From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <8662d293439a68bc0c877a922990e8c0@plan9.bell-labs.com> To: 9fans@cse.psu.edu Subject: Re: [9fans] GUI toolkit for Plan 9 From: "Russ Cox" MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Tue, 26 Feb 2002 15:25:33 -0500 Topicbox-Message-UUID: 57576514-eaca-11e9-9e20-41e7f4b1d025 > > Ten percent buys you, what, a couple of weeks of Moore's Law? I'm not > > against fast compilers - I'm actually rather impressed by good > > compilers - but I do fret about optimizing compilers breaking my code. > > Oh, of course, but that's a matter of writing correct code. No, it's also a matter of not having buggy optimizers. > Your concern reminds me of people who are scared of garbage collection > because they think it will have a bug and free live memory. And this is a matter of not having buggy garbage collectors. In both case you are assuming that the optimizer/garbage collector itself has no bugs, which is not always a great assumption. In both cases it's a case of balancing the benefit you gain from the chance of a negative effect due to bugs in the optimizer/garbage collector. If having ten times as many optimizations comes at the cost of having ten times as many optimizer bugs, then I'd think twice about it. In the optimizer case, the number of confirmed gcc optimizer bugs at any given time seems to be fairly high, high enough that reasonable people can run into them with annoying frequency, especially on non-x86 platforms. (I know of an undergrad OS course that was using the latest gcc MIPS compiler and ran into many of these; in that case, though, there was no hope: turning off optimizations just selected a different set of code generation bugs.) Russ