From ca11b53896365c948426974cb90e8f71c70d123b Mon Sep 17 00:00:00 2001
From: Simon South <simon@simonsouth.net>
Date: Sun, 31 May 2020 20:36:43 -0400
Subject: [PATCH] Guard floating-point opcodes with explicit memory barrier

---
 src/interp/engine/interp-inlining.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/interp/engine/interp-inlining.h b/src/interp/engine/interp-inlining.h
index 3339b0e..4ee5c5a 100644
--- a/src/interp/engine/interp-inlining.h
+++ b/src/interp/engine/interp-inlining.h
@@ -78,8 +78,17 @@
    4.3, we need to insert a label, and ensure its address
    is taken (to stop it being optimised out).  However,
    this reduces performance on PowerPC by approx 1 - 2%.
+
+   With gcc 5 and newer an asm statement with a "memory"
+   clobber argument explicitly sets a memory barrier for the
+   compiler, preventing it from reordering memory accesses
+   in a way that breaks decaching.
 */
-#if (__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)
+#if (__GNUC__ > 4)
+#define DEF_GUARD_TABLE(level) /* none */
+#define GUARD(opcode, level)   __asm__("" ::: "memory");
+#define GUARD_TBLS             /* none */
+#elif (__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)
 #define DEF_GUARD_TABLE(level) DEF_HANDLER_TABLE(level, GUARD)
 #define GUARD(opcode, level)   label(opcode, level, GUARD)
 #define GUARD_TBLS             , HNDLR_TBLS(GUARD)
-- 
2.26.2

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<tr><td><span title='2021-12-13 17:48:25 +0100'>2021-12-13</span></td><td><a href='/guix/commit/gnu/packages/calcurse.scm?id=8394619baceb118df92e355377fd543bb1aa501a'>gnu: Simplify package inputs.</a></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-07-24 16:23:22 +0200'>2021-07-24</span></td><td><a href='/guix/commit/gnu/packages/calcurse.scm?id=6ea7297ea49f6c704afb727a5afe7ef9ce4a4f73'>gnu: Use 'search-input-directory' when looking for tzdata.</a></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-04-26 13:31:15 +0200'>2020-04-26</span></td><td><a href='/guix/commit/gnu/packages/calcurse.scm?id=02de4b1da184eb087f6eee794842ceb795cf38fe'>gnu: calcurse: Adjust for Guile 3.0.</a></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-12-01 00:49:12 +0100'>2019-12-01</span></td><td><a href='/guix/commit/gnu/packages/calcurse.scm?id=93a02ae98c0aa26356e96c28afc1f35cfa8187d8'>gnu: calcurse: Update to 4.5.1.</a></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-06-25 16:24:11 +0200'>2019-06-25</span></td><td><a href='/guix/commit/gnu/packages/calcurse.scm?id=fabcf8c60eb3267735e9805cbf1a4ccbddbc38bb'>gnu: calcurse: Update to 4.5.0.</a></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-03-04 19:07:10 +0100'>2019-03-04</span></td><td><a href='/guix/commit/gnu/packages/calcurse.scm?id=171234d572e720e06c34e83814d63fcadda06378'>gnu: calcurse: Update to 4.4.0.</a></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-03-04 19:07:10 +0100'>2019-03-04</span></td><td><a href='/guix/commit/gnu/packages/calcurse.scm?id=02eae558fc2a71a9425eb8f8698afe452edebb4b'>gnu: calcurse: Fix documentation directory.</a></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2018-10-29 20:45:57 -0400'>2018-10-29</span></td><td><a href='/guix/commit/gnu/packages/calcurse.scm?id=a2717e698619fed3204db978f954a1195e1d2b4b'>gnu: calcurse: Use HTTPS URLs.</a></td><td>Leo Famulari</td></tr>