Implement loop invariant code motion for check instructions.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
===================================================================
--- runtime/vm/intermediate_language.cc	(revision 11934)
+++ runtime/vm/intermediate_language.cc	(working copy)
@@ -201,6 +201,16 @@
 }
 
 
+BlockEntryInstr* Definition::GetBlock() const {
+  // TODO(fschneider): Implement a faster way to get the block of an
+  // instruction.
+  ASSERT(previous() != NULL);
+  Instruction* result = previous();
+  while (!result->IsBlockEntry()) result = result->previous();
+  return result->AsBlockEntry();
+}
+
+
 void ForwardInstructionIterator::RemoveCurrentFromGraph() {
   current_ = current_->RemoveFromGraph(true);  // Set current_ to previous.
 }
@@ -587,6 +597,16 @@
 }
 
 
+bool BlockEntryInstr::Dominates(BlockEntryInstr* other) const {
+  ASSERT(other != NULL);

[Kevin Millikin (Google), 2012/09/06 12:42:42]

Add a TODO to make this faster :)

[Florian Schneider, 2012/09/06 13:05:53]

Done.

+  BlockEntryInstr* current = other;
+  while (current != NULL && current != this) {
+    current = current->dominator();
+  }
+  return current == this;
+}
+
+
 void ControlInstruction::DiscoverBlocks(
     BlockEntryInstr* current_block,
     GrowableArray<BlockEntryInstr*>* preorder,
@@ -1274,6 +1294,12 @@
 
 
 void GotoInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  // Add deoptimization descriptor for deoptimizing instructions
+  // that may be inserted before this instruction.
+  compiler->AddCurrentDescriptor(PcDescriptors::kDeoptBefore,
+                                 GetDeoptId(),
+                                 0);  // No token position.
+
   if (HasParallelMove()) {
     compiler->parallel_move_resolver()->EmitNativeCode(parallel_move());
   }