This reapplication changes debug intrinsic declaration removal to only take
place when printing final IR, so that the processing format of the Module
does not affect the output.
This reverts commit d128448efd.
This patch adds support for printing the proposed non-instruction debug
info ("RemoveDIs") out to textual IR. This patch does not add any
bitcode support, parsing support, or documentation.
Printing of the new format is controlled by a flag added in this patch,
`--write-experimental-debuginfo`, which defaults to false. The new
format will be printed *iff* this flag is true, so whether we use the IR
format is completely independent of whether we use non-instruction debug
info during LLVM passes (which is controlled by the
`--try-experimental-debuginfo-iterators` flag).
Even with the flag disabled, some existing tests need to be updated, as this
patch causes debug intrinsic declarations to be changed in a round trip,
such that they always appear at the end of a module and have no attributes
(this has no functional change on the module).
The design of this new IR format was proposed previously on
Discourse, and any further discussion about the design can still be
contributed there:
https://discourse.llvm.org/t/rfc-debuginfo-proposed-changes-to-the-textual-ir-representation-for-debug-values/73491
llvm.dbg.assign intrinsics have 2 {value, expression} pairs; fix hwasan to
update the second expression.
Fixes#76545. This is #78606 rebased and with the addition of DPValue handling.
Note the addition of --try-experimental-debuginfo-iterators in the tests and
some shuffling of code in MemoryTaggingSupport.cpp.
With this, I get a clean test suite running under RemoveDIs, the
non-intrinsic representation of debug-info, including under asan. We've
previously established that we generate identical binaries for some
large projects, so this i just edge-case cleanup. The changes:
* CodeGenPrepare fixups need to apply to dbg.assigns as well as
dbg.values (a dbg.assign is a dbg.value).
* Pin a test for constant-deletion to intrinsic debug-info: this very
rare scenario uses a different kill-location sigil in dbg.value mode to
RemoveDIs mode, which generates spurious test differences.
* Suppress a memory leak in a unit test: the code for dealing with
trailing debug-info in a block is necessarily fiddly, leading to this
leak when testing it. Developer-facing interfaces for moving
instructions around always deal with this behind the scenes.
* SROA, when replacing some vector-loads, needs to insert the
replacement loads ahead of any debug-info records so that their values
remain dominated by a definition. Set the head-bit indicating our
insertion should come before debug-info.
This commit introduces a helper function to DWARFAcceleratorTable::Entry
which follows DW_IDX_Parent attributes to returns the corresponding
parent Entry in the table.
It is tested by enhancing dwarfdump so that it now prints:
1. When data is corrupt.
2. When parent information is present, but the parent is not indexed.
3. The parent entry offset, when the parent is present and indexed. This
is printed in terms a real entry offset (the same that gets printed at
the start of each entry: "Entry @ 0x..."), instead of the encoded number
in the table (which is an offset from the start off the Entry list).
This makes it easy to visually inspect the dwarfdump and check what the
parent is.
This is the final patch for DPVAssign support, implementing the actual
creation of DPVAssigns and allowing them to be converted along with
dbg.values and dbg.declares. Numerous tests landed in previous patches
will no longer be rotten after this patch lands (previously they would
trivially pass due to DPVAssigns not actually being used), and a further
batch of tests have been added here that require the changes in this
patch before they pass.
This patch trivially updates various opt passes to handle DPVAssigns. In
all cases, this means some combination of generifying existing code to
handle DPValues and DbgAssignIntrinsics, iterating over DPValues where
previously we did not, or duplicating code for DbgAssignIntrinsics to
the equivalent DPValue function (in inlining and salvageDebugInfo).
As part of a recent patch landing, some tests that are not yet ready
to support RemoveDIs were turned on; this patch disables those tests
in RemoveDIs mode.
Fixes buildbot failure:
https://lab.llvm.org/buildbot/#/builders/275/builds/3640
SROA needs to update llvm.dbg.assign intrinsics when it migrates debug
info in response to alloca splitting; this patch updates the debug info
migration code to handle DPVAssigns as well, making use of generic code
to avoid duplication as much as possible.
This patch fixes commit 89aa3355, which added tests for
the removal of redundant DPVAssigns; unlike other cases where
adding tests for DPVAssigns before they are enabled is harmless,
these tests require them to be enabled, so must be deleted until
we enable them.
