Initial project import

tools/v/thirdparty/builtins/compiler_builtins.c

@@ -0,0 +1,165 @@
+// Compiler runtime builtins needed for cross-compilation from macOS to Linux.
+// When cross-compiling with clang, 128-bit integer operations (e.g. in mbedtls bignum.c)
+// generate calls to __udivti3/__umodti3 which are normally provided by libgcc or compiler-rt.
+// Since the linuxroot sysroot doesn't include these libraries, we provide minimal
+// implementations here.
+
+#ifdef __SIZEOF_INT128__
+
+typedef unsigned __int128 tu_int;
+typedef unsigned long long du_int;
+
+typedef union {
+    tu_int all;
+    struct {
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+        du_int low;
+        du_int high;
+#else
+        du_int high;
+        du_int low;
+#endif
+    } s;
+} utwords;
+
+static inline unsigned __clzdi2(du_int a) {
+    unsigned n = 0;
+    if (a == 0) return 64;
+    if ((a & 0xFFFFFFFF00000000ULL) == 0) { n += 32; a <<= 32; }
+    if ((a & 0xFFFF000000000000ULL) == 0) { n += 16; a <<= 16; }
+    if ((a & 0xFF00000000000000ULL) == 0) { n +=  8; a <<=  8; }
+    if ((a & 0xF000000000000000ULL) == 0) { n +=  4; a <<=  4; }
+    if ((a & 0xC000000000000000ULL) == 0) { n +=  2; a <<=  2; }
+    if ((a & 0x8000000000000000ULL) == 0) { n +=  1; }
+    return n;
+}
+
+tu_int __udivmodti4(tu_int a, tu_int b, tu_int *rem) {
+    const unsigned n_udword_bits = sizeof(du_int) * 8;
+    const unsigned n_utword_bits = sizeof(tu_int) * 8;
+    utwords n, d, q, r;
+    unsigned sr;
+    n.all = a;
+    d.all = b;
+
+    // Special cases
+    if (n.s.high == 0) {
+        if (d.s.high == 0) {
+            if (rem) *rem = n.s.low % d.s.low;
+            return n.s.low / d.s.low;
+        }
+        if (rem) *rem = n.s.low;
+        return 0;
+    }
+    // n.s.high != 0
+    if (d.s.low == 0) {
+        if (d.s.high == 0) {
+            // Division by zero (undefined behavior, just return 0)
+            if (rem) *rem = 0;
+            return 0;
+        }
+        if (n.s.low == 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;
+        }
+        // n.s.high != 0 && n.s.low != 0 && d.s.low == 0 && d.s.high != 0
+        if ((d.s.high & (d.s.high - 1)) == 0) {
+            // 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 >> __clzdi2(d.s.high);
+        }
+        sr = __clzdi2(d.s.high) - __clzdi2(n.s.high);
+        if (sr > n_udword_bits - 2) {
+            if (rem) *rem = n.all;
+            return 0;
+        }
+        ++sr;
+        // 1 <= sr <= n_udword_bits - 1
+        q.s.low = 0;
+        q.s.high = n.s.low << (n_udword_bits - sr);
+        r.s.high = n.s.high >> sr;
+        r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr);
+        goto shift_loop;
+    }
+    // d.s.low != 0
+    if (d.s.high == 0) {
+        if ((d.s.low & (d.s.low - 1)) == 0) {
+            if (rem) *rem = n.s.low & (d.s.low - 1);
+            if (d.s.low == 1) return n.all;
+            sr = __builtin_ctzll(d.s.low);
+            q.s.high = n.s.high >> sr;
+            q.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr);
+            return q.all;
+        }
+        sr = 1 + n_udword_bits + __clzdi2(d.s.low) - __clzdi2(n.s.high);
+        if (sr == n_udword_bits) {
+            q.s.low = 0;
+            q.s.high = 0;
+            r.s.high = 0;
+            r.s.low = n.s.high;
+        } else if (sr < n_udword_bits) {
+            q.s.low = 0;
+            q.s.high = n.s.low << (n_udword_bits - sr);
+            r.s.high = n.s.high >> sr;
+            r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr);
+        } else {
+            q.s.low = n.s.low << (n_utword_bits - sr);
+            q.s.high = (n.s.high << (n_utword_bits - sr)) | (n.s.low >> (sr - n_udword_bits));
+            r.s.high = 0;
+            r.s.low = n.s.high >> (sr - n_udword_bits);
+        }
+        goto shift_loop;
+    }
+    // d.s.high != 0 && d.s.low != 0
+    sr = __clzdi2(d.s.high) - __clzdi2(n.s.high);
+    if (sr > n_udword_bits - 1) {
+        if (rem) *rem = n.all;
+        return 0;
+    }
+    ++sr;
+    q.s.low = 0;
+    if (sr == n_udword_bits) {
+        q.s.high = 0;
+        r.s.high = 0;
+        r.s.low = n.s.high;
+    } else {
+        r.s.high = n.s.high >> sr;
+        r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr);
+        q.s.high = n.s.low << (n_udword_bits - sr);
+    }
+
+shift_loop:
+    // The main shift-and-subtract loop
+    for (; sr > 0; --sr) {
+        r.s.high = (r.s.high << 1) | (r.s.low >> (n_udword_bits - 1));
+        r.s.low = (r.s.low << 1) | (q.s.high >> (n_udword_bits - 1));
+        q.s.high = (q.s.high << 1) | (q.s.low >> (n_udword_bits - 1));
+        q.s.low = (q.s.low << 1);
+        // Compute (r - d) and conditionally subtract
+        const long long s = (long long)(d.all - r.all - 1) >> (n_utword_bits - 1);
+        q.s.low |= s & 1;
+        r.all -= d.all & s;
+    }
+    if (rem) *rem = r.all;
+    return q.all;
+}
+
+tu_int __udivti3(tu_int a, tu_int b) {
+    return __udivmodti4(a, b, 0);
+}
+
+tu_int __umodti3(tu_int a, tu_int b) {
+    tu_int r;
+    __udivmodti4(a, b, &r);
+    return r;
+}
+
+#endif // __SIZEOF_INT128__