Adding upstream version 16.2.upstream/16.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 276 insertions, 0 deletions

diff --git a/src/include/common/int128.h b/src/include/common/int128.h
new file mode 100644
index 0000000..eca694b
--- /dev/null
+++ b/src/include/common/int128.h
@@ -0,0 +1,276 @@
+/*-------------------------------------------------------------------------
+ *
+ * int128.h
+ *	  Roll-our-own 128-bit integer arithmetic.
+ *
+ * We make use of the native int128 type if there is one, otherwise
+ * implement things the hard way based on two int64 halves.
+ *
+ * See src/tools/testint128.c for a simple test harness for this file.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * src/include/common/int128.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef INT128_H
+#define INT128_H
+
+/*
+ * For testing purposes, use of native int128 can be switched on/off by
+ * predefining USE_NATIVE_INT128.
+ */
+#ifndef USE_NATIVE_INT128
+#ifdef HAVE_INT128
+#define USE_NATIVE_INT128 1
+#else
+#define USE_NATIVE_INT128 0
+#endif
+#endif
+
+
+#if USE_NATIVE_INT128
+
+typedef int128 INT128;
+
+/*
+ * Add an unsigned int64 value into an INT128 variable.
+ */
+static inline void
+int128_add_uint64(INT128 *i128, uint64 v)
+{
+	*i128 += v;
+}
+
+/*
+ * Add a signed int64 value into an INT128 variable.
+ */
+static inline void
+int128_add_int64(INT128 *i128, int64 v)
+{
+	*i128 += v;
+}
+
+/*
+ * Add the 128-bit product of two int64 values into an INT128 variable.
+ *
+ * XXX with a stupid compiler, this could actually be less efficient than
+ * the other implementation; maybe we should do it by hand always?
+ */
+static inline void
+int128_add_int64_mul_int64(INT128 *i128, int64 x, int64 y)
+{
+	*i128 += (int128) x * (int128) y;
+}
+
+/*
+ * Compare two INT128 values, return -1, 0, or +1.
+ */
+static inline int
+int128_compare(INT128 x, INT128 y)
+{
+	if (x < y)
+		return -1;
+	if (x > y)
+		return 1;
+	return 0;
+}
+
+/*
+ * Widen int64 to INT128.
+ */
+static inline INT128
+int64_to_int128(int64 v)
+{
+	return (INT128) v;
+}
+
+/*
+ * Convert INT128 to int64 (losing any high-order bits).
+ * This also works fine for casting down to uint64.
+ */
+static inline int64
+int128_to_int64(INT128 val)
+{
+	return (int64) val;
+}
+
+#else							/* !USE_NATIVE_INT128 */
+
+/*
+ * We lay out the INT128 structure with the same content and byte ordering
+ * that a native int128 type would (probably) have.  This makes no difference
+ * for ordinary use of INT128, but allows union'ing INT128 with int128 for
+ * testing purposes.
+ */
+typedef struct
+{
+#ifdef WORDS_BIGENDIAN
+	int64		hi;				/* most significant 64 bits, including sign */
+	uint64		lo;				/* least significant 64 bits, without sign */
+#else
+	uint64		lo;				/* least significant 64 bits, without sign */
+	int64		hi;				/* most significant 64 bits, including sign */
+#endif
+} INT128;
+
+/*
+ * Add an unsigned int64 value into an INT128 variable.
+ */
+static inline void
+int128_add_uint64(INT128 *i128, uint64 v)
+{
+	/*
+	 * First add the value to the .lo part, then check to see if a carry needs
+	 * to be propagated into the .hi part.  A carry is needed if both inputs
+	 * have high bits set, or if just one input has high bit set while the new
+	 * .lo part doesn't.  Remember that .lo part is unsigned; we cast to
+	 * signed here just as a cheap way to check the high bit.
+	 */
+	uint64		oldlo = i128->lo;
+
+	i128->lo += v;
+	if (((int64) v < 0 && (int64) oldlo < 0) ||
+		(((int64) v < 0 || (int64) oldlo < 0) && (int64) i128->lo >= 0))
+		i128->hi++;
+}
+
+/*
+ * Add a signed int64 value into an INT128 variable.
+ */
+static inline void
+int128_add_int64(INT128 *i128, int64 v)
+{
+	/*
+	 * This is much like the above except that the carry logic differs for
+	 * negative v.  Ordinarily we'd need to subtract 1 from the .hi part
+	 * (corresponding to adding the sign-extended bits of v to it); but if
+	 * there is a carry out of the .lo part, that cancels and we do nothing.
