| ; When an SCC got split due to inlining, we have two mechanisms for reprocessing the updated SCC, first is UR.UpdatedC |
| ; that repeatedly rerun the new, current SCC; second is a worklist for all newly split SCCs. We need to avoid rerun of |
| ; the same SCC when the SCC is set to be processed by both mechanisms back to back. In pathological cases, such extra, |
| ; redundant rerun could cause exponential size growth due to inlining along cycles. |
| ; |
| ; The test cases here illustrates potential redundant rerun and how it's prevented, however there's no extra inlining |
| ; even if we allow the redundant rerun. In real code, when inliner makes different decisions for different call sites |
| ; of the same caller-callee edge, we could end up getting more recursive inlining without SCC mutation. |
| ; |
| ; REQUIRES: asserts |
| ; RUN: opt < %s -passes='cgscc(inline)' -inline-threshold=500 -debug-only=cgscc -S 2>&1 | FileCheck %s |
| |
| ; CHECK: Running an SCC pass across the RefSCC: [(test1_a, test1_b, test1_c)] |
| ; CHECK: Enqueuing the existing SCC in the worklist:(test1_b) |
| ; CHECK: Enqueuing a newly formed SCC:(test1_c) |
| ; CHECK: Enqueuing a new RefSCC in the update worklist: [(test1_b)] |
| ; CHECK: Switch an internal ref edge to a call edge from 'test1_a' to 'test1_c' |
| ; CHECK: Switch an internal ref edge to a call edge from 'test1_a' to 'test1_a' |
| ; CHECK: Re-running SCC passes after a refinement of the current SCC: (test1_c, test1_a) |
| ; CHECK: Skipping redundant run on SCC: (test1_c, test1_a) |
| |
| declare void @external(i32 %seed) |
| |
| define void @test1_a(i32 %num) { |
| entry: |
| call void @test1_b(i32 %num) |
| call void @external(i32 %num) |
| ret void |
| } |
| |
| define void @test1_b(i32 %num) { |
| entry: |
| call void @test1_c(i32 %num) |
| call void @test1_a(i32 %num) |
| call void @external(i32 %num) |
| ret void |
| } |
| |
| define void @test1_c(i32 %num) #0 { |
| call void @test1_a(i32 %num) |
| ret void |
| } |
| |
| attributes #0 = { noinline nounwind optnone } |