Both GCC and Clang write by default a `.comment` section with compiler
information:
```txt
$ gcc -c -xc /dev/null && readelf -p '.comment' null.o
String dump of section '.comment':
[ 1] GCC: (GNU) 11.2.0
$ clang -c -xc /dev/null && readelf -p '.comment' null.o
String dump of section '.comment':
[ 1] clang version 14.0.1 (https://github.com/llvm/llvm-project.git c62053979489ccb002efe411c3af059addcb5d7d)
```
They also implement the `-Qn` flag to avoid doing so:
```txt
$ gcc -Qn -c -xc /dev/null && readelf -p '.comment' null.o
readelf: Warning: Section '.comment' was not dumped because it does not exist!
$ clang -Qn -c -xc /dev/null && readelf -p '.comment' null.o
readelf: Warning: Section '.comment' was not dumped because it does not exist!
```
So far, `rustc` only does it for WebAssembly targets and only
when debug info is enabled:
```txt
$ echo 'fn main(){}' | rustc --target=wasm32-unknown-unknown --emit=llvm-ir -Cdebuginfo=2 - && grep llvm.ident rust_out.ll
!llvm.ident = !{!27}
```
In the RFC part of this PR it was decided to always add
the information, which gets us closer to other popular compilers.
An opt-out flag like GCC and Clang may be added later on if deemed
necessary.
Implementation-wise, this covers both `ModuleLlvm::new()` and
`ModuleLlvm::new_metadata()` cases by moving the addition to
`context::create_module` and adds a few test cases.
ThinLTO also sees the `llvm.ident` named metadata duplicated (in
temporary outputs), so this deduplicates it like it is done for
`wasm.custom_sections`. The tests also check this duplication does
not take place.
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Remove the ThinLTO CU hack
This reverts #46722, commit e0ab5d5feb.
Since #111167, commit 10b69dde3f, we are
generating DWARF subprograms in a way that is meant to be more compatible
with LLVM's expectations, so hopefully we don't need this workaround
rewriting CUs anymore.
This reverts #46722, commit e0ab5d5feb.
Since #111167, commit 10b69dde3f, we are
generating DWARF subprograms in a way that is meant to be more compatible
with LLVM's expectations, so hopefully we don't need this workaround
rewriting CUs anymore.
We've been relying on a custom patch to add `MCSubtargetInfo::getCPUTable`
for `rustc --print target-cpus`, and just printing that it's not supported
on external LLVM builds. LLVM `main` now has `getAllProcessorDescriptions`
that can replace ours, so now we try to use that. In addition, the fallback
path can at least print the native and default cpu options.
There were also some mismatches in the function signatures here between
`LLVM_RUSTLLVM` and otherwise; this is now mitigated by sharing these
functions and only using cpp to adjust the function bodies.
Fix printing native CPU on cross-compiled compiler.
If `rustc` is cross-compiled from a different host, then the "native" entry in `rustc --print=target-cpus` would not appear. There is a check in the printing code that will avoid printing the "native" entry if the user has passed `--target`. However, that check was comparing the `--target` value with the `LLVM_TARGET_TRIPLE` which is the triple of the host that `rustc` was built on (the "build" target in Rust lingo), not the target it was being built for (the "host" in Rust lingo). This fixes it to use the target that LLVM was built for (which I'm pretty sure this is the correct function to determine that).
This fixes the cpu listing for aarch64-apple-darwin which is built on CI using the x86_64-apple-darwin host.
Initial support for loongarch64-unknown-linux-gnu
Hi, We hope to add a new port in rust for LoongArch.
LoongArch intro
LoongArch is a RISC style ISA which is independently designed by Loongson
Technology in China. It is divided into two versions, the 32-bit version (LA32)
and the 64-bit version (LA64). LA64 applications have application-level
backward binary compatibility with LA32 applications. LoongArch is composed of
a basic part (Loongson Base) and an expanded part. The expansion part includes
Loongson Binary Translation (LBT), Loongson VirtualiZation (LVZ), Loongson SIMD
EXtension (LSX) and Loongson Advanced SIMD EXtension(LASX).
Currently the LA464 processor core supports LoongArch ISA and the Loongson
3A5000 processor integrates 4 64-bit LA464 cores. LA464 is a four-issue 64-bit
high-performance processor core. It can be used as a single core for high-end
embedded and desktop applications, or as a basic processor core to form an
on-chip multi-core system for server and high-performance machine applications.
Documentations:
ISA:
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html
ABI:
https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html
More docs can be found at:
https://loongson.github.io/LoongArch-Documentation/README-EN.html
Since last year, we have locally adapted two versions of rust, rust1.41 and rust1.57, and completed the test locally.
I'm not sure if I'm submitting all the patches at once, so I split up the patches and here's one of the commits
LLVM 15 added `Optional::has_value`, and LLVM `main` (16) has deprecated
`hasValue`. However, its `explicit operator bool` does the same thing,
and was added long ago, so we can use that across our full LLVM range of
compatibility.
No functional changes intended.
LLVM commit 633f5663c3 removed `createWriteThinLTOBitcodePass`.
This adapts PassWrapper similarly to the example mentioned upstream: 633f5663c3.
Update the minimum external LLVM to 13
With this change, we'll have stable support for LLVM 13 through 15 (pending release).
For reference, the previous increase to LLVM 12 was #90175.
r? `@nagisa`
Allow to disable thinLTO buffer to support lto-embed-bitcode lld feature
Hello
This change is to fix issue (https://github.com/rust-lang/rust/issues/84395) in which passing "-lto-embed-bitcode=optimized" to lld when linking rust code via linker-plugin-lto doesn't produce the expected result.
Instead of emitting a single unified module into a llvmbc section of the linked elf, it emits multiple submodules.
This is caused because rustc emits the BC modules after running llvm `createWriteThinLTOBitcodePass` pass.
Which in turn triggers a thinLTO linkage and causes the said issue.
This patch allows via compiler flag (-Cemit-thin-lto=<bool>) to select between running `createWriteThinLTOBitcodePass` and `createBitcodeWriterPass`.
Note this pattern of selecting between those 2 passes is common inside of LLVM code.
The default is to match the old behavior.
Revert "Work around invalid DWARF bugs for fat LTO"
Since September, the toolchain has not been generating reliable DWARF
information for static variables when LTO is on. This has affected
projects in the embedded space where the use of LTO is typical. In our
case, it has kept us from bumping past the 2021-09-22 nightly toolchain
lest our debugger break. This has been a pretty dramatic regression for
people using debuggers and static variables. See #90357 for more info
and a repro case.
This commit is a mechanical revert of
d5de680e20 from PR #89041, which caused
the issue. (Note on that PR that the commit's author has requested it be
reverted.)
I have locally verified that this fixes#90357 by restoring the
functionality of both the repro case I posted on that bug, and debugger
behavior on real programs. There do not appear to be test cases for this
in the toolchain; if I've missed them, point me at 'em and I'll update
them.
Adding the option to control from rustc CLI
if the resulted ".o" bitcode module files are with
thinLTO info or regular LTO info.
Allows using "-lto-embed-bitcode=optimized" during linkage
correctly.
Signed-off-by: Ziv Dunkelman <ziv.dunkelman@nextsilicon.com>
