Remove support for `-Zprofile` (gcov-style coverage instrumentation) #131829

Zalathar · 2024-10-17T10:43:49Z

Tracking issue: #42524

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.

rustbot · 2024-10-17T10:43:57Z

r? @chenyukang

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rustbot · 2024-10-17T10:43:59Z

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

Zalathar · 2024-10-17T11:29:00Z

MCP: rust-lang/compiler-team#798

Zalathar · 2024-10-30T22:17:24Z

Rebased; MCP accepted.

@rustbot ready

chenyukang · 2024-11-01T07:07:27Z

@bors r+ rollup

bors · 2024-11-01T07:07:30Z

📌 Commit ce3e14a has been approved by chenyukang

It is now in the queue for this repository.

jieyouxu · 2024-11-01T07:10:11Z

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

…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.

Zalathar · 2024-11-01T08:28:54Z

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.

jieyouxu · 2024-11-01T08:29:44Z

@rustbot label +relnotes

…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

…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.

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

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

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

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

Support for -Zprofile has been removed in rust-lang/rust#131829

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

and use cargo-llvm-cov instead of grcov. Support for -Zprofile has been removed from Rust nightly: rust-lang/rust#131829

Support for -Zprofile has been removed in rust-lang/rust#131829

sylvestre · 2024-11-16T13:50:06Z

@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 :)

marco-c · 2024-11-16T15:53:59Z

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.

workingjubilee · 2024-11-16T23:38:35Z

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?

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.

rustbot assigned chenyukang Oct 17, 2024

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

Zalathar mentioned this pull request Oct 17, 2024

Remove unstable -Zprofile (gcov-style coverage) rust-lang/compiler-team#798

Closed

3 tasks

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

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

ce3e14a

Zalathar force-pushed the goodbye-zprofile branch from c543244 to ce3e14a Compare October 30, 2024 22:15

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 30, 2024

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

matthiaskrgr mentioned this pull request Nov 1, 2024

Rollup of 6 pull requests #132446

Closed

Zalathar removed the S-waiting-on-MCP Status: PR has a compiler MCP and is waiting for the compiler MCP to complete. label Nov 1, 2024

rustbot added the relnotes Marks issues that should be documented in the release notes of the next release. label Nov 1, 2024

rustbot mentioned this pull request Nov 1, 2024

Tracking issue for release notes of #131829: Remove support for -Zprofile (gcov-style coverage instrumentation) #132447

Open

3 tasks

jieyouxu mentioned this pull request Nov 1, 2024

Rollup of 13 pull requests #132462

Closed

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

dc5beb3

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

a1f8be2

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

f5b7c68

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

aafd0e8

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

619b954

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

f0c6e5e

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

d4f188c

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

c60baea

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 11, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

b6728c6

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

a-wing mentioned this pull request Nov 11, 2024

fix coverage binbat/live777#250

Merged

This was referenced Nov 12, 2024

Make incremental compilation work with -Zprofile #51983

Closed

Only allow codegen-units=1 when -Zprofile is used #51705

Closed

cakebaker added a commit to cakebaker/procps that referenced this pull request Nov 12, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

e9a4a1d

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 12, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

9920670

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 12, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

b0d7c7a

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

cakebaker added a commit to cakebaker/coreutils that referenced this pull request Nov 12, 2024

ci: use -Cprofile-generate instead of -Zprofile

e2e699e

Support for -Zprofile has been removed in rust-lang/rust#131829

cakebaker added a commit to cakebaker/coreutils that referenced this pull request Nov 12, 2024

ci: use -Cprofile-generate instead of -Zprofile

6e83cd6

Support for -Zprofile has been removed in rust-lang/rust#131829

cakebaker added a commit to cakebaker/coreutils that referenced this pull request Nov 12, 2024

ci: use -Cprofile-generate instead of -Zprofile

4529003

Support for -Zprofile has been removed in rust-lang/rust#131829

cakebaker added a commit to cakebaker/coreutils that referenced this pull request Nov 12, 2024

ci: use -Cprofile-generate instead of -Zprofile

953ab1e

Support for -Zprofile has been removed in rust-lang/rust#131829

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 12, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

28c728e

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

cakebaker added a commit to cakebaker/findutils that referenced this pull request Nov 13, 2024

ci: use -Cinstrument-coverage instead of -Zprofile

bca84ba

and use cargo-llvm-cov instead of grcov. Support for -Zprofile has been removed from Rust nightly: rust-lang/rust#131829

PierreZ mentioned this pull request Nov 13, 2024

Fix coverage CI foundationdb-rs/foundationdb-rs#189

Closed

cakebaker added a commit to cakebaker/coreutils that referenced this pull request Nov 14, 2024

ci: use -Cprofile-generate instead of -Zprofile

152eccf

Support for -Zprofile has been removed in rust-lang/rust#131829

cakebaker added a commit to cakebaker/coreutils that referenced this pull request Nov 15, 2024

ci: use -Cprofile-generate instead of -Zprofile

32d8bf1

Support for -Zprofile has been removed in rust-lang/rust#131829

sylvestre mentioned this pull request Nov 16, 2024

code coverage is broken - details of the error uutils/coreutils#6857

Open

Minoru mentioned this pull request Nov 17, 2024

Migrate to source-based code coverage newsboat/newsboat#2917

Open

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Remove support for `-Zprofile` (gcov-style coverage instrumentation) #131829

Remove support for `-Zprofile` (gcov-style coverage instrumentation) #131829

Zalathar commented Oct 17, 2024 •

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Remove support for -Zprofile (gcov-style coverage instrumentation) #131829

Remove support for -Zprofile (gcov-style coverage instrumentation) #131829

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Remove support for `-Zprofile` (gcov-style coverage instrumentation) #131829

Remove support for `-Zprofile` (gcov-style coverage instrumentation) #131829

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