From: lkcl <lkcl@web>
Date: Thu, 20 Apr 2023 15:01:01 +0000 (+0100)
Subject: (no commit message)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=9d5bedef748dd120e8f1b7d04b9e93e62f20f7d4;p=libreriscv.git

---

diff --git a/openpower/sv/sprs.mdwn b/openpower/sv/sprs.mdwn
index bc55ee67f..dde527aaa 100644
--- a/openpower/sv/sprs.mdwn
+++ b/openpower/sv/sprs.mdwn
@@ -189,6 +189,15 @@ and therefore if Multi-Issue hardware chooses to allocate several batches up to
 `MAXVL` in size they are still independent.  This helps greatly simplify Multi-Issue
 systems by significantly reducing Hazards.
 
+**Considerable care** must be taken when setting `hphint`. Matrix Outer Product
+could produce corrupted results if `hphint` is set to greater than the innermost
+loop depth. Parallel Reduction, DCT and FFT REMAP all are similarly critically affected
+by `hphint` in ways that if used correctly greatly increases ease of parallelism but
+if done incorrectly will also result in data corruption.  Reduction/Iteration
+also requires care to correctly declare in `hphint` how many elements are
+independent. In the case of most Reduction use-cases the answer is almost certainly
+"none".
+
 ## SVLR
 
 SV Link Register, exactly analogous to LR (Link Register) may