regehr | 9 years ago | on: Introduction to Precision Farming
I adjusted the text a bit anyhow.
regehr's comments
regehr | 9 years ago | on: Vigorous Public Debates in Academic Computer Science
Yes, I'm adding them as I learn about them her (or, in this case, am reminded about them).
regehr | 9 years ago | on: The Melancholy of Infinite Space (1996)
Anyone who enjoys this story will likely also enjoy _Tau Zero_ by Poul Anderson.
regehr | 10 years ago | on: Superoptimizing LLVM (2014) [video]
It turns out it's harder than you'd think to decide whether or not an optimization is a good idea. Of course there are some relatively simple optimizations that are obviously good, but a lot of those have already been implemented. Also, I'm not sure how many people are going to want to add a solver into their compilation path.
On the other hand, if we simply contribute optimizations then all LLVM users benefit.
We're also using Souper to reveal imprecisions in LLVM dataflow analyses such as known bits -- this turns out to work really well.
regehr | 10 years ago | on: Superoptimizing LLVM (2014) [video]
It's definitely still an active project, but I'm on sabbatical this academic year and have had much less time than usual for my regular research. I'll be getting back to it in June. Also, Raimondas Sasnauskas, who implemented the instruction synthesizer, finished his postdoc position and moved on.
In any case, there's been a lot of progress since I did that UW talk, for example here are some early synthesis results:
regehr | 10 years ago | on: C – Preliminary C2x Charter
Meanwhile, Java runs pretty fast.
regehr | 10 years ago | on: The Strict Aliasing Situation Is Pretty Bad
Replying to myself because depth limit.
Let me try to think of a good way to update the post to capture this better...
regehr | 10 years ago | on: The Strict Aliasing Situation Is Pretty Bad
Looks like your other comment hit the max reply depth so this will need to finish up, but in any case I don't agree with your reading of the vice versa.
regehr | 10 years ago | on: The Strict Aliasing Situation Is Pretty Bad
I don't see text that justifies your one-way argument, the bit of 6.2.7.1 that we are talking about says "and vice versa".
regehr | 10 years ago | on: The Strict Aliasing Situation Is Pretty Bad
It doesn't seem straightforward to me: you're using words like base and derived that aren't in the C standard.
regehr | 10 years ago | on: The Strict Aliasing Situation Is Pretty Bad
Josh, what's your opinion about this situation?
regehr | 10 years ago | on: Frama-C: Function Contracts and Static Analysis for the C Language
Frama-C can be used in "interpreter mode" where it acts like a checking C interpreter. It then catches a superset of the bugs that would be caught by Valgrind / ASan / UBSan. On the other hand it is slower and harder to use than those tools.
regehr | 10 years ago | on: What is the best John le Carré novel?
_A Perfect Spy_ has my vote, it's an incredible book.
regehr | 10 years ago | on: The Problem with Friendly C
Also we're all waiting for the strict aliasing checker.
regehr | 10 years ago | on: The Problem with Friendly C
For new code and for actively maintained old code you are perfectly correct. But there is a huge amount of C code we still rely on that isn't getting enough attention and I don't want that getting broken either.
regehr | 10 years ago | on: Test-Case Reducers are Fuzzers
I'm not sure if the QuickCheck people have explored these ideas, perhaps they'll chime in.
regehr | 10 years ago | on: Test-Case Reducers are Fuzzers
Shrinkers, reducers, minimizers -- all are the same thing and all operate using the basic ideas outlined in the original Delta Debugging paper.
regehr | 10 years ago | on: Test-Case Reducers are Fuzzers
Delta Debugging provided a name and a generic algorithm for something that people had already been doing, but they hadn't been calling it anything and hadn't formulated it as an abstract problem.
DD just removes stuff. C-Reduce does lots more, such as inlining functions, rewriting the class hierarchy, instantiating templates, ...
regehr | 10 years ago | on: Microkernels Meet Recursive Virtual Machines (1996) [pdf]
ftp.flux.utah.edu is responding fine for me.
If you can't find what you're looking for we can help, I'm [email protected]
regehr | 10 years ago | on: 'Escape Rooms' Challenge Players To Solve Puzzles To Get Out
HintHunt in Paris is awesome.
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