This is the same metadata system that will support async callbacks. The
main thing this does is take the trampolines that used to be JIT only,
and use them in AOT too. This is partly a safety thing (there's some
extra checks that used to be skipped on AOT), but mostly just so that
the metadata system is unified between the sync and async callbacks.
More details about the design:
https://docs.google.com/document/d/1QDjyY_6wOTOgURwpeYMKU9qEz0gKxx2MUrdruC6Kp6c/edit?usp=sharing
I split this off the async CL. Some of the comments refer to async
stuff that doesn't exist yet, but it's coming immediately after this so
I didn't update them.
Change-Id: Icd5e86934ee9ae34c2c0e2ed2bbd1b928a7184ac
TEST=ffi_callback_metadata_test.cc and CI
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/302903
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Liam Appelbe <liama@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Instead of trying to make names assembler-friendly, instead just
quote the symbols names in the assembly output and use user visible
names for function and object symbols.
More specifically:
* This CL changes the symbol name from an assembler-safe version of the
scrubbed name to an assembler-unsafe version of the user visible name
that is then quoted when used in assembly output.
* For code symbols, regular stubs are prefixed with `stub`, allocation
stubs are prefixed with `new` and type testing stubs are prefixed with
`assert type is` (e.g., `stub Await`, `new RegExp`,
`assert type is List<Int>`). Function symbols have no prefix.
* Readonly data symbols begin with the type of the readonly data. If
there's any additional information (e.g., the function name for
objects like `PcDescriptors` when `SNAPSHOT_BACKTRACE` is defined),
that follows the type in parentheses.
* For direct-to-ELF snapshots, we allow symbols to have duplicate names.
Thus, internally we create unique ids for all created symbols and
refactor the ELF and DWARF subsystems to pass and store these ids
instead of the symbol names.
* For assembly output, symbols must have unique names. The namer now
has a `CStringIntMap` that keeps counts of the number of times a
given symbol name has been generated for assembly output. If the
symbol name is in the `CStringIntMap`, then the new count in the map
is added as a suffix to ensure uniqueness.
For example, the first symbol created using the name `_StringBase.[]`
has no suffix. If a second symbol is created using the same name,
the second symbol is instead named `_StringBase.[] (#2)`.
This also happens for read-only objects with additional information if
that additional information is not sufficient to make it unique, and
is added separately from that additional information.
* A further restriction for assembly output is that symbols that begin
with 'L' have special meaning to the assembler. Thus, we keep the
old system of prepending such symbol names with an underscore to
avoid this behavior.
TEST=vm/dart{,_2}/use_add_readonly_data_symbol_flag
Bug: b/248012965
Change-Id: I1b6e876f4fb4f42f4a3b90e03110a34a87a03a7c
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-nnbd-linux-release-x64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-precomp-mac-product-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/262242
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Even if the main program disables executable stacks, dlopen'ing a library that doesn't itself disable executable stack will switch the stack to executable. (Presumably in the name of compatability with GNU nested functions.)
Dart does not need executable stacks, and executable stacks are an additional attack surface.
TEST=readelf
Bug: b/229648756
Change-Id: Ia8c234ebc6178a26528d37b1359a10dd42039a9b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/241540
Reviewed-by: Tess Strickland <sstrickl@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
We used to emit an unwinding rule for caller's SP, however
this does not really work as we expected it to work. Instead there is
an unwritten rule that caller's SP is equal to the CFA which overwrites
our unwinding rule (at least in libunwindstack library used by
Android).
This leads to unwinding issues on the boundary between C++ and Dart:
when we unwind through the InvokeDartCode stub frame we arrive to
C++ code with SP equal to callee's CFA, which is set to FP by our
unwinding rules. In this case if C++ code does not use FP based frames
we will fail to unwind C++ frame property - because SP will be
incorrect. This manifest in simpleperf profiles as stacks which
abruptly truncate at DartEntry::InvokeCode.
This CL rewrites unwinding rules to fix this: instead of using
FP as CFA we define CFA to be caller's SP (FP+2*kWordSize). This ensures
that unwinding on the boundary between C++ and Dart works correctly:
as CFA will always be consistently set to caller's SP.
Additionally this CL fixes InvokeDartCode stub to remove a value
that this stub pushes above saved return address in PRODUCT mode.
