Imported Upstream version 5.18.0.179

Former-commit-id: 67aa10e65b237e1c4537630979ee99ebe1374215

external/llvm/test/Transforms/LoopStrengthReduce/dead-phi.ll

@@ -0,0 +1,21 @@
+; RUN: opt < %s -loop-reduce -S | grep phi | count 1
+
+define void @foo(i32 %n) {
+entry:
+  br label %loop
+
+loop:
+  %i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
+
+  ; These three instructions form an isolated cycle and can be deleted.
+  %j = phi i32 [ 0, %entry ], [ %j.y, %loop ]
+  %j.x = add i32 %j, 1
+  %j.y = mul i32 %j.x, 2
+
+  %i.next = add i32 %i, 1
+  %c = icmp ne i32 %i.next, %n
+  br i1 %c, label %loop, label %exit
+
+exit:
+  ret void
+}