Can we see the template instantiated code by C++ compiler

Question

is there a way to know the compiler instantiated code for a template function or a class in C++

Assume I have the following piece of code

template < class T> T add(T a, T b){             return a+b; } 

now when i call

add<int>(10,2);  

I would like to know the function that compiler creates for int specific version.

I am using G++, VC++. It will be helpful if some can help me point out the compiler options to achieve this.

Hope the question is clear. Thanks in advance.

Answer 1

Clang (https://clang.llvm.org/) can pretty-print AST of instantiated template:

For your example:

test.cpp

template < class T> T add(T a, T b){     return a+b; }  void tmp() {     add<int>(10,2);  } 

Command to pretty-print AST:

$ clang++ -Xclang -ast-print -fsyntax-only test.cpp 

Clang-5.0 output:

template <class T> T add(T a, T b) {     return a + b; } template<> int add<int>(int a, int b) {     return a + b; } void tmp() {     add<int>(10, 2); } 

Answer 2

If you want to see the assembly output, use this:

g++ -S file.cpp 

If you want to see some (pseudo) C++ code that GCC generates, you can use this:

g++ -fdump-tree-original file.cpp 

For your add function, this will output something like

;; Function T add(const T&, const T&) [with T = int] (null) ;; enabled by -tree-original  return <retval> = (int) *l + (int) *r; 

(I passed the parameters by reference to make the output a little more interesting)