From 142706fd85a6b7d1c8337df8f8755cf45d10a53b Mon Sep 17 00:00:00 2001 From: lkcl Date: Sat, 4 Jun 2022 15:41:53 +0100 Subject: [PATCH] --- openpower/sv/remap.mdwn | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/openpower/sv/remap.mdwn b/openpower/sv/remap.mdwn index af60be92a..bf4ef79f9 100644 --- a/openpower/sv/remap.mdwn +++ b/openpower/sv/remap.mdwn @@ -36,14 +36,23 @@ latency, so should realistically be used only where it is worthwhile. Commonly-used patterns such as Matrix Multiply, DCT and FFT have helper instruction options which make REMAP easier to use. +There are three types of REMAP: + +* **Matrix**, also known as 2D and 3D reshaping +* **FFT/DCT**, with full triple-loop in-place support: limited to + Power-2 RADIX +* **Indexing**, for any general-purpose reordering. Currently + under development. + # Principle -* normal vector element read/write as operands would be sequential +* normal vector element read/write of operands would be sequential (0 1 2 3 ....) * this is not appropriate for (e.g.) Matrix multiply which requires accessing elements in alternative sequences (0 3 6 1 4 7 ...) * normal Vector ISAs use either Indexed-MV or Indexed-LD/ST to "cope" with this. both are expensive (copy large vectors, spill through memory) + and very few Packed SIMD ISAs cope with non-Power-2. * REMAP **redefines** the order of access according to set "Schedules". * The Schedules are not necessarily restricted to power-of-two boundaries making it unnecessary to have for example specialised 3x4 transpose -- 2.30.2