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2025-08-19Auto merge of #145601 - jieyouxu:rollup-t5mbqhc, r=jieyouxubors-2/+7
Rollup of 10 pull requests Successful merges: - rust-lang/rust#145538 (bufreader::Buffer::backshift: don't move the uninit bytes) - rust-lang/rust#145542 (triagebot: Don't warn no-mentions on subtree updates) - rust-lang/rust#145549 (Update rust maintainers in openharmony.md) - rust-lang/rust#145550 (Avoid using `()` in `derive(From)` output.) - rust-lang/rust#145556 (Allow stability attributes on extern crates) - rust-lang/rust#145560 (Remove unused `PartialOrd`/`Ord` from bootstrap) - rust-lang/rust#145568 (ignore frontmatters in `TokenStream::new`) - rust-lang/rust#145571 (remove myself from some adhoc-groups and pings) - rust-lang/rust#145576 (Add change tracker entry for `--timings`) - rust-lang/rust#145578 (Add VEXos "linked files" support to `armv7a-vex-v5`) r? `@ghost` `@rustbot` modify labels: rollup
2025-08-19Auto merge of #145600 - jieyouxu:rollup-jw0bpnt, r=jieyouxubors-14/+16
Rollup of 15 pull requests Successful merges: - rust-lang/rust#145338 (actually provide the correct args to coroutine witnesses) - rust-lang/rust#145429 (Couple of codegen_fn_attrs improvements) - rust-lang/rust#145452 (Do not strip binaries in bootstrap everytime if they are unchanged) - rust-lang/rust#145464 (Stabilize `const_pathbuf_osstring_new` feature) - rust-lang/rust#145474 (Properly recover from parenthesized use-bounds (precise capturing lists) plus small cleanups) - rust-lang/rust#145486 (Fix `unicode_data.rs` mention message) - rust-lang/rust#145490 (Trace some basic I/O operations in bootstrap) - rust-lang/rust#145493 (remove `should_render` in `PrintAttribute` derive) - rust-lang/rust#145500 (Port must_use to the new target checking) - rust-lang/rust#145505 (Simplify span caches) - rust-lang/rust#145510 (Visit and print async_fut local for async drop.) - rust-lang/rust#145511 (Rust build fails on OpenBSD after using file_lock feature) - rust-lang/rust#145532 (resolve: debug for block module) - rust-lang/rust#145533 (Reorder `lto` options from most to least optimizing) - rust-lang/rust#145537 (Do not consider a `T: !Sized` candidate to satisfy a `T: !MetaSized` obligation.) r? `@ghost` `@rustbot` modify labels: rollup
2025-08-19Rollup merge of #145578 - vexide:armv7a-vex-v5+linked-files, r=davidtwco许杰友 Jieyou Xu (Joe)-2/+7
Add VEXos "linked files" support to `armv7a-vex-v5` Third-party programs running on the VEX V5 platform need a linker script to ensure code and data are always placed in the allowed range `0x3800000-0x8000000` which is read/write/execute. However, developers can also configure the operating system (VEXos) to preload a separate file at any location between these two addresses before the program starts (as a sort of basic linking or configuration loading system). Programs have to know about this at compile time - in the linker script - to avoid placing data in a spot that overlaps where the linked file will be loaded. This is a very popular feature with existing V5 runtimes because it can be used to modify a program's behavior without re-uploading the entire binary to the robot controller. It's important for Rust to support this because while VEXos's runtime user-exposed file system APIs may only read data from an external SD card, linked files are allowed to load data directly from the device's onboard storage. This PR adds the `__linked_file_start` symbol to the existing VEX V5 linker script which can be used to shrink the stack and heap so that they do not overlap with a memory region containing a linked file. It expects the linked file to be loaded in the final N bytes of user RAM (this is not technically required but every existing runtime does it this way to avoid having discontinuous memory regions). With these changes, a developer targeting VEX V5 might add a second linker script to their project by specifying `-Clink-arg=-Tcustom.ld` and creating the file `custom.ld` to configure their custom memory layout. The linker would prepend this to the builtin target linker script. ```c /* custom.ld: Reserves 10MiB for a linked file. */ /* (0x7600000-0x8000000) */ __linked_file_length = 10M; /* The above line is equivalent to -Clink-arg=--defsym=__linked_file_length=10M */ /* Optional: specify one or more sections that */ /* represent the developer's custom format. */ SECTIONS { .linked_file_metadata (NOLOAD) : { __linked_file_metadata_start = .; . += 1M; __linked_file_metadata_end = .; } .linked_file_data (NOLOAD) : { __linked_file_data_start = .; . += 9M; __linked_file_data_end = .; } } INSERT AFTER .stack; ``` Then, using an external tool like the `vex-v5-serial` crate, they would configure the metadata of their uploaded program to specify the path of their linked file and the address where it should be loaded into memory (in the above example, `0x7600000`).
