Fix performance issues related to chaining and unchaining.
1) Patching requests for predicted chaining cells (used by virtual/interface
methods) are now batched in a queue and processed when the VM is paused for GC.
2) When the code cache is full the reset operation is also conducted at the
end of GC pauses so this totally eliminates the need for the compiler thread
to issue suspend-all requests. This is a very rare event and when happening it
takes less than 5ms to finish.
3) Change the initial value of the branch in a predicted chaining cell from 0
(ie lsl r0, r0, #0) to 0xe7fe (ie branch to self) so that initializing a
predicted chaining cell doesn't need to suspend all threads. Together with 1)
seeing 20% speedup on some benchmarks.
4) Add TestCompability.c where defining "TEST_VM_IN_ECLAIR := true" in
buildspec.mk will activate dummy symbols needed to run libdvm.so in older
releases.
Bug: 2397689
Bug: 2396513
Bug: 2331313
diff --git a/vm/compiler/codegen/arm/ArmLIR.h b/vm/compiler/codegen/arm/ArmLIR.h
index 3254ff7..21e2a32 100644
--- a/vm/compiler/codegen/arm/ArmLIR.h
+++ b/vm/compiler/codegen/arm/ArmLIR.h
@@ -730,16 +730,9 @@
u8 defMask; // Resource mask for def
} ArmLIR;
-/* Chain cell for predicted method invocation */
-typedef struct PredictedChainingCell {
- u4 branch; /* Branch to chained destination */
- const ClassObject *clazz; /* key #1 for prediction */
- const Method *method; /* key #2 to lookup native PC from dalvik PC */
- u4 counter; /* counter to patch the chaining cell */
-} PredictedChainingCell;
-
/* Init values when a predicted chain is initially assembled */
-#define PREDICTED_CHAIN_BX_PAIR_INIT 0
+/* E7FE is branch to self */
+#define PREDICTED_CHAIN_BX_PAIR_INIT 0xe7fe
#define PREDICTED_CHAIN_CLAZZ_INIT 0
#define PREDICTED_CHAIN_METHOD_INIT 0
#define PREDICTED_CHAIN_COUNTER_INIT 0
@@ -748,7 +741,7 @@
#define PREDICTED_CHAIN_COUNTER_DELAY 512
/* Rechain after this many mis-predictions have happened */
-#define PREDICTED_CHAIN_COUNTER_RECHAIN 8192
+#define PREDICTED_CHAIN_COUNTER_RECHAIN 1024
/* Used if the resolved callee is a native method */
#define PREDICTED_CHAIN_COUNTER_AVOID 0x7fffffff