Translate global.gets of defined, immutable globals into constants
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When a global is both defined locally within the module and immutable, we can emit a constant value, rather than a vmctx load, when translating a `global.get` of that global from Wasm to CLIF. This provides a surprising amount of speed ups on sightglass benchmarks, including a 1.12x speed up for the new spidermonkey-json benchmark: <details> ``` execution :: instructions-retired :: benchmarks/spidermonkey/spidermonkey-json.wasm Δ = 159602263.67 ± 211.65 (confidence = 99%) const-globals.so is 1.12x to 1.12x faster than main.so! [1293484118 1293484381.73 1293485153] const-globals.so [1453086549 1453086645.40 1453087556] main.so execution :: instructions-retired :: benchmarks/spidermonkey/spidermonkey-regex.wasm Δ = 13152398.33 ± 57.47 (confidence = 99%) const-globals.so is 1.03x to 1.03x faster than main.so! [387099586 387099699.10 387099862] const-globals.so [400251990 400252097.43 400252306] main.so execution :: instructions-retired :: benchmarks/spidermonkey/spidermonkey-markdown.wasm Δ = 15034097.07 ± 10655.88 (confidence = 99%) const-globals.so is 1.02x to 1.02x faster than main.so! [763628883 763651147.87 763678416] const-globals.so [778659903 778685244.93 778735782] main.so execution :: instructions-retired :: benchmarks/hashset/benchmark.wasm Δ = 44391.93 ± 11.74 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [256202796 256202806.90 256202889] const-globals.so [256247196 256247198.83 256247206] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-aead_aes256gcm.wasm Δ = 0.03 ± 0.00 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [231 231.03 232] const-globals.so [231 231.00 231] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-secretbox_easy.wasm Δ = 5.10 ± 0.00 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [142584 142584.00 142584] const-globals.so [142584 142589.10 142736] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-core4.wasm Δ = 0.03 ± 0.00 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [1712 1712.00 1712] const-globals.so [1712 1712.03 1713] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-aead_xchacha20poly1305.wasm Δ = 14.03 ± 5.04 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [1749396 1749410.20 1749418] const-globals.so [1749396 1749396.17 1749397] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-chacha20.wasm Δ = 20.77 ± 0.52 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [3669797 3669797.77 3669802] const-globals.so [3669818 3669818.53 3669819] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-stream4.wasm Δ = 0.03 ± 0.00 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [7704 7704.00 7704] const-globals.so [7704 7704.03 7705] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-kdf_hkdf.wasm Δ = 28.63 ± 20.56 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [11832986 11832986.07 11832987] const-globals.so [11833007 11833014.70 11833231] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-kx.wasm Δ = 27.03 ± 8.96 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [42174047 42174047.80 42174049] const-globals.so [42174071 42174074.83 42174169] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-box_easy.wasm Δ = 7.03 ± 5.85 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [14607649 14607657.37 14607674] const-globals.so [14607649 14607650.33 14607656] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-scalarmult_ed25519.wasm Δ = 15.13 ± 6.00 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [69623939 69623956.20 69623967] const-globals.so [69623939 69623941.07 69623948] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-memmove.wasm Δ = 10.27 ± 7.81 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [127094323 127094334.60 127094359] const-globals.so [127094322 127094324.33 127094328] main.so execution :: instructions-retired :: benchmarks/rust-html-rewriter/benchmark.wasm Δ = 1.00 ± 0.79 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [19351722 19351723.50 19351725] const-globals.so [19351723 19351724.50 19351728] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-switch.wasm Δ = 6.10 ± 4.85 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [162346015 162346025.03 162346043] const-globals.so [162346015 162346018.93 162346029] main.so execution :: instructions-retired :: benchmarks/bz2/benchmark.wasm Δ = 7.00 ± 6.01 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [221270644 221270655.00 221270687] const-globals.so [221270643 221270648.00 221270660] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-keccak.wasm Δ = 1.27 ± 1.27 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [77020158 77020160.20 77020167] const-globals.so [77020158 77020158.93 77020161] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-sign.wasm Δ = 142.13 ± 116.31 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [10962329294 10962329441.17 10962329786] const-globals.so [10962329386 10962329583.30 10962330163] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-pwhash_scrypt_ll.wasm