Remove support for -Zprofile (gcov-style coverage instrumentation) by Zalathar · Pull Request #131829 · rust-lang/rust (original) (raw)

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Tracking issue: #42524

MCP: rust-lang/compiler-team#798

This PR removes the unstable -Zprofile flag, which enables ”gcov-style” coverage instrumentation, along with its associated -Zprofile-emit configuration flag.

(The profile flag predates and is almost entirely separate from the stable -Cinstrument-coverage flag.)

Notably, the -Zprofile flag:

• Is largely untested in-tree, having only one run-make test that does not check whether its output is correct or useful.
• Has no known maintainer.
• Has seen no push towards stabilization.
• Has at least one severe regression reported in 2022 that apparently remains unaddressed.
  • Regression in code coverage (-Zprofile) at some point after nightly-2021-11-11 #100125
• Is confusingly named, since it appears to be more about coverage than performance profiling, and has nothing to do with PGO.
• Is fundamentally limited by relying on counters auto-inserted by LLVM, with no knowledge of Rust beyond debuginfo.

r? @chenyukang

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rustbot added A-run-make

Area: port run-make Makefiles to rmake.rs

S-waiting-on-review

Status: Awaiting review from the assignee but also interested parties.

T-compiler

Relevant to the compiler team, which will review and decide on the PR/issue.

labels

Oct 17, 2024

This PR modifies tests/run-make/. If this PR is trying to port a Makefile
run-make test to use rmake.rs, please update the
run-make port tracking issue
so we can track our progress. You can either modify the tracking issue
directly, or you can comment on the tracking issue and link this PR.

cc @jieyouxu

jieyouxu added S-waiting-on-MCP

Status: PR has a compiler MCP and is waiting for the compiler MCP to complete.

and removed S-waiting-on-review

Status: Awaiting review from the assignee but also interested parties.

labels

Oct 17, 2024

📌 Commit ce3e14a has been approved by chenyukang

It is now in the queue for this repository.

bors added S-waiting-on-bors

Status: Waiting on bors to run and complete tests. Bors will change the label on completion.

and removed S-waiting-on-review

Status: Awaiting review from the assignee but also interested parties.

labels

Nov 1, 2024

Technically this is unstable flag, but should this get compat relnotes still?

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request

Nov 1, 2024

…ukang

Remove support for -Zprofile (gcov-style coverage instrumentation)

Tracking issue: rust-lang#42524

MCP: rust-lang/compiler-team#798

This PR removes the unstable -Zprofile flag, which enables ”gcov-style” coverage instrumentation, along with its associated -Zprofile-emit configuration flag.

(The profile flag predates and is almost entirely separate from the stable -Cinstrument-coverage flag.)

Notably, the -Zprofile flag:

• Is largely untested in-tree, having only one run-make test that does not check whether its output is correct or useful.
• Has no known maintainer.
• Has seen no push towards stabilization.
• Has at least one severe regression reported in 2022 that apparently remains unaddressed.
  • rust-lang#100125
• Is confusingly named, since it appears to be more about coverage than performance profiling, and has nothing to do with PGO.
• Is fundamentally limited by relying on counters auto-inserted by LLVM, with no knowledge of Rust beyond debuginfo.

Given the flag’s age and former importance (?), a mention in relnotes is probably warranted. I’ll try to come up with a suggested wording.

rustbot added the relnotes

Marks issues that should be documented in the release notes of the next release.

label

Nov 1, 2024

bors added a commit to rust-lang-ci/rust that referenced this pull request

Nov 1, 2024

…iaskrgr

Rollup of 6 pull requests

Successful merges:

• rust-lang#131829 (Remove support for -Zprofile (gcov-style coverage instrumentation))
• rust-lang#132341 (Reject raw lifetime followed by ', like regular lifetimes do)
• rust-lang#132369 (style-guide: Only use the new binop heuristic for assignments)
• rust-lang#132383 (Implement suggestion for never type fallback lints)
• rust-lang#132437 (coverage: Regression test for inlining into an uninstrumented crate)
• rust-lang#132438 (Remove unncessary option for default rust-analyzer setting)

r? @ghost @rustbot modify labels: rollup

jieyouxu added a commit to jieyouxu/rust that referenced this pull request

Nov 1, 2024

…ukang

Remove support for -Zprofile (gcov-style coverage instrumentation)

Tracking issue: rust-lang#42524

MCP: rust-lang/compiler-team#798

This PR removes the unstable -Zprofile flag, which enables ”gcov-style” coverage instrumentation, along with its associated -Zprofile-emit configuration flag.

(The profile flag predates and is almost entirely separate from the stable -Cinstrument-coverage flag.)

Notably, the -Zprofile flag:

• Is largely untested in-tree, having only one run-make test that does not check whether its output is correct or useful.
• Has no known maintainer.
• Has seen no push towards stabilization.
• Has at least one severe regression reported in 2022 that apparently remains unaddressed.
  • rust-lang#100125
• Is confusingly named, since it appears to be more about coverage than performance profiling, and has nothing to do with PGO.
• Is fundamentally limited by relying on counters auto-inserted by LLVM, with no knowledge of Rust beyond debuginfo.

bors added a commit to rust-lang-ci/rust that referenced this pull request

Nov 1, 2024

Rollup of 13 pull requests

Successful merges:

• rust-lang#131829 (Remove support for -Zprofile (gcov-style coverage instrumentation))
• rust-lang#132369 (style-guide: Only use the new binop heuristic for assignments)
• rust-lang#132383 (Implement suggestion for never type fallback lints)
• rust-lang#132437 (coverage: Regression test for inlining into an uninstrumented crate)
• rust-lang#132438 (Remove unncessary option for default rust-analyzer setting)
• rust-lang#132439 (Add f16 and f128 to invalid_nan_comparison)
• rust-lang#132445 (Cleanup attributes around unchecked shifts and unchecked negation in const)
• rust-lang#132448 (Add missing backtick)
• rust-lang#132450 (Show actual MIR when MIR building forgot to terminate block)
• rust-lang#132451 (remove some unnecessary rustc_allow_const_fn_unstable)
• rust-lang#132455 (make const_alloc_layout feature gate only about functions that are already stable)
• rust-lang#132456 (Move remaining inline assembly test files into asm directory)
• rust-lang#132459 (feat(byte_sub_ptr): unstably add ptr::byte_sub_ptr)

r? @ghost @rustbot modify labels: rollup

@Zalathar While not perfect, -Zprofile had advantages over the other option.
Since this change, we haven't been able to get coverage working on again on a medium size rust project:
uutils/coreutils#6857
(the size of the profraw files is way too large for Github).

Am I missing something? If not, would it be possible to reconsider this removal ? Thanks :)

Agreed with @sylvestre, there are many users, and some large projects might have difficulties switching to source-based coverage as it can be more resource intensive.
If there are no considerable benefits stemming from its removal, it would be ideal to keep it even with its limitations.

My understanding is that the "limitations" are coverage info that can be incorrect by a factor greater than 10, right? It's based on debuginfo, but either not in a way that seems to be very accurate for Rust code, or we are emitting debuginfo in a way that is not useful for it, right?

Minoru added a commit to newsboat/newsboat that referenced this pull request

Nov 17, 2024

We used to rely on -Zprofile, but it was recently removed from Rust Nightly: rust-lang/rust#131829 This commit switches to a stable alternative; cf. mozilla/grcov#1240

This change is accompanied by a change in the build environment: instead of using Clang 18 with Rust Nightly, we now use Clang 18 with Rust 1.81. That's the last Rust version based on LLVM 18. Previously we tried to match LLVM versions between C++ and Rust to avoid weird coverage results. Now, it's required to match them, otherwise no coverage is gathered at all.

