Hydrogen stubs for array constructors

src/ia32/code-stubs-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 89 matching lines @@
   descriptor->deoptimization_handler_ =
       Runtime::FunctionForId(Runtime::kTransitionElementsKind)->entry;
 }
 
 
 static void InitializeArrayConstructorDescriptor(Isolate* isolate,
     CodeStubInterfaceDescriptor* descriptor) {
   // register state
   // edi -- constructor function
   // ebx -- type info cell with elements kind
-  // eax -- number of arguments to the constructor function
-  static Register registers[] = { edi, ebx };
-  descriptor->register_param_count_ = 2;
+  static Register registers[] = { ebx };
+  descriptor->register_param_count_ = 1;
   // stack param count needs (constructor pointer, and single argument)
   descriptor->stack_parameter_count_ = &eax;
   descriptor->register_params_ = registers;
   descriptor->function_mode_ = JS_FUNCTION_STUB_MODE;
   descriptor->deoptimization_handler_ =
       FUNCTION_ADDR(ArrayConstructor_StubFailure);
 }
 
 
 void ArrayNoArgumentConstructorStub::InitializeInterfaceDescriptor(
@@ skipping 4798 matching lines @@
           result_size_ == 1;
 }
 
 
 void CodeStub::GenerateStubsAheadOfTime(Isolate* isolate) {
   CEntryStub::GenerateAheadOfTime(isolate);
   StoreBufferOverflowStub::GenerateFixedRegStubsAheadOfTime(isolate);
   StubFailureTrampolineStub::GenerateAheadOfTime(isolate);
   // It is important that the store buffer overflow stubs are generated first.
   RecordWriteStub::GenerateFixedRegStubsAheadOfTime(isolate);
+  ArrayConstructorStubBase::GenerateStubsAheadOfTime(isolate);
 }
 
 
 void CodeStub::GenerateFPStubs(Isolate* isolate) {
   if (CpuFeatures::IsSupported(SSE2)) {
     CEntryStub save_doubles(1, kSaveFPRegs);
     // Stubs might already be in the snapshot, detect that and don't regenerate,
     // which would lead to code stub initialization state being messed up.
     Code* save_doubles_code;
     if (!save_doubles.FindCodeInCache(&save_doubles_code, isolate)) {
@@ skipping 2734 matching lines @@
   // Call the entry hook.
   int32_t hook_location = reinterpret_cast<int32_t>(&entry_hook_);
   __ call(Operand(hook_location, RelocInfo::NONE32));
   __ add(esp, Immediate(2 * kPointerSize));
 
   // Restore ecx.
   __ pop(ecx);
   __ ret(0);
 }
 
+
+template<class T>
+static void CreateArrayDispatch(MacroAssembler* masm) {
+  int last_index = GetSequenceIndexFromFastElementsKind(
+      TERMINAL_FAST_ELEMENTS_KIND);
+  for (int i = 0; i <= last_index; ++i) {

[mvstanton, 2013/04/15 15:14:49]

Hannes: why not have a real table here, instead of a bunch of conditionals.

[mvstanton, 2013/04/16 11:48:52]

I talked about this with Jakob and Yang, who pointed out that it's awkward to
make a real "data table" approach because our assembler doesn't support it
directly. Then Toon pointed out that the table would cause an expensive pipeline
stall anyway...at least the way it is now the branch predictor might make a good
choice (statistically, the first branch is probably enough, for smi arrays).
Finally, this code isn't called once we are in the crankshafted version of new
Array(..)

