Fix null check elimination
The existing null check elimination mechanism suffered from the same
limitation as the SSA renaming: it took shortcuts that were valid in
a trace compilation world, but not in a method compilation world.
This CL replaces the old mechanism, and additionally takes advantage
of some the fact that "this" is always non-null, as are objects returned
from OP_NEW_* (thanks Ian!).
Two test cases added. The one for ensuring that unnecessary null checks
are elminated requires manual inspection. The other - that we don't
eliminate a necessary null check - is disabled until exceptions are working.
Change-Id: I2a9b72741f56617bf609e4d7c20244796c988f28
diff --git a/src/compiler/Dataflow.cc b/src/compiler/Dataflow.cc
index 3369e9e..827470e 100644
--- a/src/compiler/Dataflow.cc
+++ b/src/compiler/Dataflow.cc
@@ -50,13 +50,13 @@
DF_DA_WIDE | DF_UB_WIDE | DF_IS_MOVE,
// 07 OP_MOVE_OBJECT vA, vB
- DF_DA | DF_UB | DF_IS_MOVE,
+ DF_DA | DF_UB | DF_NULL_TRANSFER_0 | DF_IS_MOVE,
// 08 OP_MOVE_OBJECT_FROM16 vAA, vBBBB
- DF_DA | DF_UB | DF_IS_MOVE,
+ DF_DA | DF_UB | DF_NULL_TRANSFER_0 | DF_IS_MOVE,
// 09 OP_MOVE_OBJECT_16 vAAAA, vBBBB
- DF_DA | DF_UB | DF_IS_MOVE,
+ DF_DA | DF_UB | DF_NULL_TRANSFER_0 | DF_IS_MOVE,
// 0A OP_MOVE_RESULT vAA
DF_DA,
@@ -116,31 +116,31 @@
DF_DA,
// 1D OP_MONITOR_ENTER vAA
- DF_UA,
+ DF_UA | DF_NULL_CHK_0,
// 1E OP_MONITOR_EXIT vAA
- DF_UA,
+ DF_UA | DF_NULL_CHK_0,
- // 1F OP_CHECK_CAST vAA, type@BBBB
+ // 1F OP_CHK_CAST vAA, type@BBBB
DF_UA,
// 20 OP_INSTANCE_OF vA, vB, type@CCCC
DF_DA | DF_UB,
// 21 OP_ARRAY_LENGTH vA, vB
- DF_DA | DF_UB,
+ DF_DA | DF_UB | DF_NULL_CHK_0,
// 22 OP_NEW_INSTANCE vAA, type@BBBB
- DF_DA,
+ DF_DA | DF_NON_NULL_DST,
// 23 OP_NEW_ARRAY vA, vB, type@CCCC
- DF_DA | DF_UB,
+ DF_DA | DF_UB | DF_NON_NULL_DST,
// 24 OP_FILLED_NEW_ARRAY {vD, vE, vF, vG, vA}
- DF_FORMAT_35C,
+ DF_FORMAT_35C | DF_NON_NULL_RET,
// 25 OP_FILLED_NEW_ARRAY_RANGE {vCCCC .. vNNNN}, type@BBBB
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NON_NULL_RET,
// 26 OP_FILL_ARRAY_DATA vAA, +BBBBBBBB
DF_UA,
@@ -234,88 +234,88 @@
DF_NOP,
// 44 OP_AGET vAA, vBB, vCC
- DF_DA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_0 | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_UC | DF_NULL_CHK_0 | DF_RANGE_CHK_1 | DF_IS_GETTER,
// 45 OP_AGET_WIDE vAA, vBB, vCC
- DF_DA_WIDE | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_0 | DF_IS_GETTER,
+ DF_DA_WIDE | DF_UB | DF_UC | DF_NULL_CHK_0 | DF_RANGE_CHK_1 | DF_IS_GETTER,
// 46 OP_AGET_OBJECT vAA, vBB, vCC
- DF_DA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_0 | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_UC | DF_NULL_CHK_0 | DF_RANGE_CHK_1 | DF_IS_GETTER,
// 47 OP_AGET_BOOLEAN vAA, vBB, vCC
