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Futhark slows integer division to handle the signed minimum divided by -1

futhark-lang.org 8 min read Editor score 8/10

The compiler bug involves the unrepresentable positive counterpart of the minimum signed integer; the post puts the affected input frequency at 0.000000000000000000542%. It examines the performance cost of making a rare arithmetic edge case correct.

What

Signed integer division has an unrepresentable case: the most negative value divided by -1 cannot produce its mathematical result.

How

The Futhark compiler generates C, where this division case can involve undefined behavior; the excerpt says generated C can be subtly wrong.

Why it matters

Compiler engineers need to account for obscure C undefined behavior when generating code, not only memory-safety errors.

Read on futhark-lang.org → Lobsters · 2 comments

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