[wasm][asm.js] Allow a function to be exported more than once.

src/wasm/wasm-module-builder.cc

Index: src/wasm/wasm-module-builder.cc
diff --git a/src/wasm/wasm-module-builder.cc b/src/wasm/wasm-module-builder.cc
index 4bc569a68ca7d2f8045304944a02fddbe17dc673..111b90ba372ea58766a930587088ab02eefad28c 100644
--- a/src/wasm/wasm-module-builder.cc
+++ b/src/wasm/wasm-module-builder.cc
@@ -50,11 +50,10 @@ WasmFunctionBuilder::WasmFunctionBuilder(WasmModuleBuilder* builder)
     : builder_(builder),
       locals_(builder->zone()),
       signature_index_(0),
-      exported_(0),
       func_index_(static_cast<uint32_t>(builder->functions_.size())),
       body_(builder->zone()),
       name_(builder->zone()),
-      exported_name_(builder->zone()),
+      exported_names_(builder->zone()),
       i32_temps_(builder->zone()),
       i64_temps_(builder->zone()),
       f32_temps_(builder->zone()),
@@ -141,12 +140,9 @@ void WasmFunctionBuilder::EmitDirectCallIndex(uint32_t index) {
   EmitCode(code, sizeof(code));
 }
 
-void WasmFunctionBuilder::Export() { exported_ = true; }
-
 void WasmFunctionBuilder::ExportAs(Vector<const char> name) {
-  exported_ = true;
-  exported_name_.resize(name.length());
-  memcpy(exported_name_.data(), name.start(), name.length());
+  exported_names_.push_back(ZoneVector<char>(
+      name.start(), name.start() + name.length(), builder_->zone()));

[titzer, 2016/12/01 09:22:24]

There was a memcpy in the old code. Is that necessary still?

[bradn, 2016/12/01 09:27:08]

No, the old code was sharing a single vector, which was wrong (assumes a single
name to export under).
This creates a new ZoneVector per alternate export name.

 }
 
 void WasmFunctionBuilder::SetName(Vector<const char> name) {
@@ -172,13 +168,10 @@ void WasmFunctionBuilder::WriteSignature(ZoneBuffer& buffer) const {
   buffer.write_u32v(signature_index_);
 }
 
-void WasmFunctionBuilder::WriteExport(ZoneBuffer& buffer) const {
-  if (exported_) {
-    const ZoneVector<char>* exported_name =
-        exported_name_.size() == 0 ? &name_ : &exported_name_;
-    buffer.write_size(exported_name->size());
-    buffer.write(reinterpret_cast<const byte*>(exported_name->data()),
-                 exported_name->size());
+void WasmFunctionBuilder::WriteExports(ZoneBuffer& buffer) const {
+  for (auto name : exported_names_) {
+    buffer.write_size(name.size());
+    buffer.write(reinterpret_cast<const byte*>(name.data()), name.size());
     buffer.write_u8(kExternalFunction);
     buffer.write_u32v(func_index_ +
                       static_cast<uint32_t>(builder_->imports_.size()));
@@ -348,7 +341,7 @@ void WasmModuleBuilder::WriteTo(ZoneBuffer& buffer) const {
     buffer.write_size(functions_.size());
     for (auto function : functions_) {
       function->WriteSignature(buffer);
-      if (function->exported()) exports++;
+      exports += function->exported_names_.size();
       if (function->name_.size() > 0) has_names = true;
     }
     FixupSection(buffer, start);
@@ -451,7 +444,7 @@ void WasmModuleBuilder::WriteTo(ZoneBuffer& buffer) const {
   if (exports > 0) {
     size_t start = EmitSection(kExportSectionCode, buffer);
     buffer.write_u32v(exports);
-    for (auto function : functions_) function->WriteExport(buffer);
+    for (auto function : functions_) function->WriteExports(buffer);
     FixupSection(buffer, start);
   }
 
@@ -524,10 +517,8 @@ void WasmModuleBuilder::WriteTo(ZoneBuffer& buffer) const {
     }
     for (auto function : functions_) {
       buffer.write_size(function->name_.size());
-      if (function->name_.size() > 0) {
-        buffer.write(reinterpret_cast<const byte*>(&function->name_[0]),
-                     function->name_.size());
-      }
+      buffer.write(reinterpret_cast<const byte*>(function->name_.data()),
+                   function->name_.size());
       buffer.write_u8(0);
     }
     FixupSection(buffer, start);