Apologies for the large change, I looked for ways to break this up and
all of the ones I saw added real complexity. This change focuses on the
option's prefixed names and the array of prefixes. These are present in
every option and the dominant source of dynamic relocations for PIE or
PIC users of LLVM and Clang tooling. In some cases, 100s or 1000s of
them for the Clang driver which has a huge number of options.
This PR addresses this by building a string table and a prefixes table
that can be referenced with indices rather than pointers that require
dynamic relocations. This removes almost 7k dynmaic relocations from the
`clang` binary, roughly 8% of the remaining dynmaic relocations outside
of vtables. For busy-boxing use cases where many different option tables
are linked into the same binary, the savings add up a bit more.
The string table is a straightforward mechanism, but the prefixes
required some subtlety. They are encoded in a Pascal-string fashion with
a size followed by a sequence of offsets. This works relatively well for
the small realistic prefixes arrays in use.
Lots of code has to change in order to land this though: both all the
option library code has to be updated to use the string table and
prefixes table, and all the users of the options library have to be
updated to correctly instantiate the objects.
Some follow-up patches in the works to provide an abstraction for this
style of code, and to start using the same technique for some of the
other strings here now that the infrastructure is in place.
In some scenarios based on the split-dwarf build process, the dwo file
is not generated as expected(That is to say, no dwo file path is stored
in the binary). When the llvm-dwp tool is called to generate the .dwp
file, it will exit without any warning.
So, the plan is to prompt a warning to tell the user that the dwo file
was not actually generated.
<img width="699" alt="image"
src="https://github.com/llvm/llvm-project/assets/150100070/5e5742f6-daad-450f-87e9-cb25449c3c7a">
DWOName is still used afterwards. The only reason this works out
right now is that SmallString does not actually have a constructor
that can take advantage of the move.
Previously, some tools such as `clang` or `lld` which require strict
order for certain command-line options, such as `clang -cc1` or `lld
-flavor`, would not longer work on Windows, when these tools were linked
as part of `llvm-driver`. This was caused by `InitLLVM` which was part
of the `*_main()` function of these tools, which in turn calls
`windows::GetCommandLineArguments`. That function completly replaces
argc/argv by new UTF-8 contents, so any ajustements to argc/argv made by
`llvm-driver` prior to calling these tools was reset.
`InitLLVM` is now called by the `llvm-driver`. Any tool that
participates in (or is part of) the `llvm-driver` doesn't call
`InitLLVM` anymore.
This is follow up for https://github.com/llvm/llvm-project/pull/71902.
The
default option --continue-on-cu-index-overflow returned an error
--continue-on-cu-index-overflow: missing argument. Changed it so that it
is the
same behavior as other flags like -gsplit-dwarf. Where
--continue-on-cu-index-overflow will default to continue, and user can
set mode
with --continue-on-cu-index-overflow=\<value>.
When 'ContinueOnCuIndexOverflow' enables without this modification, the
forcibly generated '.dwp' won't be recognized by Debugger(gdb 10.1)
correctly.
<img width="657" alt="image"
src="https://github.com/llvm/llvm-project/assets/150100070/31732775-2548-453a-a47a-fa04c6d05fe9">
it looks like there's a problem with processing the dwarf header, which
makes debugging completely impossible. (unless the consumer walks the debug_info section to rebuild that column (if that's the only section that overflowed - if it's another section, there's no recovery))
**About patch:**
When llvm-dwp enables option '--continue-on-cu-index-overflow=soft-stop'
and recognizes the overflow problem , it will stop packing and generate
the '.dwp' file at once, discarding any DWO files that would not fit
within the 32 bit/4GB limits of the format.
<img width="625" alt="image"
src="https://github.com/llvm/llvm-project/assets/150100070/77d6be24-262b-4f4c-afc0-9a6c49e133c7">
This reverts commit 4e3b89483a6922d3f48670bb1c50a37f342918c6, with
fixes for places I'd missed updating in lld and lldb. I've also
renamed OptionVisibility::Default to "DefaultVis" to avoid ambiguity
since the undecorated name has to be available anywhere Options.inc is
included.
Original message follows:
This splits OptTable's "Flags" field into "Flags" and "Visibility",
updates the places where we instantiate Option tables, and adds
variants of the OptTable APIs that use Visibility mask instead of
Include/Exclude flags.
We need to do this to clean up a bunch of complexity in the clang
driver's option handling - there's a whole slew of flags like
CoreOption, NoDriverOption, and FlangOnlyOption there today to try to
handle all of the permutations of flags that the various drivers need,
but it really doesn't scale well, as can be seen by things like the
somewhat recently introduced CLDXCOption.
Instead, we'll provide an additive model for visibility that's
separate from the other flags. For things like "HelpHidden", which is
used as a "subtractive" modifier for option visibility, we leave that
in "Flags" and handle it as a special case.
Note that we don't actually update the users of the Include/Exclude
APIs here or change the flags that exist in clang at all - that will
come in a follow up that refactors clang's Options.td to use the
increased flexibility this change allows.
Differential Revision: https://reviews.llvm.org/D157149
This splits OptTable's "Flags" field into "Flags" and "Visibility",
updates the places where we instantiate Option tables, and adds
variants of the OptTable APIs that use Visibility mask instead of
Include/Exclude flags.
We need to do this to clean up a bunch of complexity in the clang
driver's option handling - there's a whole slew of flags like
CoreOption, NoDriverOption, and FlangOnlyOption there today to try to
handle all of the permutations of flags that the various drivers need,
but it really doesn't scale well, as can be seen by things like the
somewhat recently introduced CLDXCOption.
Instead, we'll provide an additive model for visibility that's
separate from the other flags. For things like "HelpHidden", which is
used as a "subtractive" modifier for option visibility, we leave that
in "Flags" and handle it as a special case.
Note that we don't actually update the users of the Include/Exclude
APIs here or change the flags that exist in clang at all - that will
come in a follow up that refactors clang's Options.td to use the
increased flexibility this change allows.
Differential Revision: https://reviews.llvm.org/D157149
All command-line tools using `llvm::opt` create an enum of option IDs and a table of `OptTable::Info` object. Most of the tools use the same ID (`OPT_##ID`), kind (`Option::KIND##Class`), group ID (`OPT_##GROUP`) and alias ID (`OPT_##ALIAS`). This patch extracts that common code into canonical macros. This results in fewer changes when tweaking the `OPTION` macros emitted by the TableGen backend.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D157028
Switch the parse of command line options from llvm::cl to OptTable.
The motivation for this change is to continue adding llvm based tools
to the llvm driver multicall. For more information about the proposal
and motivation, please see https://discourse.llvm.org/t/rfc-llvm-busybox-proposal/58494
Reviewed By: abrachet
Differential Revision: https://reviews.llvm.org/D154642
Now, if the offset overflow happens, we just silently ignore it.
We will generate a bad dwp file, which will crash the gdb or make
it undefined behavior, and hard to address the root cause. So, we
need to produce some messages if overflow happens.
Reviewed By: ayermolo, dblaikie, steven.zhang
Differential Revision: https://reviews.llvm.org/D144565
For now, we report nothing if the execution/dwo file is missing, which is confusing.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D133549
Extend the llvm-dwp to support searching the DWOs that from relative path for the
case that build from remote building system(different comp_dir).
Reviewd By: dblaikie
Differential Revision: https://reviews.llvm.org/D133480
For now, we report nothing if the execution/dwo file is missing, which is confusing.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D133549
Most notably,
llvm/Object/Binary.h no longer includes llvm/Support/MemoryBuffer.h
llvm/Object/MachOUniversal*.h no longer include llvm/Object/Archive.h
llvm/Object/TapiUniversal.h no longer includes llvm/Object/TapiFile.h
llvm-project preprocessed size:
before: 1068185081
after: 1068324320
Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D119457
There's a few relevant forward declarations in there that may require downstream
adding explicit includes:
llvm/MC/MCContext.h no longer includes llvm/BinaryFormat/ELF.h, llvm/MC/MCSubtargetInfo.h, llvm/MC/MCTargetOptions.h
llvm/MC/MCObjectStreamer.h no longer include llvm/MC/MCAssembler.h
llvm/MC/MCAssembler.h no longer includes llvm/MC/MCFixup.h, llvm/MC/MCFragment.h
Counting preprocessed lines required to rebuild llvm-project on my setup:
before: 1052436830
after: 1049293745
Which is significant and backs up the change in addition to the usual benefits of
decreasing coupling between headers and compilation units.
Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D119244
This moves the registry higher in the LLVM library dependency stack.
Every client of the target registry needs to link against MC anyway to
actually use the target, so we might as well move this out of Support.
This allows us to ensure that Support doesn't have includes from MC/*.
Differential Revision: https://reviews.llvm.org/D111454
This is a step1, mechanical refactor, of moving the bulk of llvm-dwp functionality in to a library. This should allow other tools, like BOLT, to re-use some of the llvm-dwp functionality.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D106198
This patch updates llvm-dwp to include rnglists and loclists
when parsing debug sections.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D101894
This patch adds support for DWARFv5 type units: parsing from
the .debug_info section, and writing index to the type unit index.
Previously, the type units were part of the .debug_types section
which is no longer used in DWARFv5.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D101818
This patch adds general support for DWARFv5 index writing.
In particular, this means only allowing inputs with one version,
either DWARFv5 or DWARFv4.
