Assembly Calling Convention: __thiscall (Patreon)

Calling Convention: __thiscall

• Calling convention for C++ class members
  (passing the “this” object)
• Arguments are passed on the stack (pushed right-to-left)
• An additional argument, the “this” object pointer, is passed in the ECX register
• Callee is responsible for stack cleanup

Reverse Engineering C++ Basics Tutorial 

MSDN __thiscall documentation  

Practice Examples

Attached to this post is a copy of the HelloWorld PE file from our tutorial. You are encouraged to open this sample in IDA and identify the function calling conventions as well as the class struct.