Remove `-Ztime`
Because it has a lot of overlap with `-Ztime-passes` but is generally less useful. Plus some related cleanups.
Best reviewed one commit at a time.
r? `@davidtwco`
The compiler currently has `-Ztime` and `-Ztime-passes`. I've used
`-Ztime-passes` for years but only recently learned about `-Ztime`.
What's the difference? Let's look at the `-Zhelp` output:
```
-Z time=val -- measure time of rustc processes (default: no)
-Z time-passes=val -- measure time of each rustc pass (default: no)
```
The `-Ztime-passes` description is clear, but the `-Ztime` one is less so.
Sounds like it measures the time for the entire process?
No. The real difference is that `-Ztime-passes` prints out info about passes,
and `-Ztime` does the same, but only for a subset of those passes. More
specifically, there is a distinction in the profiling code between a "verbose
generic activity" and an "extra verbose generic activity". `-Ztime-passes`
prints both kinds, while `-Ztime` only prints the first one. (It took me
a close reading of the source code to determine this difference.)
In practice this distinction has low value. Perhaps in the past the "extra
verbose" output was more voluminous, but now that we only print stats for a
pass if it exceeds 5ms or alters the RSS, `-Ztime-passes` is less spammy. Also,
a lot of the "extra verbose" cases are for individual lint passes, and you need
to also use `-Zno-interleave-lints` to see those anyway.
Therefore, this commit removes `-Ztime` and the associated machinery. One thing
to note is that the existing "extra verbose" activities all have an extra
string argument, so the commit adds the ability to accept an extra argument to
the "verbose" activities.
Previously attempting to link universal libraries into libraries (but not binaries) would produce an error that "File too small to be an archive". This works around this by using `object` to extract a library for the target platform when passed a univeral library.
Fixes#55235
Use object instead of LLVM for reading bitcode from rlibs
Together with changes I plan to make as part of https://github.com/rust-lang/rust/pull/97485 this will allow entirely removing usage of LLVM's archive reader and thus allow removing `archive_ro.rs` and `ArchiveWrapper.cpp`.
Update the minimum external LLVM to 13
With this change, we'll have stable support for LLVM 13 through 15 (pending release).
For reference, the previous increase to LLVM 12 was #90175.
r? `@nagisa`
This avoids monomorphizing all linker code for each codegen backend and
will allow passing in extra information to the archive builder from the
codegen backend.
Enable raw-dylib for bin crates
Fixes#93842
When `raw-dylib` is used in a `bin` crate, we need to collect all of the `raw-dylib` functions, generate the import library and add that to the linker command line.
I also changed the tests so that 1) the C++ dlls are created after the Rust dlls, thus there is no chance of accidentally using them in the Rust linking process and 2) disabled generating import libraries when building with MSVC.
Allow to disable thinLTO buffer to support lto-embed-bitcode lld feature
Hello
This change is to fix issue (https://github.com/rust-lang/rust/issues/84395) in which passing "-lto-embed-bitcode=optimized" to lld when linking rust code via linker-plugin-lto doesn't produce the expected result.
Instead of emitting a single unified module into a llvmbc section of the linked elf, it emits multiple submodules.
This is caused because rustc emits the BC modules after running llvm `createWriteThinLTOBitcodePass` pass.
Which in turn triggers a thinLTO linkage and causes the said issue.
This patch allows via compiler flag (-Cemit-thin-lto=<bool>) to select between running `createWriteThinLTOBitcodePass` and `createBitcodeWriterPass`.
Note this pattern of selecting between those 2 passes is common inside of LLVM code.
The default is to match the old behavior.
Revert "Work around invalid DWARF bugs for fat LTO"
Since September, the toolchain has not been generating reliable DWARF
information for static variables when LTO is on. This has affected
projects in the embedded space where the use of LTO is typical. In our
case, it has kept us from bumping past the 2021-09-22 nightly toolchain
lest our debugger break. This has been a pretty dramatic regression for
people using debuggers and static variables. See #90357 for more info
and a repro case.
This commit is a mechanical revert of
d5de680e20 from PR #89041, which caused
the issue. (Note on that PR that the commit's author has requested it be
reverted.)
I have locally verified that this fixes#90357 by restoring the
functionality of both the repro case I posted on that bug, and debugger
behavior on real programs. There do not appear to be test cases for this
in the toolchain; if I've missed them, point me at 'em and I'll update
them.
Adding the option to control from rustc CLI
if the resulted ".o" bitcode module files are with
thinLTO info or regular LTO info.
Allows using "-lto-embed-bitcode=optimized" during linkage
correctly.
Signed-off-by: Ziv Dunkelman <ziv.dunkelman@nextsilicon.com>
Remove the source archive functionality of ArchiveWriter
We now build archives through strictly additive means rather than taking an existing archive and potentially substracting parts. This is simpler and makes it easier to swap out the archive writer in https://github.com/rust-lang/rust/pull/97485.
Support lint expectations for `--force-warn` lints (RFC 2383)
Rustc has a `--force-warn` flag, which overrides lint level attributes and forces the diagnostics to always be warn. This means, that for lint expectations, the diagnostic can't be suppressed as usual. This also means that the expectation would not be fulfilled, even if a lint had been triggered in the expected scope.
This PR now also tracks the expectation ID in the `ForceWarn` level. I've also made some minor adjustments, to possibly catch more bugs and make the whole implementation more robust.
This will probably conflict with https://github.com/rust-lang/rust/pull/97718. That PR should ideally be reviewed and merged first. The conflict itself will be trivial to fix.
---
r? `@wesleywiser`
cc: `@flip1995` since you've helped with the initial review and also discussed this topic with me. 🙃
Follow-up of: https://github.com/rust-lang/rust/pull/87835
Issue: https://github.com/rust-lang/rust/issues/85549
Yeah, and that's it.
To apply the optimization the `Virtual Function Elim` module flag has to
be set. To apply this optimization post-link the `LTOPostLink` module
flag has to be set.
Add Apple WatchOS compile targets
Hello,
I would like to add the following target triples for Apple WatchOS as Tier 3 platforms:
armv7k-apple-watchos
arm64_32-apple-watchos
x86_64-apple-watchos-sim
There are some pre-requisites Pull Requests:
https://github.com/rust-lang/compiler-builtins/pull/456 (merged)
https://github.com/alexcrichton/cc-rs/pull/662 (pending)
https://github.com/rust-lang/libc/pull/2717 (merged)
There will be a subsequent PR with standard library changes for WatchOS. Previous compiler and library changes were in a single PR (https://github.com/rust-lang/rust/pull/94736) which is now closed in favour of separate PRs.
Many thanks!
Vlad.
### Tier 3 Target Requirements
Adds support for Apple WatchOS compile targets.
Below are details on how this target meets the requirements for tier 3:
> tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)
`@deg4uss3r` has volunteered to be the target maintainer. I am also happy to help if a second maintainer is required.
> Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.
Uses the same naming as the LLVM target, and the same convention as other Apple targets.
> Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.
I don't believe there is any ambiguity here.
> Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.
I don't see any legal issues here.
> The target must not introduce license incompatibilities.
> Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0).
> The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.
> If the target supports building host tools (such as rustc or cargo), those host tools must not depend on proprietary (non-FOSS) libraries, other than ordinary runtime libraries supplied by the platform and commonly used by other binaries built for the target. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.
> Targets should not require proprietary (non-FOSS) components to link a functional binary or library.
> "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.
I see no issues with any of the above.
> Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.
> This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements.
Only relevant to those making approval decisions.
> Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.
core and alloc can be used. std support will be added in a subsequent PR.
> The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running tests (even if they do not pass), the documentation must explain how to run tests for the target, using emulation if possible or dedicated hardware if necessary.
Use --target=<target> option to cross compile, just like any target. Tests can be run using the WatchOS simulator (see https://developer.apple.com/documentation/xcode/running-your-app-in-the-simulator-or-on-a-device).
> Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.
> Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.
I don't foresee this being a problem.
> Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.
> In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.
No other targets should be affected by the pull request.
Make -Cpasses= only apply to pre-link optimization
This change causes passes specified in -Cpasses= to be applied
only during pre-link optimization, not during LTO. This avoids
such passes running multiple times, which they may not be
designed for.
Fixes https://github.com/rust-lang/rust/issues/97713
This change causes passes specified in -Cpasses= to be applied
only during pre-link optimization, not during LTO. This avoids
such passes running multiple times, which they may not be
designed for.
Fixes https://github.com/rust-lang/rust/issues/97713
Begin fixing all the broken doctests in `compiler/`
Begins to fix#95994.
All of them pass now but 24 of them I've marked with `ignore HELP (<explanation>)` (asking for help) as I'm unsure how to get them to work / if we should leave them as they are.
There are also a few that I marked `ignore` that could maybe be made to work but seem less important.
Each `ignore` has a rough "reason" for ignoring after it parentheses, with
- `(pseudo-rust)` meaning "mostly rust-like but contains foreign syntax"
- `(illustrative)` a somewhat catchall for either a fragment of rust that doesn't stand on its own (like a lone type), or abbreviated rust with ellipses and undeclared types that would get too cluttered if made compile-worthy.
- `(not-rust)` stuff that isn't rust but benefits from the syntax highlighting, like MIR.
- `(internal)` uses `rustc_*` code which would be difficult to make work with the testing setup.
Those reason notes are a bit inconsistently applied and messy though. If that's important I can go through them again and try a more principled approach. When I run `rg '```ignore \(' .` on the repo, there look to be lots of different conventions other people have used for this sort of thing. I could try unifying them all if that would be helpful.
