1b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch// Copyright 2014 the V8 project authors. All rights reserved. 2b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch// Use of this source code is governed by a BSD-style license that can be 3b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch// found in the LICENSE file. 4b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 5b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/compiler/common-operator.h" 6b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/compiler/generic-node-inl.h" 7b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/compiler/graph-inl.h" 8b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/compiler/js-context-specialization.h" 9b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/compiler/js-operator.h" 10b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/compiler/node-aux-data-inl.h" 11b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/compiler/node-matchers.h" 12b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch#include "src/compiler/node-properties-inl.h" 13b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 14b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdochnamespace v8 { 15b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdochnamespace internal { 16b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdochnamespace compiler { 17b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 18b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdochclass ContextSpecializationVisitor : public NullNodeVisitor { 19b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch public: 20b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch explicit ContextSpecializationVisitor(JSContextSpecializer* spec) 21b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch : spec_(spec) {} 22b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 23b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch GenericGraphVisit::Control Post(Node* node) { 24b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch switch (node->opcode()) { 25b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch case IrOpcode::kJSLoadContext: { 26b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch Reduction r = spec_->ReduceJSLoadContext(node); 27b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch if (r.Changed() && r.replacement() != node) { 28b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch NodeProperties::ReplaceWithValue(node, r.replacement()); 29b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch node->RemoveAllInputs(); 30b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 31b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch break; 32b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 33b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch case IrOpcode::kJSStoreContext: { 34b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch Reduction r = spec_->ReduceJSStoreContext(node); 35b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch if (r.Changed() && r.replacement() != node) { 36b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch NodeProperties::ReplaceWithValue(node, r.replacement()); 37b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch node->RemoveAllInputs(); 38b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 39b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch break; 40b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 41b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch default: 42b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch break; 43b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 44b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return GenericGraphVisit::CONTINUE; 45b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 46b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 47b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch private: 48b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch JSContextSpecializer* spec_; 49b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch}; 50b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 51b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 52b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdochvoid JSContextSpecializer::SpecializeToContext() { 53b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch NodeProperties::ReplaceWithValue(context_, 54b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch jsgraph_->Constant(info_->context())); 55b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 56b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch ContextSpecializationVisitor visitor(this); 57b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch jsgraph_->graph()->VisitNodeInputsFromEnd(&visitor); 58b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch} 59b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 60b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 61b8a8cc1952d61a2f3a2568848933943a543b5d3eBen MurdochReduction JSContextSpecializer::ReduceJSLoadContext(Node* node) { 62b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch DCHECK_EQ(IrOpcode::kJSLoadContext, node->opcode()); 63b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 64b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch HeapObjectMatcher<Context> m(NodeProperties::GetValueInput(node, 0)); 65b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // If the context is not constant, no reduction can occur. 66b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch if (!m.HasValue()) { 67b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return Reducer::NoChange(); 68b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 69b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 70b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch ContextAccess access = OpParameter<ContextAccess>(node); 71b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 72b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Find the right parent context. 73b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch Context* context = *m.Value().handle(); 74b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch for (int i = access.depth(); i > 0; --i) { 75b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch context = context->previous(); 76b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 77b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 78b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // If the access itself is mutable, only fold-in the parent. 79b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch if (!access.immutable()) { 80b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // The access does not have to look up a parent, nothing to fold. 81b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch if (access.depth() == 0) { 82b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return Reducer::NoChange(); 83b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 84b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch const Operator* op = jsgraph_->javascript()->LoadContext( 85b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 0, access.index(), access.immutable()); 86b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch node->set_op(op); 87b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch Handle<Object> context_handle = Handle<Object>(context, info_->isolate()); 88b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch node->ReplaceInput(0, jsgraph_->Constant(context_handle)); 89b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return Reducer::Changed(node); 90b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 91b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch Handle<Object> value = 92b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch Handle<Object>(context->get(access.index()), info_->isolate()); 93b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 94b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Even though the context slot is immutable, the context might have escaped 95b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // before the function to which it belongs has initialized the slot. 96b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // We must be conservative and check if the value in the slot is currently the 97b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // hole or undefined. If it is neither of these, then it must be initialized. 98b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch if (value->IsUndefined() || value->IsTheHole()) { 99b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return Reducer::NoChange(); 100b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 101b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 102b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Success. The context load can be replaced with the constant. 103b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // TODO(titzer): record the specialization for sharing code across multiple 104b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // contexts that have the same value in the corresponding context slot. 105b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return Reducer::Replace(jsgraph_->Constant(value)); 106b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch} 107b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 108b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 109b8a8cc1952d61a2f3a2568848933943a543b5d3eBen MurdochReduction JSContextSpecializer::ReduceJSStoreContext(Node* node) { 110b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch DCHECK_EQ(IrOpcode::kJSStoreContext, node->opcode()); 111b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 112b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch HeapObjectMatcher<Context> m(NodeProperties::GetValueInput(node, 0)); 113b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // If the context is not constant, no reduction can occur. 114b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch if (!m.HasValue()) { 115b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return Reducer::NoChange(); 116b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 117b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 118b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch ContextAccess access = OpParameter<ContextAccess>(node); 119b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 120b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // The access does not have to look up a parent, nothing to fold. 121b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch if (access.depth() == 0) { 122b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return Reducer::NoChange(); 123b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 124b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 125b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch // Find the right parent context. 126b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch Context* context = *m.Value().handle(); 127b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch for (int i = access.depth(); i > 0; --i) { 128b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch context = context->previous(); 129b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch } 130b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 131b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch const Operator* op = jsgraph_->javascript()->StoreContext(0, access.index()); 132b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch node->set_op(op); 133b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch Handle<Object> new_context_handle = Handle<Object>(context, info_->isolate()); 134b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch node->ReplaceInput(0, jsgraph_->Constant(new_context_handle)); 135b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 136b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch return Reducer::Changed(node); 137b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch} 138b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch 139b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch} // namespace compiler 140b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch} // namespace internal 141b8a8cc1952d61a2f3a2568848933943a543b5d3eBen Murdoch} // namespace v8 142