4 files changed, 76 insertions, 30 deletions

diff --git a/src/ast/module-utils.h b/src/ast/module-utils.h
new file mode 100644
index 000000000..11a5a3530
--- /dev/null
+++ b/src/ast/module-utils.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2017 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_ast_module_h
+#define wasm_ast_module_h
+
+#include "wasm.h"
+
+namespace wasm {
+
+namespace ModuleUtils {
+
+// Computes the indexes in a wasm binary, i.e., with function imports
+// and function implementations sharing a single index space, etc.
+struct BinaryIndexes {
+  std::unordered_map<Name, Index> functionIndexes;
+  std::unordered_map<Name, Index> globalIndexes;
+
+  BinaryIndexes(Module& wasm) {
+    for (Index i = 0; i < wasm.imports.size(); i++) {
+      auto& import = wasm.imports[i];
+      if (import->kind == ExternalKind::Function) {
+        auto index = functionIndexes.size();
+        functionIndexes[import->name] = index;
+      } else if (import->kind == ExternalKind::Global) {
+        auto index = globalIndexes.size();
+        globalIndexes[import->name] = index;
+      }
+    }
+    for (Index i = 0; i < wasm.functions.size(); i++) {
+      auto index = functionIndexes.size();
+      functionIndexes[wasm.functions[i]->name] = index;
+    }
+    for (Index i = 0; i < wasm.globals.size(); i++) {
+      auto index = globalIndexes.size();
+      globalIndexes[wasm.globals[i]->name] = index;
+    }
+  }
+};
+
+} // namespace ModuleUtils
+
+} // namespace wasm
+
+#endif // wasm_ast_module_h
+
diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 6d40034fc..beae693d9 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -22,6 +22,7 @@
 #include <wasm-printing.h>
 #include <pass.h>
 #include <pretty_printing.h>
+#include <ast/module-utils.h>
 
 namespace wasm {
 
@@ -47,6 +48,8 @@ struct PrintSExpression : public Visitor<PrintSExpression> {
   Function* currFunction = nullptr;
   Function::DebugLocation lastPrintedLocation;
 
+  std::unordered_map<Name, Index> functionIndexes;
+
   PrintSExpression(std::ostream& o) : o(o) {
     setMinify(false);
     if (!full) full = isFullForced();
@@ -686,6 +689,14 @@ struct PrintSExpression : public Visitor<PrintSExpression> {
     lastPrintedLocation = { 0, 0, 0 };
     printOpening(o, "func ", true);
     printName(curr->name);
+    if (currModule && !minify) {
+      // emit the function index in a comment
+      if (functionIndexes.empty()) {
+        ModuleUtils::BinaryIndexes indexes(*currModule);
+        functionIndexes = std::move(indexes.functionIndexes);
+      }
+      o << " (; " << functionIndexes[curr->name] << " ;)";
+    }
     if (curr->type.is()) {
       o << maybeSpace << "(type " << curr->type << ')';
     }
diff --git a/src/wasm-binary.h b/src/wasm-binary.h
index bf1cb14d6..bcf6cf45f 100644
--- a/src/wasm-binary.h
+++ b/src/wasm-binary.h
@@ -696,8 +696,8 @@ public:
   void writeExports();
   void writeDataSegments();
 
-  std::map<Name, Index> mappedFunctions; // name of the Function => index. first imports, then internals
-  std::map<Name, uint32_t> mappedGlobals; // name of the Global => index. first imported globals, then internal globals
+  std::unordered_map<Name, Index> mappedFunctions; // name of the Function => index. first imports, then internals
+  std::unordered_map<Name, uint32_t> mappedGlobals; // name of the Global => index. first imported globals, then internal globals
   uint32_t getFunctionIndex(Name name);
   uint32_t getGlobalIndex(Name name);
 
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 6c79a9032..bd0684d28 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -20,6 +20,7 @@
 #include "support/bits.h"
 #include "wasm-binary.h"
 #include "ast/branch-utils.h"
+#include "ast/module-utils.h"
 
 namespace wasm {
 
@@ -31,6 +32,9 @@ void WasmBinaryWriter::prepare() {
     }
     // TODO: depending on upstream flux https://github.com/WebAssembly/spec/pull/301 might want this: assert(!func->type.isNull());
   }
+  ModuleUtils::BinaryIndexes indexes(*wasm);
+  mappedFunctions = std::move(indexes.functionIndexes);
+  mappedGlobals = std::move(indexes.globalIndexes);
 }
 
 void WasmBinaryWriter::write() {
@@ -343,39 +347,11 @@ void WasmBinaryWriter::writeDataSegments() {
 }
 
 uint32_t WasmBinaryWriter::getFunctionIndex(Name name) {
-  if (!mappedFunctions.size()) {
-    // Create name => index mapping.
-    for (auto& import : wasm->imports) {
-      if (import->kind != ExternalKind::Function) continue;
-      assert(mappedFunctions.count(import->name) == 0);
-      auto index = mappedFunctions.size();
-      mappedFunctions[import->name] = index;
-    }
-    for (size_t i = 0; i < wasm->functions.size(); i++) {
-      assert(mappedFunctions.count(wasm->functions[i]->name) == 0);
-      auto index = mappedFunctions.size();
-      mappedFunctions[wasm->functions[i]->name] = index;
-    }
-  }
   assert(mappedFunctions.count(name));
   return mappedFunctions[name];
 }
 
 uint32_t WasmBinaryWriter::getGlobalIndex(Name name) {
-  if (!mappedGlobals.size()) {
-    // Create name => index mapping.
-    for (auto& import : wasm->imports) {
-      if (import->kind != ExternalKind::Global) continue;
-      assert(mappedGlobals.count(import->name) == 0);
-      auto index = mappedGlobals.size();
-      mappedGlobals[import->name] = index;
-    }
-    for (size_t i = 0; i < wasm->globals.size(); i++) {
-      assert(mappedGlobals.count(wasm->globals[i]->name) == 0);
-      auto index = mappedGlobals.size();
-      mappedGlobals[wasm->globals[i]->name] = index;
-    }
-  }
   assert(mappedGlobals.count(name));
   return mappedGlobals[name];
 }