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Remove LLVMRustMarkAllFunctionsNounwind

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This was originally introduced in #10916 as a way to remove all landing
pads when performing LTO. However this is no longer necessary today
since rustc properly marks all functions and call-sites as nounwind
where appropriate.

In fact this is incorrect in the presence of `extern "C-unwind"` which
must create a landing pad when compiled with `-C panic=abort` so that
foreign exceptions are caught and properly turned into aborts.
This commit is contained in:
Amanieu d'Antras
2022-01-14 00:10:10 +00:00
parent 22e491ac7e
commit 606d9c0c0e
4 changed files with 1 additions and 40 deletions
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17
compiler/rustc_codegen_llvm/src/back/lto.rs
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@@ -349,13 +349,6 @@ fn fat_lto(
);
save_temp_bitcode(cgcx, &module, "lto.after-restriction");
}
if cgcx.no_landing_pads {
unsafe {
llvm::LLVMRustMarkAllFunctionsNounwind(llmod);
}
save_temp_bitcode(cgcx, &module, "lto.after-nounwind");
}
}
Ok(LtoModuleCodegen::Fat { module: Some(module), _serialized_bitcode: serialized_bitcode })
@@ -770,16 +763,6 @@ pub unsafe fn optimize_thin_module(
return Err(write::llvm_err(&diag_handler, msg));
}
// Like with "fat" LTO, get some better optimizations if landing pads
// are disabled by removing all landing pads.
if cgcx.no_landing_pads {
let _timer = cgcx
.prof
.generic_activity_with_arg("LLVM_thin_lto_remove_landing_pads", thin_module.name());
llvm::LLVMRustMarkAllFunctionsNounwind(llmod);
save_temp_bitcode(cgcx, &module, "thin-lto-after-nounwind");
}
// Up next comes the per-module local analyses that we do for Thin LTO.
// Each of these functions is basically copied from the LLVM
// implementation and then tailored to suit this implementation. Ideally