I'm not sure if there was a better existing way to do this but I wrote my own script to help me run all the doctests and wade through the output. If that would be useful to anyone else, I put it here: https://github.com/Elliot-Roberts/rust_doctest_fixing_tool
Generate synthetic object file to ensure all exported and used symbols participate in the linking
Fix#50007 and #47384
This is the synthetic object file approach that I described in https://github.com/rust-lang/rust/pull/95363#issuecomment-1079932354, allowing all exported and used symbols to be linked while still allowing them to be GCed.
Related #93791, #95363
r? `@petrochenkov`
cc `@carbotaniuman`
Since September, the toolchain has not been generating reliable DWARF
information for static variables when LTO is on. This has affected
projects in the embedded space where the use of LTO is typical. In our
case, it has kept us from bumping past the 2021-09-22 nightly toolchain
lest our debugger break. This has been a pretty dramatic regression for
people using debuggers and static variables. See #90357 for more info
and a repro case.
This commit is a mechanical revert of
d5de680e20 from PR #89041, which caused
the issue. (Note on that PR that the commit's author has requested it be
reverted.)
I have locally verified that this fixes#90357 by restoring the
functionality of both the repro case I posted on that bug, and debugger
behavior on real programs. There do not appear to be test cases for this
in the toolchain; if I've missed them, point me at 'em and I'll update
them.
Direct users towards using Rust target feature names in CLI
This PR consists of a couple of changes on how we handle target features.
In particular there is a bug-fix wherein we avoid passing through features that aren't prefixed by `+` or `-` to LLVM. These appear to be causing LLVM to assert, which is pretty poor a behaviour (and also makes it pretty clear we expect feature names to be prefixed).
The other commit, I anticipate to be somewhat more controversial is outputting a warning when users specify a LLVM-specific, or otherwise unknown, feature name on the CLI. In those situations we request users to either replace it with a known Rust feature name (e.g. `bmi` -> `bmi1`) or file a feature request. I've a couple motivations for this: first of all, if users are specifying these features on the command line, I'm pretty confident there is also a need for these features to be usable via `#[cfg(target_feature)]` machinery. And second, we're growing a fair number of backends recently and having ability to provide some sort of unified-ish interface in this place seems pretty useful to me.
Sponsored by: standard.ai
Implement raw-dylib support for windows-gnu
Add support for `#[link(kind = "raw-dylib")]` on windows-gnu targets. Work around binutils's linker's inability to read import libraries produced by LLVM by calling out to the binutils `dlltool` utility to create an import library from a temporary .DEF file; this approach is effectively a slightly refined version of `@mati865's` earlier attempt at this strategy in PR #88801. (In particular, this attempt at this strategy adds support for `#[link_ordinal(...)]` as well.)
In support of #58713.
This was originally introduced in #10916 as a way to remove all landing
pads when performing LTO. However this is no longer necessary today
since rustc properly marks all functions and call-sites as nounwind
where appropriate.
In fact this is incorrect in the presence of `extern "C-unwind"` which
must create a landing pad when compiled with `-C panic=abort` so that
foreign exceptions are caught and properly turned into aborts.
In #79570, `-Z split-dwarf-kind={none,single,split}` was replaced by `-C
split-debuginfo={off,packed,unpacked}`. `-C split-debuginfo`'s packed
and unpacked aren't exact parallels to single and split, respectively.
On Unix, `-C split-debuginfo=packed` will put debuginfo into object
files and package debuginfo into a DWARF package file (`.dwp`) and
`-C split-debuginfo=unpacked` will put debuginfo into dwarf object files
and won't package it.
In the initial implementation of Split DWARF, split mode wrote sections
which did not require relocation into a DWARF object (`.dwo`) file which
was ignored by the linker and then packaged those DWARF objects into
DWARF packages (`.dwp`). In single mode, sections which did not require
relocation were written into object files but ignored by the linker and
were not packaged. However, both split and single modes could be
packaged or not, the primary difference in behaviour was where the
debuginfo sections that did not require link-time relocation were
written (in a DWARF object or the object file).
This commit re-introduces a `-Z split-dwarf-kind` flag, which can be
used to pick between split and single modes when `-C split-debuginfo` is
used to enable Split DWARF (either packed or unpacked).
Signed-off-by: David Wood <david.wood@huawei.com>
Allow loading LLVM plugins with both legacy and new pass manager
Opening a draft PR to get feedback and start discussion on this feature. There is already a codegen option `passes` which allow giving a list of LLVM pass names, however we currently can't use a LLVM pass plugin (as described here : https://llvm.org/docs/WritingAnLLVMPass.html), the only available passes are the LLVM built-in ones.