- DF_DA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_0 | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_UC | DF_NULL_CHK_0 | DF_RANGE_CHK_1 | DF_IS_GETTER,
// 48 OP_AGET_BYTE vAA, vBB, vCC
- DF_DA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_0 | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_UC | DF_NULL_CHK_0 | DF_RANGE_CHK_1 | DF_IS_GETTER,
// 49 OP_AGET_CHAR vAA, vBB, vCC
- DF_DA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_0 | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_UC | DF_NULL_CHK_0 | DF_RANGE_CHK_1 | DF_IS_GETTER,
// 4A OP_AGET_SHORT vAA, vBB, vCC
- DF_DA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_0 | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_UC | DF_NULL_CHK_0 | DF_RANGE_CHK_1 | DF_IS_GETTER,
// 4B OP_APUT vAA, vBB, vCC
- DF_UA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_1 | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_UC | DF_NULL_CHK_1 | DF_RANGE_CHK_2 | DF_IS_SETTER,
// 4C OP_APUT_WIDE vAA, vBB, vCC
- DF_UA_WIDE | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_2 | DF_IS_SETTER,
+ DF_UA_WIDE | DF_UB | DF_UC | DF_NULL_CHK_1 | DF_RANGE_CHK_2 | DF_IS_SETTER,
// 4D OP_APUT_OBJECT vAA, vBB, vCC
- DF_UA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_1 | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_UC | DF_NULL_CHK_1 | DF_RANGE_CHK_2 | DF_IS_SETTER,
// 4E OP_APUT_BOOLEAN vAA, vBB, vCC
- DF_UA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_1 | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_UC | DF_NULL_CHK_1 | DF_RANGE_CHK_2 | DF_IS_SETTER,
// 4F OP_APUT_BYTE vAA, vBB, vCC
- DF_UA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_1 | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_UC | DF_NULL_CHK_1 | DF_RANGE_CHK_2 | DF_IS_SETTER,
// 50 OP_APUT_CHAR vAA, vBB, vCC
- DF_UA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_1 | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_UC | DF_NULL_CHK_1 | DF_RANGE_CHK_2 | DF_IS_SETTER,
// 51 OP_APUT_SHORT vAA, vBB, vCC
- DF_UA | DF_UB | DF_UC | DF_NULL_N_RANGE_CHECK_1 | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_UC | DF_NULL_CHK_1 | DF_RANGE_CHK_2 | DF_IS_SETTER,
// 52 OP_IGET vA, vB, field@CCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 53 OP_IGET_WIDE vA, vB, field@CCCC
- DF_DA_WIDE | DF_UB | DF_IS_GETTER,
+ DF_DA_WIDE | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 54 OP_IGET_OBJECT vA, vB, field@CCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 55 OP_IGET_BOOLEAN vA, vB, field@CCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 56 OP_IGET_BYTE vA, vB, field@CCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 57 OP_IGET_CHAR vA, vB, field@CCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 58 OP_IGET_SHORT vA, vB, field@CCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 59 OP_IPUT vA, vB, field@CCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 5A OP_IPUT_WIDE vA, vB, field@CCCC
