diff --git a/lib/compiler-rt/builtins/udivmoddi4.c b/lib/compiler-rt/builtins/udivmoddi4.c
index 0c8b4ff..123e5fb 100644
--- a/lib/compiler-rt/builtins/udivmoddi4.c
+++ b/lib/compiler-rt/builtins/udivmoddi4.c
@@ -1,231 +1,200 @@
-/* ===-- udivmoddi4.c - Implement __udivmoddi4 -----------------------------===
- *
- *                     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 __udivmoddi4 for the compiler_rt library.
- *
- * ===----------------------------------------------------------------------===
- */
+//===-- udivmoddi4.c - Implement __udivmoddi4 -----------------------------===//
+//
+// 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 __udivmoddi4 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
 
 #include "int_lib.h"
 
-/* Effects: if rem != 0, *rem = a % b
- * Returns: a / b
- */
+// Effects: if rem != 0, *rem = a % b
+// Returns: a / b
 
-/* Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide */
+// Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide
 
-COMPILER_RT_ABI du_int
-__udivmoddi4(du_int a, du_int b, du_int* rem)
-{
-    const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT;
-    const unsigned n_udword_bits = sizeof(du_int) * CHAR_BIT;
-    udwords n;
-    n.all = a;
-    udwords d;
-    d.all = b;
-    udwords q;
-    udwords r;
-    unsigned sr;
-    /* special cases, X is unknown, K != 0 */
-    if (n.s.high == 0)
-    {
-        if (d.s.high == 0)
-        {
-            /* 0 X
-             * ---
-             * 0 X
-             */
-            if (rem)
-                *rem = n.s.low % d.s.low;
-            return n.s.low / d.s.low;
-        }
-        /* 0 X
-         * ---
-         * K X
-         */
-        if (rem)
-            *rem = n.s.low;
-        return 0;
+#if defined(_MSC_VER) && !defined(__clang__)
+// MSVC throws a warning about mod 0 here, disable it for builds that
+// warn-as-error
+#pragma warning(push)
+#pragma warning(disable : 4723 4724)
+#endif
+
+COMPILER_RT_ABI du_int __udivmoddi4(du_int a, du_int b, du_int *rem) {
+  const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT;
+  const unsigned n_udword_bits = sizeof(du_int) * CHAR_BIT;
+  udwords n;
+  n.all = a;
+  udwords d;
+  d.all = b;
+  udwords q;
+  udwords r;
+  unsigned sr;
+  // special cases, X is unknown, K != 0
+  if (n.s.high == 0) {
+    if (d.s.high == 0) {
+      // 0 X
+      // ---
+      // 0 X
+      if (rem)
+        *rem = n.s.low % d.s.low;
+      return n.s.low / d.s.low;
     }
-    /* n.s.high != 0 */
-    if (d.s.low == 0)
-    {
-        if (d.s.high == 0)
-        {
-            /* K X
-             * ---
-             * 0 0
-             */ 
-            if (rem)
-                *rem = n.s.high % d.s.low;
-            return n.s.high / d.s.low;
-        }
-        /* d.s.high != 0 */
-        if (n.s.low == 0)
-        {
-            /* K 0
-             * ---
-             * K 0
-             */
-            if (rem)
-            {
-                r.s.high = n.s.high % d.s.high;
-                r.s.low = 0;
-                *rem = r.all;
-            }
-            return n.s.high / d.s.high;
-        }
-        /* K K
-         * ---
-         * K 0
-         */
-        if ((d.s.high & (d.s.high - 1)) == 0)     /* if d is a power of 2 */
-        {
-            if (rem)
-            {
-                r.s.low = n.s.low;
-                r.s.high = n.s.high & (d.s.high - 1);
-                *rem = r.all;
-            }
-            return n.s.high >> __builtin_ctz(d.s.high);
-        }
-        /* K K
-         * ---
-         * K 0
-         */
-        sr = __builtin_clz(d.s.high) - __builtin_clz(n.s.high);
-        /* 0 <= sr <= n_uword_bits - 2 or sr large */
-        if (sr > n_uword_bits - 2)
-        {
-           if (rem)
-                *rem = n.all;
-            return 0;
-        }
-        ++sr;
-        /* 1 <= sr <= n_uword_bits - 1 */
-        /* q.all = n.all << (n_udword_bits - sr); */
+    // 0 X
+    // ---
+    // K X
