Uses an object pool on x64

runtime/vm/assembler_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/heap.h"
 #include "vm/memory_region.h"
@@ skipping 77 matching lines @@
 
 
 void Assembler::call(Label* label) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   static const int kSize = 5;
   EmitUint8(0xE8);
   EmitLabel(label, kSize);
 }
 
 
+void Assembler::LoadExternalLabel(const ExternalLabel* label) {
+  const int32_t offset = Array::element_offset(AddExternalLabel(label));
+  LoadWordFromPoolOffset(TMP, offset - kHeapObjectTag);
+}
+
+
 void Assembler::call(const ExternalLabel* label) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
-  intptr_t call_start = buffer_.GetPosition();
 
   // Encode movq(TMP, Immediate(label->address())), but always as imm64.
   EmitRegisterREX(TMP, REX_W);
   EmitUint8(0xB8 | (TMP & 7));
   EmitInt64(label->address());
 
   // Encode call(TMP).
   Operand operand(TMP);
   EmitOperandREX(2, operand, REX_NONE);
   EmitUint8(0xFF);
   EmitOperand(2, operand);
-
-  ASSERT((buffer_.GetPosition() - call_start) == kCallExternalLabelSize);
 }
 
 
+void Assembler::CallPatchable(const ExternalLabel* label) {
+  LoadExternalLabel(label);
+  {
+    AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+    // Encode call(TMP).
+    Operand operand(TMP);
+    EmitOperandREX(2, operand, REX_NONE);
+    EmitUint8(0xFF);
+    EmitOperand(2, operand);
+  }
+}
+
 void Assembler::pushq(Register reg) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitRegisterREX(reg, REX_NONE);
   EmitUint8(0x50 | (reg & 7));
 }
 
 
 void Assembler::pushq(const Address& address) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitOperandREX(6, address, REX_NONE);
@@ skipping 1861 matching lines @@
     EmitNearLabelLink(label);
   } else {
     EmitUint8(0xE9);
     EmitLabelLink(label);
   }
 }
 
 
 void Assembler::jmp(const ExternalLabel* label) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
-  intptr_t call_start = buffer_.GetPosition();
 
   // Encode movq(TMP, Immediate(label->address())), but always as imm64.
   EmitRegisterREX(TMP, REX_W);
   EmitUint8(0xB8 | (TMP & 7));
   EmitInt64(label->address());
 
   // Encode jmp(TMP).
   Operand operand(TMP);
   EmitOperandREX(4, operand, REX_NONE);
   EmitUint8(0xFF);
   EmitOperand(4, operand);
-
-  ASSERT((buffer_.GetPosition() - call_start) == kCallExternalLabelSize);
 }
 
 
 void Assembler::lock() {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitUint8(0xF0);
 }
 
 
 void Assembler::cmpxchgl(const Address& address, Register reg) {
@@ skipping 62 matching lines @@
   if (stack_elements <= 4) {
     for (intptr_t i = 0; i < stack_elements; i++) {
       popq(TMP);
     }
     return;
   }
   addq(RSP, Immediate(stack_elements * kWordSize));
 }
 
 
+int32_t Assembler::AddObject(const Object& obj) {
+  ASSERT(obj.IsNotTemporaryScopedHandle());
+  ASSERT(obj.IsOld());
+  if (object_pool_.IsNull()) {
+    // The object pool cannot be used in the vm isolate.
+    ASSERT(Isolate::Current() != Dart::vm_isolate());
+    object_pool_ = GrowableObjectArray::New(Heap::kOld);
+  }
+  for (int i = 0; i < object_pool_.Length(); i++) {
+    if (object_pool_.At(i) == obj.raw()) {
+      return i;
+    }
+  }
+  object_pool_.Add(obj, Heap::kOld);
+  return object_pool_.Length() - 1;
+}
+
+
+int32_t Assembler::AddExternalLabel(const ExternalLabel* label) {
+  if (object_pool_.IsNull()) {
+    // The object pool cannot be used in the vm isolate.
+    ASSERT(Isolate::Current() != Dart::vm_isolate());
+    object_pool_ = GrowableObjectArray::New(Heap::kOld);
+  }
+  const word address = label->address();
+  ASSERT(Utils::IsAligned(address, 4));
+  // The address is stored in the object array as a RawSmi.
+  const Smi& smi = Smi::Handle(Smi::New(address >> kSmiTagShift));
+  // Do not reuse an existing entry, since each reference may be patched
+  // independently.
+  object_pool_.Add(smi, Heap::kOld);
+  return object_pool_.Length() - 1;
+}
+
+
+void Assembler::LoadWordFromPoolOffset(Register dst, int32_t offset) {
+  movq(dst, Address(PP, offset));
+  // This sequence must be of fixed size. If offset fits in a signed byte we
+  // have to pad with nops.
+  if (Utils::IsInt(8, offset)) {
+    nop(3);
+  }
+}
+
+
 void Assembler::LoadObject(Register dst, const Object& object) {
   if (object.IsSmi() || object.InVMHeap()) {
     movq(dst, Immediate(reinterpret_cast<int64_t>(object.raw())));
   } else {
     ASSERT(object.IsNotTemporaryScopedHandle());
     ASSERT(object.IsOld());
-    AssemblerBuffer::EnsureCapacity ensured(&buffer_);
-    EmitRegisterREX(dst, REX_W);
-    EmitUint8(0xB8 | (dst & 7));
-    buffer_.EmitObject(object);
+    const int32_t offset = Array::element_offset(AddObject(object));
+    LoadWordFromPoolOffset(dst, offset - kHeapObjectTag);
   }
 }
 
 
 void Assembler::StoreObject(const Address& dst, const Object& object) {
   if (object.IsSmi() || object.InVMHeap()) {
     movq(dst, Immediate(reinterpret_cast<int64_t>(object.raw())));
   } else {
     ASSERT(object.IsNotTemporaryScopedHandle());
     ASSERT(object.IsOld());
@@ skipping 171 matching lines @@
   }
   pushq(RBP);
   movq(RBP, RSP);
   if (frame_size != 0) {
     Immediate frame_space(frame_size);
     subq(RSP, frame_space);
   }
 }
 
 
-void Assembler::LeaveFrame() {
-  movq(RSP, RBP);
-  popq(RBP);
+void Assembler::LeaveFrame(bool restore_pp) {
+  if (restore_pp) {
+    leaq(RSP, Address(RBP, -2 * kWordSize));  // Restore stack pointer.

[Ivan Posva, 2013/08/22 05:26:25]

Wouldn't this be shorter?

if (restore_pp) {
  movq(PP, Address(RBP, -2 * kWordSize));
}
movq(RSP, RBP);
popq(RBP);

+    popq(PP);  // Restore PP.
+    popq(RBP);  // Ignore PC marker.
+  } else {
+    movq(RSP, RBP);  // Restore stack pointer.
+  }
+  popq(RBP);  // Restore frame pointer.
 }
 
 
 void Assembler::ReserveAlignedFrameSpace(intptr_t frame_space) {
   // Reserve space for arguments and align frame before entering
   // the C++ world.
   AddImmediate(RSP, Immediate(-frame_space));
   if (OS::ActivationFrameAlignment() > 0) {
     andq(RSP, Immediate(~(OS::ActivationFrameAlignment() - 1)));
   }
@@ skipping 62 matching lines @@
 
   leave();
 }
 
 
 void Assembler::CallRuntime(const RuntimeEntry& entry) {
   entry.Call(this);
 }
 
 
+void Assembler::LoadPoolPointer() {
+  Label next;
+  call(&next);
+  Bind(&next);
+
+  // Load new pool pointer.
+  const intptr_t object_pool_pc_dist =
+      Instructions::HeaderSize() - Instructions::object_pool_offset() +
+      CodeSize();
+  addq(Address(RSP, 0), Immediate(-object_pool_pc_dist));
+  popq(PP);
+  movq(PP, Address(PP, 0));

