From 1702d51a5974c23f8de861a0c01fc2925fed4477 Mon Sep 17 00:00:00 2001
From: simonmar <unknown>
Date: Mon, 1 Jul 2002 11:37:35 +0000
Subject: [PATCH] [project @ 2002-07-01 11:37:35 by simonmar] Replace divInt#
 with a version which doesn't suffer from overflow problems
 (thanks to Dylan Thurston for the code).

---
 GHC/Base.lhs |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/GHC/Base.lhs b/GHC/Base.lhs
index 8abd593..3945397 100644
--- a/GHC/Base.lhs
+++ b/GHC/Base.lhs
@@ -644,11 +644,18 @@ data (:*:) a b = a :*: b
 %*********************************************************
 
 \begin{code}
-divInt#, modInt# :: Int# -> Int# -> Int#
+divInt# :: Int# -> Int# -> Int#
 x# `divInt#` y#
-    | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
-    | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
+	-- careful NOT to overflow if we do any additional arithmetic
+	-- on the arguments...  the following  previous version of this
+	-- code has problems with overflow:
+--    | (x# ># 0#) && (y# <# 0#) = ((x# -# y#) -# 1#) `quotInt#` y#
+--    | (x# <# 0#) && (y# ># 0#) = ((x# -# y#) +# 1#) `quotInt#` y#
+    | (x# ># 0#) && (y# <# 0#) = (x# -# 1#) `quotInt#` y# -# 1#
+    | (x# <# 0#) && (y# ># 0#) = (x# +# 1#) `quotInt#` y# -# 1#
     | otherwise                = x# `quotInt#` y#
+
+modInt# :: Int# -> Int# -> Int#
 x# `modInt#` y#
     | (x# ># 0#) && (y# <# 0#) ||
       (x# <# 0#) && (y# ># 0#)    = if r# /=# 0# then r# +# y# else 0#
-- 
1.7.10.4