From 66262576817a3bedcf38217db06dd075b8628bc9 Mon Sep 17 00:00:00 2001 From: Luke Kenneth Casson Leighton Date: Sun, 3 Jun 2018 08:23:15 +0100 Subject: [PATCH 1/1] add images --- simple_v_extension/simple_v_chennai_2018.tex | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/simple_v_extension/simple_v_chennai_2018.tex b/simple_v_extension/simple_v_chennai_2018.tex index 9c5eab707..1ca0cab71 100644 --- a/simple_v_extension/simple_v_chennai_2018.tex +++ b/simple_v_extension/simple_v_chennai_2018.tex @@ -333,19 +333,22 @@ for (int i = 0; i < VL; ++i) } -\frame{\frametitle{Why no Zeroing (place zeros in non-predicated elements)?} +\frame{\frametitle{To Zero or not to place zeros in non-predicated elements?} \begin{itemize} - \item Zeroing is an implementation optimisation favouring OoO\vspace{8pt} - \item Simple implementations may skip non-predicated operations\vspace{8pt} - \item Simple implementations explicitly have to destroy data\vspace{8pt} + \item Zeroing is an implementation optimisation favouring OoO + \item Simple implementations may skip non-predicated operations + \item Simple implementations explicitly have to destroy data \item Complex implementations may use reg-renames to save power\\ Zeroing on predication chains makes optimisation harder + \item Compromise: REQUIRE both (specified in predication CSRs). \end{itemize} - Considerations:\vspace{10pt} + Considerations: \begin{itemize} - \item Complex not really impacted, Simple impacted a LOT - \item Overlapping "Vectors" may issue overlapping ops + \item Complex not really impacted, simple impacted a LOT\\ + with Zeroing... however it's useful (memset) + \item Non-zero'd overlapping "Vectors" may issue overlapping ops\\ + (2nd op's predicated elements slot in 1st's non-predicated ops) \item Please don't use Vectors for "security" (use Sec-Ext) \end{itemize} } -- 2.30.2