https://bugs.gentoo.org/955813
diff '--color=auto' --text --new-file --unified libgcrypt-1.11.1/cipher/simd-common-riscv.h libgcrypt/cipher/simd-common-riscv.h
--- a/cipher/simd-common-riscv.h	1970-01-01 08:00:00.000000000 +0800
+++ b/cipher/simd-common-riscv.h	2025-05-13 08:06:01.221102266 +0800
@@ -0,0 +1,48 @@
+/* simd-common-riscv.h  -  Common macros for RISC-V vector code
+ *
+ * Copyright (C) 2025 Jussi Kivilinna <jussi.kivilinna@iki.fi>
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef GCRY_SIMD_COMMON_RISCV_H
+#define GCRY_SIMD_COMMON_RISCV_H
+
+#include <config.h>
+
+#define memory_barrier_with_vec(a) __asm__("" : "+vr"(a) :: "memory")
+
+#define clear_vec_regs() __asm__ volatile("vsetvli zero, %0, e8, m1, ta, ma;\n" \
+					  "vmv.v.i v0, 0;\n" \
+					  "vmv.v.i v1, 0;\n" \
+					  "vmv2r.v v2, v0;\n" \
+					  "vmv4r.v v4, v0;\n" \
+					  "vmv8r.v v8, v0;\n" \
+					  "vmv8r.v v16, v0;\n" \
+					  "vmv8r.v v24, v0;\n" \
+					  : \
+					  : "r" (~0) \
+					  : "memory", "vl", "vtype", \
+					    "v0", "v1", "v2", "v3", \
+					    "v4", "v5", "v6", "v7", \
+					    "v8", "v9", "v10", "v11", \
+					    "v12", "v13", "v14", "v15", \
+					    "v16", "v17", "v18", "v19", \
+					    "v20", "v21", "v22", "v23", \
+					    "v24", "v25", "v26", "v27", \
+					    "v28", "v29", "v30", "v31")
+
+#endif /* GCRY_SIMD_COMMON_RISCV_H */