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1; When an SCC got split due to inlining, we have two mechanisms for reprocessing the updated SCC, first is UR.UpdatedC2; that repeatedly rerun the new, current SCC; second is a worklist for all newly split SCCs. We need to avoid rerun of3; the same SCC when the SCC is set to be processed by both mechanisms back to back. In pathological cases, such extra,4; redundant rerun could cause exponential size growth due to inlining along cycles.5;6; The test cases here illustrates potential redundant rerun and how it's prevented, however there's no extra inlining7; even if we allow the redundant rerun. In real code, when inliner makes different decisions for different call sites8; of the same caller-callee edge, we could end up getting more recursive inlining without SCC mutation.9;10; REQUIRES: asserts11; RUN: opt < %s -passes='cgscc(inline)' -inline-threshold=500 -debug-only=cgscc -S 2>&1 | FileCheck %s12 13; CHECK: Running an SCC pass across the RefSCC: [(test1_a, test1_b, test1_c)]14; CHECK: Enqueuing the existing SCC in the worklist:(test1_b)15; CHECK: Enqueuing a newly formed SCC:(test1_c)16; CHECK: Switch an internal ref edge to a call edge from 'test1_a' to 'test1_c'17; CHECK: Switch an internal ref edge to a call edge from 'test1_a' to 'test1_a'18; CHECK: Re-running SCC passes after a refinement of the current SCC: (test1_c, test1_a)19; CHECK: Skipping redundant run on SCC: (test1_c, test1_a)20 21declare void @external(i32 %seed)22 23define void @test1_a(i32 %num) {24entry:25 call void @test1_b(i32 %num)26 call void @external(i32 %num)27 ret void28}29 30define void @test1_b(i32 %num) {31entry:32 call void @test1_c(i32 %num)33 call void @test1_a(i32 %num)34 call void @external(i32 %num)35 ret void36}37 38define void @test1_c(i32 %num) #0 {39 call void @test1_a(i32 %num)40 ret void41}42 43attributes #0 = { noinline nounwind optnone }44