bech32

commit 95c41c2a1064d3b433bfe6d0087a2f4776b00c23
parent 5909ce98c22a1a82465b4f806e70df426f89f070
Author: Jared Tobin <jared@jtobin.io>
Date:   Tue, 23 Dec 2025 08:40:47 -0330

meta: add llvm flag

Diffstat:
M
README.md
 | 
25
++++++++++---------------
M
flake.nix
 | 
5
+++--
M
ppad-bech32.cabal
 | 
7
+++++++

3 files changed, 20 insertions(+), 17 deletions(-)
diff --git a/README.md b/README.md
@@ -43,33 +43,28 @@ Haddocks (API documentation, etc.) are hosted at
 
 ## Performance
 
-The aim is best-in-class performance for pure, highly-auditable Haskell
-code. At present we're a little over twice as fast as the official
-BIP173 reference implementation.
+The aim is best-in-class performance for pure Haskell code.
 
 Current benchmark figures on a M4 Silicon MacBook Air look like (use
 `cabal bench` to run the benchmark suite):
 
 ```
   benchmarking benchmarks/ppad-bech32/bech32 encode/120b
-  time                 783.5 ns   (781.4 ns .. 786.6 ns)
+  time                 462.7 ns   (460.8 ns .. 465.5 ns)
                        1.000 R²   (1.000 R² .. 1.000 R²)
-  mean                 791.1 ns   (788.7 ns .. 793.5 ns)
-  std dev              8.193 ns   (7.461 ns .. 8.973 ns)
+  mean                 465.5 ns   (464.3 ns .. 466.6 ns)
+  std dev              3.955 ns   (3.485 ns .. 4.602 ns)
 
   benchmarking benchmarks/ppad-bech32/bech32 decode/120b
-  time                 944.0 ns   (943.1 ns .. 944.7 ns)
+  time                 499.4 ns   (497.5 ns .. 502.3 ns)
                        1.000 R²   (1.000 R² .. 1.000 R²)
-  mean                 942.4 ns   (941.7 ns .. 943.1 ns)
-  std dev              2.197 ns   (1.838 ns .. 2.669 ns)
-
-  benchmarking benchmarks/reference/bech32 encode/120b
-  time                 1.282 μs   (1.281 μs .. 1.283 μs)
-                       1.000 R²   (1.000 R² .. 1.000 R²)
-  mean                 1.282 μs   (1.282 μs .. 1.283 μs)
-  std dev              1.338 ns   (996.0 ps .. 1.881 ns)
+  mean                 508.0 ns   (505.2 ns .. 510.8 ns)
+  std dev              9.101 ns   (7.828 ns .. 11.23 ns)
+  variance introduced by outliers: 21% (moderately inflated)
 ```
 
+You should compile with the 'llvm' flag for maximum performance.
+
 ## Security
 
 This library aims at the maximum security achievable in a
diff --git a/flake.nix b/flake.nix
@@ -18,6 +18,7 @@
 
         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" {};
@@ -38,10 +39,9 @@
             buildInputs = [
               cabal
               cc
+              llvm
             ];
 
-            inputsFrom = builtins.attrValues self.packages.${system};
-
             doBenchmark = true;
 
             shellHook = ''
@@ -50,6 +50,7 @@
               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-bech32.cabal b/ppad-bech32.cabal
@@ -14,6 +14,11 @@ description:
   bech32 and bech32m encoding/decoding on strict bytestrings, per BIPs
   173 & 350.
 
+flag llvm
+  description: Use GHC's LLVM backend.
+  default:     False
+  manual:      True
+
 source-repository head
   type:     git
   location: git.ppad.tech/bech32.git
@@ -23,6 +28,8 @@ library
   hs-source-dirs:   lib
   ghc-options:
       -Wall
+  if flag(llvm)
+    ghc-options: -fllvm -O2
   exposed-modules:
       Data.ByteString.Base32
     , Data.ByteString.Bech32.Internal