VM: Link native calls lazily.

runtime/vm/instructions_arm64.cc

Index: runtime/vm/instructions_arm64.cc
diff --git a/runtime/vm/instructions_arm64.cc b/runtime/vm/instructions_arm64.cc
index 83de46e38bc535ffdca02fc102a8606cdea65f9f..59da8d5ff247b14e4eacf41721ad77c8b764d7f3 100644
--- a/runtime/vm/instructions_arm64.cc
+++ b/runtime/vm/instructions_arm64.cc
@@ -32,6 +32,51 @@ CallPattern::CallPattern(uword pc, const Code& code)
 }
 
 
+NativeCallPattern::NativeCallPattern(uword pc, const Code& code)
+    : object_pool_(ObjectPool::Handle(code.GetObjectPool())),
+      end_(pc),
+      native_function_pool_index_(-1),
+      target_address_pool_index_(-1) {
+  ASSERT(code.ContainsInstructionAt(pc));
+  // Last instruction: blr ip0.
+  ASSERT(*(reinterpret_cast<uint32_t*>(end_) - 1) == 0xd63f0200);
+
+  Register reg;
+  uword native_function_load_end =
+      InstructionPattern::DecodeLoadWordFromPool(end_ - Instr::kInstrSize,
+                                                 &reg,
+                                                 &target_address_pool_index_);
+  ASSERT(reg == IP0);
+  InstructionPattern::DecodeLoadWordFromPool(native_function_load_end,
+                                             &reg,
+                                             &native_function_pool_index_);
+  ASSERT(reg == R5);
+}
+
+
+uword NativeCallPattern::target() const {
+  return object_pool_.RawValueAt(target_address_pool_index_);
+}
+
+
+void NativeCallPattern::set_target(uword target_address) const {
+  object_pool_.SetRawValueAt(target_address_pool_index_, target_address);
+  // No need to flush the instruction cache, since the code is not modified.
+}
+
+
+NativeFunction NativeCallPattern::native_function() const {
+  return reinterpret_cast<NativeFunction>(
+      object_pool_.RawValueAt(native_function_pool_index_));
+}
+
+
+void NativeCallPattern::set_native_function(NativeFunction func) const {
+  object_pool_.SetRawValueAt(native_function_pool_index_,
+      reinterpret_cast<uword>(func));
+}
+
+
 intptr_t InstructionPattern::OffsetFromPPIndex(intptr_t index) {
   return Array::element_offset(index);
 }