Perhaps there is some reason to provide a mechanism for asserting, in a particular patch of code, that the compiler is free to make optimistic assumptions about the kinds of aliasing that can occur. I don’t know any acceptable way of
Pearl: Of course, but you cannot see this noble aspiration in scientific equations. The language of algebra is symmetric: If x tells us about y, then y tells us about x. I’m talking about deterministic relationships. There’s no way to write in mathematics a simple fact—for example,
C STANDARD UNDEFINED BEHAVIOR VERSUS WITTGENSTEIN 1. DEPRESSING AND FAINTLY TERRIFYING Chris Lattner, the architect of the Clang/LLVM C compiler explained the effects of the C standard’s “undefined behavior (UB): UB is an inseperable part of C programming, […] this
See also: Damore’s Defenders. Scott Aaronson is a distinguished professor of computer science at the University of Texas. I ran into his blog a while back, when someone sent me to his muddled defense of Damore and the Google Memo
A FSMLabs whitepaper. [gview file=”https://www.yodaiken.com/wp-content/uploads/2018/05/financeandbeyond.pdf”]
What’s a tree? First define a sequence or length n> 0 as a total map s: {1,.. n}→ X. Let Nil be the empty sequence. If s is a sequence of length n, and x is an element, then u
What’s a linked list? Let V be a set of values and A be a set of “addresses”. Say a map f is a “linked list element” compatible with values V and addresses A if and only if f(value)∈ V
My new favorite line: “My good sir, I worry that your groundbreaking treatise will go overlooked here on Twitter” This is a great essay on programming: Operant Conditioning by Software Bugs. This is a good point on mathematics versus the
The xor i mod 128 “multiplication table” as presented by Mathematica. Here is the mod 64 matrix.
Via @johnregehr this further tale of compiler “optimizations” that break correct C code without even a warning by deleting a necessary null pointer check. In this example, Bar contains a stack of Foos. Sometimes the Foo stack is empty, so