2 files changed, 61 insertions, 2 deletions
diff --git a/src/support/path.h b/src/support/path.h
new file mode 100644
index 000000000..18dde8ea8
--- /dev/null
+++ b/src/support/path.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2015 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.
+ */
+
+//
+// Command line helpers.
+//
+
+#ifndef wasm_support_path_h
+#define wasm_support_path_h
+
+#include <cstdlib>
+#include <string>
+
+namespace wasm {
+
+namespace Path {
+
+inline std::string getPathSeparator() {
+  // TODO: use c++17's path separator
+  //       http://en.cppreference.com/w/cpp/experimental/fs/path
+#if defined(WIN32) || defined(_WIN32) 
+  return "\\";
+#else
+  return "/";
+#endif
+}
+
+inline std::string getBinaryenRoot() {
+  auto* envVar = getenv("BINARYEN_ROOT");
+  if (envVar) return envVar;
+  return ".";
+}
+
+// Gets the path to a binaryen binary tool, like wasm-opt
+inline std::string getBinaryenBinaryTool(std::string name) {
+  return getBinaryenRoot() + getPathSeparator() +
+         "bin" + getPathSeparator() +
+         name;
+}
+
+} // namespace Path
+
+} // namespace wasm
+
+#endif // wasm_support_path_h
diff --git a/src/tools/wasm-reduce.cpp b/src/tools/wasm-reduce.cpp
index da6f4fa6e..784c11942 100644
--- a/src/tools/wasm-reduce.cpp
+++ b/src/tools/wasm-reduce.cpp
@@ -30,6 +30,7 @@
 #include "pass.h"
 #include "support/command-line.h"
 #include "support/file.h"
+#include "support/path.h"
 #include "wasm-io.h"
 #include "wasm-builder.h"
 #include "ir/literal-utils.h"
@@ -137,7 +138,7 @@ struct Reducer : public WalkerPass<PostWalker<Reducer, UnifiedExpressionVisitor<
       // try both combining with a generic shrink (so minor pass overhead is compensated for), and without
       for (auto shrinking : { false, true }) {
         for (auto pass : passes) {
-          std::string currCommand = "bin/wasm-opt ";
+          std::string currCommand = Path::getBinaryenBinaryTool("wasm-opt") + " ";
           if (shrinking) currCommand += " --dce --vacuum ";
           currCommand += working + " -o " + test + " " + pass;
           if (debugInfo) currCommand += " -g ";
@@ -576,7 +577,7 @@ int main(int argc, const char* argv[]) {
   std::cerr << "|checking that command has expected behavior on canonicalized (read-written) binary\n";
   {
     // read and write it
-    ProgramResult readWrite(std::string("bin/wasm-opt ") + input + " -o " + test);
+    ProgramResult readWrite(Path::getBinaryenBinaryTool("wasm-opt") + " " + input + " -o " + test);
     if (readWrite.failed()) {
       stopIfNotForced("failed to read and write the binary", readWrite);
     } else {