Fixes #2912.

If there are no considerable benefits stemming from its removal, it would be ideal to keep it even with its limitations.

Unfortunately, the existing code was causing real maintenance problems in other parts of the compiler, which was one of the reasons for removing it.

It would also be nice if someone reported to LLVM about the storage usage being excessive. I feel it is doubtful they have done any optimizations on the profdata format's space usage.

elcoosp added a commit to elcoosp/scrpr that referenced this pull request

Nov 23, 2024

rwestphal added a commit to holo-routing/holo that referenced this pull request

Nov 25, 2024

The rustc's -Zprofile compiler flag was removed on nightly [1], which means gcov-style coverage instrumentation is no longer possible.

[1] rust-lang/rust#131829

Signed-off-by: Renato Westphal renato@opensourcerouting.org

rwestphal added a commit to holo-routing/holo that referenced this pull request

Nov 25, 2024

The rustc's -Zprofile compiler flag was removed on nightly [1], which means gcov-style coverage instrumentation is no longer possible.

[1] rust-lang/rust#131829

Signed-off-by: Renato Westphal renato@opensourcerouting.org

Grinkers added a commit to tiipotto/tii that referenced this pull request

Jan 18, 2025

Grinkers added a commit to tiipotto/tii that referenced this pull request

Jan 18, 2025

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Jan 18, 2025

tmeijn pushed a commit to tmeijn/dotfiles that referenced this pull request

Jan 22, 2025

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mbehr1 added a commit to mbehr1/adlt that referenced this pull request

Feb 2, 2025

mbehr1 added a commit to mbehr1/adlt that referenced this pull request

Feb 2, 2025

wip-sync pushed a commit to NetBSD/pkgsrc-wip that referenced this pull request

Feb 2, 2025

Pkgsrc changes:

• Adapt patches, one of the patched files were restructured upstream.
• Checksum changes.

Upstream changes:

Version 1.84.1 (2025-01-30)

• [Fix ICE 132920 in duplicate-crate diagnostics.] (rust-lang/rust#133304)
• [Fix errors for overlapping impls in incremental rebuilds.] (rust-lang/rust#133828)
• [Fix slow compilation related to the next-generation trait solver.] (rust-lang/rust#135618)
• [Fix debuginfo when LLVM's location discriminator value limit is exceeded.] (rust-lang/rust#135643)
• Fixes for building Rust from source:
  • [Only try to distribute llvm-objcopy if llvm tools are enabled.] (rust-lang/rust#134240)
  • [Add Profile Override for Non-Git Sources.] (rust-lang/rust#135433)
  • [Resolve symlinks of LLVM tool binaries before copying them.] (rust-lang/rust#135585)
  • [Make it possible to use ci-rustc on tarball sources.] (rust-lang/rust#135722)

Version 1.84.0 (2025-01-09)

Language

• [Allow #[deny] inside #[forbid] as a no-op] (rust-lang/rust#121560)
• [Show a warning when -Ctarget-feature is used to toggle features that can lead to unsoundness due to ABI mismatches] (rust-lang/rust#129884)
• [Use the next-generation trait solver in coherence] (rust-lang/rust#130654)
• [Allow coercions to drop the principal of trait objects] (rust-lang/rust#131857)
• [Support / as the path separator for include!() in all cases on Windows] (rust-lang/rust#125205)
• [Taking a raw ref (raw (const|mut)) of a deref of a pointer (*ptr) is now safe] (rust-lang/rust#129248)
• [Stabilize s390x inline assembly] (rust-lang/rust#131258)
• [Stabilize Arm64EC inline assembly] (rust-lang/rust#131781)
• [Lint against creating pointers to immediately dropped temporaries] (rust-lang/rust#128985)
• [Execute drop glue when unwinding in an extern "C" function] (rust-lang/rust#129582)

Compiler

• [Add --print host-tuple flag to print the host target tuple and affirm the "target tuple" terminology over "target triple"] (rust-lang/rust#125579)
• [Declaring functions with a calling convention not supported on the current target now triggers a hard error] (rust-lang/rust#129935)
• [Set up indirect access to external data for loongarch64-unknown-linux-{musl,ohos}] (rust-lang/rust#131583)
• [Enable XRay instrumentation for LoongArch Linux targets] (rust-lang/rust#131818)
• [Extend the unexpected_cfgs lint to also warn in external macros] (rust-lang/rust#132577)
• [Stabilize WebAssembly multivalue, reference-types, and tail-call target features] (rust-lang/rust#131080)
• [Added Tier 2 support for the wasm32v1-none target] (rust-lang/rust#131487)

Libraries

• [Implement From<&mut {slice}> for Box/Rc/Arc<{slice}>] (rust-lang/rust#129329)
• [Move <float>::copysign, <float>::abs, <float>::signum to core] (rust-lang/rust#131304)
• [Add LowerExp and UpperExp implementations to NonZero] (rust-lang/rust#131377)
• [Implement FromStr for CString and TryFrom<CString> for String] (rust-lang/rust#130608)
• [std::os::darwin has been made public] (rust-lang/rust#130635)

Stabilized APIs

• [Ipv6Addr::is_unique_local] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.is_unique_local)
• [Ipv6Addr::is_unicast_link_local] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.is_unicast_link_local)
• [core::ptr::with_exposed_provenance] (https://doc.rust-lang.org/stable/core/ptr/fn.with_exposed_provenance.html)
• [core::ptr::with_exposed_provenance_mut] (https://doc.rust-lang.org/stable/core/ptr/fn.with_exposed_provenance_mut.html)
• [<ptr>::addr] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.addr)
• [<ptr>::expose_provenance] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.expose_provenance)
• [<ptr>::with_addr] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.with_addr)
• [<ptr>::map_addr] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.map_addr)
• [<int>::isqrt] (https://doc.rust-lang.org/stable/core/primitive.i32.html#method.isqrt)
• [<int>::checked_isqrt] (https://doc.rust-lang.org/stable/core/primitive.i32.html#method.checked_isqrt)
• [<uint>::isqrt] (https://doc.rust-lang.org/stable/core/primitive.u32.html#method.isqrt)
• [NonZero::isqrt] (https://doc.rust-lang.org/stable/core/num/struct.NonZero.html#impl-NonZero%3Cu128%3E/method.isqrt)
• [core::ptr::without_provenance] (https://doc.rust-lang.org/stable/core/ptr/fn.without_provenance.html)
• [core::ptr::without_provenance_mut] (https://doc.rust-lang.org/stable/core/ptr/fn.without_provenance_mut.html)
• [core::ptr::dangling] (https://doc.rust-lang.org/stable/core/ptr/fn.dangling.html)
• [core::ptr::dangling_mut] (https://doc.rust-lang.org/stable/core/ptr/fn.dangling_mut.html)