2025-08-19Rollup merge of #145429 - bjorn3:codegen_fn_attrs_improvements, r=jdonszelmann许杰友 Jieyou Xu (Joe)-14/+16
Couple of codegen_fn_attrs improvements As noted in https://github.com/rust-lang/rust/pull/144678#discussion_r2245060329 here is no need to keep link_name and export_name separate, which the third commit fixes by merging them. The second commit removes some dead code and the first commit merges two ifs with equivalent conditions. The last commit is an unrelated change which removes an unused `feature(autodiff)`.
2025-08-19Rollup merge of #139345 - smoelius:into-iter-stability, r=lcnr许杰友 Jieyou Xu (Joe)-0/+1
Extend `QueryStability` to handle `IntoIterator` implementations This PR extends the `rustc::potential_query_instability` lint to check values passed as `IntoIterator` implementations. Full disclosure: I want the lint to warn about this line (please see #138871 for why): https://github.com/rust-lang/rust/blob/aa8f0fd7163a2f23aa958faed30c9c2b77b934a5/src/librustdoc/json/mod.rs#L261 However, the lint warns about several other lines as well. Final note: the functions `get_callee_generic_args_and_args` and `get_input_traits_and_projections` were copied directly from [Clippy's source code](https://github.com/rust-lang/rust/blob/4fd8c04da0674af2c51310c9982370bfadfa1b98/src/tools/clippy/clippy_lints/src/methods/unnecessary_to_owned.rs#L445-L496).
2025-08-18Specify linker scripts after user link argsLewis McClelland-2/+7
2025-08-18Remove the no_sanitize attribute in favor of sanitizeBastian Kersting-64/+22
This removes the #[no_sanitize] attribute, which was behind an unstable feature named no_sanitize. Instead, we introduce the sanitize attribute which is more powerful and allows to be extended in the future (instead of just focusing on turning sanitizers off). This also makes sanitize(kernel_address = ..) attribute work with -Zsanitize=address To do it the same as how clang disables address sanitizer, we now disable ASAN on sanitize(kernel_address = "off") and KASAN on sanitize(address = "off"). The same was added to clang in https://reviews.llvm.org/D44981.
2025-08-18Implement the #[sanitize(..)] attributeBastian Kersting-2/+108
This change implements the #[sanitize(..)] attribute, which opts to replace the currently unstable #[no_sanitize]. Essentially the new attribute works similar as #[no_sanitize], just with more flexible options regarding where it is applied. E.g. it is possible to turn a certain sanitizer either on or off: `#[sanitize(address = "on|off")]` This attribute now also applies to more places, e.g. it is possible to turn off a sanitizer for an entire module or impl block: ```rust \#[sanitize(address = "off")] mod foo { fn unsanitized(..) {} #[sanitize(address = "on")] fn sanitized(..) {} } \#[sanitize(thread = "off")] impl MyTrait for () { ... } ``` This attribute is enabled behind the unstable `sanitize` feature.
