RecursivelyDeleteTriviallyDeadInstructions() could remove

more than 1 instruction. The caller need to be aware of this
and adjust instruction iterators accordingly.

rdar://16679376



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207302 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstSimplify/dead-code-removal.ll

@@ -0,0 +1,15 @@
+; RUN: opts -instsimplify -S < %s | FileCheck %s
+
+define void @foo() nounwind {
+  br i1 undef, label %1, label %4
+
+; <label>:1                                       ; preds = %1, %0
+; CHECK-NOT: phi
+; CHECK-NOT: sub
+  %2 = phi i32 [ %3, %1 ], [ undef, %0 ]
+  %3 = sub i32 0, undef
+  br label %1
+
+; <label>:4                                       ; preds = %0
+  ret void
+}