base configuration

modules/simd.nix

@@ -0,0 +1,27 @@
+{ config, lib, libS, ... }:
+
+let
+  cfg = config.simd;
+in
+{
+  options.simd = {
+    enable = lib.mkEnableOption "optimized builds with simd instructions";
+    arch = lib.mkOption {
+      type = with lib.types; nullOr str;
+      default = null;
+      description = ''
+        Microarchitecture string for nixpkgs.hostPlatform.gcc.march and to generate system-features.
+        Can be determined with: ``nix shell nixpkgs#gcc -c gcc -march=native -Q --help=target | grep march``
+      '';
+    };
+  };
+
+  config = {
+    nix.settings.system-features = lib.mkIf (cfg.arch != null) (libS.nix.gcc-system-features config.simd.arch);
+
+    nixpkgs.hostPlatform = lib.mkIf cfg.enable {
+      gcc.arch = config.simd.arch;
+      inherit (config.nixpkgs) system;
+    };
+  };
+}