1 files changed, 35 insertions, 0 deletions
diff --git a/cpukit/compiler-rt/lib/builtins/clzdi2.c b/cpukit/compiler-rt/lib/builtins/clzdi2.c
new file mode 100644
index 0000000000..12c17982a5
--- /dev/null
+++ b/cpukit/compiler-rt/lib/builtins/clzdi2.c
@@ -0,0 +1,35 @@
+//===-- clzdi2.c - Implement __clzdi2 -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __clzdi2 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+
+// Returns: the number of leading 0-bits
+
+#if !defined(__clang__) &&                                                     \
+    ((defined(__sparc__) && defined(__arch64__)) || defined(__mips64) ||       \
+     (defined(__riscv) && __SIZEOF_POINTER__ >= 8))
+// On 64-bit architectures with neither a native clz instruction nor a native
+// ctz instruction, gcc resolves __builtin_clz to __clzdi2 rather than
+// __clzsi2, leading to infinite recursion.
+#define __builtin_clz(a) __clzsi2(a)
+extern int __clzsi2(si_int);
+#endif
+
+// Precondition: a != 0
+
+COMPILER_RT_ABI int __clzdi2(di_int a) {
+  dwords x;
+  x.all = a;
+  const si_int f = -(x.s.high == 0);
+  return clzsi((x.s.high & ~f) | (x.s.low & f)) +
+         (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
+}