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cgay merged 2 commits into from
Jun 24, 2026
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<table> implementation improvements #1822

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b0525e1
dylan: Improve table rehash parameters
housel Jun 23, 2026
f4caf0a
dylan: Improve <table> implementation method dispatch
housel Jun 23, 2026
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58 changes: 29 additions & 29 deletions sources/dylan/table.dylan
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Original file line number Diff line number Diff line change
Expand Up @@ -33,32 +33,31 @@ define constant $default-table-size = 10;
// Must be a prime number.
define constant $minimum-entries = 31;


define constant $entry-counts =
#[ 2, 3, 5, 7, 11, 13, 17, 19,
23, 29, 31, 37, 41, 47, 53, 59,
67, 71, 79, 83, 89, 97, 103, 109,
127, 137, 149, 157, 167, 179, 191, 211,
223, 239, 251, 269, 283, 307, 331, 349,
367, 389, 409, 431, 457, 487, 521, 557,
587, 617, 653, 691, 727, 769, 809, 853,
907, 953, 1009, 1061, 1117, 1181, 1249, 1319,
1399, 1471, 1549, 1627, 1709, 1801, 1901, 1997,
2099, 2207, 2333, 2459, 2591, 2729, 2879, 3023,
3181, 3343, 3511, 3691, 3877, 4073, 4283, 4507,
4733, 4973, 5227, 5501, 5779, 6073, 6379, 6701,
7039, 7393, 7789, 8179, 8597, 9029, 9491, 9967,
10477, 11003, 11579, 12161, 12781, 13421, 14107, 14813,
15559, 16339, 17159, 18041, 18947, 19913, 20921, 21977,
23081, 24239, 25453, 26729, 28069, 29473, 30949, 32497,
34123, 35831, 37633, 39521, 41507, 43591, 45779, 48073,
50497, 55547, 61121, 67247, 73973, 81371, 89513, 98467,
108343, 119179, 131101, 144223, 158647, 174527, 191999, 211199,
232333, 255571, 281131, 309251, 340183, 374203, 411637, 452807,
498089, 547901, 602711, 662999, 729301, 802253, 882481, 970747,
1067831, 1174619, 1292089, 1421309, 1563449, 1719799, 1891789, 2080979,
2289083, 2518003, 2769841, 3046829, 3351521, 3686677, 4055347, 4460891,
4906991, 5397697, 5937469, 6531221, 7184351, 7902787, 8693071, 9562387];
// Sequence of primes, each greater than its predecessor by a factor
// of at least 1.25. All are less than the maximum positive fixed
// integer on 32-bit platforms.
define constant $entry-counts :: <simple-object-vector> =
#[ 2, 3, 5, 7,
11, 17, 23, 29,
37, 47, 59, 79,
101, 127, 163, 211,
269, 337, 431, 541,
677, 853, 1_069, 1_361,
1_709, 2_137, 2_677, 3_347,
4_201, 5_261, 6_577, 8_231,
10_289, 12_889, 16_127, 20_161,
25_219, 31_531, 39_419, 49_277,
61_603, 77_017, 96_281, 120_371,
150_473, 188_107, 235_159, 293_957,
367_453, 459_317, 574_157, 717_697,
897_133, 1_121_423, 1_401_791, 1_752_239,
2_190_299, 2_737_937, 3_422_429, 4_278_037,
5_347_553, 6_684_443, 8_355_563, 10_444_457,
13_055_587, 16_319_519, 20_399_411, 25_499_291,
31_874_149, 39_842_687, 49_803_361, 62_254_207,
77_817_767, 97_272_239, 121_590_311, 151_987_889,
189_984_863, 237_481_091, 296_851_369, 371_064_217,
463_830_313];

define constant $entry-last :: <integer> = $entry-counts.size - 1;

Expand All @@ -74,10 +73,11 @@ define function search-for-entry-count
// smallest good entry count that is not smaller than the
// needed number of entries.
if (lower = upper)
vector-element($entry-counts, lower);
primitive-the(<integer>, vector-element($entry-counts, lower))

@cgay cgay Jun 23, 2026

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Just curious, couldn't this also be achieved by making $entry-counts be a limited(<vector>, of: <integer>)?

@housel housel Jun 24, 2026 •
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Just curious, couldn't this also be achieved by making $entry-counts be a limited(<vector>, of: <integer>)?

Not quite as easily, you'd have to initialize it with as(limited(<vector>, of: <integer>), #[...]) which would have an initialization-time cost. I don't think the compiler can do the conversion at compile time (yet).

else
let index = ash(lower + upper, -1);
let elt :: <integer> = vector-element($entry-counts, index);
let elt :: <integer>
= primitive-the(<integer>, vector-element($entry-counts, index));
if (elt < needed)
loop(index + 1, upper);
else
Expand All @@ -98,7 +98,7 @@ define function compute-entry-count (desired :: <integer>)
compute-entry-count(0);
else
let needed = max(ceiling/(desired, $grow-threshold), $minimum-entries);
if (needed <= vector-element($entry-counts, $entry-last))
if (needed <= primitive-the(<integer>, vector-element($entry-counts, $entry-last)))
search-for-entry-count(needed);
else
// Signal some more specific class of error?
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