Add lox-mmap crate

Cargo.toml

@@ -7,7 +7,8 @@ members = [
     "lox-vm",
     "lox-syntax",
     "lox-std",
-    "lox-gc"
+    "lox-gc",
+    "lox-mmap"
 ]
 
 # For flamegraph

README.md

@@ -15,4 +15,10 @@ Also constants are not yet deduplicated in the compiler.
 
 # Test suite
 
-Tests are copied from https://github.com/munificent/craftinginterpreters/tree/master/test.
+Tests are copied from https://github.com/munificent/craftinginterpreters/tree/master/test.
+
+# Instruments
+
+Run `codesign -s - -v -f --entitlements debug.plist target/release/lox` to codesign the release binary.
+This will allow instruments to work properly.
+

debug.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "https://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+  <dict>
+    <key>com.apple.security.get-task-allow</key>
+    <true/>
+  </dict>
+</plist>

lox-gc/Cargo.toml

@@ -6,5 +6,5 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-mmap = "*"
 arrayvec = "0.7.2"
+lox-mmap = { path = "../lox-mmap" }

lox-gc/src/heap.rs

@@ -1,41 +1,7 @@
 use std::cell::Cell;
+use lox_mmap::MemoryMap;
 
-//TODO Use mmap again
-//TODO Impl mmap ourselves
 //TODO Merge reams when sweeping
-//TODO Figure out dropping
-
-struct MemoryMap {
-    size: usize,
-    data: *mut u8,
-}
-
-impl MemoryMap {
-    pub fn new(size: usize) -> Self {
-        unsafe {
-            let layout = std::alloc::Layout::array::<u8>(size).unwrap().align_to(4096).unwrap();
-            let data = std::alloc::alloc(layout);
-
-            Self {
-                size,
-                data,
-            }
-        }
-    }
-
-    pub fn data(&self) -> *mut u8 {
-        self.data
-    }
-}
-
-impl Drop for MemoryMap {
-    fn drop(&mut self) {
-        let layout = std::alloc::Layout::array::<u8>(self.size).unwrap().align_to(4096).unwrap();
-        unsafe {
-            std::alloc::dealloc(self.data, layout);
-        }
-    }
-}
 
 /// Returns the number of pages needed for `n` bytes (rounding up).
 const fn bytes_to_pages(n: usize) -> usize {
@@ -51,7 +17,6 @@ const fn bytes_to_pages(n: usize) -> usize {
 struct PdIdx(u32);
 
 struct AddrSpace {
-    //mem: mmap::MemoryMap,
     mem: MemoryMap,
 
     used_pds: Cell<u32>,
@@ -79,9 +44,6 @@ impl AddrSpace {
 
     /// Constructs a new [`AddrSpace`]. This will return `None` on error.
     pub fn create() -> Option<Self> {
-        //use mmap::*;
-
-        //let mem = MemoryMap::new(Self::TOTAL_BYTES, &[MapOption::MapReadable, MapOption::MapWritable]).ok()?;
         let mem = self::MemoryMap::new(Self::TOTAL_BYTES);
 
         Some(Self {

lox-mmap/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "lox-mmap"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+libc = "0.2"

lox-mmap/src/lib.rs

@@ -0,0 +1,80 @@
+use std::ptr;
+
+//TODO support windows (using 'windows' crate)
+//TODO consider replacing *mut u8 with NonNull
+//TODO use libc::MAP_HUGETLB on supported platforms
+//TODO check errno on failure and report correctly
+//TODO return Result instead of panicking
+//TODO Split into a module per platform
+
+pub struct MemoryMap {
+    size: usize,
+    data: *mut u8,
+}
+
+impl MemoryMap {
+    pub fn data(&self) -> *mut u8 {
+        self.data
+    }
+}
+
+#[cfg(miri)]
+impl MemoryMap {
+    pub fn new(size: usize) -> Self {
+        unsafe {
+            let layout = std::alloc::Layout::array::<u8>(size)
+                .unwrap()
+                .align_to(4096)
+                .unwrap();
+            let data = std::alloc::alloc(layout);
+
+            Self { size, data }
+        }
+    }
+
+}
+
+#[cfg(miri)]
+impl Drop for MemoryMap {
+    fn drop(&mut self) {
+        let layout = std::alloc::Layout::array::<u8>(self.size)
+            .unwrap()
+            .align_to(4096)
+            .unwrap();
+        unsafe {
+            std::alloc::dealloc(self.data, layout);
+        }
+    }
+}
+
+#[cfg(all(not(miri), unix))]
+impl MemoryMap {
+    pub fn new(size: usize) -> Self {
+        let addr = unsafe {
+            libc::mmap(
+                ptr::null_mut(),
+                size,
+                libc::PROT_READ | libc::PROT_WRITE,
+                libc::MAP_PRIVATE | libc::MAP_ANONYMOUS | libc::MAP_NORESERVE,
+                -1,
+                0,
+            )
+        };
+
+        assert!(!addr.is_null() && addr != libc::MAP_FAILED, "mmap failed");
+
+        Self {
+            data: addr as _,
+            size,
+        }
+    }
+}
+
+#[cfg(all(not(miri), unix))]
+impl Drop for MemoryMap {
+    fn drop(&mut self) {
+        unsafe {
+            libc::munmap(self.data as _, self.size);
+        }
+    }
+}