chacha

commit 6752c4336c1b581ae7875b1c9a0eaed115e420a3
parent 6a6281342faa0e9adaa5fce1e85de84b058e49ae
Author: Jared Tobin <jared@jtobin.io>
Date:   Sat, 27 Dec 2025 08:41:11 -0330

meta: llvm flag

Diffstat:
M
README.md
 | 
9
+++++----
M
flake.nix
 | 
7
++++---
M
ppad-chacha.cabal
 | 
7
+++++++

3 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/README.md b/README.md
@@ -45,12 +45,14 @@ benchmark suite):
 
 ```
   benchmarking ppad-chacha/cipher
-  time                 770.2 ns   (769.9 ns .. 770.5 ns)
+  time                 485.7 ns   (485.2 ns .. 486.3 ns)
                        1.000 R²   (1.000 R² .. 1.000 R²)
-  mean                 770.2 ns   (770.0 ns .. 770.5 ns)
-  std dev              794.7 ps   (653.0 ps .. 999.5 ps)
+  mean                 485.9 ns   (485.1 ns .. 486.3 ns)
+  std dev              1.943 ns   (1.389 ns .. 2.809 ns)
 ```
 
+You should compile with the 'llvm' flag for maximum performance.
+
 ## Security
 
 This library aims at the maximum security achievable in a
@@ -62,7 +64,6 @@ and the downstream AEAD-ChaCha20-Poly1305 implementation in
 [ppad-aead](https://github.com/ppad-tech/aead) passes all the [Project
 Wycheproof vectors][wyche].
 
-
 If you discover any vulnerabilities, please disclose them via
 security@ppad.tech.
 
diff --git a/flake.nix b/flake.nix
@@ -26,10 +26,11 @@
 
         pkgs = import nixpkgs { inherit system; };
         hlib = pkgs.haskell.lib;
+        llvm = pkgs.llvmPackages_15.llvm;
 
         hpkgs = pkgs.haskell.packages.ghc981.extend (new: old: {
-          ${lib} = old.callCabal2nixWithOptions lib ./. "--enable-profiling" {};
           ppad-base16 = ppad-base16.packages.${system}.default;
+          ${lib} = new.callCabal2nixWithOptions lib ./. "--enable-profiling" {};
         });
 
         cc    = pkgs.stdenv.cc;
@@ -47,10 +48,9 @@
             buildInputs = [
               cabal
               cc
+              llvm
             ];
 
-            inputsFrom = builtins.attrValues self.packages.${system};
-
             doBenchmark = true;
 
             shellHook = ''
@@ -59,6 +59,7 @@
               echo "cc:    $(${cc}/bin/cc --version)"
               echo "ghc:   $(${ghc}/bin/ghc --version)"
               echo "cabal: $(${cabal}/bin/cabal --version)"
+              echo "llc:   $(${llvm}/bin/llc --version | head -2 | tail -1)"
             '';
           };
         }
diff --git a/ppad-chacha.cabal b/ppad-chacha.cabal
@@ -13,6 +13,11 @@ extra-doc-files:    CHANGELOG
 description:
   A pure ChaCha20 stream cipher and block function.
 
+flag llvm
+  description: Use GHC's LLVM backend.
+  default:     False
+  manual:      True
+
 source-repository head
   type:     git
   location: git.ppad.tech/chacha.git
@@ -22,6 +27,8 @@ library
   hs-source-dirs:   lib
   ghc-options:
       -Wall
+  if flag(llvm)
+    ghc-options: -fllvm -O2
   exposed-modules:
       Crypto.Cipher.ChaCha20
   build-depends: