5 ms·
There was code in IE 5 that used the original SSE instructions if the chip had them, and regular code as a fallback We found a stepping of a 486 chip where thi
by craz8 7y ago
There was code in IE 5 that used the original SSE instructions if the chip had them, and regular code as a fallback
We found a stepping of a 486 chip where this code crashed about 25% of the time
Since it was only that stepping, and we already had a fallback path, we just skipped the optimization for that chip version and didn’t investigate exactly what was broken though
Having a lot of customers with various CPU versions helped to track this down pretty quickly
- mrb 7y agoSurely you meant x87 FP instructions? The 486 didn't have SSE instructions.
- craz8 7y agoProbably not 486 - this was 1999-2000 timeframe, so some sort of Pentium thing. It was definitely the new instructions though, so whatever Intel chip had the new features had this 1 stepping that had this bug (and it wasn’t the first version of the chip either)
- gpderetta 7y agoMMX then instead of SSE?
- wahern 7y ago486 didn't necessarily have FP, either. I started using Linux on a 486SX. FP instructions were trapped and emulated by the kernel.