Discard `.pdr` in the PSP linker script by ItsNoHax · Pull Request #161484 · rust-lang/rust

ItsNoHax · 2026-08-21T20:45:00Z

The mipsel-sony-psp target passes --emit-relocs and relies on --gc-sections. .pdr (MIPS procedure-descriptor debug data) is not allocated, so it survives collection, but the relocations kept for it still point at the functions that were collected. rust-lld reports every one of those:

rust-lld: relocation refers to a discarded section: .text._RNvNtNtCs1mwba6qCgei_4libm4math3log3log
>>> referenced by libm-...-cgu.3.rcgu.o:(.rel.pdr+0xbfa0) in archive .../liblibm-....rlib

A hello-world picks up 70 of these. They were always emitted; they only became visible when cargo stopped suppressing linker output, and are now reported by the linker_messages lint. Reported downstream as overdrivenpotato/rust-psp#203.

Nothing on the PSP reads .pdr, so this discards it alongside the non-loadable sections the script already drops (.MIPS.abiflags, .reginfo). Discarding .pdr also removes .rel.pdr, since --emit-relocs only emits relocations for sections that survive.

Verification

Building rust-psp's ci/tests suite and running it on PPSSPP:

	before	after
discarded-section warnings	70	0
`EBOOT.PBP` size	1,395,948 B	1,264,396 B (−9.4%)
test suite	47 pass / 0 fail	47 pass / 0 fail (`FINAL_SUCCESS`)

Since the linker script lives in the target spec, I validated the exact change by building against a patched --print target-spec-json copy of the target, and cross-checked it by passing an equivalent /DISCARD/ fragment as an extra --script to a normal cargo psp build. Both give the same result.

This is the target's own linker script and affects no other target. The remaining warnings in that issue have a separate cause (EF_MIPS_CPIC) and are handled in a follow-up PR.

rustbot · 2026-08-21T20:45:03Z

These commits modify compiler targets.
(See the Target Tier Policy.)

rustbot · 2026-08-21T20:45:06Z

Thanks for the pull request, and welcome! The Rust Project has assigned @nnethercote (or someone else) to review your changes, you should hear from them (or someone else) within the next two weeks.

Please see the contribution instructions and our LLM policy for more information.

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: compiler
compiler expanded to 75 candidates
Random selection from 21 candidates

ItsNoHax · 2026-08-21T21:10:27Z

@nnethercote This is LLM assisted, not able to edit the label. Considering the blast radius is small and the logic is solid I thought I'd go for it.

`.pdr` holds MIPS procedure-descriptor debug data. It is not allocated, so `--gc-sections` does not collect it, but the relocations kept for it by the target's `--emit-relocs` still refer to the functions that were collected. rust-lld reports each of those as "relocation refers to a discarded section"; a hello-world picks up 70 such warnings, now that cargo no longer suppresses linker output. Nothing on the PSP reads `.pdr`, so discard it alongside the other non-loadable sections already listed. This also drops ~9% off the resulting EBOOT. Fixes overdrivenpotato/rust-psp#203 (in part)

nnethercote · 2026-08-22T06:24:03Z

@ItsNoHax: can you clarify what you mean by "LLM assisted"? The policy permits certain LLM uses (e.g. analysis, review) and generally disallows others (e.g. creation).

ItsNoHax · 2026-08-22T11:06:00Z

It was used for analysis @nnethercote.

nnethercote · 2026-08-25T06:24:08Z

@bors r+ rollup

rust-bors · 2026-08-25T06:24:11Z

📌 Commit 8639b1f has been approved by nnethercote

It is now in the queue for this repository.

…rcote Discard `.pdr` in the PSP linker script The `mipsel-sony-psp` target passes `--emit-relocs` and relies on `--gc-sections`. `.pdr` (MIPS procedure-descriptor debug data) is not allocated, so it survives collection, but the relocations kept for it still point at the functions that *were* collected. rust-lld reports every one of those: ``` rust-lld: relocation refers to a discarded section: .text._RNvNtNtCs1mwba6qCgei_4libm4math3log3log >>> referenced by libm-...-cgu.3.rcgu.o:(.rel.pdr+0xbfa0) in archive .../liblibm-....rlib ``` A hello-world picks up **70** of these. They were always emitted; they only became visible when cargo stopped suppressing linker output, and are now reported by the `linker_messages` lint. Reported downstream as overdrivenpotato/rust-psp#203. Nothing on the PSP reads `.pdr`, so this discards it alongside the non-loadable sections the script already drops (`.MIPS.abiflags`, `.reginfo`). Discarding `.pdr` also removes `.rel.pdr`, since `--emit-relocs` only emits relocations for sections that survive. ### Verification Building `rust-psp`'s `ci/tests` suite and running it on PPSSPP: | | before | after | | ---------------------- | ----------- | ----------- | | discarded-section warnings | 70 | **0** | | `EBOOT.PBP` size | 1,395,948 B | 1,264,396 B (−9.4%) | | test suite | 47 pass / 0 fail | 47 pass / 0 fail (`FINAL_SUCCESS`) | Since the linker script lives in the target spec, I validated the exact change by building against a patched `--print target-spec-json` copy of the target, and cross-checked it by passing an equivalent `/DISCARD/` fragment as an extra `--script` to a normal `cargo psp` build. Both give the same result. This is the target's own linker script and affects no other target. The remaining warnings in that issue have a separate cause (`EF_MIPS_CPIC`) and are handled in a follow-up PR.

