fix Minus wrapping MIN_LONG

2 files changed, 20 insertions, 2 deletions

diff --git a/chapter14/src/main/java/com/seaofnodes/simple/node/MinusNode.java b/chapter14/src/main/java/com/seaofnodes/simple/node/MinusNode.java
index 8a2c9406..8ba45d26 100644
--- a/chapter14/src/main/java/com/seaofnodes/simple/node/MinusNode.java
+++ b/chapter14/src/main/java/com/seaofnodes/simple/node/MinusNode.java
@@ -22,7 +22,9 @@ public class MinusNode extends Node {
     public Type compute() {
         if( in(1)._type instanceof TypeInteger i0 ) {
             if( i0.isHigh() ) return TypeInteger.TOP;
-            return i0==TypeInteger.BOT ? TypeInteger.BOT : TypeInteger.make(-i0._max,-i0._min);
+            // Catch overflow wrapping on `-Long.MIN_VALUE`
+            if( i0 == TypeInteger.BOT || i0._min == Long.MIN_VALUE ) return TypeInteger.BOT;
+            return TypeInteger.make(-i0._max,-i0._min);
         }
         return TypeInteger.TOP.meet(in(1)._type);
     }
diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index 5f7cf954..5a62b905 100644
--- a/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -15,7 +15,7 @@ public class Chapter14Test {
 """
 return 3.14;
 """);
-        StopNode stop = parser.parse(false).iterate(false);
+        StopNode stop = parser.parse(false).iterate(true);
         assertEquals("return 3.14;", stop.toString());
         assertEquals(3.14, Evaluator.evaluate(stop,  0));
     }
@@ -142,6 +142,22 @@ return c;                       //
     }
 
     @Test
+    public void testWrapMinus() {
+        Parser parser = new Parser(
+"""
+int MAX = 9223372036854775807; //0x7FFFFFFFFFFFFFFF;
+int i = (arg&MAX) + -MAX + -1; // Basically (e0) + Long.MIN_VALUE
+int j = -i; // Negating Long.MIN_VALUE wraps, cannot constant fold
+if (arg) j = 1;
+return j;
+""");
+        StopNode stop = parser.parse(false).iterate(true);
+        assertEquals("return Phi(Region28,1,(-((arg&9223372036854775807)+-9223372036854775808)));", stop.toString());
+        assertEquals(-9223372036854775808L, Evaluator.evaluate(stop,  0));
+        assertEquals(1, Evaluator.evaluate(stop,  1));
+    }
+
+    @Test
     public void testOr() {
         Parser parser = new Parser(
 """