Initial import

third_party/compiler_rt/clzdi2.c

@@ -0,0 +1,43 @@
+/* clang-format off */
+/* ===-- clzdi2.c - Implement __clzdi2 -------------------------------------===
+ *
+ *               The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file implements __clzdi2 for the compiler_rt library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+STATIC_YOINK("huge_compiler_rt_license");
+
+#include "third_party/compiler_rt/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 si_int __clzsi2(si_int);
+#endif
+
+/* Precondition: a != 0 */
+
+COMPILER_RT_ABI si_int
+__clzdi2(di_int a)
+{
+    dwords x;
+    x.all = a;
+    const si_int f = -(x.s.high == 0);
+    return __builtin_clz((x.s.high & ~f) | (x.s.low & f)) +
+           (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
+}