aaronpuchert added inline comments.
================ Comment at: lib/CodeGen/BackendUtil.cpp:1345 Conf.RemarksPasses = CGOpts.OptRecordPasses; - Conf.DwoPath = CGOpts.SplitDwarfFile; + Conf.DwoPath = CGOpts.SplitDwarfOutput; switch (Action) { ---------------- tejohnson wrote: > 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). Ok, then it makes sense to do the changes for LTO as well. You're right that `-split-dwarf-file` is produced for `-gsplit-dwarf`, but not with LTO, right? When I set `-gsplit-dwarf` on a vanilla ThinLTO build, then the flag is just ignored and I'm getting the debug info in the final executables/shared objects. (At least with Clang 8.) I'm asking because this changes the cc1-interface, and while I have adapted `Clang::ConstructJob`, I'm not sure how distributed ThinLTO works, and whether there have to be changes. If it works like test/CodeGen/thinlto-split-dwarf.c, using cc1-options, then users might have to adapt after this change. 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