2025-08-15Extend `QueryStability` to handle `IntoIterator` implementationsSamuel Moelius-0/+1
Fix adjacent code Fix duplicate warning; merge test into `tests/ui-fulldeps/internal-lints` Use `rustc_middle::ty::FnSig::inputs` Address two review comments - https://github.com/rust-lang/rust/pull/139345#discussion_r2109006991 - https://github.com/rust-lang/rust/pull/139345#discussion_r2109058588 Use `Instance::try_resolve` Import `rustc_middle::ty::Ty` as `Ty` rather than `MiddleTy` Simplify predicate handling Add more `#[allow(rustc::potential_query_instability)]` following rebase Remove two `#[allow(rustc::potential_query_instability)]` following rebase Address review comment Update compiler/rustc_lint/src/internal.rs Co-authored-by: lcnr <rust@lcnr.de>
2025-08-15Merge link_name and export_namebjorn3-7/+12
2025-08-15All weak lang items have an explicit link name and vice versabjorn3-9/+6
2025-08-15Rollup merge of #145004 - bjorn3:remove_unused_fields, r=WaffleLapkinStuart Cook-40/+31
Couple of minor cleanups
2025-08-15Rollup merge of #144865 - WaffleLapkin:track-tail, r=lqdStuart Cook-6/+28
Fix tail calls to `#[track_caller]` functions We want `#[track_caller]` to be semver independent, i.e. it should not be a breaking change to add or remove it. Since it changes ABI of a function (adding an additional argument) we have to be careful to preserve this property when adding tail calls. The only way to achieve this that I can see is: - we forbid tail calls in functions which are marked with `#[track_caller]` (already implemented) - tail-calling a `#[track_caller]` marked function downgrades the tail-call to a normal call (or equivalently tail-calls the shim made by fn def to fn ptr cast) (this pr) Ideally the downgrade would be performed by a MIR pass, but that requires post mono MIR opts (cc ```@saethlin,``` rust-lang/rust#131650). For now I've changed code in cg_ssa to accomodate this behaviour (+ added a hack to mono collector so that the shim is actually generated) Additionally I added a lint, although I don't think it's strictly necessary. Alternative to rust-lang/rust#144762 (and thus closes rust-lang/rust#144762) Fixes https://github.com/rust-lang/rust/issues/144755
2025-08-14drive-by: fix typoWaffle Lapkin-1/+1
2025-08-14Complete functionality and general cleanupMarcelo Domínguez-32/+5
2025-08-13Port the `#[linkage]` attribute to the new attribute systemSasha Pourcelot-60/+30
2025-08-13fix tail calls to `#[track_caller]` functionsWaffle Lapkin-5/+27
2025-08-12Auto merge of #144678 - jdonszelmann:no-mangle-extern, r=bjorn3bors-1/+22
Make no_mangle on foreign items explicit instead of implicit for a followup PR I'm working on I need some foreign items to mangle. I could add a new attribute: `no_no_mangle` or something silly like that but by explicitly putting `no_mangle` in the codegen fn attrs of foreign items we can default it to `no_mangle` and then easily remove it when we don't want it. I guess you'd know about this r? `@bjorn3.` Shouldn't be too hard to review :) Builds on rust-lang/rust#144655 which should merge first.
2025-08-12make no_mangle explicit on foreign itemsJana Dönszelmann-1/+22
2025-08-11Always attempt to invoke xcrun to get the Apple SDKMads Marquart-4/+8
The exact reasoning why we do not always pass the SDK root when linking on macOS eludes me, but I suspect it's because we want to support compiler drivers which do not support the `-isysroot` option. Since we now pass the SDK root via the environment variable SDKROOT, compiler drivers that don't support it can just ignore it. Similarly, since we only warn when xcrun fails, users that expect their compiler driver to provide the SDK location can do so now.
2025-08-11Only warn when invoking xcrunMads Marquart-3/+21
To allow using zig-cc or similar as the compiler driver.
2025-08-11Pass Apple SDK root to compiler driver via SDKROOT env varMads Marquart-8/+36
This is more in-line with what Apple's tooling expects, and allows us to better support custom compiler drivers (such as certain Homebrew and Nixpkgs compilers) that prefer their own `-isysroot` flag. Effectively, we now invoke the compiler driver as-if it was invoked as `xcrun -sdk $sdk_name $tool`.
2025-08-11Simplify `add_apple_sdk`Mads Marquart-25/+20
Reduce indentation and avoid needless checks (checking the target OS and vendor is unnecessary).
2025-08-09Rollup merge of #141828 - Fulgen301:status-stack-buffer-overrun-diagnostic, ↵Stuart Cook-0/+20
r=wesleywiser Add diagnostic explaining STATUS_STACK_BUFFER_OVERRUN not only being used for stack buffer overruns if link.exe exits with that exit code `STATUS_STACK_BUFFER_OVERRUN` is also used for fast abnormal program termination, e.g. by abort(). Emit a special diagnostic to let people know that this most likely doesn't indicate a stack buffer overrun. This doesn't look up the crash report in the event log to determine what the fast fail error code is. This is due to the way crashes are logged: When a process crash happens, the system logs an "Application Error" event, which contains the exit code and the process ID, but not the fast fail error code. A second event by Windows Error Reporting does contain that fast fail code, but not the process ID - but that event is not emitted at process exit, but when WER has dealt with it (on my system, it happens roughly two seconds later), so querying the code would have to read the `IntegratorReportId`, wait two seconds or potentially longer for the WER event with the same `ReportID`, and read out the code. (Also, that second event doesn't happen if WER is disabled.) Fixes rust-lang/rust#100519.
2025-08-08Rollup merge of #144192 - RalfJung:atomicrmw-ptr, r=nikicTrevor Gross-16/+77
atomicrmw on pointers: move integer-pointer cast hacks into backend Conceptually, we want to have atomic operations on pointers of the form `fn atomic_add(ptr: *mut T, offset: usize, ...)`. However, LLVM does not directly support such operations (https://github.com/llvm/llvm-project/issues/120837), so we have to cast the `offset` to a pointer somewhere. This PR moves that hack into the LLVM backend, so that the standard library, intrinsic, and Miri all work with the conceptual operation we actually want. Hopefully, one day LLVM will gain a way to represent these operations without integer-pointer casts, and then the hack will disappear entirely. Cc ```@nikic``` -- this is the best we can do right now, right? Fixes https://github.com/rust-lang/rust/issues/134617
2025-08-08Add target_env = "macabi" and target_env = "sim"Mads Marquart-6/+6
2025-08-08Remove bitcode_llvm_cmdlinebjorn3-2/+0
It used to be necessary on Apple platforms to ship with the App Store, but XCode 15 has stopped embedding LLVM bitcode and the App Store no longer accepts apps with bitcode embedded.
2025-08-08Rollup merge of #145055 - bjorn3:move_metadata_symbol_export, r=saethlinStuart Cook-24/+10
Move metadata symbol export from exported_non_generic_symbols to exported_symbols The metadata symbol must not be encoded in the crate metadata, and must be exported from proc-macros. Handling the export of the metadata symbol in exported_symbols handles both things at once without requiring manual fixups elsewhere.
2025-08-08Rollup merge of #144999 - Zalathar:remove-mcdc, r=oli-obkStuart Cook-9/+0
coverage: Remove all unstable support for MC/DC instrumentation Preliminary support for a partial implementation of “Modified Condition/Decision Coverage” instrumentation was added behind the unstable flag `-Zcoverage-options=mcdc` in 2024. These are the most substantial PRs involved: - rust-lang/rust#123409 - rust-lang/rust#126733 At the time, I accepted these PRs with relatively modest scrutiny, because I did not want to stand in the way of independent work on MC/DC instrumentation. My hope was that ongoing work by interested contributors would lead to the code becoming clearer and more maintainable over time. --- However, that MC/DC code has proven itself to be a major burden on overall maintenance of coverage instrumentation, and a major obstacle to other planned improvements, such as internal changes needed for proper support of macro expansion regions. I have also become reluctant to accept any further MC/DC-related changes that would increase this burden. That tension has resulted in an unhappy impasse. On one hand, the present MC/DC implementation is not yet complete, and shows little sign of being complete at an acceptable level of code quality in the foreseeable future. On the other hand, the continued existence of this partial MC/DC implementation is imposing serious maintenance burdens on every other aspect of coverage instrumentation, and is preventing some of the very improvements that would make it easier to accept expanded MC/DC support in the future. While I know this will be disappointing to some, I think the healthy way forward is accept that I made the wrong call in accepting the current implementation, and to remove it entirely from the compiler.
2025-08-08Rollup merge of #144899 - Kobzol:cgu-reuse, r=saethlinStuart Cook-0/+9
Print CGU reuse statistics in `-Zprint-mono-items` I'm trying to expose more information about incremental profiling from rustc (https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/Profiling.2Fanalysis.20of.20incremental.20builds/with/531383501). One of the things that would be quite useful to expose is the CGU reuse state, so that when you do a rebuild, you can see all the CGUs (and all the functions) that had to be recompiled. Currently, we have (AFAIK) two ways of outputting monomorphization statistics: 1) `-Zdump-mono-stats` outputs statistics about number of instantiations and expected compilation cost of individual functions in the local crate being compiled. It can be outputted either as Markdown or JSON. 2) `-Zprint-mono-items` outputs a pair (item, CGU) for each monomorphized item. I was thinking about recording CGU statistics in the self-profile output, but I realized that as a simpler step, we could just add CGU reuse data to `-Zprint-mono-items`, as an additional output. That is what this PR does.
