[issue37500] 3.8.0b2 no longer optimizes away "if 0:" ?

[Tim Peters]

Tim Peters <tim at python.org> added the comment:

> Using jumps is not removing the optimization
> entirely, is just a weaker and more incomplete
> way of doing the same. 

Sorry, I'm afraid I have no idea what that means.  The generated code before and after was wildly different, as shown in Ned's original report here.  In what possible sense was his "if 0:" being "optimized" if it generated code to load 0 onto the stack, then POP_JUMP_IF_FALSE, and then jumped over all the code generated for the dead block?

The generated code after is nearly identical if I replace his "if 0:" with "if x:" (which the compiler takes to mean a global or builtin about whose truthiness it knows nothing at all).  Indeed, the only difference in the byte code is that instead of doing a LOAD_CONST to load 0, it does a LOAD_GLOBAL to load x.

So, to my eyes, absolutely nothing of the optimization remained.  At least not in the example Ned posted here.

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<https://bugs.python.org/issue37500>
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