Support verified heap pointer writes on x64.

runtime/vm/assembler_x64.cc

Index: runtime/vm/assembler_x64.cc
===================================================================
--- runtime/vm/assembler_x64.cc	(revision 41785)
+++ runtime/vm/assembler_x64.cc	(working copy)
@@ -2384,6 +2384,9 @@
 
 void Assembler::j(Condition condition, 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 = 6;
@@ -2436,6 +2439,9 @@
 
 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;
@@ -2871,12 +2877,46 @@
 }
 
 
+void Assembler::VerifyHeapWord(const Address& address) {
+  if (VerifiedMemory::enabled()) {
+    Register addr_reg = RDX;
+    Register value = RBX;
+    // Preserve registers.
+    pushq(addr_reg);
+    pushq(value);
+    leaq(addr_reg, address);
+    // ASSERT(*address == *(address + offset))
+    movq(value, Address(addr_reg, 0));
+    cmpq(value, Address(addr_reg, VerifiedMemory::offset()));
+    Label ok;
+    j(EQUAL, &ok);
+    Stop("Write barrier verification failed");
+    Bind(&ok);
+    popq(value);
+    popq(addr_reg);
+  }
+}
+
+
+void Assembler::VerifiedWrite(const Address& dest, Register value) {
+  VerifyHeapWord(dest);
+  movq(dest, value);
+  if (VerifiedMemory::enabled()) {
+    Register temp = (value == RDX) ? RCX : RDX;
+    pushq(temp);
+    leaq(temp, dest);
+    movq(Address(temp, VerifiedMemory::offset()), value);
+    popq(temp);
+  }
+}
+
+
 void Assembler::StoreIntoObject(Register object,
                                 const Address& dest,
                                 Register value,
                                 bool can_value_be_smi) {
   ASSERT(object != value);
-  movq(dest, value);
+  VerifiedWrite(dest, value);
   Label done;
   if (can_value_be_smi) {
     StoreIntoObjectFilter(object, value, &done);
@@ -2898,7 +2938,7 @@
 void Assembler::StoreIntoObjectNoBarrier(Register object,
                                          const Address& dest,
                                          Register value) {
-  movq(dest, value);
+  VerifiedWrite(dest, value);
 #if defined(DEBUG)
   Label done;
   pushq(value);
@@ -2911,6 +2951,50 @@
 }
 
 
+void Assembler::StoreIntoSmiField(const Address& dest, Register value) {
+  VerifiedWrite(dest, value);
+#if defined(DEBUG)
+  Label done;
+  testq(value, Immediate(kHeapObjectTag));
+  j(ZERO, &done);
+  Stop("Smi expected");
+  Bind(&done);
+#endif  // defined(DEBUG)
+}
+
+
+void Assembler::ZeroSmiField(const Address& dest) {
+  // TODO(koda): Add VerifySmi once we distinguish initalization.
+  VerifyHeapWord(dest);
+  Immediate zero(Smi::RawValue(0));
+  movq(dest, zero);
+  if (VerifiedMemory::enabled()) {
+    Register temp = RCX;
+    pushq(temp);
+    leaq(temp, dest);
+    movq(Address(temp, VerifiedMemory::offset()), zero);
+    popq(temp);
+  }
+}
+
+
+void Assembler::IncrementSmiField(const Address& dest, int64_t increment) {
+  // Note: FlowGraphCompiler::EdgeCounterIncrementSizeInBytes depends on
+  // the length of this instruction sequence.
+  // TODO(koda): Add VerifySmi once we distinguish initalization.
+  VerifyHeapWord(dest);
+  Immediate inc_imm(Smi::RawValue(increment));
+  addq(dest, inc_imm);
+  if (VerifiedMemory::enabled()) {
+    Register temp = RCX;
+    pushq(temp);
+    leaq(temp, dest);
+    addq(Address(temp, VerifiedMemory::offset()), inc_imm);
+    popq(temp);
+  }
+}
+
+
 void Assembler::DoubleNegate(XmmRegister d) {
   static const struct ALIGN16 {
     uint64_t a;