Rollup merge of #136611 - Zalathar:llvm-underscore, r=workingjubilee

cg_llvm: Remove the `mod llvm_` hack, which should no longer be necessary

This re-export was introduced in c76fc3d, as a workaround for #53912.

In short, there was/is an assumption in some LLVM LTO code that symbol names would not contain `.llvm.`, but legacy symbol mangling would naturally produce that sequence for symbols in a module named `llvm`.

This was later “fixed” by adding a special case to the legacy symbol mangler in #61195, which detects the sequence `llvm` and emits the `m` in an escaped form. As a result, there should no longer be any need to avoid the module name `llvm` in the compiler itself.

(Symbol mangling v0 avoids this problem by not using `.` in the first place, outside of the “vendor-specific suffix”.)

Author: workingjubilee

Diff for: compiler/rustc_codegen_llvm/src/lib.rs

@@ -71,14 +71,9 @@ mod debuginfo;
 mod declare;
 mod errors;
 mod intrinsic;
-
-// The following is a workaround that replaces `pub mod llvm;` and that fixes issue 53912.
-#[path = "llvm/mod.rs"]
-mod llvm_;
-pub mod llvm {
-    pub use super::llvm_::*;
-}
-
+// FIXME(Zalathar): Fix all the unreachable-pub warnings that would occur if
+// this isn't pub, then make it not pub.
+pub mod llvm;
 mod llvm_util;
 mod mono_item;
 mod type_;

Diff for: compiler/rustc_codegen_llvm/src/llvm/mod.rs

@@ -10,13 +10,9 @@ use libc::c_uint;
 use rustc_abi::{Align, Size, WrappingRange};
 use rustc_llvm::RustString;
 
-pub use self::AtomicRmwBinOp::*;
 pub use self::CallConv::*;
 pub use self::CodeGenOptSize::*;
-pub use self::IntPredicate::*;
-pub use self::Linkage::*;
 pub use self::MetadataType::*;
-pub use self::RealPredicate::*;
 pub use self::ffi::*;
 use crate::common::AsCCharPtr;