diff options
Diffstat (limited to 'compiler/optimizing/ssa_phi_elimination.cc')
| -rw-r--r-- | compiler/optimizing/ssa_phi_elimination.cc | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/compiler/optimizing/ssa_phi_elimination.cc b/compiler/optimizing/ssa_phi_elimination.cc index 2eef307295..6816b6a028 100644 --- a/compiler/optimizing/ssa_phi_elimination.cc +++ b/compiler/optimizing/ssa_phi_elimination.cc @@ -154,6 +154,7 @@ void SsaRedundantPhiElimination::Run() { cycle_worklist.push_back(phi); visited_phis_in_cycle.insert(phi->GetId()); bool catch_phi_in_cycle = phi->IsCatchPhi(); + bool irreducible_loop_phi_in_cycle = phi->IsIrreducibleLoopHeaderPhi(); // First do a simple loop over inputs and check if they are all the same. for (size_t j = 0; j < phi->InputCount(); ++j) { @@ -187,6 +188,7 @@ void SsaRedundantPhiElimination::Run() { cycle_worklist.push_back(input->AsPhi()); visited_phis_in_cycle.insert(input->GetId()); catch_phi_in_cycle |= input->AsPhi()->IsCatchPhi(); + irreducible_loop_phi_in_cycle |= input->IsIrreducibleLoopHeaderPhi(); } else { // Already visited, nothing to do. } @@ -206,6 +208,15 @@ void SsaRedundantPhiElimination::Run() { continue; } + if (irreducible_loop_phi_in_cycle && !candidate->IsConstant()) { + // For irreducible loops, we need to keep the phis to satisfy our linear scan + // algorithm. + // There is one exception for constants, as the type propagation requires redundant + // cyclic phis of a constant to be removed. This is ok for the linear scan as it + // has to deal with constants anyway, and they can trivially be rematerialized. + continue; + } + for (HPhi* current : cycle_worklist) { // The candidate may not dominate a phi in a catch block: there may be non-throwing // instructions at the beginning of a try range, that may be the first input of |