Allow usage of the mimalloc allocator

Signed-off-by: webbeef <me@webbeef.org>

Cargo.lock

@@ -1488,6 +1488,12 @@ dependencies = [
  "cipher",
 ]
 
+[[package]]
+name = "cty"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b365fabc795046672053e29c954733ec3b05e4be654ab130fe8f1f94d7051f35"
+
 [[package]]
 name = "cursor-icon"
 version = "1.2.0"
@@ -4311,6 +4317,17 @@ version = "0.2.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f9fbbcab51052fe104eb5e5d351cf728d30a5be1fe14d9be8a3b097481fb97de"
 
+[[package]]
+name = "libmimalloc-sys"
+version = "0.1.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec9d6fac27761dabcd4ee73571cdb06b7022dc99089acbe5435691edffaac0f4"
+dependencies = [
+ "cc",
+ "cty",
+ "libc",
+]
+
 [[package]]
 name = "libredox"
 version = "0.1.3"
@@ -4622,6 +4639,15 @@ dependencies = [
  "servo_url",
 ]
 
+[[package]]
+name = "mimalloc"
+version = "0.1.46"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "995942f432bbb4822a7e9c3faa87a695185b0d09273ba85f097b54f4e458f2af"
+dependencies = [
+ "libmimalloc-sys",
+]
+
 [[package]]
 name = "mime"
 version = "0.3.17"
@@ -6894,6 +6920,8 @@ name = "servo_allocator"
 version = "0.0.1"
 dependencies = [
  "libc",
+ "libmimalloc-sys",
+ "mimalloc",
  "tikv-jemalloc-sys",
  "tikv-jemallocator",
  "windows-sys 0.59.0",

components/allocator/Cargo.toml

@@ -12,6 +12,7 @@ path = "lib.rs"
 
 [features]
 use-system-allocator = ["libc"]
+use-mimalloc = ["mimalloc", "libmimalloc-sys"]
 
 [target.'cfg(not(any(windows, target_env = "ohos")))'.dependencies]
 libc = { workspace = true, optional = true }
@@ -23,3 +24,7 @@ windows-sys = { workspace = true, features = ["Win32_System_Memory"] }
 
 [target.'cfg(target_env = "ohos")'.dependencies]
 libc = { workspace = true }
+
+[dependencies]
+mimalloc = { version = "0.1", features = ["extended"], optional = true }
+libmimalloc-sys = { version = "0.1", optional = true }

components/allocator/lib.rs

@@ -9,7 +9,7 @@ static ALLOC: Allocator = Allocator;
 
 pub use crate::platform::*;
 
-#[cfg(not(any(windows, feature = "use-system-allocator", target_env = "ohos")))]
+#[cfg(not(any(windows, feature = "use-system-allocator", feature = "use-mimalloc", target_env = "ohos")))]
 mod platform {
     use std::os::raw::c_void;
 
@@ -32,6 +32,7 @@ mod platform {
 
 #[cfg(all(
     not(windows),
+    not(feature = "use-mimalloc"),
     any(feature = "use-system-allocator", target_env = "ohos")
 ))]
 mod platform {
@@ -60,7 +61,7 @@ mod platform {
     }
 }
 
-#[cfg(windows)]
+#[cfg(all(windows, not(feature = "use-mimalloc")))]
 mod platform {
     pub use std::alloc::System as Allocator;
     use std::os::raw::c_void;
@@ -85,3 +86,24 @@ mod platform {
         }
     }
 }
+
+#[cfg(feature = "use-mimalloc")]
+mod platform {
+    use std::os::raw::c_void;
+
+    pub use mimalloc::MiMalloc as Allocator;
+
+    /// Get the size of a heap block.
+    ///
+    /// # Safety
+    ///
+    /// Passing a non-heap allocated pointer to this function results in undefined behavior.
+    pub unsafe extern "C" fn usable_size(ptr: *const c_void) -> usize {
+        unsafe { Allocator.usable_size(ptr as _) }
+    }
+
+    /// Memory allocation APIs compatible with libc
+    pub mod libc_compat {
+        pub use libmimalloc_sys::{ mi_free as free, mi_malloc as malloc, mi_realloc as realloc };
+    }
+}

ports/servoshell/Cargo.toml

@@ -52,6 +52,7 @@ webdriver = ["libservo/webdriver"]
 webgl_backtrace = ["libservo/webgl_backtrace"]
 webgpu = ["libservo/webgpu"]
 webxr = ["libservo/webxr"]
+use-mimalloc = ["servo_allocator/use-mimalloc"]
 
 [dependencies]
 cfg-if = { workspace = true }