The proposed modification would be to add another codegen option `pass-plugins`, which can be set with a list of paths to shared library files. These libraries are loaded using the LLVM function `PassPlugin::Load`, which calls the expected symbol `lvmGetPassPluginInfo`, and register the pipeline parsing and optimization callbacks.
An example usage with a single plugin and 3 passes would look like this in the `.cargo/config`:
```toml
rustflags = [
"-C", "pass-plugins=/tmp/libLLVMPassPlugin",
"-C", "passes=pass1 pass2 pass3",
]
```
This would give the same functionality as the opt LLVM tool directly integrated in rust build system.
Additionally, we can also not specify the `passes` option, and use a plugin which inserts passes in the optimization pipeline, as one could do using clang.
Remove `in_band_lifetimes` from `rustc_codegen_llvm`
See #91867 for more information.
This one took a while. This crate has dozens of functions not associated with any type, and most of them were using in-band lifetimes for `'ll` and `'tcx`.
Apply path remapping to DW_AT_GNU_dwo_name when producing split DWARF
`--remap-path-prefix` doesn't apply to paths to `.o` (in case of packed) or `.dwo` (in case of unpacked) files in `DW_AT_GNU_dwo_name`. GCC also has this bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91888
Use module inline assembly to embed bitcode
In LLVM 14, our current method of setting section flags to avoid
embedding the `.llvmbc` section into final compilation artifacts
will no longer work, see issue #90326. The upstream recommendation
is to instead embed the entire bitcode using module-level inline
assembly, which is what this change does.
I've kept the existing code for platforms where we do not need to
set section flags, but possibly we should always be using the
inline asm approach (which would have to look a bit different for MachO).
r? `@nagisa`
In LLVM 14, our current method of setting section flags to avoid
embedding the `.llvmbc` section into final compilation artifacts
will no longer work, see issue #90326. The upstream recommendation
is to instead embed the entire bitcode using module-level inline
assembly, which is what this change does.
I've kept the existing code for platforms where we do not need to
set section flags, but possibly we should always be using the
inline asm approach.
The default diagnostic handler considers all remarks to be disabled by
default unless configured otherwise through LLVM internal flags:
`-pass-remarks`, `-pass-remarks-missed`, and `-pass-remarks-analysis`.
This behaviour makes `-Cremark` ineffective on its own.
Fix this by configuring a custom diagnostic handler that enables
optimization remarks based on the value of `-Cremark` option. With
`-Cremark=all` enabling all remarks.
Record more artifact sizes during self-profiling.
This PR adds artifact size recording for
- "linked artifacts" (executables, RLIBs, dylibs, static libs)
- object files
- dwo files
- assembly files
- crate metadata
- LLVM bitcode files
- LLVM IR files
- codegen unit size estimates
Currently the identifiers emitted for these are hard-coded as string literals. Is it worth adding constants to https://github.com/rust-lang/measureme/blob/master/measureme/src/rustc.rs instead? We don't do that for query names and the like -- but artifact kinds might be more stable than query names.
The only reason to use `abort_if_errors` is when the program is so broken that either:
1. later passes get confused and ICE
2. any diagnostics from later passes would be noise
This is never the case for lints, because the compiler has to be able to deal with `allow`-ed lints.
So it can continue to lint and compile even if there are lint errors.
Add -Z no-unique-section-names to reduce ELF header bloat.
This change adds a new compiler flag that can help reduce the size of ELF binaries that contain many functions.
By default, when enabling function sections (which is the default for most targets), the LLVM backend will generate different section names for each function. For example, a function `func` would generate a section called `.text.func`. Normally this is fine because the linker will merge all those sections into a single one in the binary. However, starting with [LLVM 12](https://github.com/llvm/llvm-project/commit/ee5d1a04), the backend will also generate unique section names for exception handling, resulting in thousands of `.gcc_except_table.*` sections ending up in the final binary because some linkers like LLD don't currently merge or strip these EH sections (see discussion [here](https://reviews.llvm.org/D83655)). This can bloat the ELF headers and string table significantly in binaries that contain many functions.
The new option is analogous to Clang's `-fno-unique-section-names`, and instructs LLVM to generate the same `.text` and `.gcc_except_table` section for each function, resulting in a smaller final binary.
The motivation to add this new option was because we have a binary that ended up with so many ELF sections (over 65,000) that it broke some existing ELF tools, which couldn't handle so many sections.
Here's our old binary:
```
$ readelf --sections old.elf | head -1
There are 71746 section headers, starting at offset 0x2a246508:
$ readelf --sections old.elf | grep shstrtab
[71742] .shstrtab STRTAB 0000000000000000 2977204c ad44bb 00 0 0 1
```
That's an 11MB+ string table. Here's the new binary using this option:
```
$ readelf --sections new.elf | head -1
There are 43 section headers, starting at offset 0x29143ca8:
$ readelf --sections new.elf | grep shstrtab
[40] .shstrtab STRTAB 0000000000000000 29143acc 0001db 00 0 0 1
```
The whole binary size went down by over 20MB, which is quite significant.
