Copied from Debian.

From: Dave Martin
Subject: "rsc" doesnt exist anymore in thumb2

diff --git a/fixed.h b/fixed.h
index 4b58abf..ba4bc26 100644
--- a/fixed.h
+++ b/fixed.h
@@ -275,12 +275,25 @@ mad_fixed_t mad_f_mul_inline(mad_fixed_t x, mad_fixed_t y)
 	 : "+r" (lo), "+r" (hi)  \
 	 : "%r" (x), "r" (y))
 
+#ifdef __thumb__
+/* In Thumb-2, the RSB-immediate instruction is only allowed with a zero
+	operand.  If needed this code can also support Thumb-1 
+	(simply append "s" to the end of the second two instructions). */
+#  define MAD_F_MLN(hi, lo)  \
+    asm ("rsbs        %0, %0, #0\n\t"  \
+	 "sbc   %1, %1, %1\n\t"  \
+	 "sub   %1, %1, %2"  \
+	 : "+&r" (lo), "=&r" (hi)  \
+	 : "r" (hi)  \
+	 : "cc")
+#else /* ! __thumb__ */
 #  define MAD_F_MLN(hi, lo)  \
     asm ("rsbs	%0, %2, #0\n\t"  \
 	 "rsc	%1, %3, #0"  \
-	 : "=r" (lo), "=r" (hi)  \
+	 : "=&r" (lo), "=r" (hi)  \
 	 : "0" (lo), "1" (hi)  \
 	 : "cc")
+#endif /* __thumb__ */
 
 #  define mad_f_scale64(hi, lo)  \
     ({ mad_fixed_t __result;  \
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<div class='path'>path: <a href='/guix/log/?id=8c6114b920507a1104a06d34dc2312428a9899f0'>root</a>/<a href='/guix/log/tests?id=8c6114b920507a1104a06d34dc2312428a9899f0'>tests</a>/<a href='/guix/log/tests/gremlin.scm?id=8c6114b920507a1104a06d34dc2312428a9899f0'>gremlin.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/gremlin.scm?id=8c6114b920507a1104a06d34dc2312428a9899f0&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2024-11-12 23:40:39 +0100'>2024-11-12</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=9793403bc0f304053c6f1bd427814482273faa26'>tests: Fix gremlin.scm for GCC 14</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/gremlin.scm: Include stdio.h before using puts since GCC 14 no
longer allows implicit declarations.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Ting-Wei Lan</td></tr>
<tr><td><span title='2022-01-16 20:21:27 -0800'>2022-01-16</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=24c3485bb3ffc05e687ef6513ac287b8d3048bab'>tests: Fix file-needed/recursive on aarch64-linux.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes: &lt;https://issues.guix.gnu.org/52943&gt;.

* tests/gremlin.scm (file-needed/recursive)[ground-truth]: On aarch64-linux,
remove the dynamic linker from this list.
</span></span></td><td>Pierre Langlois</td></tr>
<tr><td><span title='2022-01-14 22:39:24 +0100'>2022-01-14</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=e7ad192de008a6a21638def6eb973b9cc0c91116'>gremlin: Adjust tests for i686 and beyond.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://issues.guix.gnu.org/52752&gt;.
Reported by Denis 'GNUtoo' Carikli &lt;GNUtoo@cyberdimension.org&gt;.

* tests/gremlin.scm ("file-needed/recursive"): Augment the list of vDSO
names.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-01-08 15:51:22 -0800'>2022-01-08</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=6a2050b1e1c7f09ef9b6af43044b7c0e4786d39d'>tests: Fix file-needed/recursive on powerpc64le-linux.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes: &lt;https://issues.guix.gnu.org/52940&gt;.

* tests/gremlin.scm (file-needed/recursive): Consider two entries to be
equivalent not when they are the same string, but rather when they refer to
the same file.
[ground-truth]: In addition to strings that begin with "linux-vdso.so", remove
strings that begin with "linux-vdso64.so".
</span></span></td><td>Chris Marusich</td></tr>
<tr><td><span title='2021-06-23 20:30:22 -0700'>2021-06-23</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=e4b5a23841bc6a92e2e21dd8b1038addee55eb02'>tests: gremlin: Skip file-needed/recursive if DT_NEEDED is empty.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/gremlin.scm (file-needed/recursive): Skip the test when (file-runpath
%guile-executable) evaluates to the empty list.  This causes the test to be
correctly skipped in the case where Guix has been built using a foreign
distro's toolchain and libraries.
</span></span></td><td>Chris Marusich</td></tr>
<tr><td><span title='2021-04-22 14:04:27 +0200'>2021-04-22</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=1010171280cb34c8dc361644b66fdd1a041d297a'>gremlin: 'elf-dynamic-info' returns a file name rathern than a dynamic entry.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/gremlin.scm (elf-dynamic-info): Return the dynamic entry
value, not the dynamic entry.
* tests/gremlin.scm ("elf-dynamic-info-soname"): New test.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Dion Mendel</td></tr>
<tr><td><span title='2020-12-01 21:30:28 +0100'>2020-12-01</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=53fd256e5ba43e516fb9d6eaf085b88fe8bd12b6'>gremlin: Add 'file-needed/recursive'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/gremlin.scm (file-needed/recursive): New procedure.
* tests/gremlin.scm ("file-needed/recursive"): New test.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-09-19 17:28:46 +0200'>2020-09-19</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=49a1203d67a90a6a7ce4e4537697a6da96ceb213'>gremlin: Add 'set-file-runpath', 'file-runpath', and 'file-needed'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/gremlin.scm (file-dynamic-info, file-runpath, file-needed):
New procedures.
(&amp;missing-runpath-error, &amp;runpath-too-long-error): New condition types.
(set-file-runpath): New procedure.
* tests/gremlin.scm ("set-file-runpath + file-runpath"): New test.
</span></span></td><td>Ludovic Courtès</td></tr>