This value acts as a profiler marker used by builtin profiler
which is only included in non-PRODUCT builds - but the presence of this
value interfers with unwinding (caller's SP will be off by 1 due the
presence of this value).
We could produce custom unwinding information for this stub instead, but
just removing this value in PRODUCT builds should solve the problem
as we usually only profile Flutter release builds with simpleperf.
Fixes b/220804295
TEST=manually profiled a Flutter app and confirmed correct flamegraph.
Change-Id: I2094afaab6e54e89625c0b5a89aebc6b9823d67c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/235226
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
Implements a backend targeting RV32GC and RV64GC, based on Linux standardizing around GC. The assembler is written to make it easy to disable usage of C, but because the sizes of some instruction sequences are compile-time constants, an additional build configuration would need to be defined to make use of it.
The assembler and disassembler cover every RV32/64GC instruction. The simulator covers all instructions except accessing CSRs and the floating point state accessible through such, include accrued exceptions and dynamic rounding mode.
Quirks:
- RISC-V is a compare-and-branch architecture, but some existing "architecture-independent" parts of the Dart compiler assume a condition code architecture. To avoid rewriting these parts, we use a peephole in the assembler to map to compare-and-branch. See Assembler::BranchIf. Luckily nothing depended on taking multiple branches on the same condition code set.
- There are no hardware overflow checks, so we must use Hacker's Delight style software checks. Often these are very cheap: if the sign of one operand is known, a single branch is needed.
- The ranges of RISC-V branches and jumps are such that we use 3 levels of generation for forward branches, instead of the 2 levels of near and far branches used on ARM[64]. Nearly all code is handled by the first two levels with 20-bits of range, with enormous regex matchers triggering the third level that uses aupic+jalr to get 32-bits of range.
- For PC-relative calls in AOT, we always generate auipc+jalr pairs with 32-bits of range, so we never generate trampolines.
- Only a subset of registers are available in some compressed instructions, so we assign the most popular uses to these registers. In particular, THR, TMP[2], CODE and PP. This has the effect of assigning CODE and PP to volatile registers in the C calling convention, whereas they are assigned preserved registers on the other architectures. As on ARM64, PP is untagged; this is so short indices can be accessed with a compressed instruction.
- There are no push or pop instructions, so combining pushes and pops is preferred so we can update SP once.
- The C calling convention has a strongly aligned stack, but unlike on ARM64 we don't need to use an alternate stack pointer. The author ensured language was added to the RISC-V psABI making the OS responsible for realigning the stack pointer for signal handlers, allowing Dart to leave the stack pointer misaligned from the C calling convention's point of view until a foreign call.
- We don't bother with the link register tracking done on ARM[64]. Instead we make use of an alternate link register to avoid inline spilling in the write barrier.
Unimplemented:
- non-trivial FFI cases
- Compressed pointers - No intention to implement.
- Unboxed SIMD - We might make use of the V extension registers when the V extension is ratified.
- BigInt intrinsics
TEST=existing tests for IL level, new tests for assembler/disassembler/simulator
Bug: https://github.com/dart-lang/sdk/issues/38587
Bug: https://github.com/dart-lang/sdk/issues/48164
Change-Id: I991d1df4be5bf55efec5371b767b332d37dfa3e0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/217289
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
This ensures that the relocated addresses of sections with file contents
are contained in the loaded segment.
Fixes https://github.com/dart-lang/sdk/issues/47289
TEST=vm/dart{,_2}/use_save_debugging_info_flag
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-nnbd-linux-debug-x64-try,vm-kernel-precomp-nnbd-linux-release-x64-try
Change-Id: I6f7f94900ab1f9f0cb5ead4b0dd63bd2402e5a19
Fixed: 47289
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/214800
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
On Android native libraries can be mapped directly from an APK
they are stored uncompressed in it. In such situations the name
of the mapping no longer provides enough information for libunwindstack
to find the original ELF file and instead it has to rely on heuristics
to locate program header table. These heuristics currently assume that
program header table will be located in the RO mapping which precedes
RX mapping. This implies the following order of segments: RO (program
header, build id section if present, .rodata), RX (.text), RW (.dynamic
and .bss).