Fixes failures on llvm-new-debug-iterators buildbot:
https://lab.llvm.org/buildbot/#/builders/275/builds/3581
DPValues are already supported by most of the utilities that remove
redundant debug info after certain passes; the exception to this is
`removeUndefDbgAssignsFromEntryBlock`, which applies only to
llvm.dbg.assigns which were previously unimplemented for DPValues. Now
that DPVAssigns exist, we have to support removing redundant instances
in the same way, which this patch implements.
This implements the ideas discussed in [1].
To summarize, this commit changes AsmPrinter so that it outputs
DW_IDX_parent information for debug_name entries. It will enable
debuggers to speed up queries for fully qualified types (based on a
DWARFDeclContext) significantly, as debuggers will no longer need to
parse the entire CU in order to inspect the parent chain of a DIE.
Instead, a debugger can simply take the parent DIE offset from the
accelerator table and peek at its name in the debug_info/debug_str
sections.
The implementation uses two types of DW_FORM for the DW_IDX_parent
attribute:
1. DW_FORM_ref4, which points to the accelerator table entry for the
parent.
2. DW_FORM_flag_present, when the entry has a parent that is not in the
table (that is, the parent doesn't have a name, or isn't allowed to be
in the table as per the DWARF spec). This is space-efficient, since it
takes 0 bytes.
The implementation works by:
1. Changing how abbreviations are encoded (so that they encode which
form, if
any, was used to encode IDX_Parent)
2. Creating an MCLabel per accelerator table entry, so that they may be
referred by IDX_parent references.
When all patches related to this are merged, we are able to show that
evaluating an expression such as:
```
lldb --batch -o 'b CodeGenFunction::GenerateCode' -o run -o 'expr Fn' -- \
clang++ -c -g test.cpp -o /dev/null
```
is far faster: from ~5000 ms to ~1500ms.
Building llvm-project + clang with and without this patch, and looking
at its impact on object file size:
```
ls -la $(find build_stage2_Debug_idx_parent_assert_dwarf5 -name \*.cpp.o) | awk '{s+=$5} END {printf "%\047d\n", s}'
11,507,327,592
-la $(find build_stage2_Debug_no_idx_parent_assert_dwarf5 -name \*.cpp.o) | awk '{s+=$5} END {printf "%\047d\n", s}'
11,436,446,616
```
That is, an increase of 0.62% in total object file size.
Looking only at debug_names:
```
$stage1_build/bin/llvm-objdump --section-headers $(find build_stage2_Debug_idx_parent_assert_dwarf5 -name \*.cpp.o) | grep __debug_names | awk '{s+="0x"$3} END {printf "%\047d\n", s}'
440,772,348
$stage1_build/bin/llvm-objdump --section-headers $(find build_stage2_Debug_no_idx_parent_assert_dwarf5 -name \*.cpp.o) | grep __debug_names | awk '{s+="0x"$3} END {printf "%\047d\n", s}'
369,867,920
```
That is an increase of 19%.
DWARF Linkers need to be changed in order to support this. This commit
already brings support to "base" linker, but it does not attempt to
modify the parallel linker. Accelerator entries refer to the
corresponding DIE offset, and this patch also requires the parent DIE
offset -- it's not clear how the parallel linker can access this. It may
be obvious to someone familiar with it, but it would be nice to get help
from its authors.
[1]:
https://discourse.llvm.org/t/rfc-improve-dwarf-5-debug-names-type-lookup-parsing-speed/74151/
- [DebugMetadata][DwarfDebug] Support function-local types in lexical
block scopes (4/7)
- [CloneFunction][DebugInfo] Avoid cloning DILocalVariables of inlined
functions
This is a follow-up for https://reviews.llvm.org/D144006, fixing a crash
reported
in Chromium (https://reviews.llvm.org/D144006#4651955).
The first commit is added for convenience, as it has already been
accepted.
If DISubpogram was not cloned (e.g. we are cloning a function that has
other
functions inlined into it, and subprograms of the inlined functions are
not supposed to be cloned), it doesn't make sense to clone its
DILocalVariables as well.
Otherwise get duplicated DILocalVariables not tracked in their
subprogram's retainedNodes, that crash LTO with Chromium.
This is meant to be committed along with
https://reviews.llvm.org/D144006.
The change is fairly mechanical:
1. Factor code from `FastISel::selectIntrinsicCall`, which converts
debug intrinsics into debug instructions, into functions (NFC).
2. Call those functions for DPValues attached to instructions too.
The test updates look the same as other RemoveDIs changes: re-run the
tests with `--try-experimental-debuginfo-iterators`, which checks the
output is identical using the new debug info format (if it has been
enabled in the cmake configuration).
