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Re: What is acceptable for -ffast-math? (Was: associative law in combine)
- To: dewar at gnat dot com, gdr at codesourcery dot com
- Subject: Re: What is acceptable for -ffast-math? (Was: associative law in combine)
- From: dewar at gnat dot com
- Date: Tue, 31 Jul 2001 00:13:36 -0400 (EDT)
- Cc: amylaar at redhat dot com, aoliva at redhat dot com, gcc at gcc dot gnu dot org,moshier at moshier dot ne dot mediaone dot net, torvalds at transmeta dot com,tprince at computer dot org
<<What I intended to mean is that the compiler has, first, to prove that
such transformmation yields the same result. The only argument I've
seen so far is that, GCC should make the program run fast...
>>
Not quite, "the same result" is too strong. Instead, the rule is that
the transformation must yield a result that is still conforming to the
requirements of the standard. Since the standard is (deliberately) not
100% precise in saying what this result should be, there is some legitimate
wiggle room.