Add deoptimization environments to instructions.

vm/flow_graph_builder.cc

 // Copyright (c) 2012, 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/flow_graph_builder.h"
 
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/code_descriptors.h"
 #include "vm/dart_entry.h"
@@ skipping 2635 matching lines @@
 static intptr_t WhichPred(BlockEntryInstr* predecessor,
                           JoinEntryInstr* join_block) {
   for (intptr_t i = 0; i < join_block->PredecessorCount(); ++i) {
     if (join_block->PredecessorAt(i) == predecessor) return i;
   }
   UNREACHABLE();
   return -1;
 }
 
 
+// Helper to a copy a value iff it is a UseVal.
+static Value* CopyValue(Value* value) {
+  return value->IsUse()
+      ? new UseVal(value->AsUse()->definition())
+      : value;
+}
+
+
 void FlowGraphBuilder::RenameRecursive(BlockEntryInstr* block_entry,
                                        ZoneGrowableArray<Value*>* env,
                                        intptr_t var_count) {
   // 1. Process phis first.
   if (block_entry->IsJoinEntry()) {
     JoinEntryInstr* join = block_entry->AsJoinEntry();
     if (join->phis() != NULL) {
       for (intptr_t i = 0; i < join->phis()->length(); ++i) {
         PhiInstr* phi = (*join->phis())[i];
         if (phi != NULL) {
           (*env)[i] = new UseVal(phi);
           phi->set_ssa_temp_index(current_ssa_temp_index_++);  // New SSA temp.
         }
       }
     }
   }
 
   // 2. Process normal instructions.
   Instruction* current = block_entry->successor();
   while ((current != NULL) && !current->IsBlockEntry()) {
-    // 2a. Handle uses of LoadLocal / StoreLocal
+    // Attach current environment to the instruction.
+    // TODO(fschneider): Currently each instruction gets a full copy of the
+    // enviroment. This should be optimized: Only instructions that can
+    // deoptimize will should have uses of the environment values.
+    current->set_env(new Environment(env));
+
+    // 2a. Handle uses:
+    // Update expression stack environment for each use.
     // For each use of a LoadLocal or StoreLocal: Replace it with the value
     // from the environment.
     for (intptr_t i = 0; i < current->InputCount(); ++i) {
       Value* v = current->InputAt(i);
-      if (v->IsUse() &&
-          v->AsUse()->definition()->IsBind() &&
+      if (!v->IsUse()) continue;
+      // Update expression stack.
+      ASSERT(env->length() > var_count);
+      env->RemoveLast();
+      if (v->AsUse()->definition()->IsBind() &&
           v->AsUse()->definition()->AsBind()->computation()->IsLoadLocal()) {
         Computation* comp = v->AsUse()->definition()->AsBind()->computation();
         intptr_t index = comp->AsLoadLocal()->local().BitIndexIn(var_count);
-        Value* new_value = (*env)[index];
-        // Make a copy if it is a UseVal.
-        if (new_value->IsUse()) {
-          new_value = new UseVal(new_value->AsUse()->definition());
-        }
-        current->SetInputAt(i, new_value);
+        current->SetInputAt(i, CopyValue((*env)[index]));
       }
-      if (v->IsUse() &&
-          v->AsUse()->definition()->IsBind() &&
+      if (v->AsUse()->definition()->IsBind() &&
           v->AsUse()->definition()->AsBind()->computation()->IsStoreLocal()) {
         // For each use of a StoreLocal: Replace it with the value from the
         // environment.
         Computation* comp = v->AsUse()->definition()->AsBind()->computation();
         intptr_t index = comp->AsStoreLocal()->local().BitIndexIn(var_count);
-        Value* new_value = (*env)[index];
-        // Make a copy if it is a UseVal.
-        if (new_value->IsUse()) {
-          new_value = new UseVal(new_value->AsUse()->definition());
-        }
-        current->SetInputAt(i, new_value);
+        current->SetInputAt(i, CopyValue((*env)[index]));
       }
     }
 
     // 2b. Handle LoadLocal and StoreLocal.
     // For each LoadLocal: Remove it from the graph.
     // For each StoreLocal: Remove it from the graph and update the environment.
     ASSERT(!current->IsDo() ||
            !current->AsDo()->computation()->IsLoadLocal());  // Not possible.
     LoadLocalComp* load = NULL;
     if (current->IsBind() &&
         current->AsBind()->computation()->IsLoadLocal()) {
       load = current->AsBind()->computation()->AsLoadLocal();
     }
     StoreLocalComp* store = NULL;
     if (current->IsDo() &&
         current->AsDo()->computation()->IsStoreLocal()) {
       store = current->AsDo()->computation()->AsStoreLocal();
     } else if (current->IsBind() &&
                current->AsBind()->computation()->IsStoreLocal()) {
       store = current->AsBind()->computation()->AsStoreLocal();
     }
 
     if (load != NULL) {
+      ASSERT(current->IsBind());
+      // Update expression stack.
+      intptr_t index = load->local().BitIndexIn(var_count);
+      env->Add(CopyValue((*env)[index]));
       // Remove instruction.
       current = current->RemoveFromGraph();
     } else if (store != NULL) {
+      // Update renaming environment.
+      (*env)[store->local().BitIndexIn(var_count)] = store->value();
+      if (current->IsBind()) {
+        // Update expression stack.
+        intptr_t index = store->local().BitIndexIn(var_count);
+        env->Add(CopyValue((*env)[index]));
+      }
       // Remove instruction and update renaming environment.
       current = current->RemoveFromGraph();
-      (*env)[store->local().BitIndexIn(var_count)] = store->value();
     } else {
       if (current->IsBind()) {
         // Assign new SSA temporary.
         current->AsDefinition()->set_ssa_temp_index(current_ssa_temp_index_++);
+        // Update expression stack.
+        env->Add(new UseVal(current->AsDefinition()));
       }
       current = current->successor();
     }
   }
 
   // 3. Process dominated blocks.
   for (intptr_t i = 0; i < block_entry->dominated_blocks().length(); ++i) {
     BlockEntryInstr* block = block_entry->dominated_blocks()[i];
     ZoneGrowableArray<Value*>* new_env =
         new ZoneGrowableArray<Value*>(var_count);
@@ skipping 31 matching lines @@
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len));
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart