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llvm-project/llvm/test/Other/devirtualization-undef.ll

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Reland [CGSCC] Detect devirtualization in more cases The devirtualization wrapper misses cases where if it wraps a pass manager, an individual pass may devirtualize an indirect call created by a previous pass. For example, inlining may create a new indirect call which is devirtualized by instcombine. Currently the devirtualization wrapper will not see that because it only checks cgscc edges at the very beginning and end of the pass (manager) it wraps. This fixes some tests testing this exact behavior in the legacy PM. Instead of checking WeakTrackingVHs for CallBases at the very beginning and end of the pass it wraps, check every time updateCGAndAnalysisManagerForPass() is called. check-llvm and check-clang with -abort-on-max-devirt-iterations-reached on by default doesn't show any failures outside of tests specifically testing it so it doesn't needlessly rerun passes more than necessary. (The NPM -O2/3 pipeline run the inliner/function simplification pipeline under a devirtualization repeater pass up to 4 times by default). http://llvm-compile-time-tracker.com/?config=O3&stat=instructions&remote=aeubanks shows that 7zip has ~1% compile time regression. I looked at it and saw that there indeed was devirtualization happening that was not previously caught, so now it reruns the CGSCC pipeline on some SCCs, which is WAI. The initial land assumed CallBase WeakTrackingVHs would always be CallBases, but they can be RAUW'd with undef. Reviewed By: asbirlea Differential Revision: https://reviews.llvm.org/D89587
2020-10-15 08:56:38 +08:00
; RUN: opt -passes='devirt<2>(function(simplifycfg))' %s -S | FileCheck %s
; CHECK: unreachable
declare void @llvm.assume(i1 noundef)
declare i1 @bar(i8* nonnull dereferenceable(1))
define void @foo() {
%a = call i1 null()
call void @llvm.assume(i1 %a)
ret void
}