rust/tests/codegen/llvm-ident.rs

// 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() {}
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> 2022-05-28 23:10:44 +00:00			// 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() {}`