be055d96c4
Optimize catch_unwind to match C++ try/catch This refactors the implementation of catching unwinds to allow LLVM to inline the "try" closure directly into the happy path, avoiding indirection. This means that the catch_unwind implementation is (after this PR) zero-cost unless a panic is thrown. https://rust.godbolt.org/z/cZcUSB is an example of the current codegen in a simple case. Notably, the codegen is *exactly the same* if `-Cpanic=abort` is passed, which is clearly not great. This PR, on the other hand, generates the following assembly: ```asm # -Cpanic=unwind: push rbx mov ebx,0x2a call QWORD PTR [rip+0x1c53c] # <happy> mov eax,ebx pop rbx ret mov rdi,rax call QWORD PTR [rip+0x1c537] # cleanup function call call QWORD PTR [rip+0x1c539] # <unfortunate> mov ebx,0xd mov eax,ebx pop rbx ret # -Cpanic=abort: push rax call QWORD PTR [rip+0x20a1] # <happy> mov eax,0x2a pop rcx ret ``` Fixes #64224, and resolves #64222. |
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| .. | ||
| abi | ||
| spec | ||
| build.rs | ||
| Cargo.toml | ||
| lib.rs | ||
| README.md | ||
librustc_target contains some very low-level details that are
specific to different compilation targets and so forth.
For more information about how rustc works, see the rustc dev guide.