debuginfo: emit DW_TAG_call_site entries by resrever · Pull Request #154200 · rust-lang/rust

resrever · 2026-03-22T03:56:11Z

Set FlagAllCallsDescribed on function definition DIEs so LLVM emits DW_TAG_call_site entries, letting debuggers and analysis tools track tail calls.

rustbot · 2026-03-22T12:16:46Z

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rustbot · 2026-03-22T12:38:53Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

JohnTitor · 2026-03-25T11:41:17Z

@rustbot reroll

dingxiangfei2009 · 2026-03-25T12:42:10Z

Thank you for your contribution! 🙇

@bors r+

rust-bors · 2026-03-25T12:42:14Z

📌 Commit 9677d7a has been approved by dingxiangfei2009

It is now in the queue for this repository.

dingxiangfei2009 · 2026-03-25T12:48:57Z

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

 ASSERT_DIFLAG_VALUE(FlagNonTrivial, 1 << 26);
 ASSERT_DIFLAG_VALUE(FlagBigEndian, 1 << 27);
 ASSERT_DIFLAG_VALUE(FlagLittleEndian, 1 << 28);
+static_assert(DINode::DIFlags::FlagAllCallsDescribed == (1 << 29));


I have filed a PR upstream llvm/llvm-project#188477 to add this flag bit to the C header.

Oh I forgot to link my upstream PR to add the flag. Yours appears to be format changes only?

Okay... so my clangd automatically apply those formatting and apparently git-clang-format agreed with it.

dingxiangfei2009 · 2026-03-25T15:11:01Z

@bors r-

dingxiangfei2009 · 2026-03-25T15:13:06Z

Sorry, fat finger.

@bors r+

rust-bors · 2026-03-25T15:13:10Z

📌 Commit 9677d7a has been approved by dingxiangfei2009

It is now in the queue for this repository.

…r=dingxiangfei2009 debuginfo: emit DW_TAG_call_site entries Set `FlagAllCallsDescribed` on function definition DIEs so LLVM emits DW_TAG_call_site entries, letting debuggers and analysis tools track tail calls.

…uwer Rollup of 22 pull requests Successful merges: - #153049 (Add `-Zsanitize=kernel-hwaddress`) - #153702 (Add macro matcher for `guard` fragment specifier) - #154200 (debuginfo: emit DW_TAG_call_site entries) - #154263 (interpret: when passing an argument fails, point at that argument) - #154269 (miri recursive validation: only check one layer deep) - #154313 (Init `self_decl` with a correct visibility) - #154344 (Update LLVM to 22.1.2) - #154348 (re-enable enzyme/autodiff builds on dist-aarch64-apple) - #154351 (Overhaul `Erasable` impls) - #154363 (delegation: fix zero-args nested delegation ICE) - #154364 (delegation: don't propagate synthetic params, remove lifetime hacks) - #151148 (Add functions to `GrowableBitSet`) - #154090 (Move tests in the statics category) - #154112 (some `tests/ui/macros` cleanup) - #154131 (begin `tests/ui/structs-enums` cleanup) - #154216 (unstably mark `NonNull::with_exposed_provenance` as const) - #154230 (Moved and rename issue-50411 to tests/ui/mir/inliner-double-elaborate) - #154233 (Move ui/issues tests to relevant subdirectories) - #154288 (Fix typo in doc comment for `char::to_titlecase`) - #154355 (delegation: add const type ICE test) - #154358 (install-template.sh: Optimize by using Bourne shell builtins.) - #154360 (fromrangeiter-overflow-checks: accept optional `signext` for argument)

…uwer Rollup of 22 pull requests Successful merges: - rust-lang/rust#153049 (Add `-Zsanitize=kernel-hwaddress`) - rust-lang/rust#153702 (Add macro matcher for `guard` fragment specifier) - rust-lang/rust#154200 (debuginfo: emit DW_TAG_call_site entries) - rust-lang/rust#154263 (interpret: when passing an argument fails, point at that argument) - rust-lang/rust#154269 (miri recursive validation: only check one layer deep) - rust-lang/rust#154313 (Init `self_decl` with a correct visibility) - rust-lang/rust#154344 (Update LLVM to 22.1.2) - rust-lang/rust#154348 (re-enable enzyme/autodiff builds on dist-aarch64-apple) - rust-lang/rust#154351 (Overhaul `Erasable` impls) - rust-lang/rust#154363 (delegation: fix zero-args nested delegation ICE) - rust-lang/rust#154364 (delegation: don't propagate synthetic params, remove lifetime hacks) - rust-lang/rust#151148 (Add functions to `GrowableBitSet`) - rust-lang/rust#154090 (Move tests in the statics category) - rust-lang/rust#154112 (some `tests/ui/macros` cleanup) - rust-lang/rust#154131 (begin `tests/ui/structs-enums` cleanup) - rust-lang/rust#154216 (unstably mark `NonNull::with_exposed_provenance` as const) - rust-lang/rust#154230 (Moved and rename issue-50411 to tests/ui/mir/inliner-double-elaborate) - rust-lang/rust#154233 (Move ui/issues tests to relevant subdirectories) - rust-lang/rust#154288 (Fix typo in doc comment for `char::to_titlecase`) - rust-lang/rust#154355 (delegation: add const type ICE test) - rust-lang/rust#154358 (install-template.sh: Optimize by using Bourne shell builtins.) - rust-lang/rust#154360 (fromrangeiter-overflow-checks: accept optional `signext` for argument)

