[sfi] Move bailout reason into compiler hints

By representing "optimization disabled" with a kNoReason bailout reason,
we have enough spare bits to merge the bailout reason field into
compiler hints. This decreases SFI size by one word.

Change-Id: I0169c91dfbfa443128b060a83e483717ed31a166
Reviewed-on: https://chromium-review.googlesource.com/595980
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47080}

src/factory.cc

@@ -2559,7 +2559,6 @@ Handle<SharedFunctionInfo> Factory::NewSharedFunctionInfo(
   share->set_function_token_position(0);
   // All compiler hints default to false or 0.
   share->set_compiler_hints(0);
-  share->set_bailout_reason(0);
   share->set_kind(kind);
 
   share->set_preparsed_scope_data(*null_value());

src/objects.cc

@@ -13761,16 +13761,10 @@ std::ostream& operator<<(std::ostream& os, const SourceCodeOf& v) {
 
 
 void SharedFunctionInfo::DisableOptimization(BailoutReason reason) {
-  // Disable optimization for the shared function info and mark the
-  // code as non-optimizable. The marker on the shared function info
-  // is there because we flush non-optimized code thereby losing the
-  // non-optimizable information for the code. When the code is
-  // regenerated and set on the shared function info it is marked as
-  // non-optimizable if optimization is disabled for the shared
-  // function info.
   DCHECK(reason != kNoReason);
-  set_optimization_disabled(true);
-  set_disable_optimization_reason(reason);
+
+  set_compiler_hints(
+      DisabledOptimizationReasonBits::update(compiler_hints(), reason));
   // Code should be the lazy compilation stub or else unoptimized.
   DCHECK(abstract_code()->kind() == AbstractCode::FUNCTION ||
          abstract_code()->kind() == AbstractCode::INTERPRETED_FUNCTION ||

src/objects/shared-function-info-inl.h

@@ -58,8 +58,6 @@ INT_ACCESSORS(SharedFunctionInfo, start_position_and_type,
 INT_ACCESSORS(SharedFunctionInfo, function_token_position,
               kFunctionTokenPositionOffset)
 INT_ACCESSORS(SharedFunctionInfo, compiler_hints, kCompilerHintsOffset)
-INT_ACCESSORS(SharedFunctionInfo, bailout_reason,
-              kCountersAndBailoutReasonOffset)
 
 bool SharedFunctionInfo::has_shared_name() const {
   return raw_name() != kNoSharedNameSentinel;
@@ -102,8 +100,14 @@ BIT_FIELD_ACCESSORS(SharedFunctionInfo, compiler_hints, force_inline,
                     SharedFunctionInfo::ForceInlineBit)
 BIT_FIELD_ACCESSORS(SharedFunctionInfo, compiler_hints, is_asm_wasm_broken,
                     SharedFunctionInfo::IsAsmWasmBrokenBit)
-BIT_FIELD_ACCESSORS(SharedFunctionInfo, compiler_hints, optimization_disabled,
-                    SharedFunctionInfo::OptimizationDisabledBit)
+
+bool SharedFunctionInfo::optimization_disabled() const {
+  return disable_optimization_reason() != BailoutReason::kNoReason;
+}
+
+BailoutReason SharedFunctionInfo::disable_optimization_reason() const {
+  return DisabledOptimizationReasonBits::decode(compiler_hints());
+}
 
 LanguageMode SharedFunctionInfo::language_mode() {
   STATIC_ASSERT(LANGUAGE_END == 2);
@@ -355,10 +359,6 @@ void SharedFunctionInfo::set_inferred_name(String* inferred_name) {
   set_function_identifier(inferred_name);
 }
 
-BIT_FIELD_ACCESSORS(SharedFunctionInfo, bailout_reason,
-                    disable_optimization_reason,
-                    SharedFunctionInfo::DisabledOptimizationReasonBits)
-
 bool SharedFunctionInfo::IsUserJavaScript() {
   Object* script_obj = script();
   if (script_obj->IsUndefined(GetIsolate())) return false;

src/objects/shared-function-info.h

@@ -281,12 +281,6 @@ class SharedFunctionInfo : public HeapObject {
   // Indicates if this function can be lazy compiled.
   DECL_BOOLEAN_ACCESSORS(allows_lazy_compilation)
 
