Optimizing/ARM: Implement kDexCachePcRelative dispatch.

Change-Id: I0fe2da50a30a3f62bec8ea01688dd1fec84b1831
diff --git a/compiler/optimizing/dex_cache_array_fixups_arm.cc b/compiler/optimizing/dex_cache_array_fixups_arm.cc
new file mode 100644
index 0000000..7f5f0e5
--- /dev/null
+++ b/compiler/optimizing/dex_cache_array_fixups_arm.cc
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2015 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 "dex_cache_array_fixups_arm.h"
+
+#include "base/arena_containers.h"
+#include "utils/dex_cache_arrays_layout-inl.h"
+
+namespace art {
+namespace arm {
+
+/**
+ * Finds instructions that need the dex cache arrays base as an input.
+ */
+class DexCacheArrayFixupsVisitor : public HGraphVisitor {
+ public:
+  explicit DexCacheArrayFixupsVisitor(HGraph* graph)
+      : HGraphVisitor(graph),
+        dex_cache_array_bases_(std::less<const DexFile*>(),
+                               // Attribute memory use to code generator.
+                               graph->GetArena()->Adapter(kArenaAllocCodeGenerator)) {}
+
+ private:
+  void VisitInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke) OVERRIDE {
+    // If this is an invoke with PC-relative access to the dex cache methods array,
+    // we need to add the dex cache arrays base as the special input.
+    if (invoke->HasPcRelativeDexCache()) {
+      // Initialize base for target method dex file if needed.
+      MethodReference target_method = invoke->GetTargetMethod();
+      HArmDexCacheArraysBase* base = GetOrCreateDexCacheArrayBase(invoke, *target_method.dex_file);
+      // Update the element offset in base.
+      DexCacheArraysLayout layout(kArmPointerSize, target_method.dex_file);
+      base->UpdateElementOffset(layout.MethodOffset(target_method.dex_method_index));
+      // Add the special argument base to the method.
+      DCHECK(!invoke->HasCurrentMethodInput());
+      invoke->AddSpecialInput(base);
+    }
+  }
+
+  HArmDexCacheArraysBase* GetOrCreateDexCacheArrayBase(HInstruction* user,
+                                                       const DexFile& dex_file) {
+    // Ensure we only initialize the pointer once for each dex file.
+    auto lb = dex_cache_array_bases_.lower_bound(&dex_file);
+    if (lb != dex_cache_array_bases_.end() &&
+        !dex_cache_array_bases_.key_comp()(&dex_file, lb->first)) {
+      return lb->second;
+    }
+
+    HGraph* graph = GetGraph();
+    HBasicBlock* entry = graph->GetEntryBlock();
+    HArmDexCacheArraysBase* base = new (graph->GetArena()) HArmDexCacheArraysBase(dex_file);
+    HInstruction* insert_pos = (user->GetBlock() == entry) ? user : entry->GetLastInstruction();
+    entry->InsertInstructionBefore(base, insert_pos);
+    dex_cache_array_bases_.PutBefore(lb, &dex_file, base);
+    return base;
+  }
+
+  using DexCacheArraysBaseMap =
+      ArenaSafeMap<const DexFile*, HArmDexCacheArraysBase*, std::less<const DexFile*>>;
+  DexCacheArraysBaseMap dex_cache_array_bases_;
+};
+
+void DexCacheArrayFixups::Run() {
+  DexCacheArrayFixupsVisitor visitor(graph_);
+  visitor.VisitInsertionOrder();
+}
+
+}  // namespace arm
+}  // namespace art