1 files changed, 70 insertions, 0 deletions
diff --git a/compiler-rt/lib/builtins/int_div_impl.inc b/compiler-rt/lib/builtins/int_div_impl.inc
new file mode 100644
index 000000000000..de0373889078
--- /dev/null
+++ b/compiler-rt/lib/builtins/int_div_impl.inc
@@ -0,0 +1,70 @@
+//===-- int_div_impl.inc - Integer division ---------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Helpers used by __udivsi3, __umodsi3, __udivdi3, and __umodsi3.
+//
+//===----------------------------------------------------------------------===//
+
+#define clz(a) (sizeof(a) == sizeof(unsigned long long) ? __builtin_clzll(a) : clzsi(a))
+
+// Adapted from Figure 3-40 of The PowerPC Compiler Writer's Guide
+static __inline fixuint_t __udivXi3(fixuint_t n, fixuint_t d) {
+  const unsigned N = sizeof(fixuint_t) * CHAR_BIT;
+  // d == 0 cases are unspecified.
+  unsigned sr = (d ? clz(d) : N) - (n ? clz(n) : N);
+  // 0 <= sr <= N - 1 or sr is very large.
+  if (sr > N - 1) // n < d
+    return 0;
+  if (sr == N - 1) // d == 1
+    return n;
+  ++sr;
+  // 1 <= sr <= N - 1. Shifts do not trigger UB.
+  fixuint_t r = n >> sr;
+  n <<= N - sr;
+  fixuint_t carry = 0;
+  for (; sr > 0; --sr) {
+    r = (r << 1) | (n >> (N - 1));
+    n = (n << 1) | carry;
+    // Branch-less version of:
+    // carry = 0;
+    // if (r >= d) r -= d, carry = 1;
+    const fixint_t s = (fixint_t)(d - r - 1) >> (N - 1);
+    carry = s & 1;
+    r -= d & s;
+  }
+  n = (n << 1) | carry;
+  return n;
+}
+
+// Mostly identical to __udivXi3 but the return values are different.
+static __inline fixuint_t __umodXi3(fixuint_t n, fixuint_t d) {
+  const unsigned N = sizeof(fixuint_t) * CHAR_BIT;
+  // d == 0 cases are unspecified.
+  unsigned sr = (d ? clz(d) : N) - (n ? clz(n) : N);
+  // 0 <= sr <= N - 1 or sr is very large.
+  if (sr > N - 1) // n < d
+    return n;
+  if (sr == N - 1) // d == 1
+    return 0;
+  ++sr;
+  // 1 <= sr <= N - 1. Shifts do not trigger UB.
+  fixuint_t r = n >> sr;
+  n <<= N - sr;
+  fixuint_t carry = 0;
+  for (; sr > 0; --sr) {
+    r = (r << 1) | (n >> (N - 1));
+    n = (n << 1) | carry;
+    // Branch-less version of:
+    // carry = 0;
+    // if (r >= d) r -= d, carry = 1;
+    const fixint_t s = (fixint_t)(d - r - 1) >> (N - 1);
+    carry = s & 1;
+    r -= d & s;
+  }
+  return r;
+}