TEST=ci, manual
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-release-x64-try
Change-Id: I3fa4de75c5d8841a90fd4cae1ab230d02c554f94
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/206620
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
Previously in Elf::Relocation, symbol names had this mapping:
* nullptr: relative to the start of the snapshot
* ".": relative to the position of the relocation
* otherwise, relative to the given static symbol value
Change this as follows:
* nullptr: relative to the position of the relocation
* "": relative to the start of the snapshot
* otherwise, relative to the given static symbol value
This uses the fact that in ELF, symbol tables always have an initial
symbol with a name of "" that has a value of 0, so now we only have to
handle the nullptr case specially there, instead of having to handle
three different cases.
TEST=Refactoring, so existing tests of snapshots.
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-dwarf-linux-product-x64-try
Change-Id: Icb428551091e5fcf04facd34a5bf57ea0d664fa4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/206544
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
To do this, BitsContainer is changed to be a more rope-like
representation of section portions. In addition to containing
most of the same information stored per-section previously, each
portion also has a section-relative offset that is calculated when
it is added. Thus, merging two compatible BitsContainer sections
is just adding the portions from the second to the first, tweaking
the section-relative offset for each.
Other changes in this CL:
* Create PseudoSections subclasses for the elf header, program
header table, and section header table, so we can treat them
more uniformly with the other parts of the ELF snapshot.
* We now only allocate as much BSS space in the snapshot as is needed
for any text sections in the snapshot, instead of always allocating
a big enough BSS space for both VM and isolate, even for deferred
snapshots where there is no VM isolate.
* We already separated segment and section alignment in previous CLs,
so the fact that our own ELF loader needs load segments to be
page-aligned no longer means that the sections within those segments
also needs to be. Thus, we align individual instructions sections to
kMaxObjectAlignment, like readonly data sections, since both hold a
single Image object. This removes unnecessary intra-section padding.
TEST=Tests that check DWARF information and trybots that use ELF
snapshots.
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-dwarf-linux-product-x64-try
Change-Id: If0315c8b7b0f31481b676a8901f49cd3a44b5561
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/206365
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Create all symbol table-related sections after all other sections, right
before section re-ordering. Also remove the need to keep fields in the
Elf object for most of these sections, only keeping fields for the
static symbol table and the dynamic table, which handles updates
and finalization for the dynamic symbol table.
Reworks symbols so that they are stored in a growable array in the
symbol table instead of as separately allocated objects. Since this
disallows constant fields in Symbol objects due to the need for a copy
constructor, initialize the offset of symbols with the section-relative
offset. This can be adjusted to a snapshot-relative offset after
section memory offsets are computed.
Instead of updating indices and offsets by individually looking up
symbols via their name, just create a map from section indices to new
section indices (for index updates) or to memory offsets (for offset
adjustment) and iterate over all the symbols, applying the map
appropriately.
Move non-PT_LOAD, non-PT_PHDR segment creation into
OrderSectionsAndCreateSegments.
TEST=Refactoring, so existing ELF-based tests.
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-dwarf-linux-product-x64-try
Change-Id: Ic22f1bf3ab0b00ff3e73c431f92209526e787927
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/206220
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
It's not used outside of elf.cc and rarely used as a type outside
of SymbolTable, so nest it to avoid defining dart::Symbol.
TEST=Refactoring, so existing tests.
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-dwarf-linux-product-x64-try
Change-Id: Idc8895b95b021edf831bc310aff0cf3106de8eb1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/206367
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Previous CLs made it so that we don't need to calculate memory offsets
until finalization. This means that we can now reorder sections as
desired and then calculate the memory offsets at the same time as the
file offsets.
Thus, we reorder them so that writable, non-executable allocated
sections come first (due to requirements by some loaders to not sandwich
writable segments between non-writable ones), followed by non-writable,
non-executable allocated sections, followed by non-writable, executable
sections, and finally unallocated sections (to avoid differences in
memory offsets between snapshots and separate debugging information).
This ordering minimizes the number of segments that need to be created
(5 or 6, depending on whether a build ID exists).
Since we can reorder, we also delay the creation of the build ID (if
generated) and BSS sections until finalization, instead of creating them
up front in the constructor.
TEST=Further refactorings, so existing tests.
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-dwarf-linux-product-x64-try
Change-Id: Id4142a021c2bb800938e8bc711b1b8a7529bff51
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/205780
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
This CL splits the creation of ELF symbols into two parts: an
initialization that creates the symbol with all information but
the offset, and a finalization that sets the offset appropriately.