2025-08-08Rollup merge of #144764 - scottmcm:tweak-impossible-discriminant-assume, ↵Stuart Cook-14/+29
r=WaffleLapkin [codegen] assume the tag, not the relative discriminant Address the issue mentioned in <https://github.com/llvm/llvm-project/issues/134024#issuecomment-3131782555> by changing discriminant calculation to `assume` on the originally-loaded `tag`, rather than on `cast(tag)-OFFSET`. The previous way does make the *purpose* of the assume clearer, IMHO, since you see `assume(x != 4); if p { x } else { 4 }`, but doing it this way instead means that the `add`s optimize away in LLVM21, which is more important. And this new way is still easily thought of as being like metadata on the load saying specifically which value is impossible. Demo of the LLVM20 vs LLVM21 difference: <https://llvm.godbolt.org/z/n54x5Mq1T> r? ``@nikic``
2025-08-08Add note mentioning the event log to LinkExeStatusStackBufferOverrunGeorge Tokmaji-3/+10
2025-08-08Add diagnostic explaining STATUS_STACK_BUFFER_OVERRUN not only beingGeorge Tokmaji-0/+13
used for stack buffer overruns if link.exe exits with that exit code `STATUS_STACK_BUFFER_OVERRUN` is also used for fast abnormal program termination, e.g. by abort(). Emit a special diagnostic to let people know that this most likely doesn't indicate a stack buffer overrun.
2025-08-07Move metadata symbol export from exported_non_generic_symbols to ↵bjorn3-24/+10
exported_symbols The metadata symbol must not be encoded in the crate metadata, and must be exported from proc-macros. Handling the export of the metadata symbol in exported_symbols handles both things at once without requiring manual fixups elsewhere.
2025-08-07Auto merge of #145043 - Zalathar:rollup-3dbvdrm, r=Zalatharbors-2/+13
Rollup of 19 pull requests Successful merges: - rust-lang/rust#137831 (Tweak auto trait errors) - rust-lang/rust#138689 (add nvptx_target_feature) - rust-lang/rust#140267 (implement continue_ok and break_ok for ControlFlow) - rust-lang/rust#143028 (emit `StorageLive` and schedule `StorageDead` for `let`-`else`'s bindings after matching) - rust-lang/rust#143764 (lower pattern bindings in the order they're written and base drop order on primary bindings' order) - rust-lang/rust#143808 (Port `#[should_panic]` to the new attribute parsing infrastructure ) - rust-lang/rust#143906 (Miri: non-deterministic floating point operations in `foreign_items`) - rust-lang/rust#143929 (Mark all deprecation lints in name resolution as deny-by-default and report-in-deps) - rust-lang/rust#144133 (Stabilize const TypeId::of) - rust-lang/rust#144369 (Upgrade semicolon_in_expressions_from_macros from warn to deny) - rust-lang/rust#144439 (Introduce ModernIdent type to unify macro 2.0 hygiene handling) - rust-lang/rust#144473 (Address libunwind.a inconsistency issues in the bootstrap program) - rust-lang/rust#144601 (Allow `cargo fix` to partially apply `mismatched_lifetime_syntaxes`) - rust-lang/rust#144650 (Additional tce tests) - rust-lang/rust#144659 (bootstrap: refactor mingw dist and fix gnullvm) - rust-lang/rust#144682 (Stabilize `strict_overflow_ops`) - rust-lang/rust#145026 (Update books) - rust-lang/rust#145033 (Reimplement `print_region` in `type_name.rs`.) - rust-lang/rust#145040 (rustc-dev-guide subtree update) Failed merges: - rust-lang/rust#143857 (Port #[macro_export] to the new attribute parsing infrastructure) r? `@ghost` `@rustbot` modify labels: rollup
2025-08-07Rollup merge of #138689 - jedbrown:jed/nvptx-target-feature, r=ZuseZ4Stuart Cook-2/+13
add nvptx_target_feature Tracking issue: #141468 (nvptx), which is part of #44839 (catch-all arches) The feature gate is `#![feature(nvptx_target_feature)]` This exposes the target features `sm_20` through `sm_120a` [as defined](https://github.com/llvm/llvm-project/blob/llvmorg-20.1.1/llvm/lib/Target/NVPTX/NVPTX.td#L59-L85) by LLVM. Cc: ``````@gonzalobg`````` ``````@rustbot`````` label +O-NVPTX +A-target-feature
2025-08-06Revert "Preserve the .debug_gdb_scripts section"bjorn3-2/+10
This reverts commit 868bdde25b030e0b71a29a5dbc04a891036e702e.
