Loop Index Split can eliminate a loop if it can determin if loop body is executed only once. There was a bug in determining IV based value of the iteration for which the loop body is executed. Fix it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68071 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/LoopIndexSplit/2009-03-30-undef.ll

@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | opt -loop-index-split | llvm-dis | not grep undef
+define i32 @main() {
+entry:
+	br label %header
+
+header:
+	%r = phi i32 [ 0, %entry ], [ %r3, %skip ]
+	%i = phi i32 [ 0, %entry ], [ %i1, %skip ]
+        %i99 = add i32 %i, 99
+	%cond = icmp eq i32 %i99, 3
+        br i1 %cond, label %body, label %skip
+
+body:
+        br label %skip
+
+skip:
+        %r3 = phi i32 [ %r, %header ], [ 3, %body ]
+        %i1 = add i32 %i, 1
+        %exitcond = icmp eq i32 %i1, 10
+        br i1 %exitcond, label %exit, label %header
+
+exit:
+        ret i32 %r3
+}