Δ = 9.20 ± 7.92 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [869339510 869339515.17 869339524] const-globals.so [869339511 869339524.37 869339568] main.so execution :: instructions-retired :: benchmarks/gcc-loops/benchmark.wasm Δ = 784.27 ± 309.85 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [74362830008 74362830127.20 74362830790] const-globals.so [74362830308 74362830911.47 74362832876] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-stream2.wasm Δ = 5.60 ± 4.20 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [626659894 626659899.27 626659912] const-globals.so [626659896 626659904.87 626659922] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-pwhash_scrypt.wasm Δ = 98.67 ± 82.17 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [13152494757 13152494926.27 13152495383] const-globals.so [13152494768 13152494827.60 13152495097] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-ratelimit.wasm Δ = 1.27 ± 0.97 (confidence = 99%) const-globals.so is 1.00x to 1.00x faster than main.so! [175149590 175149591.37 175149594] const-globals.so [175149590 175149592.63 175149597] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-sieve.wasm Δ = 11.50 ± 9.59 (confidence = 99%) main.so is 1.00x to 1.00x faster than const-globals.so! [3233944543 3233944562.03 3233944615] const-globals.so [3233944542 3233944550.53 3233944561] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-box_easy2.wasm No difference in performance. [49726677 983789516.60 2793874378] const-globals.so [75238587 877793884.97 1876844760] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-sodium_utils.wasm No difference in performance. [111905571 177945377.97 251390843] const-globals.so [109756498 161402407.73 241287377] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-secretstream.wasm No difference in performance. [692182 1151252.33 1525086] const-globals.so [537504 1069691.37 1567439] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-secretstream_xchacha20poly1305.wasm No difference in performance. [558450 1058015.77 1495400] const-globals.so [727777 1049762.87 1607655] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-secretbox_easy2.wasm No difference in performance. [820755 544888840.37 1741297134] const-globals.so [1905303 542356897.47 1846687120] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-keygen.wasm No difference in performance. [86869 87301.00 92053] const-globals.so [86893 86979.40 89485] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-aead_aegis256.wasm No difference in performance. [121347810 124839812.40 127901128] const-globals.so [121113415 124532015.60 127363026] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-metamorphic.wasm No difference in performance. [253403413 255557329.33 257742703] const-globals.so [253413445 255203119.77 257113695] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-aead_aegis128l.wasm No difference in performance. [110612323 112358979.77 115589830] const-globals.so [108810849 112481902.83 114989404] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-codecs.wasm No difference in performance. [15774967 16222629.73 16784448] const-globals.so [15649696 16207671.50 16630684] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-core_ed25519.wasm No difference in performance. [25295127465 25536548061.60 25774505815] const-globals.so [25289814477 25555543225.53 25805892358] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-box8.wasm No difference in performance. [21556149565 21577547899.83 21604361637] const-globals.so [21556152576 21581254223.57 21604393549] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-box_seal.wasm No difference in performance. [38405894 38578934.67 38754505] const-globals.so [38424652 38573018.57 38678020] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-xchacha20.wasm No difference in performance. [232771060 232857737.23 233003227] const-globals.so [232762254 232880229.37 232987880] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-secretbox8.wasm No difference in performance. [285981451 286298596.33 286720158] const-globals.so [286117189 286304236.33 286548876] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-verify1.wasm No difference in performance. [444930870 445059332.87 445183428] const-globals.so [444949602 445064341.57 445189685] main.so execution :: instructions-retired :: benchmarks/rust-protobuf/benchmark.wasm No difference in performance. [15918618 15919132.77 15919797] const-globals.so [15918530 15919211.53 15919607] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-core_ristretto255.wasm No difference in performance. [28328812516 28329081203.83 28329383500] const-globals.so [28328818779 28329010032.83 28329246158] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-ed25519_convert.wasm No difference in performance. [3027360343 3027399188.03 3027448316] const-globals.so [3027364895 3027395456.10 3027448060] main.so execution :: instructions-retired :: benchmarks/blind-sig/benchmark.wasm No difference in