2025-08-06Revert "Embed GDB pretty printers in rlibs and dylibs"bjorn3-9/+1
This reverts commit b4d923cea0509933b1fb859930cb20784251f9be.
2025-08-06[codegen] assume the tag, not the relative discriminantScott McMurray-14/+29
2025-08-06Remove unused field from ModuleConfigbjorn3-5/+1
2025-08-06Include allocator module in LLVM_passes timerbjorn3-33/+30
2025-08-06coverage: Remove all unstable support for MC/DC instrumentationZalathar-9/+0
2025-08-06Embed GDB pretty printers in rlibs and dylibsSebastian Poeplau-1/+9
Instead of collecting pretty printers transitively when building executables/staticlibs/cdylibs, let the debugger find each crate's pretty printers via its .debug_gdb_scripts section. This covers the case where libraries defining custom pretty printers are loaded dynamically.
2025-08-05Preserve the .debug_gdb_scripts sectionSebastian Poeplau-10/+2
Make sure that compiler and linker don't optimize the section's contents away by adding the global holding the data to "llvm.used". The volatile load in the main shim is retained because "llvm.used", which translates to SHF_GNU_RETAIN on ELF targets, requires a reasonably recent linker; emitting the volatile load ensures compatibility with older linkers, at least when libstd is used. Pretty printers in dylib dependencies are now emitted by the main crate instead of the dylib; apart from matching how rlibs are handled, this approach has the advantage that `omit_gdb_pretty_printer_section` keeps working with dylib dependencies.
2025-08-04Print CGU reuse statistics when `-Zprint-mono-items` is enabledJakub Beránek-0/+9
2025-08-02update flags for consistencyKivooeo-2/+3
2025-07-31Rollup merge of #144726 - jdonszelmann:move-attr-data-structures, r=lcnrJana Dönszelmann-8/+6
merge rustc_attr_data_structures into rustc_hir this move was discussed on zulip: [#t-compiler > attribute parsing rework @ 💬](https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/attribute.20parsing.20rework/near/528530091) Many PRs in the attribute rework depend on this move.
2025-07-31remove rustc_attr_data_structuresJana Dönszelmann-8/+6
2025-07-31Rollup merge of #136840 - Flakebi:linker-plugin-lto-fat, r=dianqkSamuel Tardieu-1/+3
Fix linker-plugin-lto only doing thin lto When rust provides LLVM bitcode files to lld and the bitcode contains function summaries as used for thin lto, lld defaults to using thin lto. This prevents some optimizations that are only applied for fat lto. We solve this by not creating function summaries when fat lto is enabled. The bitcode for the module is just directly written out. An alternative solution would be to set the `ThinLTO=0` module flag to signal lld to do fat lto. The code in clang that sets this flag is here: https://github.com/llvm/llvm-project/blob/560149b5e3c891c64899e9912e29467a69dc3a4c/clang/lib/CodeGen/BackendUtil.cpp#L1150 The code in LLVM that queries the flag and defaults to thin lto if not set is here: https://github.com/llvm/llvm-project/blob/e258bca9505f35e0a22cb213a305eea9b76d11ea/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp#L4441-L4446 try-job: x86_64-gnu-debug try-job: aarch64-gnu-debug
2025-07-31Fix linker-plugin-lto only doing thin ltoFlakebi-1/+3
When rust provides LLVM bitcode files to lld and the bitcode contains function summaries as used for thin lto, lld defaults to using thin lto. This prevents some optimizations that are only applied for fat lto. We solve this by not creating function summaries when fat lto is enabled. The bitcode for the module is just directly written out. An alternative solution would be to set the `ThinLTO=0` module flag to signal lld to do fat lto. The code in clang that sets this flag is here: https://github.com/llvm/llvm-project/blob/560149b5e3c891c64899e9912e29467a69dc3a4c/clang/lib/CodeGen/BackendUtil.cpp#L1150 The code in LLVM that queries the flag and defaults to thin lto if not set is here: https://github.com/llvm/llvm-project/blob/e258bca9505f35e0a22cb213a305eea9b76d11ea/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp#L4441-L4446