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Re: RFC: #pragma optimization_level



On 2005-04-04, at 19:46, Dale Johannesen wrote:


On Apr 3, 2005, at 5:31 PM, Geert Bosch wrote:
On Apr 1, 2005, at 16:36, Mark Mitchell wrote:
In fact, I've long said that GCC had too many knobs.

(For example, I just had a discussion with a customer where I explained that the various optimization passes, while theoretically orthogonal, are not entirely orthogonal in practice, and that truning on another pass (GCSE, in this caes) avoided other bugs. For that reason, I'm not actually convinced that all the -f options for turning on and off passes are useful for end-users, although they are clearly useful for debugging the compiler itself. I think we might have more satisfied users if we simply had -Os, -O0, ..., -O3. However, many people in the GCC community itself, and in certain other vocal areas of the user base, do not agree.)

Pragmas have even more potential for causing problems than command-line options.
People are generally persuaded more easily to change optimization options, than
to go through hundreds of source files fixing pragmas.

I would hope so. But the reason I'm doing this is that we've got a lot of customer
requests for pragma-level control of optimization.

I don't agree with the argument presented by Geert Bosch. It's even more difficult to
muddle through the atrocities of autoconf/automake to find the places where compiler
switches get set in huge software projects then doing a grep -r \\#pragma ./
over a source tree.



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