Add a new testcase for X/-1, fix bug that prevented tests from running right

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13171 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/div.ll

@@ -12,10 +12,15 @@ int %test1(int %A) {
 
 uint %test2(uint %A) {
 	%B = div uint %A, 8   ; => Shift
-	ret int %B
+	ret uint %B
 }
 
 int %test3(int %A) {
 	%B = div int 0, %A    ; => 0, don't need to keep traps
 	ret int %B
 }
+
+int %test4(int %A) {
+	%B = div int %A, -1    ; 0-A
+	ret int %B
+}