[Ivan Posva, 2013/08/22 05:26:25]

popq(PP);
movq(PP, Address(PP, -object_pool_pc_dist));

+}
+
+
 void Assembler::EnterDartFrame(intptr_t frame_size) {
   EnterFrame(0);
   Label dart_entry;
   call(&dart_entry);
   Bind(&dart_entry);
   // The runtime system assumes that the code marker address is
   // kEntryPointToPcMarkerOffset bytes from the entry.  If there is any code
   // generated before entering the frame, the address needs to be adjusted.
+  const intptr_t object_pool_pc_dist =
+      Instructions::HeaderSize() - Instructions::object_pool_offset() +
+      CodeSize();
   const intptr_t offset = kEntryPointToPcMarkerOffset - CodeSize();
   if (offset != 0) {
     addq(Address(RSP, 0), Immediate(offset));
   }
+  // Save caller's pool pointer
+  pushq(PP);
+
+  // Load callee's pool pointer.
+  movq(PP, Address(RSP, 1 * kWordSize));
+  addq(PP, Immediate(-object_pool_pc_dist - offset));
+  movq(PP, Address(PP, 0));

[Ivan Posva, 2013/08/22 05:26:25]

Wouldn't this be shorter?
movq(PP, Address(RSP, 1* kWordSize));
movq(PP, Address(PP, -object_pool_pc_dist - offset));

+
   if (frame_size != 0) {
     subq(RSP, Immediate(frame_size));
   }
 }
 
 
 // On entry to a function compiled for OSR, the caller's frame pointer, the
 // stack locals, and any copied parameters are already in place.  The frame
 // pointer is already set up.  The PC marker is not correct for the
 // optimized function and there may be extra space for spill slots to
 // allocate.
 void Assembler::EnterOsrFrame(intptr_t extra_size) {
   Label dart_entry;
   call(&dart_entry);
   Bind(&dart_entry);
   // The runtime system assumes that the code marker address is
   // kEntryPointToPcMarkerOffset bytes from the entry.  Since there is no
   // code to set up the frame pointer, the address needs to be adjusted.
+  const intptr_t object_pool_pc_dist =
+      Instructions::HeaderSize() - Instructions::object_pool_offset() +
+      CodeSize();
   const intptr_t offset = kEntryPointToPcMarkerOffset - CodeSize();
   if (offset != 0) {
     addq(Address(RSP, 0), Immediate(offset));
   }
+
+  // Load callee's pool pointer.
+  movq(PP, Address(RSP, 0));
+  addq(PP, Immediate(-object_pool_pc_dist - offset));
+  movq(PP, Address(PP, 0));
+
   popq(Address(RBP, kPcMarkerSlotFromFp * kWordSize));
+
   if (extra_size != 0) {
     subq(RSP, Immediate(extra_size));
   }
 }
 
 
-void Assembler::EnterStubFrame() {
-  EnterFrame(0);
-  pushq(Immediate(0));  // Push 0 in the saved PC area for stub frames.
+void Assembler::EnterStubFrame(bool save_pp) {
+  if (save_pp) {
+    EnterFrame(0);
+    pushq(Immediate(0));  // Push 0 in the saved PC area for stub frames.
+    pushq(PP);  // Save caller's pool pointer
+    LoadPoolPointer();
+  } else {
+    EnterFrame(0);
+    pushq(Immediate(0));  // Push 0 in the saved PC area for stub frames.
+  }
 }
 
 
 void Assembler::TryAllocate(const Class& cls,
                             Label* failure,
                             bool near_jump,
                             Register instance_reg) {
   ASSERT(failure != NULL);
   if (FLAG_inline_alloc) {
     Heap* heap = Isolate::Current()->heap();
@@ skipping 209 matching lines @@
 
 const char* Assembler::FpuRegisterName(FpuRegister reg) {
   ASSERT((0 <= reg) && (reg < kNumberOfXmmRegisters));
   return xmm_reg_names[reg];
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64