-  // Indicates whether optimizations have been disabled for this
-  // shared function info. If a function is repeatedly optimized or if
-  // we cannot optimize the function we disable optimization to avoid
-  // spending time attempting to optimize it again.
-  DECL_BOOLEAN_ACCESSORS(optimization_disabled)
-
   // Indicates the language mode.
   inline LanguageMode language_mode();
   inline void set_language_mode(LanguageMode language_mode);
@@ -324,6 +318,14 @@ class SharedFunctionInfo : public HeapObject {
   // Recalculates the |map_index| value after modifications of this shared info.
   inline void UpdateFunctionMapIndex();
 
+  // Indicates whether optimizations have been disabled for this shared function
+  // info. If we cannot optimize the function we disable optimization to avoid
+  // spending time attempting to optimize it again.
+  inline bool optimization_disabled() const;
+
+  // The reason why optimization was disabled.
+  inline BailoutReason disable_optimization_reason() const;
+
   // Disable (further) attempted optimization of all functions sharing this
   // shared function info.
   void DisableOptimization(BailoutReason reason);
@@ -333,12 +335,6 @@ class SharedFunctionInfo : public HeapObject {
   Handle<Object> GetSourceCode();
   Handle<Object> GetSourceCodeHarmony();
 
-  // Stores bailout_reason as a bit-field.
-  DECL_INT_ACCESSORS(bailout_reason)
-
-  inline BailoutReason disable_optimization_reason() const;
-  inline void set_disable_optimization_reason(BailoutReason reason);
-
   // Tells whether this function should be subject to debugging.
   inline bool IsSubjectToDebugging();
 
@@ -414,33 +410,32 @@ class SharedFunctionInfo : public HeapObject {
 #endif
 
 // Layout description.
-#define SHARED_FUNCTION_INFO_FIELDS(V)           \
-  /* Pointer fields. */                          \
-  V(kCodeOffset, kPointerSize)                   \
-  V(kNameOffset, kPointerSize)                   \
-  V(kScopeInfoOffset, kPointerSize)              \
-  V(kOuterScopeInfoOffset, kPointerSize)         \
-  V(kConstructStubOffset, kPointerSize)          \
-  V(kInstanceClassNameOffset, kPointerSize)      \
-  V(kFunctionDataOffset, kPointerSize)           \
-  V(kScriptOffset, kPointerSize)                 \
-  V(kDebugInfoOffset, kPointerSize)              \
-  V(kFunctionIdentifierOffset, kPointerSize)     \
-  V(kFeedbackMetadataOffset, kPointerSize)       \
-  V(kPreParsedScopeDataOffset, kPointerSize)     \
-  V(kEndOfPointerFieldsOffset, 0)                \
-  /* Raw data fields. */                         \
-  V(kFunctionLiteralIdOffset, kInt32Size)        \
-  V(kUniqueIdOffset, kUniqueIdFieldSize)         \
-  V(kLengthOffset, kInt32Size)                   \
-  V(kFormalParameterCountOffset, kInt32Size)     \
-  V(kExpectedNofPropertiesOffset, kInt32Size)    \
-  V(kStartPositionAndTypeOffset, kInt32Size)     \
-  V(kEndPositionOffset, kInt32Size)              \
-  V(kFunctionTokenPositionOffset, kInt32Size)    \
-  V(kCompilerHintsOffset, kInt32Size)            \
-  V(kCountersAndBailoutReasonOffset, kInt32Size) \
-  /* Total size. */                              \
+#define SHARED_FUNCTION_INFO_FIELDS(V)        \
+  /* Pointer fields. */                       \
+  V(kCodeOffset, kPointerSize)                \
+  V(kNameOffset, kPointerSize)                \
+  V(kScopeInfoOffset, kPointerSize)           \
+  V(kOuterScopeInfoOffset, kPointerSize)      \
+  V(kConstructStubOffset, kPointerSize)       \
+  V(kInstanceClassNameOffset, kPointerSize)   \
+  V(kFunctionDataOffset, kPointerSize)        \
+  V(kScriptOffset, kPointerSize)              \
+  V(kDebugInfoOffset, kPointerSize)           \
+  V(kFunctionIdentifierOffset, kPointerSize)  \
+  V(kFeedbackMetadataOffset, kPointerSize)    \
+  V(kPreParsedScopeDataOffset, kPointerSize)  \
+  V(kEndOfPointerFieldsOffset, 0)             \
+  /* Raw data fields. */                      \
+  V(kFunctionLiteralIdOffset, kInt32Size)     \
+  V(kUniqueIdOffset, kUniqueIdFieldSize)      \
+  V(kLengthOffset, kInt32Size)                \
+  V(kFormalParameterCountOffset, kInt32Size)  \
+  V(kExpectedNofPropertiesOffset, kInt32Size) \
+  V(kStartPositionAndTypeOffset, kInt32Size)  \
+  V(kEndPositionOffset, kInt32Size)           \
+  V(kFunctionTokenPositionOffset, kInt32Size) \
+  V(kCompilerHintsOffset, kInt32Size)         \
+  /* Total size. */                           \
   V(kSize, 0)
 
   DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize,
@@ -469,7 +464,6 @@ class SharedFunctionInfo : public HeapObject {
   V(FunctionKindBits, FunctionKind, 10, _) \
   V(HasDuplicateParametersBit, bool, 1, _) \
   V(AllowLazyCompilationBit, bool, 1, _)   \
-  V(OptimizationDisabledBit, bool, 1, _)   \
   V(UsesArgumentsBit, bool, 1, _)          \
   V(NeedsHomeObjectBit, bool, 1, _)        \
   V(ForceInlineBit, bool, 1, _)            \
@@ -477,13 +471,14 @@ class SharedFunctionInfo : public HeapObject {
   V(IsDeclarationBit, bool, 1, _)          \
   V(IsAsmWasmBrokenBit, bool, 1, _)        \
   V(FunctionMapIndexBits, int, 5, _)       \
-  /* Bits 26-31 are unused. */
-  // TODO(leszeks): Move DisabledOptimizationReason into here once there is
-  // space.
+  V(DisabledOptimizationReasonBits, BailoutReason, 7, _)
 
   DEFINE_BIT_FIELDS(COMPILER_HINTS_BIT_FIELDS)
 #undef COMPILER_HINTS_BIT_FIELDS
 
+  // Bailout reasons must fit in the DisabledOptimizationReason bitfield.
+  STATIC_ASSERT(kLastErrorMessage <= DisabledOptimizationReasonBits::kMax);
+
   // Masks for checking if certain FunctionKind bits are set without fully
   // decoding of the FunctionKind bit field.
   static const int kClassConstructorMask = FunctionKind::kClassConstructor
@@ -505,16 +500,6 @@ class SharedFunctionInfo : public HeapObject {
   DEFINE_BIT_FIELDS(DEBUGGER_HINTS_BIT_FIELDS)
 #undef DEBUGGER_HINTS_BIT_FIELDS
 
-// Bit fields in |bailout_reason|.
-#define BAILOUT_REASON_BIT_FIELDS(V, _) \
-  V(DisabledOptimizationReasonBits, BailoutReason, 7, _)
-
-  DEFINE_BIT_FIELDS(BAILOUT_REASON_BIT_FIELDS)
-#undef BAILOUT_REASON_BIT_FIELDS
-
-  // Bailout reasons must fit in the DisabledOptimizationReason bitfield.
-  STATIC_ASSERT(kLastErrorMessage <= DisabledOptimizationReasonBits::kMax);
-
  private:
   // [raw_name]: Function name string or kNoSharedNameSentinel.
   DECL_ACCESSORS(raw_name, Object)

src/runtime/runtime-function.cc

@@ -151,7 +151,6 @@ RUNTIME_FUNCTION(Runtime_SetCode) {
   target_shared->set_end_position(source_shared->end_position());
   bool was_native = target_shared->native();
   target_shared->set_compiler_hints(source_shared->compiler_hints());
-  target_shared->set_bailout_reason(source_shared->bailout_reason());
   target_shared->set_native(was_native);
   target_shared->set_function_literal_id(source_shared->function_literal_id());
 

src/runtime/runtime-test.cc

@@ -316,9 +316,7 @@ RUNTIME_FUNCTION(Runtime_NeverOptimizeFunction) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_CHECKED(JSFunction, function, 0);
-  function->shared()->set_disable_optimization_reason(
-      kOptimizationDisabledForTest);
-  function->shared()->set_optimization_disabled(true);
+  function->shared()->DisableOptimization(kOptimizationDisabledForTest);
   return isolate->heap()->undefined_value();
 }