Unify SoftDeoptimize and Deoptimize hydrogen instructions

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index 531c25c2b1e26d608f828925f94a07688d12b9f1..f777fd74ffce4e2e69cd7053118f87be9163aa97 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -178,7 +178,7 @@ bool CodeStubGraphBuilderBase::BuildGraph() {
   AddInstruction(context_);
   start_environment->BindContext(context_);
 
-  AddSimulate(BailoutId::StubEntry());
+  Add<HSimulate>(BailoutId::StubEntry());
 
   NoObservableSideEffectsScope no_effects(this);
 
@@ -366,9 +366,10 @@ HValue* CodeStubGraphBuilder<FastCloneShallowArrayStub>::BuildCodeStub() {
                                                length));
   }
 
-  HValue* result = environment()->Pop();
   checker.ElseDeopt();
-  return result;
+  checker.End();
+
+  return environment()->Pop();
 }
 
 
@@ -416,8 +417,11 @@ HValue* CodeStubGraphBuilder<FastCloneShallowObjectStub>::BuildCodeStub() {
     AddStore(object, access, AddLoad(boilerplate, access));
   }
 
+  environment()->Push(object);

[Jakob Kummerow, 2013/07/22 16:53:12]

I don't understand why this Push/Pop sequence is necessary. Why was the old code
not safe?

[danno, 2013/07/23 12:18:14]

Sort of. The problem is that there was no real merge of paths before, so no phi
node was needed at all for the result. Now that the deoptimize path actually
merges into the join at the end of the if, the return value from the "true" path
must be the input to a phi that the "else deopt" path contributes a undefined or
some other dummy value to. Otherwise, the register allocator complains that
there is a use before a definition along the else path. It doesn't know that the
the deoptimize instruction makes the else value of the phi irrelevant.

   checker.ElseDeopt();
-  return object;
+  checker.End();
+
+  return environment()->Pop();
 }
 
 
@@ -852,8 +856,7 @@ HValue* CodeStubGraphBuilder<StoreGlobalStub>::BuildCodeInitializedStub() {
 
   if (stub->is_constant()) {
     // Assume every store to a constant value changes it.
-    current_block()->FinishExitWithDeoptimization(HDeoptimize::kUseAll);
-    set_current_block(NULL);
+    Add<HDeoptimize>(Deoptimizer::EAGER);
   } else {
     HValue* cell = Add<HConstant>(placeholder_cell, Representation::Tagged());
 
@@ -894,8 +897,7 @@ HValue* CodeStubGraphBuilder<ElementsTransitionAndStoreStub>::BuildCodeStub() {
 
   if (FLAG_trace_elements_transitions) {
     // Tracing elements transitions is the job of the runtime.
-    current_block()->FinishExitWithDeoptimization(HDeoptimize::kUseAll);
-    set_current_block(NULL);
+    Add<HDeoptimize>(Deoptimizer::EAGER);
   } else {
     info()->MarkAsSavesCallerDoubles();