The Godbolt compiler explorer allows the user to compile a function and see the corresponding assembly code. It can highlight matching parts in the language and assembly, making it easy to understand how individual expressions are compiled. It supports common languages like C, C++, Go, Rust. It can also work with assembler and LLVM IR.
Another nice feature is, that it can show statistics about assembler code, like needed cycles, instructions, and which resources the instructions need. This uses the LLVM Machine Code Analyzer.