[wasm] Generate source position information

src/compiler/pipeline.cc

Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index fad9e489b7562dbf5a58bd1461cc597b3435a4b5..60ce5fa27965b57673d2859e536b99877045e26f 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -103,7 +103,6 @@ class PipelineData {
         register_allocation_data_(nullptr) {
     PhaseScope scope(pipeline_statistics, "init pipeline data");
     graph_ = new (graph_zone_) Graph(graph_zone_);
-    source_positions_.Reset(new SourcePositionTable(graph_));
     simplified_ = new (graph_zone_) SimplifiedOperatorBuilder(graph_zone_);
     machine_ = new (graph_zone_) MachineOperatorBuilder(
         graph_zone_, MachineType::PointerRepresentation(),
@@ -127,7 +126,6 @@ class PipelineData {
         graph_zone_scope_(zone_pool_),
         graph_zone_(nullptr),
         graph_(graph),
-        source_positions_(new SourcePositionTable(graph_)),
         loop_assignment_(nullptr),
         simplified_(nullptr),
         machine_(nullptr),
@@ -194,7 +192,12 @@ class PipelineData {
 
   Zone* graph_zone() const { return graph_zone_; }
   Graph* graph() const { return graph_; }
-  SourcePositionTable* source_positions() const {
+  SourcePositionTable* source_positions() {
+    // First check whether the CompilationInfo provides the table
+    if (auto* table = info()->GetSourcePositionTable()) return table;
+    // Lazy initialization
+    if (source_positions_.is_empty())
+      source_positions_.Reset(new SourcePositionTable(graph()));
     return source_positions_.get();
   }
   MachineOperatorBuilder* machine() const { return machine_; }
@@ -400,15 +403,15 @@ class AstGraphBuilderWithPositions final : public AstGraphBuilder {
         start_position_(info->shared_info()->start_position()) {}
 
   bool CreateGraph(bool stack_check) {
-    SourcePositionTable::Scope pos_scope(source_positions_, start_position_);
+    SourcePositionScope pos_scope(source_positions_, start_position_);
     return AstGraphBuilder::CreateGraph(stack_check);
   }
 
-#define DEF_VISIT(type)                                               \
-  void Visit##type(type* node) override {                             \
-    SourcePositionTable::Scope pos(source_positions_,                 \
-                                   SourcePosition(node->position())); \
-    AstGraphBuilder::Visit##type(node);                               \
+#define DEF_VISIT(type)                                        \
+  void Visit##type(type* node) override {                      \
+    SourcePositionScope pos(source_positions_,                 \
+                            SourcePosition(node->position())); \
+    AstGraphBuilder::Visit##type(node);                        \
   }
   AST_NODE_LIST(DEF_VISIT)
 #undef DEF_VISIT
@@ -427,7 +430,7 @@ class SourcePositionWrapper final : public Reducer {
 
   Reduction Reduce(Node* node) final {
     SourcePosition const pos = table_->GetSourcePosition(node);
-    SourcePositionTable::Scope position(table_, pos);
+    SourcePositionScope position(table_, pos);
     return reducer_->Reduce(node);
   }