The initialization happens eagerly when adding sections, and the
finalization happens just prior to writing out the ELF contents,
after all memory and file offsets have been calculated.
To ensure safety, retrieving the offset from a symbol checks that
the symbol has been properly finalized.
This removes another obstacle to reordering sections and segments.
TEST=Further refactorings, so existing tests.
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-dwarf-linux-product-x64-try
Change-Id: I5dcb0d2c685fb341478e9a7d90c67fc4649a4e75
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/205481
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
This removes the need for the image snapshot writer to know the
starting memory offset of any ELF sections. Instead, relocation
and symbol information are recorded in the ELF writer to be
resolved during finalization.
This is a step towards being able to reorder sections in the
ELF memory space for better packing into segments. Delaying
relocation and symbol resolution also moves towards merging
multiple text or data sections into a single section if desired.
In addition, this CL removes redundant rows from the DWARF line
number program matrix to reduce the size of debugging information.
Originally, rows were written for every PC offset visited by the
CodeSourceMap. However, no row is needed if the source information
(file, line, column) is the same as the previously written row.
There are also fixes to Utils::{IsInt,IsUint,IsAbsoluteUint} to
allow N >= the bit size of the value.
TEST=Refactoring, so existing tests.
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-dwarf-linux-product-x64-try
Change-Id: I09f87cea214bca06b6fca60cd66138dae6da9e83
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/203766
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
* Make sure to emit .eh_frame before .dynamic section to satisfy
a single non-writable segment requirement (see Elf::WriteProgramTable)
* Use compiler::target::kWordSize instead of kWordSize when aligning
CIE/FDE and for data alignment factor.
TBR=aam@google.com
TEST=dartkp-linux-debug-simarm-crossword
Fixes https://github.com/dart-lang/sdk/issues/46403
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-simarm_x64-try
Change-Id: Ieb73b7b90edcce91709201dc92caf0bb74ac1189
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/204201
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
TEST=tested manually
This is a reland of ddfbe05eee
Original change's description:
> [vm/aot] Emit simple .eh_frame in ARM/ARM64 ELF snapshots.
>
> This allows simpleperf to unwind through AOT compiled frames and
> consequently allows Android tooling to produce useful
> timelines and flamegraphs.
>
> Note: emitted .eh_frame is rather primitive and does not cover all possible
> asynchronous unwinding cases (e.g. tick might arrive before Dart frame was
> fully setup). We will address this in a separate CL.
>
> Additionally, this CL tweaks .eh_frame emitted in assembly snapshots to
> workaround Android-specific unwinding bug in libunwindstack (b/191113792):
> current versions of libunwindstack don't push CFA value when evaluating
> DW_CFA_expression.
>
> TEST=tested manually
>
> Bug: b/184102680,b/190248517
> Change-Id: Iea209b2354cca0753385093f165b0320857104b1
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/203771
> Commit-Queue: Slava Egorov <vegorov@google.com>
> Reviewed-by: Tess Strickland <sstrickl@google.com>
Bug: b/184102680,b/190248517
Cq-Include-Trybots: luci.dart.try:vm-kernel-linux-release-simarm64-try,vm-kernel-linux-release-simarm-try
Change-Id: Id888f906307ec3b2e73deec3cf1c2ead5672a2af
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/204100
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
This reverts commit ddfbe05eee.
Reason for revert: broke ARM32 builds
Original change's description:
> [vm/aot] Emit simple .eh_frame in ARM/ARM64 ELF snapshots.
>
> This allows simpleperf to unwind through AOT compiled frames and
> consequently allows Android tooling to produce useful
> timelines and flamegraphs.
>
> Note: emitted .eh_frame is rather primitive and does not cover all possible
> asynchronous unwinding cases (e.g. tick might arrive before Dart frame was
> fully setup). We will address this in a separate CL.
>
> Additionally, this CL tweaks .eh_frame emitted in assembly snapshots to
> workaround Android-specific unwinding bug in libunwindstack (b/191113792):
> current versions of libunwindstack don't push CFA value when evaluating
> DW_CFA_expression.