- DF_UA_WIDE | DF_UB | DF_IS_SETTER,
+ DF_UA_WIDE | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 5B OP_IPUT_OBJECT vA, vB, field@CCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 5C OP_IPUT_BOOLEAN vA, vB, field@CCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 5D OP_IPUT_BYTE vA, vB, field@CCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 5E OP_IPUT_CHAR vA, vB, field@CCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 5F OP_IPUT_SHORT vA, vB, field@CCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 60 OP_SGET vAA, field@BBBB
DF_DA | DF_IS_GETTER,
@@ -360,13 +360,13 @@
DF_UA | DF_IS_SETTER,
// 6E OP_INVOKE_VIRTUAL {vD, vE, vF, vG, vA}
- DF_FORMAT_35C,
+ DF_FORMAT_35C | DF_NULL_CHK_OUT0,
// 6F OP_INVOKE_SUPER {vD, vE, vF, vG, vA}
- DF_FORMAT_35C,
+ DF_FORMAT_35C | DF_NULL_CHK_OUT0,
// 70 OP_INVOKE_DIRECT {vD, vE, vF, vG, vA}
- DF_FORMAT_35C,
+ DF_FORMAT_35C | DF_NULL_CHK_OUT0,
// 71 OP_INVOKE_STATIC {vD, vE, vF, vG, vA}
DF_FORMAT_35C,
@@ -378,13 +378,13 @@
DF_NOP,
// 74 OP_INVOKE_VIRTUAL_RANGE {vCCCC .. vNNNN}
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NULL_CHK_OUT0,
// 75 OP_INVOKE_SUPER_RANGE {vCCCC .. vNNNN}
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NULL_CHK_OUT0,
// 76 OP_INVOKE_DIRECT_RANGE {vCCCC .. vNNNN}
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NULL_CHK_OUT0,
// 77 OP_INVOKE_STATIC_RANGE {vCCCC .. vNNNN}
DF_FORMAT_3RC,
@@ -711,10 +711,10 @@
DF_DA | DF_UB,
// E3 OP_IGET_VOLATILE
- DF_DA | DF_UB,
+ DF_DA | DF_UB | DF_NULL_CHK_0,
// E4 OP_IPUT_VOLATILE
- DF_UA | DF_UB,
+ DF_UA | DF_UB | DF_NULL_CHK_1,
// E5 OP_SGET_VOLATILE
DF_DA,
@@ -723,13 +723,13 @@
DF_UA,
// E7 OP_IGET_OBJECT_VOLATILE
- DF_DA | DF_UB,
+ DF_DA | DF_UB | DF_NULL_CHK_0,
// E8 OP_IGET_WIDE_VOLATILE
- DF_DA_WIDE | DF_UB,
+ DF_DA_WIDE | DF_UB | DF_NULL_CHK_0,
// E9 OP_IPUT_WIDE_VOLATILE
- DF_UA_WIDE | DF_UB,
+ DF_UA_WIDE | DF_UB | DF_NULL_CHK_1,
// EA OP_SGET_WIDE_VOLATILE
DF_DA_WIDE,
@@ -750,43 +750,43 @@
DF_FORMAT_3RC,
// F0 OP_INVOKE_OBJECT_INIT_RANGE
- DF_NOP,
+ DF_NOP | DF_NULL_CHK_0,
// F1 OP_RETURN_VOID_BARRIER
DF_NOP,
// F2 OP_IGET_QUICK
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// F3 OP_IGET_WIDE_QUICK
- DF_DA_WIDE | DF_UB | DF_IS_GETTER,
+ DF_DA_WIDE | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// F4 OP_IGET_OBJECT_QUICK
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// F5 OP_IPUT_QUICK
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// F6 OP_IPUT_WIDE_QUICK
- DF_UA_WIDE | DF_UB | DF_IS_SETTER,
+ DF_UA_WIDE | DF_UB | DF_NULL_CHK_1 |DF_IS_SETTER,
// F7 OP_IPUT_OBJECT_QUICK
