I've always argued against the idea that "portable assembly" is a useful way to look at C. It is terrible for the purpose in the sense that the compiler is allo

I've always argued against the idea that "portable assembly" is a useful way to look at C. It is terrible for the purpose in the sense that the compiler is allowed to generate code that has little to do with what you wrote in terms of procedure. Assembly on the other hand is useful exactly because it affords minute control of procedure. In my view, C is a secretly declarative language where your program is a declaration of constraints for the optimizing back-end that just happens to look a lot like procedural code. I can write what looks like function containing a loop or a memory write and call it from main only to end up with a program that only loads a constant in a register and returns. Because of this and the sometimes complex conditions that enable some optimizations, it's hard to argue about C code in terms of its performance without falling back on analyzing the actual "non-portable" assembler output of the compiler.