Generate first ARM assembler test and execute (simulate) it.

runtime/vm/assembler_arm.cc

Index: runtime/vm/assembler_arm.cc
===================================================================
--- runtime/vm/assembler_arm.cc	(revision 18162)
+++ runtime/vm/assembler_arm.cc	(working copy)
@@ -72,7 +72,7 @@
   const uint32_t offset_mask = (1 << 12) - 1;
   uint32_t offset = encoding_ & offset_mask;
   ASSERT(offset < (1 << 10));  // In the range 0 to +1020.
-  ASSERT(Utils::Utils::IsAligned(offset, 2));  // Multiple of 4.
+  ASSERT(Utils::IsAligned(offset, 4));  // Multiple of 4.
   int mode = encoding_ & ((8|4|1) << 21);
   ASSERT((mode == Offset) || (mode == NegOffset));
   uint32_t vencoding = (encoding_ & (0xf << kRnShift)) | (offset >> 2);
@@ -83,6 +83,17 @@
 }
 
 
+void Assembler::InitializeMemoryWithBreakpoints(uword data, int length) {
+  ASSERT(Utils::IsAligned(data, 4));
+  ASSERT(Utils::IsAligned(length, 4));
+  const uword end = data + length;
+  while (data < end) {
+    *reinterpret_cast<int32_t*>(data) = Instr::kBreakPointInstruction;
+    data += 4;
+  }
+}
+
+
 void Assembler::Emit(int32_t value) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   buffer_.Emit<int32_t>(value);
@@ -1020,7 +1031,18 @@
 
 
 void Assembler::LoadObject(Register rd, const Object& object) {
-  UNIMPLEMENTED();
+  // TODO(regis): If the object is never relocated (null, true, false, ...),
+  // load as immediate.
+  int32_t offset = AddObject(object);
+  ASSERT(Utils::IsAligned(offset, 4) && (offset >= 0));
+  if (Address::CanHoldLoadOffset(kLoadWord, offset)) {
+    ldr(rd, Address(CP, offset));
+  } else {
+    int32_t offset12_hi = offset & ~kOffset12Mask;  // signed
+    uint32_t offset12_lo = offset & kOffset12Mask;  // unsigned
+    AddConstant(rd, CP, offset12_hi);
+    ldr(rd, Address(rd, offset12_lo));
+  }
 }
 
 
@@ -1139,22 +1161,28 @@
 
 
 void Assembler::Branch(const ExternalLabel* label) {
-  // TODO(regis): Revisit this code sequence.
   LoadImmediate(IP, label->address());  // Target address is never patched.
   mov(PC, ShifterOperand(IP));
 }
 
 
 void Assembler::BranchLink(const ExternalLabel* label) {
-  // TODO(regis): Revisit this code sequence.
-  // Make sure that CodePatcher is able to patch this code sequence.
+  // TODO(regis): Make sure that CodePatcher is able to patch the label referred
+  // to by this code sequence.
   // For added code robustness, use 'blx lr' in a patchable sequence and
   // use 'blx ip' in a non-patchable sequence (see other BranchLink flavors).
-  ldr(LR, Address(PC));
-  Label skip;
-  b(&skip);
-  Emit(label->address());  // May get patched.
-  Bind(&skip);
+  int32_t offset = AddExternalLabel(label);
+  ASSERT(Utils::IsAligned(offset, 4) && (offset >= 0));
+  if (Address::CanHoldLoadOffset(kLoadWord, offset)) {
+    ldr(LR, Address(CP, offset));
+  } else {
+    int32_t offset12_hi = offset & ~kOffset12Mask;  // signed
+    uint32_t offset12_lo = offset & kOffset12Mask;  // unsigned
+    // TODO(regis): Using AddConstant may generate too many sequences to be
+    // easily decoded by CodePatcher. If so, use a simpler fixed sequence.
+    AddConstant(LR, CP, offset12_hi);

[Ivan Posva, 2013/02/06 23:33:50]

As discussed, please do not use macros here as they will make it really hard to
patch.

[regis, 2013/02/07 00:53:24]

Done.

+    ldr(LR, Address(LR, offset12_lo));
+  }
   blx(LR);  // Use blx instruction so that the return branch prediction works.
 }
 
@@ -1494,6 +1522,32 @@
   return ((((inst & kBranchOffsetMask) << 8) >> 6) + 8);
 }
 
+
+int32_t Assembler::AddObject(const Object& obj) {
+  for (int i = 0; i < objects_.Length(); i++) {

[Ivan Posva, 2013/02/06 23:33:50]

As discussed we should just return the offset here and deal with the indexing
and offsetting at the use.

[regis, 2013/02/07 00:53:24]

Done.

+    if (objects_.At(i) == obj.raw()) {
+      // TODO(regis): Skip over header.
+      return /*kCodeObjectsHeaderSize +*/ 4*i;
+    }
+  }
+  objects_.Add(obj);
+  // TODO(regis): Skip over header.
+  return /*kCodeObjectsHeaderSize +*/ 4*(objects_.Length() - 1);
+}
+
+
+int32_t Assembler::AddExternalLabel(const ExternalLabel* label) {
+  const uword 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.
+  objects_.Add(smi);
+  // TODO(regis): Skip over header.
+  return /*kCodeObjectsHeaderSize +*/ 4*(objects_.Length() - 1);

[Ivan Posva, 2013/02/06 23:33:50]

ditto.

[regis, 2013/02/07 00:53:24]

Done.

+}
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM