diff options
Diffstat (limited to 'compiler/optimizing/ssa_builder.cc')
| -rw-r--r-- | compiler/optimizing/ssa_builder.cc | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/compiler/optimizing/ssa_builder.cc b/compiler/optimizing/ssa_builder.cc index 1a8e784..ba11e90 100644 --- a/compiler/optimizing/ssa_builder.cc +++ b/compiler/optimizing/ssa_builder.cc @@ -199,9 +199,9 @@ void SsaBuilder::BuildSsa() { // our code generator will complain if the inputs of a phi do not have the same // type. The marking allows the type propagation to know which phis it needs // to handle. We mark but do not eliminate: the elimination will be done in - // step 8). - SsaDeadPhiElimination dead_phis(GetGraph()); - dead_phis.MarkDeadPhis(); + // step 9). + SsaDeadPhiElimination dead_phis_for_type_propagation(GetGraph()); + dead_phis_for_type_propagation.MarkDeadPhis(); // 4) Propagate types of phis. At this point, phis are typed void in the general // case, or float/double/reference when we created an equivalent phi. So we @@ -209,7 +209,11 @@ void SsaBuilder::BuildSsa() { PrimitiveTypePropagation type_propagation(GetGraph()); type_propagation.Run(); - // 5) Now that the graph is correclty typed, we can get rid of redundant phis. + // 5) Mark dead phis again. Steph 4) may have introduced new phis. + SsaDeadPhiElimination dead_phis(GetGraph()); + dead_phis.MarkDeadPhis(); + + // 6) Now that the graph is correclty typed, we can get rid of redundant phis. // Note that we cannot do this phase before type propagation, otherwise // we could get rid of phi equivalents, whose presence is a requirement for the // type propagation phase. Note that this is to satisfy statement (a) of the @@ -217,7 +221,7 @@ void SsaBuilder::BuildSsa() { SsaRedundantPhiElimination redundant_phi(GetGraph()); redundant_phi.Run(); - // 6) Make sure environments use the right phi "equivalent": a phi marked dead + // 7) Make sure environments use the right phi "equivalent": a phi marked dead // can have a phi equivalent that is not dead. We must therefore update // all environment uses of the dead phi to use its equivalent. Note that there // can be multiple phis for the same Dex register that are live (for example @@ -244,7 +248,7 @@ void SsaBuilder::BuildSsa() { } } - // 7) Deal with phis to guarantee liveness of phis in case of a debuggable + // 8) Deal with phis to guarantee liveness of phis in case of a debuggable // application. This is for satisfying statement (c) of the SsaBuilder // (see ssa_builder.h). if (GetGraph()->IsDebuggable()) { @@ -252,7 +256,7 @@ void SsaBuilder::BuildSsa() { dead_phi_handler.Run(); } - // 8) Now that the right phis are used for the environments, and we + // 9) Now that the right phis are used for the environments, and we // have potentially revive dead phis in case of a debuggable application, // we can eliminate phis we do not need. Regardless of the debuggable status, // this phase is necessary for statement (b) of the SsaBuilder (see ssa_builder.h), @@ -260,7 +264,7 @@ void SsaBuilder::BuildSsa() { // input types. dead_phis.EliminateDeadPhis(); - // 9) Clear locals. + // 10) Clear locals. for (HInstructionIterator it(GetGraph()->GetEntryBlock()->GetInstructions()); !it.Done(); it.Advance()) { |