Need some clarification about optimization flags, what "exactly" does -O1 do?
Sat Nov 29 11:50:00 GMT 2008
Andrzej Giniewicz wrote:
>> That's interesting. tree-dce is Dead Code Elimination on trees, where
>> gcc removes code that can't possibly be reached. It's possible that
>> there's a bug in DCE, but I bet it's something like the enum bug above.
>> If you're interested in finding the real bug I can tell you how to read
>> the compiler dumps.
> that would be sweet, finding real bugs is always better than workaround :)
Compile with -fdump-tree-all. You'll see dozens of dump files like
Diff the pass before dce and the post-dce dump and you'll see what dce did.
There are several dce passes.
Also, you can diff the final optimized code with and without dce.
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