Depends on #76941 (otherwise some modified tests spuriously fail).
Temporarily fix for issue #76545
Hwasan does not attach tags to @llvm.dbg.assign. It's not clear if we
can attach tags to @llvm.dbg.assign.
For now we just disable the path replacing llvm.dbg.declare with
llvm.dbg.assign.
It may reduce the quality of interactive debugging with HWASAN, but
usually it's
a smaller priority for sanitizers than the quality if reports.
Handle dbg.declares in SROA using DPValues.
In order to reduce duplication, the migrate-debug-info loop has been changed
to a generic lambda with some helper function overloads, which is called
for dbg.declares, dbg.assigns, and DPValues alike.
The tests will become "live" once #74090 lands (see for more info).
This is a boring mechanical update to support DPValues that look like
dbg.declares in SelectionDAG.
The tests will become "live" once #74090 lands (see for more info).
This patch updates the last few places in LLVM using findDbgValues that
don't also collect and handle DPValue objects. This largely involves
instcombine and mem2reg changes, and are largely mechanical, calling
existing utilities on collections of DPValues instead of just
DbgValuesInsts.
A variety of tests have had RemoveDIs RUN lines added to them to cover
these behaviours. We have some technical debt of the instcombine sinking
code for DPValues not being implemented yet, so I've left FIXME stubs
indicating that we intend to cover tests with RemoveDIs but haven't yet.
With intrinsics representing debug-info, we just clone all the
intrinsics when inlining a function and don't think about it any
further. With non-instruction debug-info however we need to be a bit
more careful and manually move the debug-info from one place to another.
For the most part, this means keeping a "cursor" during block cloning of
where we last copied debug-info from, and performing debug-info copying
whenever we successfully clone another instruction.
There are several utilities in LLVM for doing this, all of which now
need to manually call cloneDebugInfo. The testing story for this is not
well covered as we could rely on normal instruction-cloning mechanisms
to do all the hard stuff. Thus, I've added a few tests to explicitly
test dbg.value behaviours, ahead of them becoming not-instructions.
This was reverted because it broke the OCaml LLVM bindings.
Relanding the original patch but without changing the C-API.
They'll continue to work just fine as they do today. If in the
future there is a need to pass a new tag to the C-API for creating
static members, then we'll make the change to the OCaml bindings
at that time.
Original commit message:
"""
This patch adds the LLVM-side infrastructure to implement DWARFv5 issue
161118.1: "DW_TAG for C++ static data members".
The clang-side of this patch will simply construct the DIDerivedType
with a different DW_TAG.
"""
This reverts commit 9a9933fae2.
The OCaml bindings were using `LLVMDIBuilderCreateStaticMemberType`,
causing the API change in `9a9933fae23249fbf6cf5b3c090e630f578b7f98`
to break buildbots that built the bindings. Revert until we figure out
whether to fixup the bindings or just not change the C-API
This patch adds the LLVM-side infrastructure to implement DWARFv5 issue
161118.1: "DW_TAG for C++ static data members".
The clang-side of this patch will simply construct the DIDerivedType
with a different DW_TAG.
After performing sink-and-fold over a COPY, the original instruction is
replaced with one that produces its output in the destination of the
copy. Its value is still available (in a hard register), so if there are
debug instructions which refer to the (now deleted) virtual register
they could be updated to refer to the hard register, in principle.
However, it's not clear how to do that, moreover in some cases the debug
instructions may need to be replicated proportionally to the number of
the COPY instructions replaced and in some extreme cases we can end up
with quadratic increase in the number of debug instructions, e.g:
int f(int);
void g(int x) {
int y = x + 1;
int t0 = y;
f(t0);
int t1 = y;
f(t1);
}
The base-type field of a DICompositeType is optional in the IR syntax,
however it makes no sense to have an array of an unspecified type. Such
debug-info would be meaningless, and the added test crashes otherwise
(see #70787). Thus, add a verifier check to reject such ill-formed debug
info metadata. Test produced by Christian Ulmann.
fixes#70787
Reapply now that generation of incorrect debuginfo for FnDef
in rustc has been fixed.
-----
Add a check that the DILocalVariable fragment size in dbg.declare
does not exceed the size of the alloca.
This would have caught the invalid debuginfo regenerated by rustc
in https://github.com/llvm/llvm-project/issues/64149.
Differential Revision: https://reviews.llvm.org/D158743