This change adds a new compiler flag that can help reduce the size of
ELF binaries that contain many functions.
By default, when enabling function sections (which is the default for most
targets), the LLVM backend will generate different section names for each
function. For example, a function "func" would generate a section called
".text.func". Normally this is fine because the linker will merge all those
sections into a single one in the binary. However, starting with LLVM 12
(llvm/llvm-project@ee5d1a0), the backend will
also generate unique section names for exception handling, resulting in
thousands of ".gcc_except_table.*" sections ending up in the final binary
because some linkers don't currently merge or strip these EH sections.
This can bloat the ELF headers and string table significantly in
binaries that contain many functions.
The new option is analogous to Clang's -fno-unique-section-names, and
instructs LLVM to generate the same ".text" and ".gcc_except_table"
section for each function, resulting in smaller object files and
potentially a smaller final binary.
Implement `#[link_ordinal(n)]`
Allows the use of `#[link_ordinal(n)]` with `#[link(kind = "raw-dylib")]`, allowing Rust to link against DLLs that export symbols by ordinal rather than by name. As long as the ordinal matches, the name of the function in Rust is not required to match the name of the corresponding function in the exporting DLL.
Part of #58713.
This largely involves implementing the options debug-info-for-profiling
and profile-sample-use and forwarding them on to LLVM.
AutoFDO can be used on x86-64 Linux like this:
rustc -O -Cdebug-info-for-profiling main.rs -o main
perf record -b ./main
create_llvm_prof --binary=main --out=code.prof
rustc -O -Cprofile-sample-use=code.prof main.rs -o main2
Now `main2` will have feedback directed optimization applied to it.
The create_llvm_prof tool can be obtained from this github repository:
https://github.com/google/autofdoFixes#64892.
Fix clippy lints
I'm currently working on allowing clippy to run on librustdoc after a discussion I had with `@Mark-Simulacrum.` So in the meantime, I fixed a few lints on the compiler crates.
Fix use after drop in self-profile with llvm events
self-profile with `-Z self-profile-events=llvm` have failed with a segmentation fault due to this use after drop.
this type of events can be more useful now that the new passmanager is the default.
The new pass manager is enabled by default in clang since
Clang/LLVM 13. While the discussion about this is still ongoing
(https://lists.llvm.org/pipermail/llvm-dev/2021-August/152305.html)
it's expected that support for the legacy pass manager will be
dropped either in LLVM 14 or 15.
This switches us to use the new pass manager if LLVM >= 13 is used.
This does not yet support #[link_name] attributes on functions, the #[link_ordinal]
attribute, #[link(kind = "raw-dylib")] on extern blocks in bin crates, or
stdcall functions on 32-bit x86.
This doesn't seem to be necessary anymore, although I don't know
at which point or why that changed.
Forcing -O1 makes some tests fail under NewPM, because NewPM also
performs inlining at -O1, so it ends up performing much more
optimization in practice than before.
This commit implements both the native linking modifiers infrastructure
as well as an initial attempt at the individual modifiers from the RFC.
It also introduces a feature flag for the general syntax along with
individual feature flags for each modifier.
Use FromStr trait for number option parsing
Replace `parse_uint` with generic `parse_number` based on `FromStr`.
Use it for parsing inlining threshold to avoid casting later.
Run LLVM coverage instrumentation passes before optimization passes
This matches the behavior of Clang and allows us to remove several
hacks which were needed to ensure functions weren't optimized away
before reaching the instrumentation pass.
Fixes#83429
cc `@richkadel`
r? `@tmandry`
This matches the behavior of Clang and allows us to remove several
hacks which were needed to ensure functions weren't optimized away
before reaching the instrumentation pass.
Adjust `-Ctarget-cpu=native` handling in cg_llvm
When cg_llvm encounters the `-Ctarget-cpu=native` it computes an
explciit set of features that applies to the target in order to
correctly compile code for the host CPU (because e.g. `skylake` alone is
not sufficient to tell if some of the instructions are available or
not).
However there were a couple of issues with how we did this. Firstly, the
order in which features were overriden wasn't quite right – conceptually
you'd expect `-Ctarget-cpu=native` option to override the features that
are implicitly set by the target definition. However due to how other
`-Ctarget-cpu` values are handled we must adopt the following order
of priority:
* Features from -Ctarget-cpu=*; are overriden by
* Features implied by --target; are overriden by
* Features from -Ctarget-feature; are overriden by
* function specific features.
