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/compiler_enums.h b/compiler/dex/compiler_enums.h
index e4003bf..78da420 100644
--- a/compiler/dex/compiler_enums.h
+++ b/compiler/dex/compiler_enums.h
@@ -311,7 +311,8 @@
kMIRCallee, // Instruction is inlined from callee.
kMIRIgnoreSuspendCheck,
kMIRDup,
- kMIRMark, // Temporary node mark.
+ kMIRMark, // Temporary node mark can be used by
+ // opt passes for their private needs.
kMIRStoreNonTemporal,
kMIRLastMIRFlag,
};