Emit stackmaps even in unoptimized code if slow path pushes untagged values.

runtime/vm/flow_graph_compiler.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 85 matching lines @@
     const GrowableArray<const Function*>& inline_id_to_function,
     const GrowableArray<intptr_t>& caller_inline_id)
       : isolate_(Isolate::Current()),
         assembler_(assembler),
         parsed_function_(parsed_function),
         flow_graph_(*flow_graph),
         block_order_(*flow_graph->CodegenBlockOrder(is_optimizing)),
         current_block_(NULL),
         exception_handlers_list_(NULL),
         pc_descriptors_list_(NULL),
-        stackmap_table_builder_(
-            is_optimizing ? new StackmapTableBuilder() : NULL),
+        stackmap_table_builder_(NULL),
         block_info_(block_order_.length()),
         deopt_infos_(),
         static_calls_target_table_(GrowableObjectArray::ZoneHandle(
             GrowableObjectArray::New())),
         is_optimizing_(is_optimizing),
         may_reoptimize_(false),
         intrinsic_mode_(false),
         double_class_(Class::ZoneHandle(
             isolate_->object_store()->double_class())),
         mint_class_(Class::ZoneHandle(
@@ skipping 543 matching lines @@
                             ICData::kDeoptAtCall,
                             0,  // No flags.
                             pending_deoptimization_env_);
   info->set_pc_offset(assembler()->CodeSize());
   deopt_infos_.Add(info);
 }
 
 
 // This function must be in sync with FlowGraphCompiler::SaveLiveRegisters
 // and FlowGraphCompiler::SlowPathEnvironmentFor.
+// See StackFrame::VisitObjectPointers for the details of how stack map is
+// interpreted.
 void FlowGraphCompiler::RecordSafepoint(LocationSummary* locs) {
-  if (is_optimizing()) {
+  if (is_optimizing() || locs->live_registers()->HasUntaggedValues()) {
+    const intptr_t spill_area_size = is_optimizing() ?
+        flow_graph_.graph_entry()->spill_slot_count() : 0;
+
     RegisterSet* registers = locs->live_registers();
     ASSERT(registers != NULL);
     const intptr_t kFpuRegisterSpillFactor =
             kFpuRegisterSize / kWordSize;
     const intptr_t live_registers_size = registers->CpuRegisterCount() +
         (registers->FpuRegisterCount() * kFpuRegisterSpillFactor);
+
     BitmapBuilder* bitmap = locs->stack_bitmap();
-    ASSERT(bitmap != NULL);
+
     // An instruction may have two safepoints in deferred code. The
     // call to RecordSafepoint has the side-effect of appending the live
     // registers to the bitmap. This is why the second call to RecordSafepoint
     // with the same instruction (and same location summary) sees a bitmap that
     // is larger that StackSize(). It will never be larger than StackSize() +
     // live_registers_size.
-    ASSERT(bitmap->Length() <= (StackSize() + live_registers_size));
-    // The first safepoint will grow the bitmap to be the size of StackSize()
-    // but the second safepoint will truncate the bitmap and append the
-    // live registers to it again. The bitmap produced by both calls will
-    // be the same.
-    bitmap->SetLength(StackSize());
+    ASSERT(bitmap->Length() <= (spill_area_size + live_registers_size));
+    // The first safepoint will grow the bitmap to be the size of
+    // spill_area_size but the second safepoint will truncate the bitmap and
+    // append the live registers to it again. The bitmap produced by both calls
+    // will be the same.
+    bitmap->SetLength(spill_area_size);
 
     // Mark the bits in the stack map in the same order we push registers in
     // slow path code (see FlowGraphCompiler::SaveLiveRegisters).
     //
     // Slow path code can have registers at the safepoint.
     if (!locs->always_calls()) {
       RegisterSet* regs = locs->live_registers();
       if (regs->FpuRegisterCount() > 0) {
         // Denote FPU registers with 0 bits in the stackmap.  Based on the
         // assumption that there are normally few live FPU registers, this
@@ skipping 14 matching lines @@
       // General purpose registers have the lowest register number at the
       // highest address (i.e., first in the stackmap).
       for (intptr_t i = 0; i < kNumberOfCpuRegisters; ++i) {
         Register reg = static_cast<Register>(i);
         if (locs->live_registers()->ContainsRegister(reg)) {
           bitmap->Set(bitmap->Length(), locs->live_registers()->IsTagged(reg));
         }
       }
     }
 
-    intptr_t register_bit_count = bitmap->Length() - StackSize();
-    stackmap_table_builder_->AddEntry(assembler()->CodeSize(),
-                                      bitmap,
-                                      register_bit_count);
+    intptr_t register_bit_count = bitmap->Length() - spill_area_size;
+    stackmap_table_builder()->AddEntry(assembler()->CodeSize(),
+                                       bitmap,
+                                       register_bit_count);
   }
 }
 
 
 // This function must be kept in sync with:
 //
 //     FlowGraphCompiler::RecordSafepoint
 //     FlowGraphCompiler::SaveLiveRegisters
 //     MaterializeObjectInstr::RemapRegisters
 //
@@ skipping 116 matching lines @@
     const Array& object_array =
         Array::Handle(Array::MakeArray(builder.object_table()));
     ASSERT(code.object_table() == Array::null());
     code.set_object_table(object_array);
   }
 }
 
 
 void FlowGraphCompiler::FinalizeStackmaps(const Code& code) {
   if (stackmap_table_builder_ == NULL) {
     // The unoptimizing compiler has no stack maps.

[koda, 2015/03/03 17:57:48]

Update comment.

[Vyacheslav Egorov (Google), 2015/03/03 18:01:06]

Acknowledged.

     code.set_stackmaps(Object::null_array());
   } else {
     // Finalize the stack map array and add it to the code object.
-    ASSERT(is_optimizing());
     code.set_stackmaps(
         Array::Handle(stackmap_table_builder_->FinalizeStackmaps(code)));
   }
 }
 
 
 void FlowGraphCompiler::FinalizeVarDescriptors(const Code& code) {
   LocalVarDescriptors& var_descs = LocalVarDescriptors::Handle();
   if (parsed_function().node_sequence() == NULL) {
     ASSERT(flow_graph().IsIrregexpFunction());
@@ skipping 706 matching lines @@
   const Array& res = Array::Handle(
       Array::New(inline_id_to_function_.length(), Heap::kOld));
   for (intptr_t i = 0; i < inline_id_to_function_.length(); i++) {
     res.SetAt(i, *inline_id_to_function_[i]);
   }
   return res.raw();
 }
 
 
 }  // namespace dart