Another problem was in that the function level `target-features`
attribute would overwrite the entire set of the globally enabled
features, rather than just the features the
`#[target_feature(enable/disable)]` specified. With something like
`-Ctarget-cpu=native` we'd end up in a situation wherein a function
without `#[target_feature(enable)]` annotation would have a broader
set of features compared to a function with one such attribute. This
turned out to be a cause of heavy run-time regressions in some code
using these function-level attributes in conjunction with
`-Ctarget-cpu=native`, for example.
With this PR rustc is more careful about specifying the entire set of
features for functions that use `#[target_feature(enable/disable)]` or
`#[instruction_set]` attributes.
Sadly testing the original reproducer for this behaviour is quite
impossible – we cannot rely on `-Ctarget-cpu=native` to be anything in
particular on developer or CI machines.
cc https://github.com/rust-lang/rust/issues/83027 `@BurntSushi`
When cg_llvm encounters the `-Ctarget-cpu=native` it computes an
explciit set of features that applies to the target in order to
correctly compile code for the host CPU (because e.g. `skylake` alone is
not sufficient to tell if some of the instructions are available or
not).
However there were a couple of issues with how we did this. Firstly, the
order in which features were overriden wasn't quite right – conceptually
you'd expect `-Ctarget-cpu=native` option to override the features that
are implicitly set by the target definition. However due to how other
`-Ctarget-cpu` values are handled we must adopt the following order
of priority:
* Features from -Ctarget-cpu=*; are overriden by
* Features implied by --target; are overriden by
* Features from -Ctarget-feature; are overriden by
* function specific features.
Another problem was in that the function level `target-features`
attribute would overwrite the entire set of the globally enabled
features, rather than just the features the
`#[target_feature(enable/disable)]` specified. With something like
`-Ctarget-cpu=native` we'd end up in a situation wherein a function
without `#[target_feature(enable)]` annotation would have a broader
set of features compared to a function with one such attribute. This
turned out to be a cause of heavy run-time regressions in some code
using these function-level attributes in conjunction with
`-Ctarget-cpu=native`, for example.
With this PR rustc is more careful about specifying the entire set of
features for functions that use `#[target_feature(enable/disable)]` or
`#[instruction_set]` attributes.
Sadly testing the original reproducer for this behaviour is quite
impossible – we cannot rely on `-Ctarget-cpu=native` to be anything in
particular on developer or CI machines.
Set path of the compile unit to the source directory
As part of the effort to implement split dwarf debug info, we ended up
setting the compile unit location to the output directory rather than
the source directory. Furthermore, it seems like we failed to remap the
prefixes for this as well!
The desired behaviour is to instead set the `DW_AT_GNU_dwo_name` to a
path relative to compiler's working directory. This still allows
debuggers to find the split dwarf files, while not changing the
behaviour of the code that is compiling with regular debug info, and not
changing the compiler's behaviour with regards to reproducibility.
Fixes#82074
cc `@alexcrichton` `@davidtwco`
In the backend we may want to remove certain temporary files, but in
certain other situations these files might not be produced in the first
place. We don't exactly care about that, and the intent is really that
these files are gone after a certain point in the backend.
Here we unify the backend file removing calls to use `ensure_removed`
which will attempt to delete a file, but will not fail if it does not
exist (anymore).
The tradeoff to this approach is, of course, that we may miss instances
were we are attempting to remove files at wrong paths due to some bug –
compilation would silently succeed but the temporary files would remain
there somewhere.
As part of the effort to implement split dwarf debug info, we ended up
setting the compile unit location to the output directory rather than
the source directory. Furthermore, it seems like we failed to remap the
prefixes for this as well!
The desired behaviour is to instead set the `DW_AT_GNU_dwo_name` to a
path relative to compiler's working directory. This still allows
debuggers to find the split dwarf files, while not changing the
behaviour of the code that is compiling with regular debug info, and not
changing the compiler's behaviour with regards to reproducibility.
Fixes#82074
This commit adds a new stable codegen option to rustc,
`-Csplit-debuginfo`. The old `-Zrun-dsymutil` flag is deleted and now
subsumed by this stable flag. Additionally `-Zsplit-dwarf` is also
subsumed by this flag but still requires `-Zunstable-options` to
actually activate. The `-Csplit-debuginfo` flag takes one of
three values:
* `off` - This indicates that split-debuginfo from the final artifact is
not desired. This is not supported on Windows and is the default on
Unix platforms except macOS. On macOS this means that `dsymutil` is
not executed.
* `packed` - This means that debuginfo is desired in one location
separate from the main executable. This is the default on Windows
(`*.pdb`) and macOS (`*.dSYM`). On other Unix platforms this subsumes
`-Zsplit-dwarf=single` and produces a `*.dwp` file.
* `unpacked` - This means that debuginfo will be roughly equivalent to
object files, meaning that it's throughout the build directory
rather than in one location (often the fastest for local development).
This is not the default on any platform and is not supported on Windows.
