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Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."

From: Richard Kenner
Subject: Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
Date: Fri, 29 Dec 2006 19:26:21 EST

> I'm not sure what data you're asking for.  

Here's the data *I'd* like to see:

(1) What is the maximum performance loss that can be shown using a real
program (e.g,. one in SPEC) and some compiler (not necessarily GCC) when
one assumes wrapping semantics?

(2) In the current SPEC, how many programs benefit from undefined overflow
semantics and how much does each benefit?

(3) How many programs are known to rely on wrap semantics?  For each:
  (a) How hard was it to determine there was a problem with that assumption?
  (b) How much work was it to modify the program to not rely on such semantics?

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