summaryrefslogtreecommitdiffstats
path: root/lib/compiler-rt/builtins/udivmoddi4.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/compiler-rt/builtins/udivmoddi4.c')
-rw-r--r--lib/compiler-rt/builtins/udivmoddi4.c200
1 files changed, 200 insertions, 0 deletions
diff --git a/lib/compiler-rt/builtins/udivmoddi4.c b/lib/compiler-rt/builtins/udivmoddi4.c
new file mode 100644
index 0000000..123e5fb
--- /dev/null
+++ b/lib/compiler-rt/builtins/udivmoddi4.c
@@ -0,0 +1,200 @@
+//===-- 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
+
+// Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide
+
+#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;
+ }
+ // 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.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 = 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);
+ }
+ }
+ }
+ // 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