Each target can indicate its own default preference for how debuginfo is
handled. Almost all platforms default to `off` except for Windows and
macOS which default to `packed` for historical reasons.
Some equivalencies for previous unstable flags with the new flags are:
* `-Zrun-dsymutil=yes` -> `-Csplit-debuginfo=packed`
* `-Zrun-dsymutil=no` -> `-Csplit-debuginfo=unpacked`
* `-Zsplit-dwarf=single` -> `-Csplit-debuginfo=packed`
* `-Zsplit-dwarf=split` -> `-Csplit-debuginfo=unpacked`
Note that `-Csplit-debuginfo` still requires `-Zunstable-options` for
non-macOS platforms since split-dwarf support was *just* implemented in
rustc.
There's some more rationale listed on #79361, but the main gist of the
motivation for this commit is that `dsymutil` can take quite a long time
to execute in debug builds and provides little benefit. This means that
incremental compile times appear that much worse on macOS because the
compiler is constantly running `dsymutil` over every single binary it
produces during `cargo build` (even build scripts!). Ideally rustc would
switch to not running `dsymutil` by default, but that's a problem left
to get tackled another day.
Closes#79361
remove unused return type of dropck::check_drop_obligations()
don't wrap return type in Option in get_macro_by_def_id() since we would always return Some(..)
remove redundant return type of back::write::optimize()
don't Option-wrap return type of compute_type_parameters() since we always return Some(..)
don't return empty Result in assemble_generator_candidates()
don't return empty Result in assemble_closure_candidates()
don't return empty result in assemble_fn_pointer_candidates()
don't return empty result in assemble_candidates_from_impls()
don't return empty result in assemble_candidates_from_auto_impls()
don't return emtpy result in assemble_candidates_for_trait_alias()
don't return empty result in assemble_builtin_bound_candidates()
don't return empty results in assemble_extension_candidates_for_traits_in_scope() and assemble_extension_candidates_for_trait()
remove redundant wrapping of return type of StripItem::strip() since it always returns Some(..)
remove unused return type of assemble_extension_candidates_for_all_traits()
llvm-dwp concatenates `DW_AT_comp_dir` with `DW_AT_GNU_dwo_name` (only
when `DW_AT_comp_dir` exists), which can result in it failing to find
the DWARF object files.
In earlier testing, `DW_AT_comp_dir` wasn't present in the final
object and the current directory was the output directory.
When running tests through compiletest, the working directory of the
compilation is different from output directory and that resulted in
`DW_AT_comp_dir` being in the object file (and set to the current
working directory, rather than the output directory), and
`DW_AT_GNU_dwo_name` being set to the full path (rather than just
the filename), so llvm-dwp was failing.
This commit changes the compilation directory provided to LLVM to match
the output directory, where DWARF objects are output; and ensures that
only the filename is used for `DW_AT_GNU_dwo_name`.
Signed-off-by: David Wood <david@davidtw.co>
This commit implements Split DWARF support, wiring up the flag (added in
earlier commits) to the modified FFI wrapper (also from earlier
commits).
Signed-off-by: David Wood <david@davidtw.co>
This commit removes the `TargetMachineFactory` struct and adds a
`TargetMachineFactoryFn` type alias which is used everywhere that the
previous, long type was used.
Signed-off-by: David Wood <david@davidtw.co>
This commit modifies the FFI bindings to LLVM required for Split DWARF
support in rustc. In particular:
- `addPassesToEmitFile`'s wrapper, `LLVMRustWriteOutputFile` now takes
a `DwoPath` `const char*`. When disabled, `nullptr` should be provided
which will preserve existing behaviour. When enabled, the path to the
`.dwo` file should be provided.
- `createCompileUnit`'s wrapper, `LLVMRustDIBuilderCreateCompileUnit`
now has two additional arguments, for the `DWOId` and to enable
`SplitDebugInlining`. `DWOId` should always be zero.
- `createTargetMachine`'s wrapper, `LLVMRustCreateTargetMachine` has an
additional argument which should be provided the path to the `.dwo`
when enabled.
Signed-off-by: David Wood <david@davidtw.co>
This is useful for embedded targets where small code size is desired.
For example, on my project (thumbv7em-none-eabi) this yields a 0.6% code size reduction.
This commit grepped for LLVM_VERSION_GE, LLVM_VERSION_LT, get_major_version and
min-llvm-version and statically evaluated every expression possible
(and sensible) assuming that the LLVM version is >=9 now
with an eye on merging `TargetOptions` into `Target`.
`TargetOptions` as a separate structure is mostly an implementation detail of `Target` construction, all its fields logically belong to `Target` and available from `Target` through `Deref` impls.
This lets rustc users tweak whether the linker should relax ELF relocations,
namely whether it should emit R_X86_64_GOTPCRELX relocations instead of
R_X86_64_GOTPCREL, as the former is allowed by the ABI to be further
optimised. The default value is whatever the target defines.
