Fix a bug in the type analysis phase of optimizing.
Dex code can lead to the creation of a phi with one
float input and one integer input. Since the SSA builder trusts
the verifier, it assumes that the integer input must be converted
to float. However, when the register is not used afterwards, the
verifier hasn't ensured that. Therefore, the compiler must remove
the phi prior to doing type propagation.
Change-Id: Idcd51c4dccce827c59d1f2b253bc1c919bc07df5
diff --git a/compiler/optimizing/ssa_builder.cc b/compiler/optimizing/ssa_builder.cc
index b2cc119..edfafcd 100644
--- a/compiler/optimizing/ssa_builder.cc
+++ b/compiler/optimizing/ssa_builder.cc
@@ -18,6 +18,7 @@
#include "nodes.h"
#include "ssa_type_propagation.h"
+#include "ssa_phi_elimination.h"
namespace art {
@@ -41,11 +42,20 @@
}
}
- // 3) Propagate types of phis.
+ // 3) Remove dead phis. This will remove phis that are only used by environments:
+ // at the DEX level, the type of these phis does not need to be consistent, but
+ // our code generator will complain if the inputs of a phi do not have the same
+ // type (modulo the special case of `null`).
+ SsaDeadPhiElimination dead_phis(GetGraph());
+ dead_phis.Run();
+
+ // 4) Propagate types of phis. At this point, phis are typed void in the general
+ // case, or float or double when we created a floating-point equivalent. So we
+ // need to propagate the types across phis to give them a correct type.
SsaTypePropagation type_propagation(GetGraph());
type_propagation.Run();
- // 4) Clear locals.
+ // 5) Clear locals.
// TODO: Move this to a dead code eliminator phase.
for (HInstructionIterator it(GetGraph()->GetEntryBlock()->GetInstructions());
!it.Done();