Before, picking a symbol name for a Code object when generating
assembly required adding a placeholder entry in the Dwarf object,
because the Dwarf object separately used a SnapshotTextObjectNamer
to determine the appropriate symbol name to use in relocations.
Instead, now the ImageWriter subclasses are entirely responsible for
creating the symbol name for a given Code object, and that name is
passed when adding the Code object to the Dwarf object.
For Elf output, we eagerly create symbols for sections and Code objects
again in the appropriate symbol table, and so looking up the start of a
given section or Code object can be done simply by asking for the
corresponding symbol's address, removing special case methods and other
workarounds.
We also clean up the generated static and dynamic symbol tables by
only generating local symbols for Code objects and BSS sections (these
are local in assembly output also), and only adding global symbols to
the dynamic symbol table.
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Change-Id: Ie40c0c836681e98f345483136bb6860e5588ef30
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/166002
Reviewed-by: Martin Kustermann <kustermann@google.com>
Before, we only wrapped the Instructions payloads in an
InstructionsSection in precompiled snapshots with bare instructions mode
enabled. This CL changes that to always add an InstructionsSection
wrapper in precompiled snapshots, even when not in bare instructions
mode, and moves all the information from the old ImageHeader object into
the InstructionsSection object instead. Note that in non-bare mode, the
InstructionsSection has no payload, and the Instructions objects follow
the InstructionsSection object instead of being contained by it.
This CL also wraps all implementations of AssemblyImageWriter and
SnapshotTextObjectNamer methods in a single DART_PRECOMPILER ifdef
block, since we only generate assembly in precompiled mode. This
removes the need for the smaller DART_PRECOMPILER ifdef blocks scattered
across the AssemblyImageWriter method implementations.
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Change-Id: I3676fb5c6675845463707acbbb4759a465cfa342
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/165563
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
All *WriteStream classes are now part of the same hierarchy:
class BaseWriteStream : ValueObject;
Base class for all *WriteStreams. Provides all the methods from
the old WriteStream except for buffer() and SetPosition()
(relegated to NonStreamingWriteStreams). Has one pure virtual
method Realloc that must be overridden by concrete subclasses.
class NonStreamingWriteStream : BaseWriteStream;
Base class for all *WriteStreams where the entire stream is available
at all times (i.e., no flushing to an external sink). Extends the
public BaseWriteStream API with buffer() (for accessing the stream
contents) and SetPosition() (for changing the current stream pointer
to the given absolute position in the stream).
class MallocWriteStream : NonStreamingWriteStream;
Uses realloc to reallocate the internal buffer. Almost the same as
the old WriteStream, except that it only takes an initial size. Adds
one public method Steal() for taking ownership of the current buffer
contents (after which the buffer is reset to an empty state). Instead
of passing a pointer to a buffer, the internal buffer must be accessed
via either Steal() or buffer(), which allows access to the current
stream contents without changing ownership or resetting the stream.
The internal buffer is freed on stream destruction.
class ZoneWriteStream: NonStreamingWriteStream;
Takes a zone and reallocates the internal buffer in that zone. No
additional public methods beyond those available from
NonStreamingWriteStream.
class StreamingWriteStream : BaseWriteStream;
Uses realloc to reallocate the internal buffer. Generally same as
before, where the contents of the stream are periodically flushed
using Dart_StreamingWriteCallback. Since it extends BaseWriteStream,
there are now more methods available for writing data to the stream
than just Print/VPrint/WriteBytes. Since portions of the stream may be
flushed and thus no longer in the internal buffer, does not provide
access to the contents of the stream or a way to reposition the
current stream pointer. Flushes any unflushed data and frees the
internal buffer on stream destruction.
Also refactor things so that write streams are passed to appropriate
recipients, instead of the recipients taking arguments they only used to
create a WriteStream internally. Thus, recipients now can just specify
the appropriate base class for the public API used:
* BaseWriteStream for just writing to the stream, or
* NonStreamingWriteStream if re-positioning or the stream contents are
needed.
Change-Id: I419096ecd9331483d168b079fca55b69ef397f15
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164080
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Since we've run out of room for more fields in the Image object header
on 64-bit architectures, the serializer instead creates an ImageHeader
object for precompiled snapshots that is placed at the start of text
segments. The new ImageHeader object contains the following information:
* The offset of the BSS segment from the text segment, previously
stored in the Image object header.
