From 8a06bb28a0ab7f40dd77172845f87ee28b076d89 Mon Sep 17 00:00:00 2001
From: mratsim <mamy_github@numforge.co>
Date: Fri, 20 Apr 2018 11:55:15 +0200
Subject: [PATCH] Improve codegen for borrow. Fix #10

---
 src/private/uint_binary_ops.nim | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/private/uint_binary_ops.nim b/src/private/uint_binary_ops.nim
index bf06540..d5ae0fb 100644
--- a/src/private/uint_binary_ops.nim
+++ b/src/private/uint_binary_ops.nim
@@ -35,9 +35,8 @@ proc `-=`*(x: var MpUintImpl, y: MpUintImpl) {.noSideEffect, inline.}=
   # Optimized assembly should contain sbb instruction (substract with borrow)
   # Clang on MacOS does with the -d:release switch and MpUint[uint32] (uint64)
   type SubTy = type x.lo
-  let original = x.lo
+  x.hi -= (x.lo < x.lo).toSubtype(SubTy) + y.hi
   x.lo -= y.lo
-  x.hi -= (original < x.lo).toSubtype(SubTy) + y.hi
 
 proc `-`*(x, y: MpUintImpl): MpUintImpl {.noSideEffect, noInit, inline.}=
   # Substraction for multi-precision unsigned int