An ex-ARM engineer critiques RISC-V

Re:An ex-ARM engineer critiques RISC-V by pizlonator on Sunday November 01, 2020 @12:53PM (#24961162)

Yes. In many ways:

1) it’s pretty important to have easy syntax for math with overflow checks. Otherwise there will be bugs. Bad bugs. We have those and it sucks.

2) it’s pretty important that if the overflow wraps in ISA then it wraps in language semantics but C just says “meh whatever” for signed overflow. That leads to even more bugs.

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Re:An ex-ARM engineer critiques RISC-V by GeorgeTirebiter on Sunday November 01, 2020 @04:40PM (#24962752)

The HP3000 had "SPL" - Systems Programming Language -- as its way of doing what C does. It had a specific syntax for checking the error codes: if <> then <whatever> so whatever previous arithmetic did, you could check the machine's flags directly. Can't do that in C. https://en.wikipedia.org/wiki/Systems_Programming_Language

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Re:An ex-ARM engineer critiques RISC-V by the5avage on Monday November 02, 2020 @02:27AM (#24965494)

At the time C was designed not all machines did represent signed integers in 2 complement. Therefore it was not possible to define behavior for signed overflow. They probably should change that 2020^^

GCC has intrinsics for integer math with overflow checks

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Re:An ex-ARM engineer critiques RISC-V by ncmncm on Monday November 02, 2020 @11:46AM (#24970065)

C++ formalized two's complement already. Formalizing power-of-two word size and 8-bit bytes might come.

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