* The relocated address of the text segment in the dynamic shared
object. Due to restrictions when generating assembly snapshots, this
field is only set for ELF snapshots, and so it can also be used to
detect whether a snapshot was compiled to assembly or ELF.
* The offset of the build ID description field from the text segment.
* The length of the build ID description field.
We replace the BSS offset in the Image object header with the offset of
the ImageHeader object within the text segment, so that we can detect
when a given Image has an ImageHeader object available.
There are no methods available on ImageHeader objects, but instead the
Image itself controls access to the information. In particular, the
relocated address method either returns the relocated address
information from the ImageHeader object or from the initialized BSS
depending on the type of snapshot, so the caller need not do this work.
Also, instead of returning the raw offset to the BSS section and having
the caller turn that into an appropriate pointer, the method for
accessing the BSS segment now returns a pointer to the segment.
Bug: https://github.com/dart-lang/sdk/issues/43274
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Change-Id: I15eae4ad0a088260b127f3d07da79374215b7f56
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/163207
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
For proper crashpad integration, we need to generate a build ID, as the
build ID generated by crashpad if there is not one will be a simple XOR
of the first text page, which rarely changes for Dart snapshots.
Assembly snapshots already have a build ID included by the assembler, so
we currently only do this for ELF snapshots.
Currently the build ID is a 128-bit hash value that is four separate
32-bit hash values concatenated together. Those hash values come from
the contents of the VM and isolate .text and .rodata sections.
This change also contains work to separate out the concepts of sections
and segments in the ELF builder. Now, consecutive allocated sections
with the same write and execute flags are combined into a single PT_LOAD
segment when possible, which reduces the padding needed to ensure that
segments start on page boundaries in ELF snapshots.
Bug: https://github.com/dart-lang/sdk/issues/42020
Change-Id: I42a837dae665a3902d881b8d151b49ede87d6c67
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Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150625
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Instead, we just always add a BSS section and we add the ROData
sections for ELF snapshots in BlobImageWriter::WriteText() (similar
to how AssemblyImageWriter::WriteText() handles it for assembly).
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Change-Id: I87ce64037821ce10f2344964e7f379376c4538df
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150937
Reviewed-by: Martin Kustermann <kustermann@google.com>
Previously, we created a separate DWARF object for each possible output.
For the most part, the information stored in each DWARF object was the
same, but the DWARF object was responsible for keeping track of abstract
origin addresses (in the non-assembly case) and for actually generating
the desired output (assembly or binary).
Instead, abstract out the output formatting into a DwarfWriteStream,
whose subclasses handle both the final output format and certain details
that differ between assembly and binary outputs. With this, the DWARF
class no longer depends on having direct access to the ELF file if being
used to generate ELF sections, and as such is output agnostic.
Now, if we have one or more outputs that contain DWARF information, we
only generate a single DWARF object that is shared across these outputs.
The only additional change required is in Dwarf::AddCode(), which now
handles being called multiple times for the same Code object.
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Change-Id: I71de887a07a673164b3ccfa7fbbab2ccef80c576
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150302
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Introduce an internal StreamingWriteStream wrapper and use that instead.
Also add more ELF-defined constants and use those appropriately.
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Change-Id: I2bd34ebac60e789aea82c8f064c59351e2c55dd3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149291
Reviewed-by: Clement Skau <cskau@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
The relocated addresses are populated during BSS::Initialize() for
natively loaded ELF snapshots, and during the non-native loader when it
is used. Putting this information in the BSS segment avoids having to
change the embedder interface, since we only need this information for
AOT snapshots. This also avoids depending on our ELF snapshot layout
to reverse-engineer the DSO base for ELF-compiled snapshots.
We now always print the DSO base for both the VM and isolate in
non-symbolic stack traces, not just for ELF-compiled snapshots. However,
we still only print the relocated addresses in individual stack frames
if we're guaranteed they match those in separately saved debugging
information.
Bug: https://github.com/dart-lang/sdk/issues/41880
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Change-Id: I4837262f78e6e73a32eb7e24ef7a68ccb8ec2669
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/148441
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Only the case for unstripped snapshots and debugging information.
Stripped snapshots still have no static symbol table, only the
dynamic one.