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// F8 OP_INVOKE_VIRTUAL_QUICK
- DF_FORMAT_35C,
+ DF_FORMAT_35C | DF_NULL_CHK_OUT0,
// F9 OP_INVOKE_VIRTUAL_QUICK_RANGE
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NULL_CHK_OUT0,
// FA OP_INVOKE_SUPER_QUICK
- DF_FORMAT_35C,
+ DF_FORMAT_35C | DF_NULL_CHK_OUT0,
// FB OP_INVOKE_SUPER_QUICK_RANGE
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NULL_CHK_OUT0,
// FC OP_IPUT_OBJECT_VOLATILE
- DF_UA | DF_UB,
+ DF_UA | DF_UB | DF_NULL_CHK_1,
// FD OP_SGET_OBJECT_VOLATILE
DF_DA,
@@ -797,65 +797,67 @@
// FF OP_DISPATCH_FF
DF_NOP,
+ //TODO: remove jumbo opcodes
+
// 100 OP_CONST_CLASS_JUMBO vAAAA, type@BBBBBBBB
DF_DA,
- // 101 OP_CHECK_CAST_JUMBO vAAAA, type@BBBBBBBB
+ // 101 OP_CHK_CAST_JUMBO vAAAA, type@BBBBBBBB
DF_UA,
// 102 OP_INSTANCE_OF_JUMBO vAAAA, vBBBB, type@CCCCCCCC
DF_DA | DF_UB,
// 103 OP_NEW_INSTANCE_JUMBO vAAAA, type@BBBBBBBB
- DF_DA,
+ DF_DA | DF_NON_NULL_DST,
// 104 OP_NEW_ARRAY_JUMBO vAAAA, vBBBB, type@CCCCCCCC
- DF_DA | DF_UB,
+ DF_DA | DF_UB | DF_NON_NULL_DST,
// 105 OP_FILLED_NEW_ARRAY_JUMBO {vCCCC .. vNNNN}, type@BBBBBBBB
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NON_NULL_RET,
// 106 OP_IGET_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 107 OP_IGET_WIDE_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_DA_WIDE | DF_UB | DF_IS_GETTER,
+ DF_DA_WIDE | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 108 OP_IGET_OBJECT_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 109 OP_IGET_BOOLEAN_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 10A OP_IGET_BYTE_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 10B OP_IGET_CHAR_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 10C OP_IGET_SHORT_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_DA | DF_UB | DF_IS_GETTER,
+ DF_DA | DF_UB | DF_NULL_CHK_0 | DF_IS_GETTER,
// 10D OP_IPUT_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 10E OP_IPUT_WIDE_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_UA_WIDE | DF_UB | DF_IS_SETTER,
+ DF_UA_WIDE | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 10F OP_IPUT_OBJECT_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 110 OP_IPUT_BOOLEAN_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 111 OP_IPUT_BYTE_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 112 OP_IPUT_CHAR_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 113 OP_IPUT_SHORT_JUMBO vAAAA, vBBBB, field@CCCCCCCC
- DF_UA | DF_UB | DF_IS_SETTER,
+ DF_UA | DF_UB | DF_NULL_CHK_1 | DF_IS_SETTER,
// 114 OP_SGET_JUMBO vAAAA, vBBBB, field@CCCCCCCC
DF_DA | DF_IS_GETTER,
@@ -900,13 +902,13 @@
DF_UA | DF_IS_SETTER,
// 122 OP_INVOKE_VIRTUAL_JUMBO {vCCCC .. vNNNN}, meth@BBBBBBBB
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NULL_CHK_OUT0,
