[VM] Introduction of type testing stubs - Part 1

This CL:

  * Adds a field to [RawAbstractType] which will always hold a pointer
    to the entrypoint of a type testing stub

  * Makes this new field be initialized to a default stub whenever a
    instances are created (e.g. via Type::New(), snapshot reader, ...)

  * Makes the clustered snapshotter write a reference to the
    corresponding [RawInstructions] object when writing the field and do
    the reverse when reading it.

  * Makes us call the type testing stub for performing assert-assignable
    checks.

To reduce unnecessary loads on callsites, we store the entrypoint of the
type testing stubs directly in the type objects.  This means that the
caller of type testing stubs can simply branch there without populating
a code object first.  This also means that the type testing stubs
themselves have no access to a pool and we therefore also don't hold on
to the [Code] object, only the [Instruction] object is necessary.

The type testing stubs do not setup a frame themselves and also have no
safepoint.  In the case when the type testing stubs could not determine
a positive answer they will tail-call a general-purpose stub.

The general-purpose stub sets up a stub frame, tries to consult a
[SubtypeTestCache] and bails out to runtime if this was unsuccessful.

This CL is just the the first, for ease of reviewing.  The actual
type-specialized type testing stubs will be generated in later CLs.

Issue dart-lang#31798

Change-Id: I174a11b3b812799f399a60af799144c2ba3c26ec
Reviewed-on: https://dart-review.googlesource.com/44787
Reviewed-by: Vyacheslav Egorov <[email protected]>
Reviewed-by: Régis Crelier <[email protected]>

Author: mkustermann

assembler_arm.h

@@ -353,6 +353,13 @@ class Assembler : public ValueObject {
   void Bind(Label* label);
   void Jump(Label* label) { b(label); }
 
+  void LoadField(Register dst, FieldAddress address) { ldr(dst, address); }
+
+  void CompareWithFieldValue(Register value, FieldAddress address) {
+    ldr(TMP, address);
+    cmp(value, Operand(TMP));
+  }
+
   // Misc. functionality
   intptr_t CodeSize() const { return buffer_.Size(); }
   intptr_t prologue_offset() const { return prologue_offset_; }

assembler_arm64.h

@@ -438,6 +438,8 @@ class Assembler : public ValueObject {
   void Bind(Label* label);
   void Jump(Label* label) { b(label); }
 
+  void LoadField(Register dst, FieldAddress address) { ldr(dst, address); }
+
   // Misc. functionality
   intptr_t CodeSize() const { return buffer_.Size(); }
   intptr_t prologue_offset() const { return prologue_offset_; }
@@ -1506,6 +1508,7 @@ class Assembler : public ValueObject {
 
   void EnterFrame(intptr_t frame_size);
   void LeaveFrame();
+  void Ret() { ret(LR); }
 
   void CheckCodePointer();
   void RestoreCodePointer();

assembler_x64.h

@@ -651,6 +651,7 @@ class Assembler : public ValueObject {
   }
 
   // Methods for High-level operations and implemented on all architectures.
+  void Ret() { ret(); }
   void CompareRegisters(Register a, Register b);
   void BranchIf(Condition condition, Label* label) { j(condition, label); }
 
@@ -799,6 +800,12 @@ class Assembler : public ValueObject {
   void Bind(Label* label);
   void Jump(Label* label) { jmp(label); }
 
+  void LoadField(Register dst, FieldAddress address) { movq(dst, address); }
+
+  void CompareWithFieldValue(Register value, FieldAddress address) {
+    cmpq(value, address);
+  }
+
   void Comment(const char* format, ...) PRINTF_ATTRIBUTE(2, 3);
   static bool EmittingComments();
 

assembler_x64_test.cc

@@ -3226,7 +3226,7 @@ ASSEMBLER_TEST_RUN(PackedDoubleNegate, test) {
   EXPECT_FLOAT_EQ(-1.0, res, 0.000001f);
   EXPECT_DISASSEMBLY_NOT_WINDOWS_ENDS_WITH(
       "movups xmm10,[rax]\n"
-      "movq r11,[thr+0xf8]\n"
+      "movq r11,[thr+0x...]\n"
       "xorpd xmm10,[r11]\n"
       "movaps xmm0,xmm10\n"
       "pop thr\n"