Auto merge of #83682 - bjorn3:mmap_wrapper, r=cjgillot

Add an Mmap wrapper to rustc_data_structures

This wrapper implements StableAddress and falls back to directly reading the file on wasm32.

Taken from #83640, which I will close due to the perf regression.

2 files changed, 4 insertions, 2 deletions

diff --git a/compiler/rustc_codegen_ssa/src/back/lto.rs b/compiler/rustc_codegen_ssa/src/back/lto.rs
index c6aea22a63e..0ff05229466 100644
--- a/compiler/rustc_codegen_ssa/src/back/lto.rs
+++ b/compiler/rustc_codegen_ssa/src/back/lto.rs
@@ -2,6 +2,7 @@ use super::write::CodegenContext;
 use crate::traits::*;
 use crate::ModuleCodegen;
 
+use rustc_data_structures::memmap::Mmap;
 use rustc_errors::FatalError;
 
 use std::ffi::CString;
@@ -93,7 +94,7 @@ impl<B: WriteBackendMethods> LtoModuleCodegen<B> {
 pub enum SerializedModule<M: ModuleBufferMethods> {
     Local(M),
     FromRlib(Vec<u8>),
-    FromUncompressedFile(memmap2::Mmap),
+    FromUncompressedFile(Mmap),
 }
 
 impl<M: ModuleBufferMethods> SerializedModule<M> {
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index b0324236373..c45c90f24de 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -10,6 +10,7 @@ use crate::{
 use crate::traits::*;
 use jobserver::{Acquired, Client};
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::profiling::TimingGuard;
 use rustc_data_structures::profiling::VerboseTimingGuard;
@@ -1958,7 +1959,7 @@ pub fn submit_pre_lto_module_to_llvm<B: ExtraBackendMethods>(
         .unwrap_or_else(|e| panic!("failed to open bitcode file `{}`: {}", bc_path.display(), e));
 
     let mmap = unsafe {
-        memmap2::Mmap::map(&file).unwrap_or_else(|e| {
+        Mmap::map(file).unwrap_or_else(|e| {
             panic!("failed to mmap bitcode file `{}`: {}", bc_path.display(), e)
         })
     };