MIPS32R2: Share address computation
For array accesses the element address has the following structure:
Address = CONST_OFFSET + base_addr + index << ELEM_SHIFT
The address part (index << ELEM_SHIFT) can be shared across array
accesses with the same data type and index.
For example, in the following loop 5 accesses can share address
computation:
void foo(int[] a, int[] b, int[] c) {
for (i...) {
a[i] = a[i] + 5;
b[i] = b[i] + c[i];
}
}
Test: test-art-host, test-art-target
Change-Id: Id09fa782934aad4ee47669275e7e1a4d7d23b0fa
diff --git a/compiler/optimizing/instruction_simplifier_mips.cc b/compiler/optimizing/instruction_simplifier_mips.cc
new file mode 100644
index 0000000..4bf1bfb
--- /dev/null
+++ b/compiler/optimizing/instruction_simplifier_mips.cc
@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "instruction_simplifier_mips.h"
+
+#include "arch/mips/instruction_set_features_mips.h"
+#include "mirror/array-inl.h"
+
+namespace art {
+namespace mips {
+
+class InstructionSimplifierMipsVisitor : public HGraphVisitor {
+ public:
+ InstructionSimplifierMipsVisitor(HGraph* graph,
+ CodeGenerator* codegen,
+ OptimizingCompilerStats* stats)
+ : HGraphVisitor(graph),
+ stats_(stats),
+ codegen_(down_cast<CodeGeneratorMIPS*>(codegen)) {}
+
+ private:
+ void RecordSimplification() {
+ if (stats_ != nullptr) {
+ stats_->RecordStat(kInstructionSimplificationsArch);
+ }
+ }
+
+ bool TryExtractArrayAccessIndex(HInstruction* access,
+ HInstruction* index,
+ DataType::Type packed_type);
+ void VisitArrayGet(HArrayGet* instruction) OVERRIDE;
+ void VisitArraySet(HArraySet* instruction) OVERRIDE;
+
+ OptimizingCompilerStats* stats_;
+ CodeGeneratorMIPS* codegen_;
+};
+
+bool InstructionSimplifierMipsVisitor::TryExtractArrayAccessIndex(HInstruction* access,
+ HInstruction* index,
+ DataType::Type packed_type) {
+ if (codegen_->GetInstructionSetFeatures().IsR6() ||
+ codegen_->GetInstructionSetFeatures().HasMsa()) {
+ return false;
+ }
+ if (index->IsConstant() ||
+ (index->IsBoundsCheck() && index->AsBoundsCheck()->GetIndex()->IsConstant())) {
+ // If index is constant the whole address calculation often can be done by load/store
+ // instructions themselves.
+ // TODO: Treat the case with non-embeddable constants.
+ return false;
+ }
+
+ if (packed_type != DataType::Type::kInt16 && packed_type != DataType::Type::kUint16 &&
+ packed_type != DataType::Type::kInt32 && packed_type != DataType::Type::kInt64 &&
+ packed_type != DataType::Type::kFloat32 && packed_type != DataType::Type::kFloat64) {
+ return false;
+ }
+
+ if (access->IsArrayGet() && access->AsArrayGet()->IsStringCharAt()) {
+ return false;
+ }
+
+ HGraph* graph = access->GetBlock()->GetGraph();
+ ArenaAllocator* arena = graph->GetArena();
+ size_t component_shift = DataType::SizeShift(packed_type);
+
+ bool is_extracting_beneficial = false;
+ // It is beneficial to extract index intermediate address only if there are at least 2 users.
+ for (const HUseListNode<HInstruction*>& use : index->GetUses()) {
+ HInstruction* user = use.GetUser();
+ if (user->IsArrayGet() && user != access && !user->AsArrayGet()->IsStringCharAt()) {
+ HArrayGet* another_access = user->AsArrayGet();
+ DataType::Type another_packed_type = another_access->GetType();
+ size_t another_component_shift = DataType::SizeShift(another_packed_type);
+ if (another_component_shift == component_shift) {
+ is_extracting_beneficial = true;
+ break;
+ }
+ } else if (user->IsArraySet() && user != access) {
+ HArraySet* another_access = user->AsArraySet();
+ DataType::Type another_packed_type = another_access->GetType();
+ size_t another_component_shift = DataType::SizeShift(another_packed_type);
+ if (another_component_shift == component_shift) {
+ is_extracting_beneficial = true;
+ break;
+ }
+ } else if (user->IsIntermediateArrayAddressIndex()) {
+ HIntermediateArrayAddressIndex* another_access = user->AsIntermediateArrayAddressIndex();
+ size_t another_component_shift = another_access->GetShift()->AsIntConstant()->GetValue();
+ if (another_component_shift == component_shift) {
+ is_extracting_beneficial = true;
+ break;
+ }
+ }
+ }
+
+ if (!is_extracting_beneficial) {
+ return false;
+ }
+
+ HIntConstant* shift = graph->GetIntConstant(component_shift);
+ HIntermediateArrayAddressIndex* address =
+ new (arena) HIntermediateArrayAddressIndex(index, shift, kNoDexPc);
+ access->GetBlock()->InsertInstructionBefore(address, access);
+ access->ReplaceInput(address, 1);
+ return true;
+}
+
+void InstructionSimplifierMipsVisitor::VisitArrayGet(HArrayGet* instruction) {
+ DataType::Type packed_type = instruction->GetType();
+ if (TryExtractArrayAccessIndex(instruction, instruction->GetIndex(), packed_type)) {
+ RecordSimplification();
+ }
+}
+
+void InstructionSimplifierMipsVisitor::VisitArraySet(HArraySet* instruction) {
+ DataType::Type packed_type = instruction->GetComponentType();
+ if (TryExtractArrayAccessIndex(instruction, instruction->GetIndex(), packed_type)) {
+ RecordSimplification();
+ }
+}
+
+void InstructionSimplifierMips::Run() {
+ InstructionSimplifierMipsVisitor visitor(graph_, codegen_, stats_);
+ visitor.VisitReversePostOrder();
+}
+
+} // namespace mips
+} // namespace art