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rust/tests/codegen/llvm-ident.rs

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Support `.comment` section like GCC/Clang (`!llvm.ident`) 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>
2022-05-29 07:10:44 +08:00
// Verifies that the `!llvm.ident` named metadata is emitted.
//
//@ revisions: NONE OPT DEBUG
//
//@ [OPT] compile-flags: -Copt-level=2
//@ [DEBUG] compile-flags: -Cdebuginfo=2
// The named metadata should contain a single metadata node (see
// `LLVMRustPrepareThinLTOImport` for details).
// CHECK: !llvm.ident = !{![[ID:[0-9]+]]}
// In addition, check that the metadata node has the expected content.
// CHECK: ![[ID]] = !{!"rustc version 1.{{.*}}"}
fn main() {}