…=dingxiangfei2009" This reverts commit 2f16030, reversing changes made to 6e3c174.

Revert "Rollup merge of #154200 - resrever:enable-dwarf-call-sites, r=dingxiangfei2009"

…-sites, r=dingxiangfei2009" This reverts commit 2f16030, reversing changes made to 6e3c174.

RalfJung · 2026-03-28T11:20:13Z

FTR this is being reverted in #154468.

Revert "Rollup merge of #154200 - resrever:enable-dwarf-call-sites, r=dingxiangfei2009" This reverts commit 2f16030, reversing changes made to 6e3c174. Debugging perf. hit from #154384. The binary size hits from #154468 (comment) were due to this PR, not all of the copmile-time hits though.

Set `FlagAllCallsDescribed` on function definition DIEs when optimizations are enabled, so LLVM emits DW_TAG_call_site entries. This lets debuggers and analysis tools track tail calls. Unlike the previous attempt (rust-lang#154200, reverted in rust-lang#154468), this gates the flag on opt-level != 0, matching Clang's behavior. At -O0 no tail-call optimization occurs, so the debugger can reconstruct the full call stack without call site entries. This eliminates the ~2% binary size and ~0.3% compile-time regressions that were observed in debug (unoptimized) builds. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

resrever · 2026-03-29T05:34:12Z

FTR this is being reverted in #154468.

Thank you for bringing this to my attention. I would have missed it without your message. This is my first PR to rust-lang, and I'm learning a lot about the process!

I'll make a follow-up PR to gate this behind optimized debug builds, since tailcalls will only occur with optimization. That should soften the perf impact in the reverted PR. Looks like in the perf suite only ripgrep does optimized debug builds, so the rest shouldn't see a perf diff, and those ripgrep will be more debuggable.

resrever force-pushed the enable-dwarf-call-sites branch from 74a48c8 to 79e7936 Compare March 22, 2026 03:58

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resrever marked this pull request as ready for review March 22, 2026 12:16

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 22, 2026

rustbot assigned JohnTitor Mar 22, 2026

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Mar 22, 2026

resrever force-pushed the enable-dwarf-call-sites branch from 79e7936 to 84ad0ab Compare March 22, 2026 12:38

debuginfo: emit DW_TAG_call_site entries

9677d7a

resrever force-pushed the enable-dwarf-call-sites branch from 84ad0ab to 9677d7a Compare March 22, 2026 12:42

rustbot assigned dingxiangfei2009 and unassigned JohnTitor Mar 25, 2026

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dingxiangfei2009 reviewed Mar 25, 2026

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This was referenced Mar 25, 2026

Rollup of 21 pull requests #154378

Closed

Rollup of 22 pull requests #154384

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rust-bors bot merged commit 2f16030 into rust-lang:main Mar 25, 2026
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resrever deleted the enable-dwarf-call-sites branch March 25, 2026 23:15

rust-bors bot pushed a commit that referenced this pull request Mar 27, 2026

Revert "Rollup merge of #154200 - resrever:enable-dwarf-call-sites, r…

26dfbab

…=dingxiangfei2009" This reverts commit 2f16030, reversing changes made to 6e3c174.

rust-bors bot pushed a commit that referenced this pull request Mar 27, 2026

Auto merge of #154468 - Kobzol:revert-154200, r=<try>

1be14f9

Revert "Rollup merge of #154200 - resrever:enable-dwarf-call-sites, r=dingxiangfei2009"

Kobzol added a commit to Kobzol/rust that referenced this pull request Mar 27, 2026

Revert "Rollup merge of rust-lang#154200 - resrever:enable-dwarf-call…

8b44562

…-sites, r=dingxiangfei2009" This reverts commit 2f16030, reversing changes made to 6e3c174.

Kobzol mentioned this pull request Mar 28, 2026

Revert "Rollup merge of #154344 - dianqk:update-llvm, r=nikic" #154470

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resrever mentioned this pull request Mar 29, 2026

debuginfo: emit DW_TAG_call_site entries on optimized builds #154532

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