ART: Move exception clearing into own instruction
Runtime delivers exceptions only to catch blocks which begin with a
MOVE_EXCEPTION instruction (in DEX). In that case, the catch block is
expected to clear the thread-local exception storage after having
read the exception reference.
This patch changes Optimizing to represent MOVE_EXCEPTION with two
instructions - HLoadException and HClearException - instead of one.
If the exception reference is not used, HLoadException can be safely
removed, saving a memory load without breaking the runtime behaviour.
Change-Id: Idad8a714467bf9d9d5fccefbc43c0bd8ae13ddba
diff --git a/compiler/optimizing/code_generator_mips64.cc b/compiler/optimizing/code_generator_mips64.cc
index e7d2ec6..a5bad65 100644
--- a/compiler/optimizing/code_generator_mips64.cc
+++ b/compiler/optimizing/code_generator_mips64.cc
@@ -2544,6 +2544,10 @@
}
}
+static int32_t GetExceptionTlsOffset() {
+ return Thread::ExceptionOffset<kMips64WordSize>().Int32Value();
+}
+
void LocationsBuilderMIPS64::VisitLoadException(HLoadException* load) {
LocationSummary* locations =
new (GetGraph()->GetArena()) LocationSummary(load, LocationSummary::kNoCall);
@@ -2552,8 +2556,15 @@
void InstructionCodeGeneratorMIPS64::VisitLoadException(HLoadException* load) {
GpuRegister out = load->GetLocations()->Out().AsRegister<GpuRegister>();
- __ LoadFromOffset(kLoadUnsignedWord, out, TR, Thread::ExceptionOffset<kMips64WordSize>().Int32Value());
- __ StoreToOffset(kStoreWord, ZERO, TR, Thread::ExceptionOffset<kMips64WordSize>().Int32Value());
+ __ LoadFromOffset(kLoadUnsignedWord, out, TR, GetExceptionTlsOffset());
+}
+
+void LocationsBuilderMIPS64::VisitClearException(HClearException* clear) {
+ new (GetGraph()->GetArena()) LocationSummary(clear, LocationSummary::kNoCall);
+}
+
+void InstructionCodeGeneratorMIPS64::VisitClearException(HClearException* clear ATTRIBUTE_UNUSED) {
+ __ StoreToOffset(kStoreWord, ZERO, TR, GetExceptionTlsOffset());
}
void LocationsBuilderMIPS64::VisitLoadLocal(HLoadLocal* load) {