+	 */
+	uint64		oldlo = i128->lo;
+
+	i128->lo += v;
+	if (v >= 0)
+	{
+		if ((int64) oldlo < 0 && (int64) i128->lo >= 0)
+			i128->hi++;
+	}
+	else
+	{
+		if (!((int64) oldlo < 0 || (int64) i128->lo >= 0))
+			i128->hi--;
+	}
+}
+
+/*
+ * INT64_AU32 extracts the most significant 32 bits of int64 as int64, while
+ * INT64_AL32 extracts the least significant 32 bits as uint64.
+ */
+#define INT64_AU32(i64) ((i64) >> 32)
+#define INT64_AL32(i64) ((i64) & UINT64CONST(0xFFFFFFFF))
+
+/*
+ * Add the 128-bit product of two int64 values into an INT128 variable.
+ */
+static inline void
+int128_add_int64_mul_int64(INT128 *i128, int64 x, int64 y)
+{
+	/* INT64_AU32 must use arithmetic right shift */
+	StaticAssertDecl(((int64) -1 >> 1) == (int64) -1,
+					 "arithmetic right shift is needed");
+
+	/*----------
+	 * Form the 128-bit product x * y using 64-bit arithmetic.
+	 * Considering each 64-bit input as having 32-bit high and low parts,
+	 * we can compute
+	 *
+	 *	 x * y = ((x.hi << 32) + x.lo) * (((y.hi << 32) + y.lo)
+	 *		   = (x.hi * y.hi) << 64 +
+	 *			 (x.hi * y.lo) << 32 +
+	 *			 (x.lo * y.hi) << 32 +
+	 *			 x.lo * y.lo
+	 *
+	 * Each individual product is of 32-bit terms so it won't overflow when
+	 * computed in 64-bit arithmetic.  Then we just have to shift it to the
+	 * correct position while adding into the 128-bit result.  We must also
+	 * keep in mind that the "lo" parts must be treated as unsigned.
+	 *----------
+	 */
+
+	/* No need to work hard if product must be zero */
+	if (x != 0 && y != 0)
+	{
+		int64		x_u32 = INT64_AU32(x);
+		uint64		x_l32 = INT64_AL32(x);
+		int64		y_u32 = INT64_AU32(y);
+		uint64		y_l32 = INT64_AL32(y);
+		int64		tmp;
+
+		/* the first term */
+		i128->hi += x_u32 * y_u32;
+
+		/* the second term: sign-extend it only if x is negative */
+		tmp = x_u32 * y_l32;
+		if (x < 0)
+			i128->hi += INT64_AU32(tmp);
+		else
+			i128->hi += ((uint64) tmp) >> 32;
+		int128_add_uint64(i128, ((uint64) INT64_AL32(tmp)) << 32);
+
+		/* the third term: sign-extend it only if y is negative */
+		tmp = x_l32 * y_u32;
+		if (y < 0)
+			i128->hi += INT64_AU32(tmp);
+		else
+			i128->hi += ((uint64) tmp) >> 32;
+		int128_add_uint64(i128, ((uint64) INT64_AL32(tmp)) << 32);
+
+		/* the fourth term: always unsigned */
+		int128_add_uint64(i128, x_l32 * y_l32);
+	}
+}
+
+/*
+ * Compare two INT128 values, return -1, 0, or +1.
+ */
+static inline int
+int128_compare(INT128 x, INT128 y)
+{
+	if (x.hi < y.hi)
+		return -1;
+	if (x.hi > y.hi)
+		return 1;
+	if (x.lo < y.lo)
+		return -1;
+	if (x.lo > y.lo)
+		return 1;
+	return 0;
+}
+
+/*
+ * Widen int64 to INT128.
+ */
+static inline INT128
+int64_to_int128(int64 v)
+{
+	INT128		val;
+
+	val.lo = (uint64) v;
+	val.hi = (v < 0) ? -INT64CONST(1) : INT64CONST(0);
+	return val;
+}
+
+/*
+ * Convert INT128 to int64 (losing any high-order bits).
+ * This also works fine for casting down to uint64.
+ */
+static inline int64
+int128_to_int64(INT128 val)
+{
+	return (int64) val.lo;
+}
+
+#endif							/* USE_NATIVE_INT128 */
+
+#endif							/* INT128_H */