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986d6bf9fb
rust/compiler/rustc_codegen_llvm
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Trevor Gross 986d6bf9fb
Rollup merge of #121533 - ratmice:wasm_init_fini_array, r=nnethercote 
Handle .init_array link_section specially on wasm

Given that wasm-ld now has support for [.init_array](8f2bd8ae68/llvm/lib/MC/WasmObjectWriter.cpp (L1852)), it appears we can easily implement that section by falling through to the normal path rather than taking the typical custom_section path for wasm.

The wasm-ld appears to have a bunch of limitations. Only one static with the `link_section` in a crate or else you hit the fatal error in the link above "only one .init_array section fragment supported". They do not get merged.

You can still call multiple constructors by setting it to an array.

```
unsafe extern "C" fn ctor() {
    println!("foo");
}
#[used]
#[link_section = ".init_array"]
static FOO: [unsafe extern "C" fn(); 2] = [ctor, ctor];
```

Another issue appears to be that if crate *A* depends on crate *B*, but *A* doesn't call any symbols from *B* and *B* doesn't `#[export_name = ...]` any symbols, then crate *B*'s constructor will not be called.  The workaround to this is to provide an exported symbol in crate *B*.
2024-07-19 03:27:46 -05:00
..
src Rollup merge of #121533 - ratmice:wasm_init_fini_array, r=nnethercote 2024-07-19 03:27:46 -05:00
Cargo.toml sanitizers: Create the rustc_sanitizers crate 2024-04-08 12:05:41 -07:00
messages.ftl Use an error struct instead of a panic 2024-05-15 11:14:45 +02:00
README.md mv compiler to compiler/ 2020-08-30 18:45:07 +03:00

README.md

The codegen crate contains the code to convert from MIR into LLVM IR, and then from LLVM IR into machine code. In general it contains code that runs towards the end of the compilation process.

For more information about how codegen works, see the rustc dev guide.