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author | Mike Pall <mike> | 2022-12-07 18:38:22 +0100 |
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committer | Mike Pall <mike> | 2022-12-07 18:38:22 +0100 |
commit | de2e1ca9d3d87e74c0c20c1e4ad3c32b31a5875b (patch) | |
tree | c6dd3a9575b77c9f019c9d8627a814a955227acf /doc | |
parent | 7d5d4a1b1a690d9fc87253868ba967bf25f4df6e (diff) | |
download | luajit-de2e1ca9d3d87e74c0c20c1e4ad3c32b31a5875b.tar.gz luajit-de2e1ca9d3d87e74c0c20c1e4ad3c32b31a5875b.tar.bz2 luajit-de2e1ca9d3d87e74c0c20c1e4ad3c32b31a5875b.zip |
Disable FMA by default. Use -Ofma or jit.opt.start("+fma") to enable.
See the discussion in #918 for the rationale.
Diffstat (limited to 'doc')
-rw-r--r-- | doc/running.html | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/doc/running.html b/doc/running.html index 9979d223..edc049fb 100644 --- a/doc/running.html +++ b/doc/running.html | |||
@@ -220,6 +220,12 @@ mix the three forms, but note that setting an optimization level | |||
220 | overrides all earlier flags. | 220 | overrides all earlier flags. |
221 | </p> | 221 | </p> |
222 | <p> | 222 | <p> |
223 | Note that <tt>-Ofma</tt> is not enabled by default at any level, | ||
224 | because it affects floating-point result accuracy. Only enable this, | ||
225 | if you fully understand the trade-offs of FMA for performance (higher), | ||
226 | determinism (lower) and numerical accuracy (higher). | ||
227 | </p> | ||
228 | <p> | ||
223 | Here are the available flags and at what optimization levels they | 229 | Here are the available flags and at what optimization levels they |
224 | are enabled: | 230 | are enabled: |
225 | </p> | 231 | </p> |
@@ -251,6 +257,8 @@ are enabled: | |||
251 | <td class="flag_name">sink</td><td class="flag_level"> </td><td class="flag_level"> </td><td class="flag_level">•</td><td class="flag_desc">Allocation/Store Sinking</td></tr> | 257 | <td class="flag_name">sink</td><td class="flag_level"> </td><td class="flag_level"> </td><td class="flag_level">•</td><td class="flag_desc">Allocation/Store Sinking</td></tr> |
252 | <tr class="even"> | 258 | <tr class="even"> |
253 | <td class="flag_name">fuse</td><td class="flag_level"> </td><td class="flag_level"> </td><td class="flag_level">•</td><td class="flag_desc">Fusion of operands into instructions</td></tr> | 259 | <td class="flag_name">fuse</td><td class="flag_level"> </td><td class="flag_level"> </td><td class="flag_level">•</td><td class="flag_desc">Fusion of operands into instructions</td></tr> |
260 | <tr class="odd"> | ||
261 | <td class="flag_name">fma </td><td class="flag_level"> </td><td class="flag_level"> </td><td class="flag_level"> </td><td class="flag_desc">Fused multiply-add</td></tr> | ||
254 | </table> | 262 | </table> |
255 | <p> | 263 | <p> |
256 | Here are the parameters and their default settings: | 264 | Here are the parameters and their default settings: |