zkas: Use fxhash as the IndexMap hasher.

Cargo.lock

@@ -1538,6 +1538,7 @@ dependencies = [
  "drk-sdk",
  "fast-socks5",
  "futures",
+ "fxhash",
  "group",
  "halo2_gadgets",
  "halo2_proofs",

Cargo.toml

@@ -61,6 +61,7 @@ url = {version = "2.2.2", optional = true}
 dirs = {version = "4.0.0", optional = true}
 subtle = {version = "2.4.1", optional = true}
 lazy_static = {version = "1.4.0", optional = true}
+fxhash = {version = "0.2.1", optional = true}
 indexmap = {version = "1.8.0", optional = true}
 itertools = {version = "0.10.3", optional = true}
 
@@ -151,6 +152,7 @@ util = [
     "serde_json",
     "dirs",
     "num-bigint",
+    "fxhash",
 ]
 
 rpc = [

src/zkas/parser.rs

@@ -1,5 +1,6 @@
 use std::{iter::Peekable, str::Chars};
 
+use fxhash::FxBuildHasher;
 use indexmap::IndexMap;
 use itertools::Itertools;
 
@@ -43,7 +44,7 @@ impl Parser {
         // All the circuit statements
         let mut circuit_statements = vec![];
 
-        let mut ast = IndexMap::new();
+        let mut ast = IndexMap::with_hasher(FxBuildHasher::default());
         let mut namespace = String::new();
         let mut ast_inner = IndexMap::new();
         let mut namespace_found = false; // Nasty