x87

Usefulness of signaling NaN?

由 跟風遠走 提交于 2019-11-26 19:27:05
问题 I've recently read up quite a bit on IEEE 754 and the x87 architecture. I was thinking of using NaN as a "missing value" in some numeric calculation code I'm working on, and I was hoping that using signaling NaN would allow me to catch a floating point exception in the cases where I don't want to proceed with "missing values." Conversely, I would use quiet NaN to allow the "missing value" to propagate through a computation. However, signaling NaNs don't work as I thought they would based on

Extended (80-bit) double floating point in x87, not SSE2 - we don't miss it?

由 ↘锁芯ラ 提交于 2019-11-26 18:53:29
I was reading today about researchers discovering that NVidia's Phys-X libraries use x87 FP vs. SSE2 . Obviously this will be suboptimal for parallel datasets where speed trumps precision. However, the article author goes on to quote: Intel started discouraging the use of x87 with the introduction of the P4 in late 2000. AMD deprecated x87 since the K8 in 2003, as x86-64 is defined with SSE2 support; VIA’s C7 has supported SSE2 since 2005. In 64-bit versions of Windows, x87 is deprecated for user-mode, and prohibited entirely in kernel-mode. Pretty much everyone in the industry has recommended

Is SSE floating-point arithmetic reproducible?

由 十年热恋 提交于 2019-11-26 12:44:59
问题 The x87 FPU is notable for using an internal 80-bit precision mode, which often leads to unexpected and unreproducible results across compilers and machines. In my search for reproducible floating-point math on .NET, I discovered that both major implementations of .NET (Microsoft\'s and Mono) emit SSE instructions rather than x87 in 64-bit mode. SSE(2) uses strictly 32-bit registers for 32-bit floats, and strictly 64-bit registers for 64-bit floats. Denormals can optionally be flushed to zero

Extended (80-bit) double floating point in x87, not SSE2 - we don't miss it?

由 ▼魔方 西西 提交于 2019-11-26 06:38:56
问题 I was reading today about researchers discovering that NVidia\'s Phys-X libraries use x87 FP vs. SSE2. Obviously this will be suboptimal for parallel datasets where speed trumps precision. However, the article author goes on to quote: Intel started discouraging the use of x87 with the introduction of the P4 in late 2000. AMD deprecated x87 since the K8 in 2003, as x86-64 is defined with SSE2 support; VIA’s C7 has supported SSE2 since 2005. In 64-bit versions of Windows, x87 is deprecated for
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