Rollup of 5 pull requests Successful merges: - #156749 (remove `box_patterns`) - #161411 (avoid overlapping const suggestions) - #161484 (Discard `.pdr` in the PSP linker script) - #161663 (Reduce dependency on implicit paths in bootstrap) - #161720 (rename rust_target_features query to make it clear that these are *all* target features)

Rollup merge of #161484 - ItsNoHax:psp-discard-pdr, r=nnethercote Discard `.pdr` in the PSP linker script The `mipsel-sony-psp` target passes `--emit-relocs` and relies on `--gc-sections`. `.pdr` (MIPS procedure-descriptor debug data) is not allocated, so it survives collection, but the relocations kept for it still point at the functions that *were* collected. rust-lld reports every one of those: ``` rust-lld: relocation refers to a discarded section: .text._RNvNtNtCs1mwba6qCgei_4libm4math3log3log >>> referenced by libm-...-cgu.3.rcgu.o:(.rel.pdr+0xbfa0) in archive .../liblibm-....rlib ``` A hello-world picks up **70** of these. They were always emitted; they only became visible when cargo stopped suppressing linker output, and are now reported by the `linker_messages` lint. Reported downstream as overdrivenpotato/rust-psp#203. Nothing on the PSP reads `.pdr`, so this discards it alongside the non-loadable sections the script already drops (`.MIPS.abiflags`, `.reginfo`). Discarding `.pdr` also removes `.rel.pdr`, since `--emit-relocs` only emits relocations for sections that survive. ### Verification Building `rust-psp`'s `ci/tests` suite and running it on PPSSPP: | | before | after | | ---------------------- | ----------- | ----------- | | discarded-section warnings | 70 | **0** | | `EBOOT.PBP` size | 1,395,948 B | 1,264,396 B (−9.4%) | | test suite | 47 pass / 0 fail | 47 pass / 0 fail (`FINAL_SUCCESS`) | Since the linker script lives in the target spec, I validated the exact change by building against a patched `--print target-spec-json` copy of the target, and cross-checked it by passing an equivalent `/DISCARD/` fragment as an extra `--script` to a normal `cargo psp` build. Both give the same result. This is the target's own linker script and affects no other target. The remaining warnings in that issue have a separate cause (`EF_MIPS_CPIC`) and are handled in a follow-up PR.

Rollup of 5 pull requests Successful merges: - rust-lang/rust#156749 (remove `box_patterns`) - rust-lang/rust#161411 (avoid overlapping const suggestions) - rust-lang/rust#161484 (Discard `.pdr` in the PSP linker script) - rust-lang/rust#161663 (Reduce dependency on implicit paths in bootstrap) - rust-lang/rust#161720 (rename rust_target_features query to make it clear that these are *all* target features)

rustbot added 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 Aug 21, 2026

rustbot assigned nnethercote Aug 21, 2026

This was referenced Aug 21, 2026

Set EF_MIPS_CPIC on static MIPS targets that use abicalls #161485

Closed

Linker warnings (rust un-suppressed them recently) overdrivenpotato/rust-psp#203

Open

ItsNoHax force-pushed the psp-discard-pdr branch from 81e0aaf to 8639b1f Compare August 21, 2026 21:44

nnethercote approved these changes Aug 25, 2026

View reviewed changes

rust-bors Bot 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 Aug 25, 2026

JonathanBrouwer mentioned this pull request Aug 25, 2026

Rollup of 4 pull requests #161722

Closed

jhpratt mentioned this pull request Aug 25, 2026

Rollup of 5 pull requests #161731

Merged

rust-bors Bot merged commit 968898a into rust-lang:main Aug 25, 2026
13 checks passed

rustbot added this to the 1.100.0 milestone Aug 25, 2026

ItsNoHax deleted the psp-discard-pdr branch August 25, 2026 13:52

Navigation Menu

Uh oh!

Discard `.pdr` in the PSP linker script - #161484

Discard `.pdr` in the PSP linker script#161484
rust-bors[bot] merged 1 commit into
rust-lang:mainfrom
ItsNoHax:psp-discard-pdr

ItsNoHax commented Aug 21, 2026

Uh oh!

rustbot commented Aug 21, 2026

Uh oh!

rustbot commented Aug 21, 2026

Uh oh!

ItsNoHax commented Aug 21, 2026

Uh oh!

nnethercote commented Aug 22, 2026

Uh oh!

ItsNoHax commented Aug 22, 2026

Uh oh!

nnethercote commented Aug 25, 2026

Uh oh!

rust-bors Bot commented Aug 25, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

Conversation

ItsNoHax commented Aug 21, 2026

Verification

Uh oh!

rustbot commented Aug 21, 2026

Uh oh!

rustbot commented Aug 21, 2026

Uh oh!

ItsNoHax commented Aug 21, 2026

Uh oh!

nnethercote commented Aug 22, 2026

Uh oh!

ItsNoHax commented Aug 22, 2026

Uh oh!

nnethercote commented Aug 25, 2026

Uh oh!

rust-bors Bot commented Aug 25, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants