From cce9c13a043e6ff488cbc33d2bb51b1e50e24ea9 Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Mon, 13 Nov 2023 14:15:38 +0100
Subject: [PATCH] Remove if statement at compile time

---
 poseidon2/merkle.nim | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/poseidon2/merkle.nim b/poseidon2/merkle.nim
index ad5e3b4..b24c83f 100644
--- a/poseidon2/merkle.nim
+++ b/poseidon2/merkle.nim
@@ -15,28 +15,28 @@ func merkleRoot(xs: openArray[F], isBottomLayer: static bool) : F =
   let b = high(xs)
   let m = b-a+1
 
-  if m==1 and not isBottomLayer:
-    return xs[a]
+  when not isBottomLayer:
+    if m==1:
+      return xs[a]
 
+  let halfn  : int  = m div 2
+  let n      : int  = 2*halfn
+  let isOdd : bool = (n != m)
+
+  var ys : seq[F]
+  if not isOdd:
+    ys = newSeq[F](halfn)
   else:
-    let halfn  : int  = m div 2
-    let n      : int  = 2*halfn
-    let isOdd : bool = (n != m)
+    ys = newSeq[F](halfn+1)
 
-    var ys : seq[F]
-    if not isOdd:
-      ys = newSeq[F](halfn)
-    else:
-      ys = newSeq[F](halfn+1)
+  for i in 0..<halfn:
+    const key = when isBottomLayer: KeyBottomLayer else: KeyNone
+    ys[i] = compress( xs[a+2*i], xs[a+2*i+1], key = key )
+  if isOdd:
+    const key = when isBottomLayer: KeyOddAndBottomLayer else: KeyOdd
+    ys[halfn] = compress( xs[n], zero, key = key )
 
-    for i in 0..<halfn:
-      const key = when isBottomLayer: KeyBottomLayer else: KeyNone
-      ys[i] = compress( xs[a+2*i], xs[a+2*i+1], key = key )
-    if isOdd:
-      const key = when isBottomLayer: KeyOddAndBottomLayer else: KeyOdd
-      ys[halfn] = compress( xs[n], zero, key = key )
-
-    return merkleRoot(ys, isBottomLayer = false)
+  return merkleRoot(ys, isBottomLayer = false)
 
 func merkleRoot*(xs: openArray[F]) : F =
   merkleRoot(xs, isBottomLayer = true)