[issue2506] Add mechanism to disable optimizations

[Raymond Hettinger]

Raymond Hettinger added the comment:

Ned, why is your proposal to turn-off ALL peephole transformations with COMMAND-LINE switch?

* Why not just turn-off the jump-to-jump?  Do you really need to disable constant folding and other transformations?

* Have you explored whether the peephole.c code can be changed to indicate the continue-statement was visited?

* Why does this have to be a command-line setting rather than a flag or environment variable settable by coverage.py?

* Is there some less radical way the coverage.py can be taught to make the continue-statement as visited?

* Are you requesting that optimization constraints be placed on all of the implementations of Python (Jython, PyPy, and IronPython) to make coverage.py perfect?

* Do you want to place limits on what can be done by Victor's proposed AST tranformations which will occur upstream from the peepholer and will make higher level semantically-neutral transformations *prior* to code generation.

* Have you considered whether the genererated PYC files need a different magic number or some other way to indicate that they aren't production code?

* If coverage.py produces a report on different code than the production run, doesn't that undermine some of the confidence the meaningfulness of the report?

In other words, are you sure that you're making the right request and that it is really worth it?  Do we really have to open this can of worms to make coverage.py happy?

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versions: +Python 3.5 -Python 3.4

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<http://bugs.python.org/issue2506>
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