[wasm] Generate source position information

src/compiler/wasm-compiler.h

Index: src/compiler/wasm-compiler.h
diff --git a/src/compiler/wasm-compiler.h b/src/compiler/wasm-compiler.h
index 4a4b1a7cd04ba05f638bbe7a35879364a926fbcd..1b46f37ff01ceed396371a112f6815d3de4f017d 100644
--- a/src/compiler/wasm-compiler.h
+++ b/src/compiler/wasm-compiler.h
@@ -18,6 +18,8 @@ namespace compiler {
 class Node;
 class JSGraph;
 class Graph;
+class SourcePositionTable;
+class SourcePositionScope;
 }
 
 namespace wasm {
@@ -55,7 +57,14 @@ Handle<JSFunction> CompileJSToWasmWrapper(
 class WasmTrapHelper;
 class WasmGraphBuilder {
  public:
-  WasmGraphBuilder(Zone* z, JSGraph* g, wasm::FunctionSig* function_signature);
+  WasmGraphBuilder(
+      Zone* z, JSGraph* g, wasm::FunctionSig* function_signature,
+      compiler::SourcePositionTable* source_position_table = nullptr);
+
+  ~WasmGraphBuilder() {
+    // check that Enter- / LeaveSourcePositionScope is balanced
+    DCHECK_NULL(source_position_scope_);
+  }
 
   Node** Buffer(size_t count) {
     if (count > cur_bufsize_) {
@@ -141,6 +150,18 @@ class WasmGraphBuilder {
 
   void Int64LoweringForTesting();
 
+  // Register a graph decorator to assign source positions to nodes (in

[titzer, 2016/04/18 11:03:51]

I don't think we should add scoping for this. I think it'd be better to pass the
source position explicitly to the methods that build nodes, for exactly those
nodes that need positions. Those are binops (because division can trap) and
calls.

[Clemens Hammacher, 2016/04/18 11:18:10]

What about step-through debugging? Wouldn't that require source position
information on basically each single node?

+  // source_position_table_). Only has an effect if source_position_table_ is
+  // non-null. Ensure to call LeaveSourcePositionScope afterwards.
+  void EnterSourcePositionScope();
+  void LeaveSourcePositionScope();
+
+  // Set current source position, such that all nodes created after this call
+  // get the respecitve position assigned. This only has an effect if
+  // source_position_table_ is non-null and EnterSourcePositionScope was called
+  // before.
+  void SetCurrentSourcePosition(int position);
+
  private:
   static const int kDefaultBufferSize = 16;
   friend class WasmTrapHelper;
@@ -160,6 +181,9 @@ class WasmGraphBuilder {
   WasmTrapHelper* trap_;
   wasm::FunctionSig* function_signature_;
 
+  compiler::SourcePositionTable* source_position_table_ = nullptr;
+  compiler::SourcePositionScope* source_position_scope_ = nullptr;
+
   // Internal helper methods.
   JSGraph* jsgraph() { return jsgraph_; }
   Graph* graph();