This patch adds the .debug_macro section as an example,
but the DWARFv5 type support and loc and rangelists are still
missing (and upcoming).
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D102315
This patch makes llvm-dwp skip debug info sections that may not be encoding a compile unit.
In DWARF5, debug info sections are also used for type units. As in preparation to support type units,
make llvm-dwp aware of other uses of debug info sections but skip them for now.
The patch first records all .debug_info sections, then goes through them one by one and records
the cu debug info section for writing the index unit, and copies that section to the final dwp output
info section. If it's not a compile unit, skip.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D102312
This makes it possible for targets to define their own MCObjectFileInfo.
This MCObjectFileInfo is then used to determine things like section alignment.
This is a follow up to D101462 and prepares for the RISCV backend defining the
text section alignment depending on the enabled extensions.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D101921
This untangles the MCContext and the MCObjectFileInfo. There is a circular
dependency between MCContext and MCObjectFileInfo. Currently this dependency
also exists during construction: You can't contruct a MOFI without a MCContext
without constructing the MCContext with a dummy version of that MOFI first.
This removes this dependency during construction. In a perfect world,
MCObjectFileInfo wouldn't depend on MCContext at all, but only be stored in the
MCContext, like other MC information. This is future work.
This also shifts/adds more information to the MCContext making it more
available to the different targets. Namely:
- TargetTriple
- ObjectFileType
- SubtargetInfo
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D101462
Currently llvm-dwp only handled DW_FORM_string and DW_FORM_GNU_str_index; with this patch it also starts to handle DW_FORM_strx[1-4]?
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D75485
When the `DWOPath` is absolute, we want to use `DWOPath` as is, without prepending any other
components to the path. The `sys::path::append` does not join, but rather unconditionally appends
the paths, so something like `sys::path::append("/tmp", "/tmp/banana")` will result in
`/tmp/tmp/banana` rather than the desired `/tmp/banana`.
This then causes `llvm-dwp` to fail in a following situation:
```
$ clang -gsplit-dwarf /tmp/banana/test.c -c -o /tmp/outdir/foo.o
$ clang outdir/foo.o -o outdir/hm
$ llvm-dwarfdump outdir/hm | grep -C2 foo.dwo
DW_AT_comp_dir ("/tmp")
DW_AT_GNU_pubnames (true)
DW_AT_GNU_dwo_name ("/tmp/outdir/foo.dwo")
DW_AT_GNU_dwo_id (0xde4d396f3bf0e257)
DW_AT_low_pc (0x0000000000401100)
$ strace -o trace llvm-dwp -e outdir/hm -o outdir/hm.dwp
error: No such file or directory
$ cat trace | grep foo.dwo
openat(AT_FDCWD, "/tmp/tmp/outdir/foo.dwo", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
```
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D96678
The llvm-dwp tool hard-codes the target triple to x86. Instead, deduce the
target triple from the object files being read.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D93749
The library can parse DWARFv5 unit index sections of DWP files, but
llvm-dwp is not ready to process them. Refuse such input files for now.
Differential Revision: https://reviews.llvm.org/D77143
llvm-dwp did not check section identifiers read from input files.
In the case of an unexpected identifier, the calculated index for
Contributions[] pointed outside the array. This fix avoids the issue
by skipping unsupported identifiers.
Differential Revision: https://reviews.llvm.org/D76543
DWARFv5 defines index sections in package files in a slightly different
way than the pre-standard GNU proposal, see Section 7.3.5 in the DWARF
standard and https://gcc.gnu.org/wiki/DebugFissionDWP for GNU proposal.
The main concern here is values for section identifiers, which are
partially overlapped with changed meanings. The patch adds support for
v5 index sections and resolves that difficulty by defining a set of
identifiers for internal use which can represent and distinct values
of both standards.
Differential Revision: https://reviews.llvm.org/D75929
This is a preparation for an upcoming patch which adds support for
DWARFv5 unit index sections. The patch adds tag "_EXT_" to identifiers
which reference sections that are deprecated in the DWARFv5 standard.
See D75929 for the discussion.
Differential Revision: https://reviews.llvm.org/D77141
There is a number of places in llvm-dwp.cpp where a section identifier
is translated into an index of an internal array of section
contributions, and another place where the index is converted to an
on-disk value. All these places use direct expressions like
"<id> - DW_SECT_INFO" or "<index> + DW_SECT_INFO", exploiting the fact
that DW_SECT_INFO is the minimum valid value of that kind.
The patch adds distinct functions for that translation. The goal is to
make the code more readable and to prepare it to support index sections
of new versions, where the numeric scheme of section indexes is changed.
Differential Revision: https://reviews.llvm.org/D76067
The old name was a bit misleading because the functions actually return
contributions to the corresponding sections.
Differential revision: https://reviews.llvm.org/D77302
