you (or perhaps @tejohnson) comment on what the intended
> > > behavior is here, and how I can change the test so that it fails when I
> > > do the wrong thing? Is this the name of the file we write the split debug
> > > info to, or is it the value we use for the DW_AT_[GNU_]dwo_name attribute
> > > in the skeleton CU?
> > It is the name of the file the split debug info is written to. If you test
> > by changing the file name given to the -split-dwarf-file option in
> > test/CodeGen/thinlto-split-dwarf.c, make sure you clean up the old one in
> > your test output directory. When I tested it just now, it initially still
> > passed because I had an old one sitting in the output directory from a
> > prior run. Once I removed that it failed with the new name (without
> > changing the corresponding llvm-readobj invocation).
> Thanks, I didn't consider that. I wasn't even aware that test output is
> persisted.
>
> It seems `DwoPath` is used both as output filename and as value for
> `DW_AT_[GNU_]dwo_name` in the skeleton CU. `llc` has separate options for
> both: `-split-dwarf-file` for the attribute and `-split-dwarf-output` for the
> output filename. I want to do the same for Clang. Then we should probably
> separate them for LTO, too.
>
> What is the use case for `-split-dwarf-file` with an individual thin backend?
> Is that used for distributed/remote builds? Also is there any non-cc1 way to
> use it? There is `--plugin-opt=dwo_dir=...` for the LTO linker plugin, but
> that seems to go a different route.
This is the path taken for distributed ThinLTO, the plugin-opt passed to linker
are for in-process ThinLTO. While -split-dwarf-file is a cc1 option, it is
normally set automatically from the filename under -gsplit-dwarf (see where it
is set in Clang::ConstructJob).
Repository:
rC Clang
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D59673/new/
https://reviews.llvm.org/D59673
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
