Yes, you're right, the switch statement is a good example of how modern compilers fudge the boundary.
But the main point is that the difference between the generated code and the stuff you write is relatively small, when looking at the assembly that a C compiler generates I have relatively little trouble following the relationship between the two, and I can make reasonable predictions about what will pop out on the other end.
And of course processors are 'richer' than what most C compilers will use, especially when it comes to special instructions that have no equivalent in the C language.
I've worked on a 'decompiler' for the Mark Williams C compiler (yes, that's pretty long ago), and at the time the above still held true, today the boundaries are definitely fuzzier, mostly due to the increased smarts of compiler writers for the optimization stage.
Gcc is clever enough to optimize whole branches of code out of existence if you set it to be aggressive enough and the code was written naively, that's one way of dramatically losing that 1:1 correspondence.
But the main point is that the difference between the generated code and the stuff you write is relatively small, when looking at the assembly that a C compiler generates I have relatively little trouble following the relationship between the two, and I can make reasonable predictions about what will pop out on the other end.
And of course processors are 'richer' than what most C compilers will use, especially when it comes to special instructions that have no equivalent in the C language.
I've worked on a 'decompiler' for the Mark Williams C compiler (yes, that's pretty long ago), and at the time the above still held true, today the boundaries are definitely fuzzier, mostly due to the increased smarts of compiler writers for the optimization stage.
Gcc is clever enough to optimize whole branches of code out of existence if you set it to be aggressive enough and the code was written naively, that's one way of dramatically losing that 1:1 correspondence.