// 123 OP_INVOKE_SUPER_JUMBO {vCCCC .. vNNNN}, meth@BBBBBBBB
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NULL_CHK_OUT0,
// 124 OP_INVOKE_DIRECT_JUMBO {vCCCC .. vNNNN}, meth@BBBBBBBB
- DF_FORMAT_3RC,
+ DF_FORMAT_3RC | DF_NULL_CHK_OUT0,
// 125 OP_INVOKE_STATIC_JUMBO {vCCCC .. vNNNN}, meth@BBBBBBBB
DF_FORMAT_3RC,
@@ -1524,25 +1526,25 @@
DF_NOP,
// 1F2 OP_INVOKE_OBJECT_INIT_JUMBO
- DF_NOP,
+ DF_NOP | DF_NULL_CHK_0,
// 1F3 OP_IGET_VOLATILE_JUMBO
- DF_DA | DF_UB,
+ DF_DA | DF_UB | DF_NULL_CHK_0,
// 1F4 OP_IGET_WIDE_VOLATILE_JUMBO
- DF_DA_WIDE | DF_UB,
+ DF_DA_WIDE | DF_UB | DF_NULL_CHK_0,
// 1F5 OP_IGET_OBJECT_VOLATILE_JUMBO
- DF_DA | DF_UB,
+ DF_DA | DF_UB | DF_NULL_CHK_0,
// 1F6 OP_IPUT_VOLATILE_JUMBO
- DF_UA | DF_UB,
+ DF_UA | DF_UB | DF_NULL_CHK_1,
// 1F7 OP_IPUT_WIDE_VOLATILE_JUMBO
- DF_UA_WIDE | DF_UB,
+ DF_UA_WIDE | DF_UB | DF_NULL_CHK_1,
// 1F8 OP_IPUT_OBJECT_VOLATILE_JUMBO
- DF_UA | DF_UB,
+ DF_UA | DF_UB | DF_NULL_CHK_1,
// 1F9 OP_SGET_VOLATILE_JUMBO
DF_DA,
@@ -1567,7 +1569,7 @@
// Beginning of extended MIR opcodes
// 200 OP_MIR_PHI
- DF_PHI | DF_DA,
+ DF_PHI | DF_DA | DF_NULL_TRANSFER_N,
/*
* For extended MIR inserted at the MIR2LIR stage, it is okay to have
* undefined values here.
@@ -2357,3 +2359,140 @@
change &= isIterative;
}
}
+
+static bool nullCheckEliminationInit(struct CompilationUnit* cUnit,
+ struct BasicBlock* bb)
+{
+ if (bb->dataFlowInfo == NULL) return false;
+ bb->dataFlowInfo->endingNullCheckV =
+ oatAllocBitVector(cUnit->numSSARegs, false);
+ oatClearAllBits(bb->dataFlowInfo->endingNullCheckV);
+ return true;
+}
+
+/* Eliminate unnecessary null checks for a basic block. */
+static bool eliminateNullChecks( struct CompilationUnit* cUnit,
+ struct BasicBlock* bb)
+{
+ if (bb->dataFlowInfo == NULL) return false;
+ /*
+ * Set initial state. Be conservative with catch
+ * blocks and start with no assumptions about null check
+ * status (except for "this").
+ */
+
+ if ((bb->blockType == kEntryBlock) | bb->catchEntry) {
+ oatClearAllBits(cUnit->tempSSARegisterV);
+ if (!cUnit->method->IsStatic()) {
+ // If non-static method, mark "this" as non-null
+ int thisReg = cUnit->method->NumRegisters() -
+ cUnit->method->NumIns();
+ oatSetBit(cUnit->tempSSARegisterV, thisReg);
+ }
+ } else {
+ // Starting state is intesection of all incoming arcs
+ GrowableList* blockList = &cUnit->blockList;
+ ArenaBitVectorIterator bvIterator;
+ oatBitVectorIteratorInit(bb->predecessors, &bvIterator);
+ int predBBIdx = oatBitVectorIteratorNext(&bvIterator);
+ DCHECK(predBBIdx != -1);
+ BasicBlock* predBB = (BasicBlock*)oatGrowableListGetElement(
+ blockList, predBBIdx);
+ oatCopyBitVector(cUnit->tempSSARegisterV,
+ predBB->dataFlowInfo->endingNullCheckV);
+ while (true) {
+ predBBIdx = oatBitVectorIteratorNext(&bvIterator);
