On Monday, 4 August 2014 at 02:18:12 UTC, David Bregman wrote:
His post basically says that his real life experience leads him
to believe that a static analyzer based on using information
from asserts will very likely generate a ton of
warnings/errors, because real life code is imperfect.
In other words, if you use that information to optimize
instead, you are going to get a ton of bugs, because the
asserts are inconsistent with the code.
No.
My experience says deeper optimization comes from deeper
understanding of the dataflow, with deeper understanding of the
dataflow comes stricter warnings about defective usage.
ie. A Good compiler writer, as Walter and the gcc guys clearly
are, don't just slap in an optimization pass out of nowhere.
They are all too painfully aware that if their optimization pass
breaks anything, they will be fending off thousands of complaints
that "Optimization X broke....".
Compiler users always blame the optimizer long before they blame
their crappy code.
Watching the gcc mailing list over the years, those guys bend
over backwards to prevent that happening.
But since an optimization has to be based on additional hard
information, they have, with every new version of gcc, used that
information both for warnings and optimization.