+    if (rem)
+      *rem = n.s.low;
+    return 0;
+  }
+  // n.s.high != 0
+  if (d.s.low == 0) {
+    if (d.s.high == 0) {
+      // K X
+      // ---
+      // 0 0
+      if (rem)
+        *rem = n.s.high % d.s.low;
+      return n.s.high / d.s.low;
+    }
+    // d.s.high != 0
+    if (n.s.low == 0) {
+      // K 0
+      // ---
+      // K 0
+      if (rem) {
+        r.s.high = n.s.high % d.s.high;
+        r.s.low = 0;
+        *rem = r.all;
+      }
+      return n.s.high / d.s.high;
+    }
+    // K K
+    // ---
+    // K 0
+    if ((d.s.high & (d.s.high - 1)) == 0) /* if d is a power of 2 */ {
+      if (rem) {
+        r.s.low = n.s.low;
+        r.s.high = n.s.high & (d.s.high - 1);
+        *rem = r.all;
+      }
+      return n.s.high >> ctzsi(d.s.high);
+    }
+    // K K
+    // ---
+    // K 0
+    sr = clzsi(d.s.high) - clzsi(n.s.high);
+    // 0 <= sr <= n_uword_bits - 2 or sr large
+    if (sr > n_uword_bits - 2) {
+      if (rem)
+        *rem = n.all;
+      return 0;
+    }
+    ++sr;
+    // 1 <= sr <= n_uword_bits - 1
+    // q.all = n.all << (n_udword_bits - sr);
+    q.s.low = 0;
+    q.s.high = n.s.low << (n_uword_bits - sr);
+    // r.all = n.all >> sr;
+    r.s.high = n.s.high >> sr;
+    r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
+  } else /* d.s.low != 0 */ {
+    if (d.s.high == 0) {
+      // K X
+      // ---
+      // 0 K
+      if ((d.s.low & (d.s.low - 1)) == 0) /* if d is a power of 2 */ {
+        if (rem)
+          *rem = n.s.low & (d.s.low - 1);
+        if (d.s.low == 1)
+          return n.all;
+        sr = ctzsi(d.s.low);
+        q.s.high = n.s.high >> sr;
+        q.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
+        return q.all;
+      }
+      // K X
+      // ---
+      // 0 K
+      sr = 1 + n_uword_bits + clzsi(d.s.low) - clzsi(n.s.high);
+      // 2 <= sr <= n_udword_bits - 1
+      // q.all = n.all << (n_udword_bits - sr);
+      // r.all = n.all >> sr;
+      if (sr == n_uword_bits) {
+        q.s.low = 0;
+        q.s.high = n.s.low;
+        r.s.high = 0;
+        r.s.low = n.s.high;
+      } else if (sr < n_uword_bits) /* 2 <= sr <= n_uword_bits - 1 */ {
         q.s.low = 0;
         q.s.high = n.s.low << (n_uword_bits - sr);
-        /* r.all = n.all >> sr; */
         r.s.high = n.s.high >> sr;
         r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
-    }
-    else  /* d.s.low != 0 */
-    {
-        if (d.s.high == 0)
-        {
-            /* K X
-             * ---
-             * 0 K
-             */
-            if ((d.s.low & (d.s.low - 1)) == 0)     /* if d is a power of 2 */
-            {
-                if (rem)
-                    *rem = n.s.low & (d.s.low - 1);
-                if (d.s.low == 1)
-                    return n.all;
-                sr = __builtin_ctz(d.s.low);
-                q.s.high = n.s.high >> sr;
-                q.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
-                return q.all;
-            }
-            /* K X
-             * ---
-             * 0 K
-             */
-            sr = 1 + n_uword_bits + __builtin_clz(d.s.low) - __builtin_clz(n.s.high);
-            /* 2 <= sr <= n_udword_bits - 1
-             * q.all = n.all << (n_udword_bits - sr);
-             * r.all = n.all >> sr;
-             */
-            if (sr == n_uword_bits)
-            {
-                q.s.low = 0;
-                q.s.high = n.s.low;
-                r.s.high = 0;
-                r.s.low = n.s.high;
-            }
-            else if (sr < n_uword_bits)  // 2 <= sr <= n_uword_bits - 1
-            {
-                q.s.low = 0;
-                q.s.high = n.s.low << (n_uword_bits - sr);
-                r.s.high = n.s.high >> sr;
-                r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
-            }
-            else              // n_uword_bits + 1 <= sr <= n_udword_bits - 1
-            {
-                q.s.low = n.s.low << (n_udword_bits - sr);
-                q.s.high = (n.s.high << (n_udword_bits - sr)) |
-                           (n.s.low >> (sr - n_uword_bits));
-                r.s.high = 0;
-                r.s.low = n.s.high >> (sr - n_uword_bits);
-            }
-        }
-        else
-        {
-            /* K X
-             * ---
-             * K K
-             */
-            sr = __builtin_clz(d.s.high) - __builtin_clz(n.s.high);
-            /* 0 <= sr <= n_uword_bits - 1 or sr large */
-            if (sr > n_uword_bits - 1)
-            {
-                if (rem)
-                    *rem = n.all;
-                return 0;
-            }
-            ++sr;
-            /* 1 <= sr <= n_uword_bits */
-            /*  q.all = n.all << (n_udword_bits - sr); */
-            q.s.low = 0;
-            if (sr == n_uword_bits)
-            {
-                q.s.high = n.s.low;
-                r.s.high = 0;
-                r.s.low = n.s.high;
-            }
-            else
-            {
-                q.s.high = n.s.low << (n_uword_bits - sr);
-                r.s.high = n.s.high >> sr;
-                r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
-            }
-        }
-    }
-    /* Not a special case
-     * q and r are initialized with:
-     * q.all = n.all << (n_udword_bits - sr);
-     * r.all = n.all >> sr;
-     * 1 <= sr <= n_udword_bits - 1
-     */
-    su_int carry = 0;
-    for (; sr > 0; --sr)
-    {
-        /* r:q = ((r:q)  << 1) | carry */
-        r.s.high = (r.s.high << 1) | (r.s.low  >> (n_uword_bits - 1));
-        r.s.low  = (r.s.low  << 1) | (q.s.high >> (n_uword_bits - 1));
-        q.s.high = (q.s.high << 1) | (q.s.low  >> (n_uword_bits - 1));
-        q.s.low  = (q.s.low  << 1) | carry;
-        /* carry = 0;
-         * if (r.all >= d.all)
-         * {
-         *      r.all -= d.all;
-         *      carry = 1;
-         * }
-         */
-        const di_int s = (di_int)(d.all - r.all - 1) >> (n_udword_bits - 1);
-        carry = s & 1;
-        r.all -= d.all & s;
+      } else /* n_uword_bits + 1 <= sr <= n_udword_bits - 1 */ {
+        q.s.low = n.s.low << (n_udword_bits - sr);
+        q.s.high = (n.s.high << (n_udword_bits - sr)) |
+                   (n.s.low >> (sr - n_uword_bits));
+        r.s.high = 0;
+        r.s.low = n.s.high >> (sr - n_uword_bits);
+      }
+    } else {
+      // K X
+      // ---
+      // K K
+      sr = clzsi(d.s.high) - clzsi(n.s.high);
+      // 0 <= sr <= n_uword_bits - 1 or sr large
+      if (sr > n_uword_bits - 1) {
+        if (rem)
+          *rem = n.all;
+        return 0;
+      }
+      ++sr;
+      // 1 <= sr <= n_uword_bits
+      // q.all = n.all << (n_udword_bits - sr);
+      q.s.low = 0;
+      if (sr == n_uword_bits) {
+        q.s.high = n.s.low;
+        r.s.high = 0;
+        r.s.low = n.s.high;
+      } else {
+        q.s.high = n.s.low << (n_uword_bits - sr);
+        r.s.high = n.s.high >> sr;
+        r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
+      }
     }
-    q.all = (q.all << 1) | carry;
-    if (rem)
-        *rem = r.all;
-    return q.all;
+  }
+  // Not a special case
+  // q and r are initialized with:
+  // q.all = n.all << (n_udword_bits - sr);
+  // r.all = n.all >> sr;
+  // 1 <= sr <= n_udword_bits - 1
+  su_int carry = 0;
+  for (; sr > 0; --sr) {
+    // r:q = ((r:q)  << 1) | carry
+    r.s.high = (r.s.high << 1) | (r.s.low >> (n_uword_bits - 1));
+    r.s.low = (r.s.low << 1) | (q.s.high >> (n_uword_bits - 1));
+    q.s.high = (q.s.high << 1) | (q.s.low >> (n_uword_bits - 1));
+    q.s.low = (q.s.low << 1) | carry;
+    // carry = 0;
+    // if (r.all >= d.all)
+    // {
+    //      r.all -= d.all;
+    //      carry = 1;
+    // }
+    const di_int s = (di_int)(d.all - r.all - 1) >> (n_udword_bits - 1);
+    carry = s & 1;
+    r.all -= d.all & s;
+  }
+  q.all = (q.all << 1) | carry;
+  if (rem)
+    *rem = r.all;
+  return q.all;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#endif