jemalloc: Import 5.3.0 54eaed1d8b56b1aa528be3bdd1877e59c56fa90cvendor/jemalloc/5.3.0vendor/jemalloc

Import jemalloc 5.3.0.

This import changes how manage the jemalloc vendor branch (which was
just started anyway). Starting with 5.3.0, we import a clean tree from
the upstream github, removing all the old files that are no longer
upstream, or that we've kept around for some reason. We do this because
we merge from this raw version of jemalloc into the FreeBSD
contrib/jemalloc, then we run autogen stuff, generate all the generated
.h files with gmake, then finally remove much of the generated files in
contrib/jemalloc using an update script.

Sponsored by:		Netflix

1 files changed, 126 insertions, 0 deletions

diff --git a/include/jemalloc/internal/fxp.h b/include/jemalloc/internal/fxp.h
new file mode 100644
index 000000000000..415a982890a1
--- /dev/null
+++ b/include/jemalloc/internal/fxp.h
@@ -0,0 +1,126 @@
+#ifndef JEMALLOC_INTERNAL_FXP_H
+#define JEMALLOC_INTERNAL_FXP_H
+
+/*
+ * A simple fixed-point math implementation, supporting only unsigned values
+ * (with overflow being an error).
+ *
+ * It's not in general safe to use floating point in core code, because various
+ * libc implementations we get linked against can assume that malloc won't touch
+ * floating point state and call it with an unusual calling convention.
+ */
+
+/*
+ * High 16 bits are the integer part, low 16 are the fractional part.  Or
+ * equivalently, repr == 2**16 * val, where we use "val" to refer to the
+ * (imaginary) fractional representation of the true value.
+ *
+ * We pick a uint32_t here since it's convenient in some places to
+ * double the representation size (i.e. multiplication and division use
+ * 64-bit integer types), and a uint64_t is the largest type we're
+ * certain is available.
+ */
+typedef uint32_t fxp_t;
+#define FXP_INIT_INT(x) ((x) << 16)
+#define FXP_INIT_PERCENT(pct) (((pct) << 16) / 100)
+
+/*
+ * Amount of precision used in parsing and printing numbers.  The integer bound
+ * is simply because the integer part of the number gets 16 bits, and so is
+ * bounded by 65536.
+ *
+ * We use a lot of precision for the fractional part, even though most of it
+ * gets rounded off; this lets us get exact values for the important special
+ * case where the denominator is a small power of 2 (for instance,
+ * 1/512 == 0.001953125 is exactly representable even with only 16 bits of
+ * fractional precision).  We need to left-shift by 16 before dividing by
+ * 10**precision, so we pick precision to be floor(log(2**48)) = 14.
+ */
+#define FXP_INTEGER_PART_DIGITS 5
+#define FXP_FRACTIONAL_PART_DIGITS 14
+
+/*
+ * In addition to the integer and fractional parts of the number, we need to
+ * include a null character and (possibly) a decimal point.
+ */
+#define FXP_BUF_SIZE (FXP_INTEGER_PART_DIGITS + FXP_FRACTIONAL_PART_DIGITS + 2)
+
+static inline fxp_t
+fxp_add(fxp_t a, fxp_t b) {
+	return a + b;
+}
+
+static inline fxp_t
+fxp_sub(fxp_t a, fxp_t b) {
+	assert(a >= b);
+	return a - b;
+}
+
+static inline fxp_t
+fxp_mul(fxp_t a, fxp_t b) {
+	uint64_t unshifted = (uint64_t)a * (uint64_t)b;
+	/*
+	 * Unshifted is (a.val * 2**16) * (b.val * 2**16)
+	 *   == (a.val * b.val) * 2**32, but we want
+	 * (a.val * b.val) * 2 ** 16.
+	 */
+	return (uint32_t)(unshifted >> 16);
+}
+
+static inline fxp_t
+fxp_div(fxp_t a, fxp_t b) {
+	assert(b != 0);
+	uint64_t unshifted = ((uint64_t)a << 32) / (uint64_t)b;
+	/*
+	 * Unshifted is (a.val * 2**16) * (2**32) / (b.val * 2**16)
+	 *   == (a.val / b.val) * (2 ** 32), which again corresponds to a right
+	 *   shift of 16.
+	 */
+	return (uint32_t)(unshifted >> 16);
+}
+
+static inline uint32_t
+fxp_round_down(fxp_t a) {
+	return a >> 16;
+}
+
+static inline uint32_t
+fxp_round_nearest(fxp_t a) {
+	uint32_t fractional_part = (a  & ((1U << 16) - 1));
+	uint32_t increment = (uint32_t)(fractional_part >= (1U << 15));
+	return (a >> 16) + increment;
+}
+
+/*
+ * Approximately computes x * frac, without the size limitations that would be
+ * imposed by converting u to an fxp_t.
+ */
+static inline size_t
+fxp_mul_frac(size_t x_orig, fxp_t frac) {
+	assert(frac <= (1U << 16));
+	/*
+	 * Work around an over-enthusiastic warning about type limits below (on
+	 * 32-bit platforms, a size_t is always less than 1ULL << 48).
+	 */
+	uint64_t x = (uint64_t)x_orig;
+	/*
+	 * If we can guarantee no overflow, multiply first before shifting, to
+	 * preserve some precision.  Otherwise, shift first and then multiply.
+	 * In the latter case, we only lose the low 16 bits of a 48-bit number,
+	 * so we're still accurate to within 1/2**32.
+	 */
+	if (x < (1ULL << 48)) {
+		return (size_t)((x * frac) >> 16);
+	} else {
+		return (size_t)((x >> 16) * (uint64_t)frac);
+	}
+}
+
+/*
+ * Returns true on error.  Otherwise, returns false and updates *ptr to point to
+ * the first character not parsed (because it wasn't a digit).
+ */
+bool fxp_parse(fxp_t *a, const char *ptr, char **end);
+void fxp_print(fxp_t a, char buf[FXP_BUF_SIZE]);
+
+#endif /* JEMALLOC_INTERNAL_FXP_H */