+    Label next;
+    ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
+    __ cmp(edx, kind);
+    __ j(not_equal, &next);
+    T stub(kind);
+    __ TailCallStub(&stub);
+    __ bind(&next);
+  }
+
+  // If we reached this point there is a problem.
+  __ Abort("Unexpected ElementsKind in array constructor");
+}
+
+static void CreateArrayDispatchOneArgument(MacroAssembler* masm) {
+  // ebx - type info cell
+  // edx - kind
+  // eax - number of arguments
+  // edi - constructor?
+  // esp[0] - return address
+  // esp[4] - last argument
+  ASSERT(FAST_SMI_ELEMENTS == 0);
+  ASSERT(FAST_HOLEY_SMI_ELEMENTS == 1);
+  ASSERT(FAST_ELEMENTS == 2);
+  ASSERT(FAST_HOLEY_ELEMENTS == 3);
+  ASSERT(FAST_DOUBLE_ELEMENTS == 4);
+  ASSERT(FAST_HOLEY_DOUBLE_ELEMENTS == 5);
+
+  Handle<Object> undefined_sentinel(
+      masm->isolate()->heap()->undefined_value(),
+      masm->isolate());
+
+  Handle<Object> megamorphic_sentinel =
+      TypeFeedbackCells::MegamorphicSentinel(masm->isolate());
+
+  // is the low bit set?
+  __ test_b(edx, 1);
+  Label normal_sequence;
+  __ j(not_zero, &normal_sequence);
+
+  // look at the first argument
+  __ mov(ecx, Operand(esp, kPointerSize));
+  __ test(ecx, ecx);
+  __ j(zero, &normal_sequence);
+
+  // We are going to create a holey array, but our kind is non-holey.
+  // Fix kind and retry
+  __ inc(edx);
+  __ cmp(ebx, Immediate(undefined_sentinel));
+  __ j(equal, &normal_sequence);
+
+  __ cmp(FieldOperand(ebx, kPointerSize), Immediate(megamorphic_sentinel));
+  // Save the resulting elements kind in type info
+  __ SmiTag(edx);
+  __ mov(FieldOperand(ebx, kPointerSize), edx);
+  __ SmiUntag(edx);
+
+  __ bind(&normal_sequence);
+  int last_index = GetSequenceIndexFromFastElementsKind(
+      TERMINAL_FAST_ELEMENTS_KIND);
+  for (int i = 0; i <= last_index; ++i) {
+    Label next;
+    ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
+    __ cmp(edx, kind);
+    __ j(not_equal, &next);
+    ArraySingleArgumentConstructorStub stub(kind);
+    __ TailCallStub(&stub);
+    __ bind(&next);
+  }
+
+  // If we reached this point there is a problem.
+  __ Abort("Unexpected ElementsKind in array constructor");
+}
+
+
+template<class T>
+static void ArrayConstructorStubAheadOfTimeHelper(Isolate* isolate) {
+  int to_index = GetSequenceIndexFromFastElementsKind(
+      TERMINAL_FAST_ELEMENTS_KIND);
+  for (int i = 0; i <= to_index; ++i) {
+    ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
+    T stub(kind);
+    stub.GetCode(isolate)->set_is_pregenerated(true);
+  }
+}
+
+
+void ArrayConstructorStubBase::GenerateStubsAheadOfTime(Isolate* isolate) {
+  ArrayConstructorStubAheadOfTimeHelper<ArrayNoArgumentConstructorStub>(
+      isolate);
+  ArrayConstructorStubAheadOfTimeHelper<ArraySingleArgumentConstructorStub>(
+      isolate);
+  ArrayConstructorStubAheadOfTimeHelper<ArrayNArgumentsConstructorStub>(
+      isolate);
+}
+
+
+ArrayConstructorStub::ArrayConstructorStub(Isolate* isolate)
+    : argument_count_(ANY) {
+  ArrayConstructorStubBase::GenerateStubsAheadOfTime(isolate);
+}
+
+
+ArrayConstructorStub::ArrayConstructorStub(Isolate* isolate,
+                                           int argument_count) {
+  if (argument_count == 0) {
+    argument_count_ = NONE;
+  } else if (argument_count == 1) {
+    argument_count_ = ONE;
+  } else if (argument_count >= 2) {
+    argument_count_ = MORE_THAN_ONE;
+  } else {
+    UNREACHABLE();
+  }
