Introduce a class encapsulating arguments descriptor arrays.

runtime/vm/stub_code_ia32.cc

Index: runtime/vm/stub_code_ia32.cc
diff --git a/runtime/vm/stub_code_ia32.cc b/runtime/vm/stub_code_ia32.cc
index 140eb70bb1eab70ac52fe2ed55645e6e3f312b9a..289f1c04fbb900ff40f715f6b92e2948b47b8dda 100644
--- a/runtime/vm/stub_code_ia32.cc
+++ b/runtime/vm/stub_code_ia32.cc
@@ -8,6 +8,7 @@
 #include "vm/assembler.h"
 #include "vm/assembler_macros.h"
 #include "vm/compiler.h"
+#include "vm/dart_entry.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/instructions.h"
 #include "vm/object_store.h"
@@ -183,7 +184,7 @@ void StubCode::GenerateCallNativeCFunctionStub(Assembler* assembler) {
 
 
 // Input parameters:
-//   EDX: arguments descriptor array (num_args is first Smi element).
+//   EDX: arguments descriptor array.
 void StubCode::GenerateCallStaticFunctionStub(Assembler* assembler) {
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
@@ -204,7 +205,7 @@ void StubCode::GenerateCallStaticFunctionStub(Assembler* assembler) {
 
 // Called from a static call only when an invalid code has been entered
 // (invalid because its function was optimized or deoptimized).
-// EDX: arguments descriptor array (num_args is first Smi element).
+// EDX: arguments descriptor array.
 void StubCode::GenerateFixCallersTargetStub(Assembler* assembler) {
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
@@ -257,7 +258,7 @@ static void PushArgumentsArray(Assembler* assembler, intptr_t arg_offset) {
 
 // Input parameters:
 //   ECX: ic-data.
-//   EDX: arguments descriptor array (num_args is first Smi element).
+//   EDX: arguments descriptor array.
 // Note: The receiver object is the first argument to the function being
 //       called, the stub accesses the receiver from this location directly
 //       when trying to resolve the call.
@@ -277,8 +278,7 @@ void StubCode::GenerateInstanceFunctionLookupStub(Assembler* assembler) {
   // TOS + 2: Dart code return address
   // TOS + 3: Last argument of caller.
   // ....
-  // Total number of args is the first Smi in args descriptor array (EDX).
-  __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
+  __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   __ movl(EAX, Address(EBP, EAX, TIMES_2, kWordSize));  // Get receiver.
   __ pushl(EDX);  // Preserve arguments descriptor array.
   __ pushl(EAX);  // Preserve receiver.
@@ -377,7 +377,7 @@ void StubCode::GenerateInstanceFunctionLookupStub(Assembler* assembler) {
   __ pushl(raw_null);  // Setup space on stack for result from invoking Closure.
   __ pushl(ECX);  // Closure object.
   __ pushl(EDI);  // Arguments descriptor.
-  __ movl(EDI, FieldAddress(EDI, Array::data_offset()));
+  __ movl(EDI, FieldAddress(EDI, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(EDI);
   __ subl(EDI, Immediate(1));  // Arguments array length, minus the receiver.
   PushArgumentsArray(assembler, (kWordSize * 6));
@@ -409,21 +409,21 @@ void StubCode::GenerateInstanceFunctionLookupStub(Assembler* assembler) {
   //   EAX: receiver.
   //   EDX: ic-data.
   //   ECX: raw_null.
-  //   EDI: argument descriptor array.
+  //   EDI: arguments descriptor array.
 
   __ pushl(raw_null);  // Setup space on stack for result from noSuchMethod.
   __ pushl(EAX);  // Receiver.
   __ pushl(EDX);  // IC-data.
-  __ pushl(EDI);  // Argument descriptor array.
-  __ movl(EDI, FieldAddress(EDI, Array::data_offset()));
+  __ pushl(EDI);  // Arguments descriptor array.
+  __ movl(EDI, FieldAddress(EDI, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(EDI);
   __ subl(EDI, Immediate(1));  // Arguments array length, minus the receiver.
   // See stack layout below explaining "wordSize * 7" offset.
   PushArgumentsArray(assembler, (kWordSize * 7));
 
