Add C/JS APIs to copy expressions (#2840)

This API enables use cases where we want to keep the original expression, yet utilize passes like `vacuum` or `precompute` to evaluate it without implicitly modifying the original.

C-API: **BinaryenExpressionCopy**(expr, module)
JS-API: **Module#copyExpression**(expr)

3 files changed, 10 insertions, 0 deletions

diff --git a/src/binaryen-c.cpp b/src/binaryen-c.cpp
index c57beeb22..a64c46fbf 100644
--- a/src/binaryen-c.cpp
+++ b/src/binaryen-c.cpp
@@ -1319,6 +1319,11 @@ void BinaryenExpressionPrint(BinaryenExpressionRef expr) {
   std::cout << '\n';
 }
 
+BinaryenExpressionRef BinaryenExpressionCopy(BinaryenExpressionRef expr,
+                                             BinaryenModuleRef module) {
+  return ExpressionManipulator::copy(expr, *(Module*)module);
+}
+
 // Specific expression utility
 
 // Block
diff --git a/src/binaryen-c.h b/src/binaryen-c.h
index 0e1c88327..e460671b9 100644
--- a/src/binaryen-c.h
+++ b/src/binaryen-c.h
@@ -848,6 +848,8 @@ BINARYEN_API BinaryenExpressionId
 BinaryenExpressionGetId(BinaryenExpressionRef expr);
 BINARYEN_API BinaryenType BinaryenExpressionGetType(BinaryenExpressionRef expr);
 BINARYEN_API void BinaryenExpressionPrint(BinaryenExpressionRef expr);
+BINARYEN_API BinaryenExpressionRef
+BinaryenExpressionCopy(BinaryenExpressionRef expr, BinaryenModuleRef module);
 
 BINARYEN_API const char* BinaryenBlockGetName(BinaryenExpressionRef expr);
 BINARYEN_API BinaryenIndex
diff --git a/src/js/binaryen.js-post.js b/src/js/binaryen.js-post.js
index 75d6bf401..1706d2b97 100644
--- a/src/js/binaryen.js-post.js
+++ b/src/js/binaryen.js-post.js
@@ -2407,6 +2407,9 @@ function wrapModule(module, self) {
   self['setDebugLocation'] = function(func, expr, fileIndex, lineNumber, columnNumber) {
     return Module['_BinaryenFunctionSetDebugLocation'](func, expr, fileIndex, lineNumber, columnNumber);
   };
+  self['copyExpression'] = function(expr) {
+    return Module['_BinaryenExpressionCopy'](expr, module);
+  };
 
   return self;
 }