From 23074d5de8c46e0b66e805e853e905656d9d2b7f Mon Sep 17 00:00:00 2001
From: Philipp Bartsch <phil@grmr.de>
Date: Wed, 10 Apr 2024 13:47:38 +0200
Subject: [PATCH] vectorscan: improve FAT_RUNTIME and run checks

---
 .../libraries/vectorscan/default.nix          | 36 ++++++++++++++++---
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/pkgs/development/libraries/vectorscan/default.nix b/pkgs/development/libraries/vectorscan/default.nix
index 12fa0735b27f..57445d452670 100644
--- a/pkgs/development/libraries/vectorscan/default.nix
+++ b/pkgs/development/libraries/vectorscan/default.nix
@@ -30,11 +30,37 @@ stdenv.mkDerivation rec {
     boost
   ];
 
-  cmakeFlags = lib.optional enableShared "-DBUILD_STATIC_AND_SHARED=ON"
-    ++ [ "-DFAT_RUNTIME=${if stdenv.hostPlatform.isLinux then "ON" else "OFF"}" ]
-    ++ lib.optional stdenv.hostPlatform.avx2Support "-DBUILD_AVX2=ON"
-    ++ lib.optional stdenv.hostPlatform.avx512Support "-DBUILD_AVX512=ON"
-  ;
+  # FAT_RUNTIME bundles optimized implementations for different CPU extensions and uses CPUID to
+  # transparently select the fastest for the current hardware.
+  # This feature is only available on linux for x86, x86_64, and aarch64.
+  #
+  # If FAT_RUNTIME is not available, we fall back to building for a single extension based
+  # on stdenv.hostPlatform.
+  #
+  # For generic builds (e.g. x86_64) this can mean using an implementation not optimized for the
+  # potentially available more modern hardware extensions (e.g. x86_64 with AVX512).
+  cmakeFlags = [ (if enableShared then "-DBUILD_SHARED_LIBS=ON" else "BUILD_STATIC_LIBS=ON") ]
+    ++
+    (if lib.elem stdenv.hostPlatform.system [ "x86_64-linux" "i686-linux" ] then
+      [ "-DBUILD_AVX2=ON" "-DBUILD_AVX512=ON" "-DBUILD_AVX512VBMI=ON" "-DFAT_RUNTIME=ON" ]
+    else
+      (if (stdenv.isLinux && stdenv.isAarch64) then
+        [ "-DBUILD_SVE=ON" "-DBUILD_SVE2=ON" "-DBUILD_SVE2_BITPERM=ON" "-DFAT_RUNTIME=ON" ]
+      else
+        [ "-DFAT_RUNTIME=OFF" ]
+          ++ lib.optional stdenv.hostPlatform.avx2Support "-DBUILD_AVX2=ON"
+          ++ lib.optional stdenv.hostPlatform.avx512Support "-DBUILD_AVX512=ON"
+      )
+    );
+
+  doCheck = true;
+  checkPhase = ''
+    runHook preCheck
+
+    ./bin/unit-hyperscan
+
+    runHook postCheck
+  '';
 
   meta = with lib; {
     description = "A portable fork of the high-performance regular expression matching library";