Fixes: https://github.com/dart-lang/sdk/issues/41783
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Change-Id: Ibd82334597d34267a3b9e45a673d23c3f9e3fcb0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/147182
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Aske Simon Christensen <askesc@google.com>
Since the virtual addresses in ELF snapshots are the same as in
separately saved debugging information, print the virtual address in
non-symbolic frames again when running from a snapshot compiled directly
to ELF."
Storing the relocated address as an extra field in the Image header,
which requires increasing the Image header size on 64-bit platforms,
means Image pages cannot be used reliably as HeapPages as objects no
longer start after kMaxObjectAlignment bytes.
Instead, we return to an older design that just uses the lowest bit
in the BSS offset to store whether the instructions in an Image were
compiled directly to ELF.
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Change-Id: I3819b0dc2719d69f5e8764ca8be8c6ae7171a7bc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/146560
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
When generating DWARF for assembly snapshots, we use a lower bound
of the start of the isolate instructions section. Use the same bound
when generating DWARF for ELF snapshots as well.
Also avoid generating rows in the line number program for address 0.
Fixes https://github.com/dart-lang/sdk/issues/41756.
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Change-Id: I3d17e09ff8af3ba6fc70dcd6859d9b298e941ecf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/146584
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Instead of having special cases for the special sections and segments,
just add each to the appropriate array prior to calculating file offsets
and writing out the ELF file.
Also adds various checks to ensure that the contents of sections or
segments are not changed after their final size has been used to
determine memory and/or file offsets, and that new sections and
segments are not added after the section header and program header
tables have been finalized.
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Change-Id: I194b37a65b153a47c947e90930c4fe90d658d4e2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/145783
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Instead of making the ELF object handle stripping and keep track of two
possible output stream, just revert ELF objects to only output to a
single stream. Now, layers that use ELF, like the ImageWriters, handle
the stripping by deciding whether or not to add certain sections or
static symbols to the generated ELF, and we create separate DWARF
objects for each unstripped ELF object.
We also avoid duplication of writing segment and section table entries
by just creating special Sections that correspond to reserved entries,
the program table header entries for itself, etc, and then move the
section and segment entry writing into Section itself. We also lift
a lot of the same calculations used in subclass construction to the
Section level, and replace the old fields with four different kind
of object members:
* Fields that are known at construction time and thus now const
(e.g., section_type)
* Fields that are not known at construction time that have reasonable
defaults for most instances and so need not be changed from their
default value (e.g., section_link)
* Fields that are not known at construction time which must be set once
(and only once) before use. These are now accessed via getters/setters
that check whether or not the field has been set (e.g., section_name)
* Fields that are calculated from the contents of the particular
subclass, which are now just methods (e.g., FileSize())
We also change the snapshot profile writer test to test the size of
internally stripped ELF output on all platforms without running it
through an external stripping utility (previously untested), and test
assembled or externally stripped output on more platforms where we
support those. Instead of depending on pkg/vm/tool/precompiler2 for
assembling (which always uses gcc), I've added assembleSnapshot and
stripSnapshot to use_flag_test_helper.dart, which mimics the way the
test_runner determines the executable and flags to use.
Change-Id: I4ade45c5caffb443abb3f5c567343504c8085f89
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Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/129083
Commit-Queue: Teagan Strickland <sstrickl@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Removes an unnecessary change to the names of type testing stubs that
allowed name collisions to happen.
Old commit message:
The flag can be used when creating AOT snapshots. The resulting file can be
used with package:vm/dwarf/convert.dart to convert DWARF-based stack traces
to stack traces with function, file, and line number information.
Currently the saved file will be an ELF file with DWARF debugging information,
but this is subject to change in the future. To avoid being affected by any
changes in format, read the DWARF information from the file using
Dwarf.fromFile() in package:vm/dwarf/dwarf.dart.
Also adds --dwarf-stack-traces to the VM global flag list, so its value at
compilation will be read out of snapshots by the precompiled runtime.
Fixes https://github.com/dart-lang/sdk/issues/39512, which was due to
a missing compiler::target:: prefix for Instructions::HeaderSize() in
BlobImageWriter::WriteText().
Exposes the information suggested in
https://github.com/dart-lang/sdk/issues/39490 so that package:vm/dwarf
can appropriately convert absolute PC addresses to the correct virtual
address for a given DWARF line number program.
Bug: https://github.com/dart-lang/sdk/issues/35851
Change-Id: I6723449dceb0b89c054a1f1e70e7acd7749baf14
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Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/128730
Reviewed-by: Martin Kustermann <kustermann@google.com>
REASON: the first commit in the chain contains a change that breaks internal
Flutter roll due to duplicated symbols for type testing stubs in assembly
snapshots.
Revert "[vm/compiler] Add --save-debugging-info flag to gen_snapshot."
This reverts commit c2b6c2e1db.
Revert "[vm] De-obfuscate function and file names in DWARF sections."
This reverts commit 4b8fd3c412.
Revert "[vm] Add docs for DWARF stack traces and related tools/libraries."
This reverts commit 5543e5ceb8.
Revert "[vm] Weaken dwarf_stack_trace expected stack trace."
This reverts commit 5824d3ed53.
Change-Id: I95ecd16fe493f61ae761dabfdd91a6ec0c2f0ca3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/128776
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Siva Annamalai <asiva@google.com>
The flag can be used when creating AOT snapshots. The resulting file can be
used with package:vm/dwarf/convert.dart to convert DWARF-based stack traces
to stack traces with function, file, and line number information.
Currently the saved file will be an ELF file with DWARF debugging information,
but this is subject to change in the future. To avoid being affected by any
changes in format, read the DWARF information from the file using
Dwarf.fromFile() in package:vm/dwarf/dwarf.dart.
Also adds --dwarf-stack-traces to the VM global flag list, so its value at
compilation will be read out of snapshots by the precompiled runtime.
Fixes https://github.com/dart-lang/sdk/issues/39512, which was due to
a missing compiler::target:: prefix for Instructions::HeaderSize() in
BlobImageWriter::WriteText().
Exposes the information suggested in
https://github.com/dart-lang/sdk/issues/39490 so that package:vm/dwarf
can appropriately convert absolute PC addresses to the correct virtual
address for a given DWARF line number program.
Bug: https://github.com/dart-lang/sdk/issues/35851
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Change-Id: I80d900fd9e5f1e2399ad3f2fd25c85131a7ea43c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/121857
Commit-Queue: Teagan Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Fixes the changes to assembly snapshot writer in SIMARM_X64 mode. This unfortunately can't be tested until the ELF loader is available.
Take 2 is in patchset 1.
Change-Id: Ib8b067dd4f09dcba3b142705e9cb4dfbf4e3eb53
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/117726
Commit-Queue: Samir Jindel <sjindel@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
The original change is in Patchset 1.
The dependency contains the fix for the non-bare-instructions bot.
Change-Id: Iab02ab0736a2ee9144b667d2777ca526341b2a36
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Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/115241
Commit-Queue: Samir Jindel <sjindel@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
This reverts commit ecbea5a58e.
Reason for revert: broken with bare instructions and ABI bot
Original change's description:
> [vm/ffi] Implement FFI callbacks on AOT for ELF and Asm snapshots (excl. blobs).
>
> To do this, we add writable data sections (currently uninitialzed) to ELF and Asm snapshots
> and allow Instructions to have patchable relocations against (the start of) these sections.
>
> Issue https://github.com/dart-lang/sdk/issues/37295 (see also for design & discussion).
>
> Change-Id: If20bfa55776f4044aaa6bb8ea2101d2ada41842c
> Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try,vm-kernel-precomp-linux-release-x64-try,vm-kernel-precomp-android-release-arm-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/110221
> Commit-Queue: Samir Jindel <sjindel@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
TBR=kustermann@google.com,rmacnak@google.com,alexmarkov@google.com,sjindel@google.com
Change-Id: I9787da6d42575ca4f5ae0a698052a19ac4275afd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
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Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/115240
Reviewed-by: Samir Jindel <sjindel@google.com>
Commit-Queue: Samir Jindel <sjindel@google.com>
To do this, we add writable data sections (currently uninitialzed) to ELF and Asm snapshots
and allow Instructions to have patchable relocations against (the start of) these sections.
Issue https://github.com/dart-lang/sdk/issues/37295 (see also for design & discussion).
Change-Id: If20bfa55776f4044aaa6bb8ea2101d2ada41842c
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Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/110221
Commit-Queue: Samir Jindel <sjindel@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Ryan Macnak