VM: Emit compacter code for x64 branches to external labels.

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"  // NOLINT
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/heap.h"
+#include "vm/instructions.h"
 #include "vm/locations.h"
 #include "vm/memory_region.h"
 #include "vm/runtime_entry.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, print_stop_message, true, "Print stop message.");
 DECLARE_FLAG(bool, inline_alloc);
@@ skipping 2530 matching lines @@
 
 void Assembler::jmp(Register reg) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   Operand operand(reg);
   EmitOperandREX(4, operand, REX_NONE);
   EmitUint8(0xFF);
   EmitOperand(4, operand);
 }
 
 
+void Assembler::jmp(const Address& dst) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitOperandREX(4, dst, REX_NONE);
+  EmitUint8(0xFF);
+  EmitOperand(4, dst);
+}
+
+
 void Assembler::jmp(Label* label, bool near) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   if (VerifiedMemory::enabled()) {
     near = Assembler::kFarJump;
   }
   if (label->IsBound()) {
     static const int kShortSize = 2;
     static const int kLongSize = 5;
     intptr_t offset = label->Position() - buffer_.Size();
     ASSERT(offset <= 0);
@@ skipping 21 matching lines @@
     EmitUint8(0xB8 | (TMP & 7));
     EmitInt64(label->address());
   }
   jmp(TMP);
 }
 
 
 void Assembler::JmpPatchable(const ExternalLabel* label, Register pp) {
   ASSERT(allow_constant_pool());
   intptr_t call_start = buffer_.GetPosition();
-  LoadExternalLabel(TMP, label, kPatchable, pp);
-  jmp(TMP);
-  ASSERT((buffer_.GetPosition() - call_start) == kJmpExternalLabelSize);
+  const int32_t offset =
+      Array::element_offset(FindExternalLabel(label, kPatchable));
+  // Patchable jumps always use a 32-bit immediate encoding.
+  jmp(Address::AddressBaseImm32(pp, offset - kHeapObjectTag));
+  ASSERT((buffer_.GetPosition() - call_start) == JumpPattern::kLengthInBytes);
 }
 
 
 void Assembler::Jmp(const ExternalLabel* label, Register pp) {
-  LoadExternalLabel(TMP, label, kNotPatchable, pp);
-  jmp(TMP);
+  const int32_t offset =
+      Array::element_offset(FindExternalLabel(label, kNotPatchable));
+  jmp(Address(pp, offset - kHeapObjectTag));
 }
 
 
 void Assembler::lock() {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitUint8(0xF0);
 }
 
 
 void Assembler::cmpxchgl(const Address& address, Register reg) {
@@ skipping 1370 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