>
> TEST=tested manually
>
> Bug: b/184102680,b/190248517
> Change-Id: Iea209b2354cca0753385093f165b0320857104b1
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/203771
> Commit-Queue: Slava Egorov <vegorov@google.com>
> Reviewed-by: Tess Strickland <sstrickl@google.com>
TBR=vegorov@google.com,sstrickl@google.com
Change-Id: I57ab5df1d567bb4ddea813024245ef606712a79c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: b/184102680,b/190248517
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/203778
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
This allows simpleperf to unwind through AOT compiled frames and
consequently allows Android tooling to produce useful
timelines and flamegraphs.
Note: emitted .eh_frame is rather primitive and does not cover all possible
asynchronous unwinding cases (e.g. tick might arrive before Dart frame was
fully setup). We will address this in a separate CL.
Additionally, this CL tweaks .eh_frame emitted in assembly snapshots to
workaround Android-specific unwinding bug in libunwindstack (b/191113792):
current versions of libunwindstack don't push CFA value when evaluating
DW_CFA_expression.
TEST=tested manually
Bug: b/184102680,b/190248517
Change-Id: Iea209b2354cca0753385093f165b0320857104b1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/203771
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
This reverts commit 80102c981b.
Reason for revert: b/186359854
Original change's description:
> [vm] Switch datastream Write/WriteUnsigned to (S)LEB128.
>
> This reduces the number of variable-length integer encodings in our
> database from 2 to 1, and chooses the more standard one.
>
> TEST=Existing tests, in particular any that involve snapshots.
>
> Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-asan-linux-release-x64-try,vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-msan-linux-release-x64-try,vm-kernel-precomp-ubsan-linux-release-x64-try,vm-kernel-precomp-tsan-linux-release-x64-try,vm-kernel-precomp-nnbd-linux-debug-x64-try,vm-kernel-precomp-nnbd-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-simarm64c-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try
> Change-Id: Ia700158ac873ad32ac28c1027a669895961bc715
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196321
> Commit-Queue: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
# Not skipping CQ checks because original CL landed > 1 day ago.
Change-Id: Idf32bdd879cf8bb7407f6dae764312140ad6eeb2
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-asan-linux-release-x64-try,vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-msan-linux-release-x64-try,vm-kernel-precomp-ubsan-linux-release-x64-try,vm-kernel-precomp-tsan-linux-release-x64-try,vm-kernel-precomp-nnbd-linux-debug-x64-try,vm-kernel-precomp-nnbd-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-simarm64c-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196920
Reviewed-by: Ivan Inozemtsev <iinozemtsev@google.com>
Commit-Queue: Ivan Inozemtsev <iinozemtsev@google.com>
This reduces the number of variable-length integer encodings in our
database from 2 to 1, and chooses the more standard one.
TEST=Existing tests, in particular any that involve snapshots.
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Change-Id: Ia700158ac873ad32ac28c1027a669895961bc715
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196321
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
This is a reland of 5909fd111d
Does a large refactoring on the V8 snapshot profile writer
to clean things up, add more debugging support, and to fix
the problems that surfaced during the original landing.
Other changes:
Changes Serializer::CreateArtificialNodeIfNeeded() to create
artificial nodes for Code objects and immutable arrays.
Fixes CodeSerializationCluster::Trace() to only push needed parts of
discarded code objects, instead of tracing them like full code objects.
Adds test cases to v8_snapshot_profile_writer_test that exercise
the following situations (both separately and together):
* Non-symbolic stack traces are enabled and code and function objects
are dropped when not needed at runtime.
* Creation of the dispatch table is disabled.
TEST=vm/dart{,_2}/v8_snapshot_profile_writer_test
Original change's description:
> [vm] Fix V8 snapshot profile handling of the dispatch table.
>
> Fixes https://github.com/dart-lang/sdk/issues/45702.
>
> TEST=Tests listed in the issue above.
>
> Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-x64-try
> Change-Id: Ibf5e3ccf3828c01f9dda47de360314dabe8cb8a9
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/195272
> Reviewed-by: Daco Harkes <dacoharkes@google.com>
> Commit-Queue: Tess Strickland <sstrickl@google.com>
Change-Id: I8e7030267fe190079a8f68d00fe20bf7170e5719
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Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/195513
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Unlike cfc8e6de, this does _not_ replace the default variable length
encoding for {Read,Write}Streams, but insteads adds separate
{Read,Write}{S,}LEB128 methods to the appropriate classes. If we later
find the cause of the issues that led to the revert of cfc8e6de, it'll
be easy to switch over then.