These APIs are now stable in const contexts

• [AtomicBool::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicBool.html#method.from_ptr)
• [AtomicPtr::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicPtr.html#method.from_ptr)
• [AtomicU8::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicU8.html#method.from_ptr)
• [AtomicU16::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicU16.html#method.from_ptr)
• [AtomicU32::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicU32.html#method.from_ptr)
• [AtomicU64::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicU64.html#method.from_ptr)
• [AtomicUsize::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicUsize.html#method.from_ptr)
• [AtomicI8::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicI8.html#method.from_ptr)
• [AtomicI16::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicI16.html#method.from_ptr)
• [AtomicI32::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicI32.html#method.from_ptr)
• [AtomicI64::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicI64.html#method.from_ptr)
• [AtomicIsize::from_ptr] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicIsize.html#method.from_ptr)
• [<ptr>::is_null] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.is_null-1)
• [<ptr>::as_ref] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.as_ref-1)
• [<ptr>::as_mut] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.as_mut)
• [Pin::new] (https://doc.rust-lang.org/stable/core/pin/struct.Pin.html#method.new)
• [Pin::new_unchecked] (https://doc.rust-lang.org/stable/core/pin/struct.Pin.html#method.new_unchecked)
• [Pin::get_ref] (https://doc.rust-lang.org/stable/core/pin/struct.Pin.html#method.get_ref)
• [Pin::into_ref] (https://doc.rust-lang.org/stable/core/pin/struct.Pin.html#method.into_ref)
• [Pin::get_mut] (https://doc.rust-lang.org/stable/core/pin/struct.Pin.html#method.get_mut)
• [Pin::get_unchecked_mut] (https://doc.rust-lang.org/stable/core/pin/struct.Pin.html#method.get_unchecked_mut)
• [Pin::static_ref] (https://doc.rust-lang.org/stable/core/pin/struct.Pin.html#method.static_ref)
• [Pin::static_mut] (https://doc.rust-lang.org/stable/core/pin/struct.Pin.html#method.static_mut)

Cargo

• [Stabilize MSRV-aware resolver config] (rust-lang/cargo#14639)
• [Stabilize resolver v3] (rust-lang/cargo#14754)

Rustdoc

• [rustdoc-search: improve type-driven search] (rust-lang/rust#127589)

Compatibility Notes

• [Enable by default the LSX target feature for LoongArch Linux targets] (rust-lang/rust#132140)
• The unstable -Zprofile flag ("gcov-style" coverage instrumentation) has been removed. This does not affect the stable flags for coverage instrumentation (-Cinstrument-coverage) and profile-guided optimization (-Cprofile-generate, -Cprofile-use), which are unrelated and remain available.
• Support for the target named wasm32-wasi has been removed as the target is now named wasm32-wasip1. This completes the [transition] (rust-lang/compiler-team#607) plan for this target following [the introduction of wasm32-wasip1] (rust-lang/rust#120468) in Rust 1.78. Compiler warnings on [use of wasm32-wasi] (rust-lang/rust#126662) introduced in Rust 1.81 are now gone as well as the target is removed.
• [The syntax &pin (mut|const) T is now parsed as a type which in theory could affect macro expansion results in some edge cases] (rust-lang/rust#130635 (comment))
• [Legacy syntax for calling std::arch functions is no longer permitted to declare items or bodies (such as closures, inline consts, or async blocks).] (rust-lang/rust#130443 (comment))
• The wasm32-unknown-emscripten target's binary release of the standard library is now [built with the latest emsdk 3.1.68] (rust-lang/rust#131533), which fixes an ABI-incompatibility with Emscripten >= 3.1.42. If you are locally using a version of emsdk with an incompatible ABI (e.g. before 3.1.42 or a future one), you should build your code with -Zbuild-std to ensure that std uses the correct ABI.
• [Declaring functions with a calling convention not supported on the current target now triggers a hard error] (rust-lang/rust#129935)
• [The next-generation trait solver is now enabled for coherence, fixing multiple soundness issues] (rust-lang/rust#130654)

cakebaker added a commit to cakebaker/findutils that referenced this pull request

Feb 7, 2025

and use cargo-llvm-cov instead of grcov.

Support for -Zprofile has been removed from Rust nightly: rust-lang/rust#131829

Zalathar added a commit to dpaoliello/rust that referenced this pull request

Feb 13, 2025

sylvestre pushed a commit to cakebaker/ansi-width that referenced this pull request

Feb 27, 2025

GJKrupa added a commit to krupa-dev/manplan that referenced this pull request

Mar 16, 2025

Labels

A-run-make

Area: port run-make Makefiles to rmake.rs

relnotes

Marks issues that should be documented in the release notes of the next release.

S-waiting-on-bors

Status: Waiting on bors to run and complete tests. Bors will change the label on completion.

T-compiler

Relevant to the compiler team, which will review and decide on the PR/issue.