Index: lib/Transforms/Scalar/LICM.cpp =================================================================== --- lib/Transforms/Scalar/LICM.cpp +++ lib/Transforms/Scalar/LICM.cpp @@ -906,7 +906,7 @@ continue; if (!DT->isReachableFromEntry(User->getParent())) { - User->replaceUsesOfWith(&I, UndefValue::get(I.getType())); + U = UndefValue::get(I.getType()); continue; } Index: test/Transforms/LICM/pr35342.ll =================================================================== --- /dev/null +++ test/Transforms/LICM/pr35342.ll @@ -0,0 +1,27 @@ +; RUN: opt -licm -S < %s | FileCheck %s + +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:1" +target triple = "x86_64-unknown-linux-gnu" + +; CHECK-LABEL: @f1 +; CHECK-LABEL: bci_524: +; CHECK: add i32 undef, undef +define void @f1(i32 %v) { +not_zero.lr.ph: + br label %not_zero + +not_zero: + br i1 undef, label %bci_748 , label %bci_314 + +bci_314: + %0 = select i1 undef, i32 undef, i32 undef + br label %not_zero + +bci_524: ; No predecessors! + %add = add i32 %0, %0 + br label %bci_748 + +bci_748: + ret void +} +