Note that WriteLEB128 asserts that the value is non-negative if used
with a signed type (since negative values suggests that SLEB128 should
be used instead for minimal encoding).
Also removes the various other encoding and decoding methods for
(S)LEB128 across the codebase and changes those clients to use
{Read,Write}Streams instead.
Other cleanups:
* Various constant-related cleanups in datastream.h.
* Adds DART_FORCE_INLINE to ReadStream::ReadByte and uses it in the
default variable length decoding methods for retrieving bytes
from the stream instead of managing current_ by hand.
* Creates a canonical empty CompressedStackMaps instance and uses
that instead of the null CompressedStackMaps instance in most cases.
The only remaining (expected) use of the null CompressedStackMaps
instance is for the global table in the object store when no global
table exists (e.g., in JIT mode before any snapshotting).
* Moves CompressedStackMapsIterator from code_descriptors.h to an
Iterator class within CompressedStackMaps in object.h (similar to
PcDescriptors::Iterator), to limit friend declarations and because it
conceptually makes more sense as part of CompressedStackMaps.
* Removed CompressedStackMaps::PayloadByte, since existing clients
(CompressedStackMaps::Iterator, StackMapEntry in program_visitor.cc)
are better served by just operating on the payload buffer directly
(with appropriate NoSafepointScopes).
* WriteStreams no longer allocate their initial space on construction,
but rather on the first write, so no allocation is performed by
constructing a never-used WriteStream.
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Change-Id: Ice63321abaa79157fbe9f230a864c8bba0e6dea9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/166421
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
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>
Fixes errors introduced by adding PRINTF_ATTRIBUTE to
BaseWriteStream::Printf due to attempting to print a
compiler::target::uword using the format for uword.
Original description:
For snapshot writing, we generally only have aligned writes so the old
methods worked well, but in some formats (like DWARF) we're not
guaranteed to have aligned writes and so had to use WriteBytes.
Instead, have WriteFixed call WriteBytes and replace any other uses of
WriteBytes(&value, sizeof(value)) with WriteFixed(value) instead.
Also makes the following additional changes:
* Expose WriteByte(value), instead of forcing use of
WriteFixed<uint8_t> or Raw<1,T>::Write to get the same behavior.
* Rename Print/VPrint to Printf/VPrintf, so methods taking format
strings are named consistently with others in the codebase.
* Add format string checking to Printf when supported.
* Add AddString() for non-formatted string writing.
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Change-Id: Ib70ccaa752dbf9ead5ea57e386a67725723bac84
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164324
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
This reverts commit 4e2556215a.
Reason for revert: Adding PRINTF_ATTRIBUTE broke more than expected on Mac bots.
Original change's description:
> [vm] Allow BaseWriteStream::WriteFixed to be used at unaligned positions.
>
> For snapshot writing, we generally only have aligned writes so the old
> methods worked well, but in some formats (like DWARF) we're not
> guaranteed to have aligned writes and so had to use WriteBytes.
> Instead, have WriteFixed call WriteBytes and replace any other uses of
> WriteBytes(&value, sizeof(value)) with WriteFixed(value) instead.
>
> Also makes the following additional changes:
>
> * Expose WriteByte(value), instead of forcing use of
> WriteFixed<uint8_t> or Raw<1,T>::Write to get the same behavior.
>
> * Rename Print/VPrint to Printf/VPrintf, so methods taking format
> strings are named consistently with others in the codebase.
>
> * Add format string checking to Printf when supported.
>
> * Add AddString() for non-formatted string writing.
>
> Change-Id: I5a2e91380bc41b0502e1a576acec786dfe66abbf
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164161
> Commit-Queue: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
TBR=kustermann@google.com,rmacnak@google.com,sstrickl@google.com
Change-Id: Ie90ac4477f4c581692b37429536ce8dd66788540
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164323
Reviewed-by: Tess Strickland <sstrickl@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
For snapshot writing, we generally only have aligned writes so the old
methods worked well, but in some formats (like DWARF) we're not
guaranteed to have aligned writes and so had to use WriteBytes.
Instead, have WriteFixed call WriteBytes and replace any other uses of
WriteBytes(&value, sizeof(value)) with WriteFixed(value) instead.