This lets rustc users tweak whether all functions should be put in their own
TEXT section, using whatever default value the target defines if the flag
is missing.
Set .llvmbc and .llvmcmd sections as allocatable
This marks both sections as allocatable rather than excluded, which matches what
clang does with the equivalent `-fembed-bitcode` flag.
Preparation for a subsequent change that replaces
rustc_target::config::Config with its wrapped Target.
On its own, this commit breaks the build. I don't like making
build-breaking commits, but in this instance I believe that it
makes review easier, as the "real" changes of this PR can be
seen much more easily.
Result of running:
find compiler/ -type f -exec sed -i -e 's/target\.target\([)\.,; ]\)/target\1/g' {} \;
find compiler/ -type f -exec sed -i -e 's/target\.target$/target/g' {} \;
find compiler/ -type f -exec sed -i -e 's/target.ptr_width/target.pointer_width/g' {} \;
./x.py fmt
Use llvm::computeLTOCacheKey to determine post-ThinLTO CGU reuse
During incremental ThinLTO compilation, we attempt to re-use the
optimized (post-ThinLTO) bitcode file for a module if it is 'safe' to do
so.
Up until now, 'safe' has meant that the set of modules that our current
modules imports from/exports to is unchanged from the previous
compilation session. See PR #67020 and PR #71131 for more details.
However, this turns out be insufficient to guarantee that it's safe
to reuse the post-LTO module (i.e. that optimizing the pre-LTO module
would produce the same result). When LLVM optimizes a module during
ThinLTO, it may look at other information from the 'module index', such
as whether a (non-imported!) global variable is used. If this
information changes between compilation runs, we may end up re-using an
optimized module that (for example) had dead-code elimination run on a
function that is now used by another module.
Fortunately, LLVM implements its own ThinLTO module cache, which is used
when ThinLTO is performed by a linker plugin (e.g. when clang is used to
compile a C proect). Using this cache directly would require extensive
refactoring of our code - but fortunately for us, LLVM provides a
function that does exactly what we need.
The function `llvm::computeLTOCacheKey` is used to compute a SHA-1 hash
from all data that might influence the result of ThinLTO on a module.
In addition to the module imports/exports that we manually track, it
also hashes information about global variables (e.g. their liveness)
which might be used during optimization. By using this function, we
shouldn't have to worry about new LLVM passes breaking our module re-use
behavior.
In LLVM, the output of this function forms part of the filename used to
store the post-ThinLTO module. To keep our current filename structure
intact, this PR just writes out the mapping 'CGU name -> Hash' to a
file. To determine if a post-LTO module should be reused, we compare
hashes from the previous session.
This should unblock PR #75199 - by sheer chance, it seems to have hit
this issue due to the particular CGU partitioning and optimization
decisions that end up getting made.
Secure entry functions do not support if arguments are passed on the
stack. An "unsupported" diagnostic will be emitted by LLVM if that is
the case.
This commits adds support in Rust for that diagnostic so that an error
will be output if that is the case!
Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
During incremental ThinLTO compilation, we attempt to re-use the
optimized (post-ThinLTO) bitcode file for a module if it is 'safe' to do
so.
Up until now, 'safe' has meant that the set of modules that our current
modules imports from/exports to is unchanged from the previous
compilation session. See PR #67020 and PR #71131 for more details.
However, this turns out be insufficient to guarantee that it's safe
to reuse the post-LTO module (i.e. that optimizing the pre-LTO module
would produce the same result). When LLVM optimizes a module during
ThinLTO, it may look at other information from the 'module index', such
as whether a (non-imported!) global variable is used. If this
information changes between compilation runs, we may end up re-using an
optimized module that (for example) had dead-code elimination run on a
function that is now used by another module.
Fortunately, LLVM implements its own ThinLTO module cache, which is used
when ThinLTO is performed by a linker plugin (e.g. when clang is used to
compile a C proect). Using this cache directly would require extensive
refactoring of our code - but fortunately for us, LLVM provides a
function that does exactly what we need.
The function `llvm::computeLTOCacheKey` is used to compute a SHA-1 hash
from all data that might influence the result of ThinLTO on a module.
In addition to the module imports/exports that we manually track, it
also hashes information about global variables (e.g. their liveness)
which might be used during optimization. By using this function, we
shouldn't have to worry about new LLVM passes breaking our module re-use
behavior.
In LLVM, the output of this function forms part of the filename used to
store the post-ThinLTO module. To keep our current filename structure
intact, this PR just writes out the mapping 'CGU name -> Hash' to a
file. To determine if a post-LTO module should be reused, we compare
hashes from the previous session.
This should unblock PR #75199 - by sheer chance, it seems to have hit
this issue due to the particular CGU partitioning and optimization
decisions that end up getting made.
