Reduce memory used by CompiledMethods.

Use LengthPrefixedArray<>s instead of SwapVector<>s to store
CompiledMethod data and get rid of the unnecessary members
of CompiledMethod to reduce dex2oat memory usage. Refactor
the deduplication from CompilerDriver to a new class.

Use HashSet<> instead of std::set<> for the DedupeSet<> to
further decrease the memory usage and improve performance.

This reduces the dex2oat memory usage when compiling boot
image on Nexus 5 (with Optimizing, -j1) by ~6.75MiB (5%).
This also reduces the compile time by ~2.2% (~1.6% dex2oat
time; with Optimizing, without -j).

Change-Id: I974f1f5e58350de2bf487a2bca3907fa05fb80ea
diff --git a/compiler/linker/arm/relative_patcher_arm_base.cc b/compiler/linker/arm/relative_patcher_arm_base.cc
index cb9ea38..ac38f3d 100644
--- a/compiler/linker/arm/relative_patcher_arm_base.cc
+++ b/compiler/linker/arm/relative_patcher_arm_base.cc
@@ -85,8 +85,7 @@
                                                       const CompiledMethod* compiled_method,
                                                       MethodReference method_ref,
                                                       uint32_t max_extra_space) {
-  DCHECK(compiled_method->GetQuickCode() != nullptr);
-  uint32_t quick_code_size = compiled_method->GetQuickCode()->size();
+  uint32_t quick_code_size = compiled_method->GetQuickCode().size();
   uint32_t quick_code_offset = compiled_method->AlignCode(offset) + sizeof(OatQuickMethodHeader);
   uint32_t next_aligned_offset = compiled_method->AlignCode(quick_code_offset + quick_code_size);
   // Adjust for extra space required by the subclass.
diff --git a/compiler/linker/arm64/relative_patcher_arm64.cc b/compiler/linker/arm64/relative_patcher_arm64.cc
index 6f234a8..57018af 100644
--- a/compiler/linker/arm64/relative_patcher_arm64.cc
+++ b/compiler/linker/arm64/relative_patcher_arm64.cc
@@ -74,7 +74,7 @@
   // Now that we have the actual offset where the code will be placed, locate the ADRP insns
   // that actually require the thunk.
   uint32_t quick_code_offset = compiled_method->AlignCode(offset) + sizeof(OatQuickMethodHeader);
-  ArrayRef<const uint8_t> code(*compiled_method->GetQuickCode());
+  ArrayRef<const uint8_t> code = compiled_method->GetQuickCode();
   uint32_t thunk_offset = compiled_method->AlignCode(quick_code_offset + code.size());
   DCHECK(compiled_method != nullptr);
   for (const LinkerPatch& patch : compiled_method->GetPatches()) {
diff --git a/compiler/linker/arm64/relative_patcher_arm64_test.cc b/compiler/linker/arm64/relative_patcher_arm64_test.cc
index 857d584..2a426b5 100644
--- a/compiler/linker/arm64/relative_patcher_arm64_test.cc
+++ b/compiler/linker/arm64/relative_patcher_arm64_test.cc
@@ -237,7 +237,7 @@
     CHECK(!compiled_method_refs_.empty());
     CHECK_EQ(compiled_method_refs_[0].dex_method_index, 1u);
     CHECK_EQ(compiled_method_refs_.size(), compiled_methods_.size());
-    uint32_t method1_size = compiled_methods_[0]->GetQuickCode()->size();
+    uint32_t method1_size = compiled_methods_[0]->GetQuickCode().size();
     uint32_t thunk_offset = CompiledCode::AlignCode(method1_offset + method1_size, kArm64);
     uint32_t b_diff = thunk_offset - (method1_offset + num_nops * 4u);
     ASSERT_EQ(b_diff & 3u, 0u);
diff --git a/compiler/linker/relative_patcher_test.h b/compiler/linker/relative_patcher_test.h
index e357662..92cf8ca 100644
--- a/compiler/linker/relative_patcher_test.h
+++ b/compiler/linker/relative_patcher_test.h
@@ -74,8 +74,8 @@
     compiled_method_refs_.push_back(method_ref);
     compiled_methods_.emplace_back(new CompiledMethod(
         &driver_, instruction_set_, code,
-        0u, 0u, 0u, nullptr, ArrayRef<const uint8_t>(), ArrayRef<const uint8_t>(),
-        ArrayRef<const uint8_t>(), ArrayRef<const uint8_t>(),
+        0u, 0u, 0u, ArrayRef<const SrcMapElem>(), ArrayRef<const uint8_t>(),
+        ArrayRef<const uint8_t>(), ArrayRef<const uint8_t>(), ArrayRef<const uint8_t>(),
         patches));
   }
 
@@ -93,7 +93,7 @@
 
       offset += sizeof(OatQuickMethodHeader);
       uint32_t quick_code_offset = offset + compiled_method->CodeDelta();
-      const auto& code = *compiled_method->GetQuickCode();
+      const auto code = compiled_method->GetQuickCode();
       offset += code.size();
 
       method_offset_map_.map.Put(compiled_method_refs_[idx], quick_code_offset);
@@ -125,7 +125,7 @@
 
       out_.WriteFully(dummy_header, sizeof(OatQuickMethodHeader));
       offset += sizeof(OatQuickMethodHeader);
-      ArrayRef<const uint8_t> code(*compiled_method->GetQuickCode());
+      ArrayRef<const uint8_t> code = compiled_method->GetQuickCode();
       if (!compiled_method->GetPatches().empty()) {
         patched_code_.assign(code.begin(), code.end());
         code = ArrayRef<const uint8_t>(patched_code_);
@@ -164,7 +164,7 @@
       ++idx;
     }
     CHECK_NE(idx, compiled_method_refs_.size());
-    CHECK_EQ(compiled_methods_[idx]->GetQuickCode()->size(), expected_code.size());
+    CHECK_EQ(compiled_methods_[idx]->GetQuickCode().size(), expected_code.size());
 
     auto result = method_offset_map_.FindMethodOffset(method_ref);
     CHECK(result.first);  // Must have been linked.