+  ArrayConstructorStubBase::GenerateStubsAheadOfTime(isolate);
+}
+
+
+void ArrayConstructorStub::Generate(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- eax : argc (only if argument_count_ == ANY)
+  //  -- ebx : type info cell
+  //  -- edi : constructor
+  //  -- esp[0] : return address
+  //  -- esp[4] : last argument
+  // -----------------------------------
+  Handle<Object> undefined_sentinel(
+      masm->isolate()->heap()->undefined_value(),
+      masm->isolate());
+
+  if (FLAG_debug_code) {
+    // The array construct code is only set for the global and natives
+    // builtin Array functions which always have maps.
+
+    // Initial map for the builtin Array function should be a map.
+    __ mov(ecx, FieldOperand(edi, JSFunction::kPrototypeOrInitialMapOffset));
+    // Will both indicate a NULL and a Smi.
+    __ test(ecx, Immediate(kSmiTagMask));
+    __ Assert(not_zero, "Unexpected initial map for Array function");
+    __ CmpObjectType(ecx, MAP_TYPE, ecx);
+    __ Assert(equal, "Unexpected initial map for Array function");
+
+    // We should either have undefined in ebx or a valid jsglobalpropertycell
+    Label okay_here;
+    Handle<Map> global_property_cell_map(
+        masm->isolate()->heap()->global_property_cell_map());
+    __ cmp(ebx, Immediate(undefined_sentinel));
+    __ j(equal, &okay_here);
+    __ cmp(FieldOperand(ebx, 0), Immediate(global_property_cell_map));
+    __ Assert(equal, "Expected property cell in register ebx");
+    __ bind(&okay_here);
+  }
+
+  if (FLAG_optimize_constructed_arrays) {
+    Label no_info, switch_ready;
+    // Get the elements kind and case on that.
+    __ cmp(ebx, Immediate(undefined_sentinel));
+    __ j(equal, &no_info);
+    __ mov(edx, FieldOperand(ebx, kPointerSize));
+    // There is no info if the call site went megamorphic either
+    __ cmp(edx, Immediate(TypeFeedbackCells::MegamorphicSentinel(
+        masm->isolate())));
+    __ j(equal, &no_info);
+    __ SmiUntag(edx);
+    __ jmp(&switch_ready);
+    __ bind(&no_info);
+    __ mov(edx, Immediate(GetInitialFastElementsKind()));
+    __ bind(&switch_ready);
+
+    if (argument_count_ == ANY) {
+      Label not_zero_case, not_one_case;
+      __ test(eax, eax);
+      __ j(not_zero, &not_zero_case);
+      CreateArrayDispatch<ArrayNoArgumentConstructorStub>(masm);
+
+      __ bind(&not_zero_case);
+      __ cmp(eax, 1);
+      __ j(greater, &not_one_case);
+      CreateArrayDispatchOneArgument(masm);
+
+      __ bind(&not_one_case);
+      CreateArrayDispatch<ArrayNArgumentsConstructorStub>(masm);
+    } else if (argument_count_ == NONE) {
+      CreateArrayDispatch<ArrayNoArgumentConstructorStub>(masm);
+    } else if (argument_count_ == ONE) {
+      CreateArrayDispatchOneArgument(masm);
+    } else if (argument_count_ == MORE_THAN_ONE) {
+      CreateArrayDispatch<ArrayNArgumentsConstructorStub>(masm);
+    } else {
+      UNREACHABLE();
+    }
+  } else {
+    Label generic_constructor;
+    // Run the native code for the Array function called as constructor.
+    ArrayNativeCode(masm, true, &generic_constructor);
+
+    // Jump to the generic construct code in case the specialized code cannot
+    // handle the construction.
+    __ bind(&generic_constructor);
+    Handle<Code> generic_construct_stub =
+        masm->isolate()->builtins()->JSConstructStubGeneric();
+    __ jmp(generic_construct_stub, RelocInfo::CODE_TARGET);
+  }
+}
+
+
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32