   // Stack:
-  // TOS + 0: Argument array.
-  // TOS + 1: Argument descriptor array.
+  // TOS + 0: Arguments array.
+  // TOS + 1: Arguments descriptor array.
   // TOS + 2: IC-data.
   // TOS + 3: Receiver
   // TOS + 4: Place for result from noSuchMethod.
@@ -704,8 +704,7 @@ void StubCode::GenerateAllocateArrayStub(Assembler* assembler) {
 
 
 // Input parameters:
-//   EDX: Arguments descriptor array (num_args is first Smi element, closure
-//        object is included in num_args and is first argument).
+//   EDX: Arguments descriptor array.
 // Note: The closure object is the first argument to the function being
 //       called, the stub accesses the closure from this location directly
 //       when trying to resolve the call.
@@ -714,8 +713,8 @@ void StubCode::GenerateCallClosureFunctionStub(Assembler* assembler) {
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
 
-  // Total number of args is the first Smi in args descriptor array (EDX).
-  __ movl(EAX, FieldAddress(EDX, Array::data_offset()));  // Load num_args.
+  // Load num_args.
+  __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   // Load closure object in EDI.
   __ movl(EDI, Address(ESP, EAX, TIMES_2, 0));  // EAX is a Smi.
 
@@ -764,7 +763,7 @@ void StubCode::GenerateCallClosureFunctionStub(Assembler* assembler) {
   __ Bind(&function_compiled);
   // EAX: Code.
   // ECX: Function.
-  // EDX: Arguments descriptor array (num_args is first Smi element).
+  // EDX: Arguments descriptor array.
 
   __ movl(ECX, FieldAddress(EAX, Code::instructions_offset()));
   __ addl(ECX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
@@ -774,8 +773,7 @@ void StubCode::GenerateCallClosureFunctionStub(Assembler* assembler) {
   // Call runtime to report that a closure call was attempted on a non-closure
   // object, passing the non-closure object and its arguments array.
   // EDI: non-closure object.
-  // EDX: arguments descriptor array (num_args is first Smi element, closure
-  //      object is included in num_args).
+  // EDX: arguments descriptor array.
 
   // Create a stub frame as we are pushing some objects on the stack before
   // calling into the runtime.
@@ -783,8 +781,8 @@ void StubCode::GenerateCallClosureFunctionStub(Assembler* assembler) {
 
   __ pushl(raw_null);  // Setup space on stack for result from error reporting.
   __ pushl(EDI);  // Non-closure object.
-    // Total number of args is the first Smi in args descriptor array (EDX).
-  __ movl(EDI, FieldAddress(EDX, Array::data_offset()));  // Load num_args.
+  // Load num_args.
+  __ movl(EDI, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(EDI);
   __ subl(EDI, Immediate(1));  // Arguments array length, minus the closure.
   // See stack layout below explaining "wordSize * 5" offset.
@@ -860,7 +858,7 @@ void StubCode::GenerateInvokeDartCodeStub(Assembler* assembler) {
   __ movl(EDX, Address(EDX, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Load number of arguments into EBX.
-  __ movl(EBX, FieldAddress(EDX, Array::data_offset()));
+  __ movl(EBX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(EBX);
 
   // Set up arguments for the dart call.
@@ -887,10 +885,10 @@ void StubCode::GenerateInvokeDartCodeStub(Assembler* assembler) {
   __ movl(CTX, Address(CTX, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Reread the arguments descriptor array to obtain the number of passed
-  // arguments, which is the first element of the array, a Smi.
+  // arguments.
   __ movl(EDX, Address(EBP, kArgumentsDescOffset));
   __ movl(EDX, Address(EDX, VMHandles::kOffsetOfRawPtrInHandle));
-  __ movl(EDX, FieldAddress(EDX, Array::data_offset()));
+  __ movl(EDX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   // Get rid of arguments pushed on the stack.
   __ leal(ESP, Address(ESP, EDX, TIMES_2, 0));  // EDX is a Smi.
 
@@ -1448,10 +1446,9 @@ void StubCode::GenerateCallNoSuchMethodFunctionStub(Assembler* assembler) {
   // noSuchMethod(String name, Array arguments) to something like
   // noSuchMethod(InvocationMirror call).
   // Also, the class NoSuchMethodError has to be modified accordingly.
-  // Total number of args is the first Smi in args descriptor array (EDX).
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
-  __ movl(EDI, FieldAddress(EDX, Array::data_offset()));
+  __ movl(EDI, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(EDI);
   __ movl(EAX, Address(EBP, EDI, TIMES_4, kWordSize));  // Get receiver.
 
