[nix] switch to xsfmm llvm

Signed-off-by: unlsycn <[email protected]>

Author: unlsycn

flake.lock

@@ -4,6 +4,7 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-parts.url = "github:hercules-ci/flake-parts";
+    nixpkgs-for-llvm.url = "github:NixOS/nixpkgs/nixos-unstable-small";
     mill-ivy-fetcher.url = "github:Avimitin/mill-ivy-fetcher";
     circt-follow.url = "github:sequencer/zaozi";
     treefmt-nix.url = "github:numtide/treefmt-nix";

flake.nix

@@ -1,8 +1,11 @@
+{ self }:
+
 final: prev:
 
 let
-  llvmForRVV_attrName = "llvmPackages_19";
-  rv32_pkgs = final.pkgsCross.riscv32-embedded;
+  llvmForRVV_attrName = "llvmPackages_git";
+  rv32_pkgs =
+    self.inputs.nixpkgs-for-llvm.legacyPackages."${final.system}".pkgsCross.riscv32-embedded;
   rv32_buildPkgs = rv32_pkgs.buildPackages;
 in
 rec {
@@ -92,9 +95,24 @@ rec {
         newlib = rv32_pkgs.stdenv.cc.libc.overrideAttrs (oldAttrs: {
           CFLAGS_FOR_TARGET = "-march=rv32imacf_zvl128b_zve32f -mabi=ilp32f";
         });
+
+        llvmPackages = rv32_buildPkgs.${llvmForRVV_attrName};
+        patchedCC =
+          let
+            llvmSrc = prev.fetchFromGitHub {
+              owner = "topperc";
+              repo = "llvm-project";
+              rev = "bb123ff9401b517d877de4ed6fd9ea61edf49dbb";
+              hash = "sha256-6ca5FhSsG5Qik7wi6Vn3OmUmKR/hULSDniu4JLo+5jM=";
+            };
+          in
+          llvmPackages.clang-unwrapped.override {
+            monorepoSrc = llvmSrc;
+            libllvm = llvmPackages.libllvm.override { monorepoSrc = llvmSrc; };
+          };
       in
       rv32_buildPkgs.wrapCCWith rec {
-        cc = rv32_buildPkgs.${llvmForRVV_attrName}.clang-unwrapped;
+        cc = patchedCC;
         libc = newlib;
         bintools = rv32_pkgs.stdenv.cc.bintools.override {
           inherit libc; # we must keep consistency of bintools libc and compiler libc