Move to mimalloc

This produces a small (~10% less runtime) improvement on larger files,
as difftastic spends a lot of time allocating.

Cargo.lock

@@ -110,6 +110,7 @@ dependencies = [
  "lazy_static",
  "libc",
  "log",
+ "mimalloc",
  "pretty_assertions",
  "pretty_env_logger",
  "regex",
@@ -178,6 +179,15 @@ version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a7f823d141fe0a24df1e23b4af4e3c7ba9e5966ec514ea068c93024aa7deb765"
 
+[[package]]
+name = "libmimalloc-sys"
+version = "0.1.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d1b8479c593dba88c2741fc50b92e13dbabbbe0bd504d979f244ccc1a5b1c01"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "log"
 version = "0.4.14"
@@ -193,6 +203,15 @@ version = "2.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b16bd47d9e329435e309c58469fe0791c2d0d1ba96ec0954152a5ae2b04387dc"
 
+[[package]]
+name = "mimalloc"
+version = "0.1.26"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb74897ce508e6c49156fd1476fc5922cbc6e75183c65e399c765a09122e5130"
+dependencies = [
+ "libmimalloc-sys",
+]
+
 [[package]]
 name = "output_vt100"
 version = "0.1.2"

Cargo.toml

@@ -32,6 +32,7 @@ tree-sitter = "0.19.5"
 libc = "0.2.99"
 log = "0.4.14"
 pretty_env_logger = "0.4.0"
+mimalloc = { version = "0.1.26", default-features = false }
 
 [dev-dependencies]
 pretty_assertions = "0.6.1"

src/main.rs

@@ -1,3 +1,8 @@
+use mimalloc::MiMalloc;
+
+#[global_allocator]
+static GLOBAL: MiMalloc = MiMalloc;
+
 mod dijkstra;
 mod files;
 mod graph;