+ if (predBBIdx == -1) break;
+ predBB = (BasicBlock*)oatGrowableListGetElement(
+ blockList, predBBIdx);
+ oatIntersectBitVectors(cUnit->tempSSARegisterV,
+ cUnit->tempSSARegisterV,
+ predBB->dataFlowInfo->endingNullCheckV);
+ }
+ }
+
+ // Walk through the instruction in the block, updating as necessary
+ for (MIR* mir = bb->firstMIRInsn; mir; mir = mir->next) {
+ if (mir->ssaRep == NULL) {
+ continue;
+ }
+ int dfAttributes =
+ oatDataFlowAttributes[mir->dalvikInsn.opcode];
+
+ // Mark target of NEW* as non-null
+ if (dfAttributes & DF_NON_NULL_DST) {
+ oatSetBit(cUnit->tempSSARegisterV, mir->ssaRep->defs[0]);
+ }
+
+ // Mark non-null returns from invoke-style NEW*
+ if (dfAttributes & DF_NON_NULL_RET) {
+ MIR* nextMir = mir->next;
+ // Next should be an OP_MOVE_RESULT_OBJECT
+ if (nextMir && nextMir->dalvikInsn.opcode == OP_MOVE_RESULT_OBJECT) {
+ // Mark as null checked
+ oatSetBit(cUnit->tempSSARegisterV, nextMir->ssaRep->uses[0]);
+ } else {
+ if (nextMir) {
+ LOG(WARNING) << "Unexpected opcode following new: " <<
+ (int)nextMir->dalvikInsn.opcode;
+ } else {
+ LOG(WARNING) << "Unexpected termination following new";
+ }
+ }
+ }
+
+ /*
+ * Propagate nullcheck state on register copies (including
+ * Phi pseudo copies. For the latter, nullcheck state is
+ * the "and" of all the Phi's operands.
+ */
+ if (dfAttributes & (DF_NULL_TRANSFER_0 | DF_NULL_TRANSFER_N)) {
+ int tgtSreg = mir->ssaRep->defs[0];
+ int operands = (dfAttributes & DF_NULL_TRANSFER_0) ? 1 :
+ mir->ssaRep->numUses;
+ bool nullChecked = true;
+ for (int i = 0; i < operands; i++) {
+ nullChecked &= oatIsBitSet(cUnit->tempSSARegisterV,
+ mir->ssaRep->uses[i]);
+ }
+ if (nullChecked) {
+ oatSetBit(cUnit->tempSSARegisterV, tgtSreg);
+ }
+ }
+
+ // Already nullchecked?
+ if (dfAttributes & DF_HAS_NULL_CHKS) {
+ int srcSreg = (dfAttributes & DF_NULL_CHK_1) ?
+ mir->ssaRep->uses[1] : mir->ssaRep->uses[0];
+ if (oatIsBitSet(cUnit->tempSSARegisterV, srcSreg)) {
+ // Eliminate the null check
+ mir->optimizationFlags |= MIR_IGNORE_NULL_CHECK;
+ } else {
+ // Mark sReg as null-checked
+ oatSetBit(cUnit->tempSSARegisterV, srcSreg);
+ }
+ }
+ }
+
+ // Did anything change?
+ bool res = oatCompareBitVectors(bb->dataFlowInfo->endingNullCheckV,
+ cUnit->tempSSARegisterV);
+ if (res) {
+ oatCopyBitVector(bb->dataFlowInfo->endingNullCheckV,
+ cUnit->tempSSARegisterV);
+ }
+ return res;
+}
+
+void oatMethodNullCheckElimination(CompilationUnit *cUnit)
+{
+ if (!(cUnit->disableOpt & (1 << kNullCheckElimination))) {
+ DCHECK(cUnit->tempSSARegisterV != NULL);
+ oatDataFlowAnalysisDispatcher(cUnit, nullCheckEliminationInit,
+ kAllNodes,
+ false /* isIterative */);
+ oatDataFlowAnalysisDispatcher(cUnit, eliminateNullChecks,
+ kPreOrderDFSTraversal,
+ true /* isIterative */);
+ }
+}