Revert "Revert "Introduce Goto instructions to the flow graph.""

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
diff --git a/runtime/vm/flow_graph_compiler.cc b/runtime/vm/flow_graph_compiler.cc
index c3360848eb2b68f7ea38dc6d964807670fb22cd9..5dfa90245e5316210e587be25c16ef365079abeb 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -118,10 +118,7 @@ void FlowGraphCompiler::VisitBlocks() {
       BlockEntryInstr* successor = instr->next()->AsBlockEntry();
       ASSERT(successor != NULL);
       frame_register_allocator()->Spill();
-      // The block ended with a "goto".  We can fall through if it is the
-      // next block in the list.  Otherwise, we need a jump.
-      if ((i == block_order().length() - 1) ||
-          (block_order()[i + 1] != successor)) {
+      if (!IsNextBlock(successor)) {
         assembler()->jmp(GetBlockLabel(successor));
       }
     }
@@ -155,9 +152,10 @@ Label* FlowGraphCompiler::GetBlockLabel(
 }
 
 
-bool FlowGraphCompiler::IsNextBlock(TargetEntryInstr* block_entry) const {
+bool FlowGraphCompiler::IsNextBlock(BlockEntryInstr* block_entry) const {
   intptr_t current_index = reverse_index(current_block()->postorder_number());
-  return block_order_[current_index + 1] == block_entry;
+  return (current_index < (block_order().length() - 1)) &&
+      (block_order()[current_index + 1] == block_entry);
 }
 
 
@@ -605,7 +603,7 @@ void FrameRegisterAllocator::AllocateRegisters(Instruction* instr) {
 
   // If this instruction is call spill everything that was not consumed by
   // input locations.
-  if (locs->is_call() || instr->IsBranch()) {
+  if (locs->is_call() || instr->IsBranch() || instr->IsGoto()) {
     Spill();
   }