@@ -1589,8 +1586,8 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
   // EBX: points directly to the first ic data array element.
 
   // Get the receiver's class ID (first read number of arguments from
-  // argument descriptor array and then access the receiver from the stack).
-  __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
+  // arguments descriptor array and then access the receiver from the stack).
+  __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   __ movl(EAX, Address(ESP, EAX, TIMES_2, 0));  // EAX (argument_count) is smi.
   __ call(&get_class_id_as_smi);
   // EAX: receiver's class ID (smi).
@@ -1601,7 +1598,7 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
   for (int i = 0; i < num_args; i++) {
     if (i > 0) {
       // If not the first, load the next argument's class ID.
-      __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
+      __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
       __ movl(EAX, Address(ESP, EAX, TIMES_2, - i * kWordSize));
       __ call(&get_class_id_as_smi);
       // EAX: next argument class ID (smi).
@@ -1619,7 +1616,7 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
   __ Bind(&update);
   // Reload receiver class ID.  It has not been destroyed when num_args == 1.
   if (num_args > 1) {
-    __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
+    __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
     __ movl(EAX, Address(ESP, EAX, TIMES_2, 0));
     __ call(&get_class_id_as_smi);
   }
@@ -1636,13 +1633,13 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   // Compute address of arguments (first read number of arguments from
-  // argument descriptor array and then compute address on the stack).
-  __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
+  // arguments descriptor array and then compute address on the stack).
+  __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   __ leal(EAX, Address(ESP, EAX, TIMES_2, 0));  // EAX is Smi.
   // Create a stub frame as we are pushing some objects on the stack before
   // calling into the runtime.
   AssemblerMacros::EnterStubFrame(assembler);
-  __ pushl(EDX);  // Preserve arguments array.
+  __ pushl(EDX);  // Preserve arguments descriptor array.
   __ pushl(ECX);  // Preserve IC data array
   __ pushl(raw_null);  // Setup space on stack for result (target code object).
   // Push call arguments.
@@ -1665,7 +1662,7 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
   }
   __ popl(EAX);  // Pop returned code object into EAX (null if not found).
   __ popl(ECX);  // Restore IC data array.
-  __ popl(EDX);  // Restore arguments array.
+  __ popl(EDX);  // Restore arguments descriptor array.
   __ LeaveFrame();
   Label call_target_function;
   __ cmpl(EAX, raw_null);
@@ -1712,7 +1709,7 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
 // Use inline cache data array to invoke the target or continue in inline
 // cache miss handler. Stub for 1-argument check (receiver class).
 //  ECX: Inline cache data object.
-//  EDX: Arguments array.
+//  EDX: Arguments descriptor array.
 //  TOS(0): Return address.
 // Inline cache data object structure:
 // 0: function-name
@@ -1743,7 +1740,7 @@ void StubCode::GenerateThreeArgsCheckInlineCacheStub(Assembler* assembler) {
 // cache miss handler. Stub for 1-argument check (receiver class).
 //  EDI: function which counter needs to be incremented.
 //  ECX: Inline cache data object.
-//  EDX: Arguments array.
+//  EDX: Arguments descriptor array.
 //  TOS(0): Return address.
 // Inline cache data object structure:
 // 0: function-name
@@ -1785,7 +1782,7 @@ void StubCode::GenerateMegamorphicCallStub(Assembler* assembler) {
 }
 
 
-//  EDX: Arguments array.
+//  EDX: Arguments descriptor array.
 //  TOS(0): return address (Dart code).
 void StubCode::GenerateBreakpointStaticStub(Assembler* assembler) {
   // Create a stub frame as we are pushing some objects on the stack before
@@ -1828,7 +1825,7 @@ void StubCode::GenerateBreakpointReturnStub(Assembler* assembler) {
 
 
 //  ECX: Inline cache data array.
-//  EDX: Arguments array.
+//  EDX: Arguments descriptor array.
 //  TOS(0): return address (Dart code).
 void StubCode::GenerateBreakpointDynamicStub(Assembler* assembler) {
   // Create a stub frame as we are pushing some objects on the stack before