Don't encode a DexRegisterMap if there is no live register.

Change-Id: I76a291e6a0ac37f0590d16c7f5b866115588bc55

5 files changed, 53 insertions, 18 deletions

diff --git a/compiler/optimizing/stack_map_stream.cc b/compiler/optimizing/stack_map_stream.cc
index c60a4eacaa..4784de1380 100644
--- a/compiler/optimizing/stack_map_stream.cc
+++ b/compiler/optimizing/stack_map_stream.cc
@@ -270,7 +270,7 @@ void StackMapStream::FillIn(MemoryRegion region) {
       stack_map.SetStackMask(stack_map_encoding_, *entry.sp_mask);
     }
 
-    if (entry.num_dex_registers == 0) {
+    if (entry.num_dex_registers == 0 || (entry.live_dex_registers_mask->NumSetBits() == 0)) {
       // No dex map available.
       stack_map.SetDexRegisterMapOffset(stack_map_encoding_, StackMap::kNoDexRegisterMap);
     } else {
diff --git a/compiler/optimizing/stack_map_test.cc b/compiler/optimizing/stack_map_test.cc
index 560502fde6..604787fd92 100644
--- a/compiler/optimizing/stack_map_test.cc
+++ b/compiler/optimizing/stack_map_test.cc
@@ -614,6 +614,10 @@ TEST(StackMapTest, TestNoDexRegisterMap) {
   stream.BeginStackMapEntry(0, 64, 0x3, &sp_mask, number_of_dex_registers, 0);
   stream.EndStackMapEntry();
 
+  number_of_dex_registers = 1;
+  stream.BeginStackMapEntry(1, 67, 0x4, &sp_mask, number_of_dex_registers, 0);
+  stream.EndStackMapEntry();
+
   size_t size = stream.PrepareForFillIn();
   void* memory = arena.Alloc(size, kArenaAllocMisc);
   MemoryRegion region(memory, size);
@@ -622,7 +626,7 @@ TEST(StackMapTest, TestNoDexRegisterMap) {
   CodeInfo code_info(region);
   StackMapEncoding encoding = code_info.ExtractEncoding();
   ASSERT_EQ(0u, encoding.NumberOfBytesForStackMask());
-  ASSERT_EQ(1u, code_info.GetNumberOfStackMaps());
+  ASSERT_EQ(2u, code_info.GetNumberOfStackMaps());
 
   uint32_t number_of_location_catalog_entries = code_info.GetNumberOfLocationCatalogEntries();
   ASSERT_EQ(0u, number_of_location_catalog_entries);
@@ -638,6 +642,16 @@ TEST(StackMapTest, TestNoDexRegisterMap) {
 
   ASSERT_FALSE(stack_map.HasDexRegisterMap(encoding));
   ASSERT_FALSE(stack_map.HasInlineInfo(encoding));
+
+  stack_map = code_info.GetStackMapAt(1, encoding);
+  ASSERT_TRUE(stack_map.Equals(code_info.GetStackMapForDexPc(1, encoding)));
+  ASSERT_TRUE(stack_map.Equals(code_info.GetStackMapForNativePcOffset(67, encoding)));
+  ASSERT_EQ(1u, stack_map.GetDexPc(encoding));
+  ASSERT_EQ(67u, stack_map.GetNativePcOffset(encoding));
+  ASSERT_EQ(0x4u, stack_map.GetRegisterMask(encoding));
+
+  ASSERT_FALSE(stack_map.HasDexRegisterMap(encoding));
+  ASSERT_FALSE(stack_map.HasInlineInfo(encoding));
 }
 
 TEST(StackMapTest, InlineTest) {
diff --git a/runtime/quick_exception_handler.cc b/runtime/quick_exception_handler.cc
index 9cb37eed58..786cf06e2d 100644
--- a/runtime/quick_exception_handler.cc
+++ b/runtime/quick_exception_handler.cc
@@ -221,18 +221,22 @@ void QuickExceptionHandler::SetCatchEnvironmentForOptimizedHandler(StackVisitor*
   CodeInfo code_info = handler_method_header_->GetOptimizedCodeInfo();
   StackMapEncoding encoding = code_info.ExtractEncoding();
 
+  // Find stack map of the catch block.
+  StackMap catch_stack_map = code_info.GetCatchStackMapForDexPc(GetHandlerDexPc(), encoding);
+  DCHECK(catch_stack_map.IsValid());
+  DexRegisterMap catch_vreg_map =
+      code_info.GetDexRegisterMapOf(catch_stack_map, encoding, number_of_vregs);
+  if (!catch_vreg_map.IsValid()) {
+    return;
+  }
+
   // Find stack map of the throwing instruction.
   StackMap throw_stack_map =
       code_info.GetStackMapForNativePcOffset(stack_visitor->GetNativePcOffset(), encoding);
   DCHECK(throw_stack_map.IsValid());
   DexRegisterMap throw_vreg_map =
       code_info.GetDexRegisterMapOf(throw_stack_map, encoding, number_of_vregs);
-
-  // Find stack map of the catch block.
-  StackMap catch_stack_map = code_info.GetCatchStackMapForDexPc(GetHandlerDexPc(), encoding);
-  DCHECK(catch_stack_map.IsValid());
-  DexRegisterMap catch_vreg_map =
-      code_info.GetDexRegisterMapOf(catch_stack_map, encoding, number_of_vregs);
+  DCHECK(throw_vreg_map.IsValid());
 
