ART: NullCheckElimination should converge with MIR_IGNORE_NULL_CHECK
If the MIRGraph::EliminateNullChecksAndInferTypes() function managed
to prove that some regs are non-null then it sets the flag
MIR_IGNORE_NULL_CHECK and resets this flag for all the other regs.
If some previous optimizations have already set MIR_IGNORE_NULL_CHECK
then it can be reset by EliminateNullChecksAndInferTypes. This way
NullCheckElimination discards some optimization efforts.
Optimization passes should not reset MIR_IGNORE_NULL_CHECK unless
they 100% sure NullCheck is needed.
This patch makes the NCE_TypeInference pass merge its own
calculated MIR_IGNORE_NULL_CHECK with the one came from previous
optimizations. Technically NCE_TypeInference calculates the flag
in a temporary MIR_MARK-th bit by preserving MIR_IGNORE_NULL_CHECK.
Then at the end of NCE pass MIR_MARK is or-ed with
MIR_IGNORE_NULL_CHECK.
Change-Id: Ib26997c70ecf2c158f61496dee9b1fe45c812096
Signed-off-by: Yevgeny Rouban <yevgeny.y.rouban@intel.com>
diff --git a/compiler/dex/mir_graph.h b/compiler/dex/mir_graph.h
index cc215bd..90cdded 100644
--- a/compiler/dex/mir_graph.h
+++ b/compiler/dex/mir_graph.h
@@ -160,6 +160,7 @@
#define MIR_CALLEE (1 << kMIRCallee)
#define MIR_IGNORE_SUSPEND_CHECK (1 << kMIRIgnoreSuspendCheck)
#define MIR_DUP (1 << kMIRDup)
+#define MIR_MARK (1 << kMIRMark)
#define MIR_STORE_NON_TEMPORAL (1 << kMIRStoreNonTemporal)
#define BLOCK_NAME_LEN 80