update flake to support metal on m1/m2

Author: jpetrucciani

flake.lock

@@ -6,6 +6,10 @@
   outputs = { self, nixpkgs, flake-utils }:
     flake-utils.lib.eachDefaultSystem (system:
       let
+        inherit (pkgs.stdenv) isAarch64 isDarwin;
+        inherit (pkgs.lib) optionals;
+        isM1 = isAarch64 && isDarwin;
+        osSpecific = with pkgs.darwin.apple_sdk_11_0.frameworks; (optionals isDarwin [ Accelerate ]) ++ (optionals isM1 [ MetalKit MetalPerformanceShaders MetalPerformanceShadersGraph ]);
         pkgs = import nixpkgs {
           inherit system;
         };
@@ -18,17 +22,22 @@
         packages.default = pkgs.stdenv.mkDerivation {
           name = "llama.cpp";
           src = ./.;
+          postPatch =
+            if isM1 then ''
+              substituteInPlace ./ggml-metal.m \
+                --replace '[[NSBundle mainBundle] pathForResource:@"ggml-metal" ofType:@"metal"];' "@\"$out/ggml-metal.metal\";"
+            '' else "";
           nativeBuildInputs = with pkgs; [ cmake ];
-          buildInputs = with pkgs; lib.optionals stdenv.isDarwin [
-            darwin.apple_sdk.frameworks.Accelerate
-          ];
-          cmakeFlags = with pkgs; lib.optionals (system == "aarch64-darwin") [
+          buildInputs = osSpecific;
+          cmakeFlags = [ "-DLLAMA_BUILD_SERVER=ON" ] ++ (optionals isM1 [
             "-DCMAKE_C_FLAGS=-D__ARM_FEATURE_DOTPROD=1"
-          ];
+            "-DLLAMA_METAL=ON"
+          ]);
           installPhase = ''
             mkdir -p $out/bin
             mv bin/* $out/bin/
             mv $out/bin/main $out/bin/llama
+            mv $out/bin/server $out/bin/llama-server
 
             echo "#!${llama-python}/bin/python" > $out/bin/convert.py
             cat ${./convert.py} >> $out/bin/convert.py
@@ -40,9 +49,7 @@
           packages = with pkgs; [
             cmake
             llama-python
-          ] ++ lib.optionals stdenv.isDarwin [
-            darwin.apple_sdk.frameworks.Accelerate
-          ];
+          ] ++ osSpecific;
         };
       }
     );