commit b73323c50d10d3850d2d8719a481f4f430fc51ce
author David Srbecky <dsrbecky@google.com> Sun Jul 15 23:58:44 2018 +0100
committer David Srbecky <dsrbecky@google.com> Wed Aug 01 12:41:36 2018 +0100
tree b5c2eb181dd398229fb7b7e852923efd247e5710
parent ca182f2c81e7102d3ccd1c4ec5c96e602ad343fe

Deduplicate stackmaps at BitTable level.

Make it possible to share BitTables between CodeInfos.

This saves 1% of .oat file size.

Test: test-art-host-gtest
Change-Id: I14172cba6b65e734b94f8c232f24eeee1fc67113

compiler/optimizing/stack_map_stream.cc

diff --git a/compiler/optimizing/stack_map_stream.cc b/compiler/optimizing/stack_map_stream.cc
index da6c711..e1b6575 100644
--- a/compiler/optimizing/stack_map_stream.cc
+++ b/compiler/optimizing/stack_map_stream.cc
@@ -292,6 +292,12 @@
   }
 }
 
+template<typename Writer, typename Builder>
+ALWAYS_INLINE static void EncodeTable(Writer& out, const Builder& bit_table) {
+  out.WriteBit(false);  // Is not deduped.
+  bit_table.Encode(out);
+}
+
 size_t StackMapStream::PrepareForFillIn() {
   DCHECK_EQ(out_.size(), 0u);
 
@@ -309,13 +315,13 @@
   EncodeUnsignedLeb128(&out_, fp_spill_mask_);
   EncodeUnsignedLeb128(&out_, num_dex_registers_);
   BitMemoryWriter<ScopedArenaVector<uint8_t>> out(&out_, out_.size() * kBitsPerByte);
-  stack_maps_.Encode(out);
-  inline_infos_.Encode(out);
-  register_masks_.Encode(out);
-  stack_masks_.Encode(out);
-  dex_register_masks_.Encode(out);
-  dex_register_maps_.Encode(out);
-  dex_register_catalog_.Encode(out);
+  EncodeTable(out, stack_maps_);
+  EncodeTable(out, inline_infos_);
+  EncodeTable(out, register_masks_);
+  EncodeTable(out, stack_masks_);
+  EncodeTable(out, dex_register_masks_);
+  EncodeTable(out, dex_register_maps_);
+  EncodeTable(out, dex_register_catalog_);
 
   return out_.size();
 }

compiler/optimizing/stack_map_test.cc

diff --git a/compiler/optimizing/stack_map_test.cc b/compiler/optimizing/stack_map_test.cc
index 42f9789..16a9216 100644
--- a/compiler/optimizing/stack_map_test.cc
+++ b/compiler/optimizing/stack_map_test.cc
@@ -758,4 +758,48 @@
             stack_map2.GetStackMaskIndex());
 }
 
+TEST(StackMapTest, TestDedupeBitTables) {
+  MallocArenaPool pool;
+  ArenaStack arena_stack(&pool);
+  ScopedArenaAllocator allocator(&arena_stack);
+  StackMapStream stream(&allocator, kRuntimeISA);
+  stream.BeginMethod(32, 0, 0, 2);
+
+  stream.BeginStackMapEntry(0, 64 * kPcAlign);
+  stream.AddDexRegisterEntry(Kind::kInStack, 0);
+  stream.AddDexRegisterEntry(Kind::kConstant, -2);
+  stream.EndStackMapEntry();
+
+  stream.EndMethod();
+  std::vector<uint8_t> memory(stream.PrepareForFillIn());
+  MemoryRegion region(memory.data(), memory.size());
+  stream.FillInCodeInfo(region);
+
+  std::vector<uint8_t> out;
+  CodeInfo::DedupeMap dedupe_map;
+  size_t deduped1 = CodeInfo::Dedupe(&out, memory.data(), &dedupe_map);
+  size_t deduped2 = CodeInfo::Dedupe(&out, memory.data(), &dedupe_map);
+
+  for (size_t deduped : { deduped1, deduped2 }) {
+    CodeInfo code_info(out.data() + deduped);
+    ASSERT_EQ(1u, code_info.GetNumberOfStackMaps());
+
+    StackMap stack_map = code_info.GetStackMapAt(0);
+    ASSERT_TRUE(stack_map.Equals(code_info.GetStackMapForDexPc(0)));
+    ASSERT_TRUE(stack_map.Equals(code_info.GetStackMapForNativePcOffset(64 * kPcAlign)));
+    ASSERT_EQ(0u, stack_map.GetDexPc());
+    ASSERT_EQ(64u * kPcAlign, stack_map.GetNativePcOffset(kRuntimeISA));
+
+    ASSERT_TRUE(stack_map.HasDexRegisterMap());
+    DexRegisterMap dex_register_map = code_info.GetDexRegisterMapOf(stack_map);
+
+    ASSERT_EQ(Kind::kInStack, dex_register_map[0].GetKind());
+    ASSERT_EQ(Kind::kConstant, dex_register_map[1].GetKind());
+    ASSERT_EQ(0, dex_register_map[0].GetStackOffsetInBytes());
+    ASSERT_EQ(-2, dex_register_map[1].GetConstant());
+  }
+
+  ASSERT_GT(memory.size() * 2, out.size());
+}
+
 }  // namespace art