[turbofan] Sparse representation for state values

src/compiler/instruction-selector.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/instruction-selector.h"
 
 #include <limits>
 
 #include "src/base/adapters.h"
 #include "src/compiler/compiler-source-position-table.h"
@@ skipping 467 matching lines @@
 };
 
 
 // Returns the number of instruction operands added to inputs.
 size_t AddOperandToStateValueDescriptor(StateValueDescriptor* descriptor,
                                         InstructionOperandVector* inputs,
                                         OperandGenerator* g,
                                         StateObjectDeduplicator* deduplicator,
                                         Node* input, MachineType type,
                                         FrameStateInputKind kind, Zone* zone) {
+  if (input == nullptr) {
+    inputs->push_back(g->TempImmediate(FrameStateDescriptor::kImpossibleValue));

[Jarin, 2016/11/16 15:32:42]

This should be the optimized_out value, no?

[Leszek Swirski, 2016/11/17 09:23:04]

Yeah, I had a problem here that the jsgraph isn't available, so I couldn't get
at that node. I figured that any value here would be sufficiently valid (if not
a great marker) for testing, so that I don't have to wire the jsgraph through
into here.

+    descriptor->fields().push_back(
+        StateValueDescriptor::Plain(zone, MachineType::None()));

[Jarin, 2016/11/16 15:32:42]

MachineType::AnyTagged()

[Leszek Swirski, 2016/11/17 09:23:04]

As above.

+    return 1;
+  }
+
   switch (input->opcode()) {
     case IrOpcode::kObjectState: {
       UNREACHABLE();
       return 0;
     }
     case IrOpcode::kTypedObjectState: {
       size_t id = deduplicator->GetObjectId(input);
       if (id == StateObjectDeduplicator::kNotDuplicated) {
         size_t entries = 0;
         id = deduplicator->InsertObject(input);
@@ skipping 1612 matching lines @@
   return new (instruction_zone()) FrameStateDescriptor(
       instruction_zone(), state_info.type(), state_info.bailout_id(),
       state_info.state_combine(), parameters, locals, stack,
       state_info.shared_info(), outer_state);
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8