Also makes the following additional changes:
* Expose WriteByte(value), instead of forcing use of
WriteFixed<uint8_t> or Raw<1,T>::Write to get the same behavior.
* Rename Print/VPrint to Printf/VPrintf, so methods taking format
strings are named consistently with others in the codebase.
* Add format string checking to Printf when supported.
* Add AddString() for non-formatted string writing.
Change-Id: I5a2e91380bc41b0502e1a576acec786dfe66abbf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164161
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@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>
This reverts commit cfc8e6de3f.
Reason for revert: b/167520550
Original change's description:
> [vm] Have Read/WriteStream use (S)LEB128 for variable-length encoding.
>
> Previously, the non-fixed read and write methods of ReadStream and
> WriteStream used a similar but slightly different encoding to LEB128 for
> unsigned values and SLEB128 for signed values. The only difference was
> the high continuation marker bit, which was unset in non-final parts and
> set in final parts in the previous encoding, but is set for non-final
> parts and unset in final parts in (S)LEB128.
>
> This CL changes it so that they instead use the standard LEB128 and
> SLEB128 encodings. Among other things, this means that one-byte
> encodings of values in snapshots will be the value itself, not the value
> with the high bit set. This also means that when outputting specific
> formats that use (S)LEB128, like DWARF, the format writers can just use
> WriteStream::Write(Unsigned) directly instead of needing to write a
> separate encoder.
>
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> Change-Id: I409a22e7da9e4672011dfaccd3790c122ec3e522
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150526
> Commit-Queue: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
TBR=kustermann@google.com,rmacnak@google.com,sstrickl@google.com
Change-Id: Ie5b9e595e4dbe9bbed5f0dd5bdc6f78bd1233f5d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/161540
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
Previously, the non-fixed read and write methods of ReadStream and
WriteStream used a similar but slightly different encoding to LEB128 for
unsigned values and SLEB128 for signed values. The only difference was
the high continuation marker bit, which was unset in non-final parts and
set in final parts in the previous encoding, but is set for non-final
parts and unset in final parts in (S)LEB128.
This CL changes it so that they instead use the standard LEB128 and
SLEB128 encodings. Among other things, this means that one-byte
encodings of values in snapshots will be the value itself, not the value
with the high bit set. This also means that when outputting specific
formats that use (S)LEB128, like DWARF, the format writers can just use
WriteStream::Write(Unsigned) directly instead of needing to write a
separate encoder.
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Change-Id: I409a22e7da9e4672011dfaccd3790c122ec3e522
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150526
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
(Assignment of libraries to loading units is already done in the kernel generation step.)
After compiling and before serializing, we walk the program and for each Code we assign its Instructions, CodeSourceMap and CompressedStackMap to the loading unit of that Code's defining library. Deduplication may cause Instructions, CodeSourceMaps and CompressedStackMaps to belong to more than one loading unit; in this case the objects are assigned to the root loading unit. Later they can be more precisely assigned to the dominating loading unit.
All objects except some Instructions, CodeSourceMaps and CompressedStackMaps belong to the root loading unit's snapshot. This snapshot is written like an unsplit snapshot, except that when serializing Code, we will write a reference to a stub or null when the Code's Instructions, CodeSourceMap or CompressedStackMap belongs to a non-root loading unit. The snapshots of non-root loading units contain these deferred objects and references to the corresponding Code objects to patch. The types of objects we defer (Instructions, CodeSourceMaps and CompressedStackMaps) usually represent 70+% of the snapshot size.
Bare instructions mode must be disabled when splitting because we cannot have PC-relative calls between loading units. Later we can re-enable this for calls within loading units.
Broken: Compactor probably crashes we can now have an unbounded number of image pages and the compactor assumes a fixed number.
Embedder's guide:
At compile-time, gen_snapshot should be passed --loading_unit_manifest with a path, which will enable splitting and output a mapping from loading unit ids to snapshot output paths.
At runtime, sometime during isolate startup, an embedder should call Dart_SetDeferredLoadHandler, probably near an existing call to Dart_SetLibraryTagHandler. The callback is given a loading unit id, and should eventually call Dart_DeferredLoadComplete[Error].
Bug: https://github.com/dart-lang/sdk/issues/41974
Change-Id: Ib597eb87c8cd634416d5ee1f00629c5550aebb00
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/152427
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@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>
Ryan Macnak