Fix e_flags for 32-bit MIPS targets in generated object file
In #95604 the compiler started generating a temporary symbols.o which is added to the linker invocation. This object file has an `e_flags` which is invalid for 32-bit MIPS targets. Even though symbols.o doesn't contain code, linking these targets with [lld fails](https://github.com/llvm/llvm-project/blob/main/lld/ELF/Arch/MipsArchTree.cpp#L76-L79) with
```
rust-lld: error: foo-cgu.0.rcgu.o: ABI 'o32' is incompatible with target ABI 'n64'
```
because it omits the ABI bits (`EF_MIPS_ABI_O32`) so lld assumes it's using the N64 ABI. This breaks linking on nightly for the out-of-tree [mipsel-sony-psx target](https://github.com/ayrtonm/psx-sdk-rs/issues/9), the builtin mipsel-sony-psp target (cc `@overdrivenpotato)` and probably any other 32-bit MIPS target using lld.
This PR sets the ABI in `e_flags` to O32 since that's the only ABI for 32-bit MIPS that LLVM supports. It also sets other `e_flags` bits based on the target to avoid similar issues with the object file arch and PIC. I had to bump the object crate version since some of these constants were [added recently](https://github.com/gimli-rs/object/pull/433). I'm not sure if this PR needs a test, but I can confirm that it fixes the linking issue on both targets I mentioned.
Like we have `add`/`sub` which are the `usize` version of `offset`, this adds the `usize` equivalent of `offset_from`. Like how `.add(d)` replaced a whole bunch of `.offset(d as isize)`, you can see from the changes here that it's fairly common that code actually knows the order between the pointers and *wants* a `usize`, not an `isize`.
As a bonus, this can do `sub nuw`+`udiv exact`, rather than `sub`+`sdiv exact`, which can be optimized slightly better because it doesn't have to worry about negatives. That's why the slice iterators weren't using `offset_from`, though I haven't updated that code in this PR because slices are so perf-critical that I'll do it as its own change.
This is an intrinsic, like `offset_from`, so that it can eventually be allowed in CTFE. It also allows checking the extra safety condition -- see the test confirming that CTFE catches it if you pass the pointers in the wrong order.
In #95604 the compiler started generating a temporary symbols.o which is added
to the linker invocation. This object file has an `e_flags` which may be invalid
for 32-bit MIPS targets. Even though symbols.o doesn't contain code, linking
with [lld fails](https://github.com/llvm/llvm-project/blob/main/lld/ELF/Arch/MipsArchTree.cpp#L79) with
```
rust-lld: error: foo-cgu.0.rcgu.o: ABI 'o32' is incompatible with target ABI 'n64'
```
because it omits the ABI bits (EF_MIPS_ABI_O32) so lld assumes it's using the
N64 ABI. This breaks linking on nightly for the out-of-tree [psx
target](https://github.com/ayrtonm/psx-sdk-rs/issues/9), the builtin
mipsel-sony-psp target (cc @overdrivenpotato) and any other 32-bit MIPS
target using lld.
This PR sets the ABI in `e_flags` to O32 since that's the only ABI for 32-bit
MIPS that LLVM supports. It also sets other `e_flags` bits based on the target.
I had to bump the object crate version since some of these constants were [added
recently](https://github.com/gimli-rs/object/pull/433). I'm not sure if this
PR needs a test, but I can confirm that it fixes the linking issue on both
targets I mentioned.
Add a new Rust attribute to support embedding debugger visualizers
Implemented [this RFC](https://github.com/rust-lang/rfcs/pull/3191) to add support for embedding debugger visualizers into a PDB.
Added a new attribute `#[debugger_visualizer]` and updated the `CrateMetadata` to store debugger visualizers for crate dependencies.
RFC: https://github.com/rust-lang/rfcs/pull/3191
Cleanup `DebuggerVisualizerFile` type and other minor cleanup of queries.
Merge the queries for debugger visualizers into a single query.
Revert move of `resolve_path` to `rustc_builtin_macros`. Update dependencies in Cargo.toml for `rustc_passes`.
Respond to PR comments. Load visualizer files into opaque bytes `Vec<u8>`. Debugger visualizers for dynamically linked crates should not be embedded in the current crate.
Update the unstable book with the new feature. Add the tracking issue for the debugger_visualizer feature.
Respond to PR comments and minor cleanups.
Use reverse postorder in `non_ssa_locals`
The reverse postorder, unlike preorder, is now cached inside the MIR
body. Code generation uses reverse postorder anyway, so it might be
a small perf improvement to use it here as well.
Refactor the WriteBackendMethods and ExtraBackendMethods traits
The new interface is slightly less confusing and is easier to implement for non-LLVM backends.
The reverse postorder, unlike preorder, is now cached inside the MIR
body. Code generation uses reverse postorder anyway, so it might be
a small perf improvement to use it here as well.
Reduce duplication of RPO calculation of mir
Computing the RPO of mir is not a low-cost thing, but it is duplicate in many places. In particular the `iterate_to_fixpoint` method which is called multiple times when computing the data flow.
This PR reduces the number of times the RPO is recalculated as much as possible, which should save some compile time.
not need `Option` for `dbg_scope`
This PR fixes a few FIXME about not using `Option` in `dbg_scope` field of `DebugScope`, during `create_function_debug_context` func in codegen parts.
Added a `BitSet<SourceScope>` parameter to `make_mir_scope` to indicate whether the `DebugScope` has been instantiated.
cc ````@eddyb````
Generate synthetic object file to ensure all exported and used symbols participate in the linking
Fix#50007 and #47384
This is the synthetic object file approach that I described in https://github.com/rust-lang/rust/pull/95363#issuecomment-1079932354, allowing all exported and used symbols to be linked while still allowing them to be GCed.
Related #93791, #95363
r? `@petrochenkov`
cc `@carbotaniuman`
bootstrap: add split-debuginfo config
Replace `run-dysutil` option with more general `split-debuginfo` option that works on all platforms.
r? `@Mark-Simulacrum`
Stop using CRATE_DEF_INDEX outside of metadata encoding.
`CRATE_DEF_ID` and `CrateNum::as_def_id` are almost always what we want. We should not manipulate raw `DefIndex` outside of metadata encoding.
errors: lazily load fallback fluent bundle
Addresses (hopefully) https://github.com/rust-lang/rust/pull/95667#issuecomment-1094794087.
Loading the fallback bundle in compilation sessions that won't go on to emit any errors unnecessarily degrades compile time performance, so lazily create the Fluent bundle when it is first required.
r? `@ghost` (just for perf initially)
Loading the fallback bundle in compilation sessions that won't go on to
emit any errors unnecessarily degrades compile time performance, so
lazily create the Fluent bundle when it is first required.
Signed-off-by: David Wood <david.wood@huawei.com>