   // Copy values between them.
   for (uint16_t vreg = 0; vreg < number_of_vregs; ++vreg) {
@@ -387,6 +391,10 @@ class DeoptimizeStackVisitor FINAL : public StackVisitor {
                                              number_of_vregs)
         : code_info.GetDexRegisterMapOf(stack_map, encoding, number_of_vregs);
 
+    if (!vreg_map.IsValid()) {
+      return;
+    }
+
     for (uint16_t vreg = 0; vreg < number_of_vregs; ++vreg) {
       if (updated_vregs != nullptr && updated_vregs[vreg]) {
         // Keep the value set by debugger.
diff --git a/runtime/stack.cc b/runtime/stack.cc
index 9098d38bb0..5faff93b97 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -322,6 +322,9 @@ bool StackVisitor::GetVRegFromOptimizedCode(ArtMethod* m, uint16_t vreg, VRegKin
                                            number_of_dex_registers)
       : code_info.GetDexRegisterMapOf(stack_map, encoding, number_of_dex_registers);
 
+  if (!dex_register_map.IsValid()) {
+    return false;
+  }
   DexRegisterLocation::Kind location_kind =
       dex_register_map.GetLocationKind(vreg, number_of_dex_registers, code_info, encoding);
   switch (location_kind) {
diff --git a/runtime/stack_map.h b/runtime/stack_map.h
index a15a08180e..aa23998bb4 100644
--- a/runtime/stack_map.h
+++ b/runtime/stack_map.h
@@ -473,6 +473,9 @@ class DexRegisterLocationCatalog {
 class DexRegisterMap {
  public:
   explicit DexRegisterMap(MemoryRegion region) : region_(region) {}
+  DexRegisterMap() {}
+
+  bool IsValid() const { return region_.pointer() != nullptr; }
 
   // Get the surface kind of Dex register `dex_register_number`.
   DexRegisterLocation::Kind GetLocationKind(uint16_t dex_register_number,
@@ -1136,11 +1139,15 @@ class CodeInfo {
   DexRegisterMap GetDexRegisterMapOf(StackMap stack_map,
                                      const StackMapEncoding& encoding,
                                      uint32_t number_of_dex_registers) const {
-    DCHECK(stack_map.HasDexRegisterMap(encoding));
-    uint32_t offset = GetDexRegisterMapsOffset(encoding)
-                      + stack_map.GetDexRegisterMapOffset(encoding);
-    size_t size = ComputeDexRegisterMapSizeOf(offset, number_of_dex_registers);
-    return DexRegisterMap(region_.Subregion(offset, size));
+
+    if (!stack_map.HasDexRegisterMap(encoding)) {
+      return DexRegisterMap();
+    } else {
+      uint32_t offset = GetDexRegisterMapsOffset(encoding)
+                        + stack_map.GetDexRegisterMapOffset(encoding);
+      size_t size = ComputeDexRegisterMapSizeOf(offset, number_of_dex_registers);
+      return DexRegisterMap(region_.Subregion(offset, size));
+    }
   }
 
   // Return the `DexRegisterMap` pointed by `inline_info` at depth `depth`.
@@ -1148,11 +1155,14 @@ class CodeInfo {
                                           InlineInfo inline_info,
                                           const StackMapEncoding& encoding,
                                           uint32_t number_of_dex_registers) const {
-    DCHECK(inline_info.HasDexRegisterMapAtDepth(depth));
-    uint32_t offset = GetDexRegisterMapsOffset(encoding)
-                      + inline_info.GetDexRegisterMapOffsetAtDepth(depth);
-    size_t size = ComputeDexRegisterMapSizeOf(offset, number_of_dex_registers);
-    return DexRegisterMap(region_.Subregion(offset, size));
+    if (!inline_info.HasDexRegisterMapAtDepth(depth)) {
+      return DexRegisterMap();
+    } else {
+      uint32_t offset = GetDexRegisterMapsOffset(encoding)
+                        + inline_info.GetDexRegisterMapOffsetAtDepth(depth);
+      size_t size = ComputeDexRegisterMapSizeOf(offset, number_of_dex_registers);
+      return DexRegisterMap(region_.Subregion(offset, size));
+    }
   }
 
   InlineInfo GetInlineInfoOf(StackMap stack_map, const StackMapEncoding& encoding) const {