performance. [1329547322 1329671466.33 1329835926] const-globals.so [1329578791 1329673031.20 1329811888] main.so execution :: instructions-retired :: benchmarks/tract-onnx-image-classification/benchmark.wasm No difference in performance. [4102103117 4102123508.43 4102160849] const-globals.so [4102112269 4102128322.40 4102147555] main.so execution :: instructions-retired :: benchmarks/rust-json/benchmark.wasm No difference in performance. [38122633 38123313.27 38124114] const-globals.so [38122846 38123350.10 38123895] main.so execution :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm No difference in performance. [20771195 20771224.40 20771488] const-globals.so [20771203 20771234.90 20771467] main.so execution :: instructions-retired :: benchmarks/regex/benchmark.wasm No difference in performance. [744373531 744376020.40 744380370] const-globals.so [744373242 744376333.90 744383147] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-secretbox7.wasm No difference in performance. [88018607 88018618.40 88018832] const-globals.so [88018628 88018644.70 88018853] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-aead_chacha20poly1305.wasm No difference in performance. [1872724 1872724.67 1872728] const-globals.so [1872724 1872724.20 1872725] main.so execution :: instructions-retired :: benchmarks/quicksort/benchmark.wasm No difference in performance. [92263435 92272535.97 92354350] const-globals.so [92263407 92272558.30 92355111] main.so execution :: instructions-retired :: benchmarks/intgemm-simd/benchmark.wasm No difference in performance. [2782418375 2782428339.13 2782518124] const-globals.so [2782418701 2782428908.27 2782518087] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-generichash2.wasm No difference in performance. [608950 608950.03 608951] const-globals.so [608950 608950.13 608951] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-onetimeauth7.wasm No difference in performance. [89920328 89920344.63 89920554] const-globals.so [89920349 89920358.07 89920574] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-kdf.wasm No difference in performance. [376989 376989.07 376990] const-globals.so [376989 376989.03 376990] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-box_seed.wasm No difference in performance. [1145094 1145094.13 1145095] const-globals.so [1145094 1145094.03 1145095] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-scalarmult7.wasm No difference in performance. [7276772 7276772.77 7276773] const-globals.so [7276772 7276773.23 7276777] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-scalarmult2.wasm No difference in performance. [1135962 1135962.03 1135963] const-globals.so [1135962 1135962.10 1135963] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-generichash3.wasm No difference in performance. [584616 584616.07 584617] const-globals.so [584616 584616.03 584617] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-generichash.wasm No difference in performance. [9506095 9506095.87 9506098] const-globals.so [9506095 9506095.50 9506098] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-scalarmult6.wasm No difference in performance. [3639833 3639833.47 3639834] const-globals.so [3639833 3639833.33 3639834] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-scalarmult8.wasm No difference in performance. [215675203 215675228.57 215675456] const-globals.so [215675202 215675220.73 215675433] main.so execution :: instructions-retired :: benchmarks/blake3-simd/benchmark.wasm No difference in performance. [1432879 1432879.10 1432880] const-globals.so [1432879 1432879.13 1432880] main.so execution :: instructions-retired :: benchmarks/blake3-scalar/benchmark.wasm No difference in performance. [1481473 1481473.17 1481474] const-globals.so [1481473 1481473.13 1481474] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-scalarmult.wasm No difference in performance. [13188546 13188546.13 13188547] const-globals.so [13188546 13188546.40 13188548] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-xblabla20.wasm No difference in performance. [14307156 14307156.33 14307157] const-globals.so [14307156 14307156.57 14307159] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-xchacha20.wasm No difference in performance. [20317153 20317154.20 20317156] const-globals.so [20317153 20317153.90 20317155] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-box.wasm No difference in performance. [7308812 7308812.73 7308815] const-globals.so [7308812 7308812.83 7308815] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-box2.wasm No difference in performance. [7316174 7316174.70 7316176] const-globals.so [7316174 7316174.60 7316175] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-gimli.wasm No difference in performance. [32540194 32540194.50 32540196] const-globals.so [32540194 32540194.90 32540200] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-scalarmult5.wasm No difference in performance. [3639369 3639369.23 3639370] const-globals.so [3639369 3639369.20 3639370] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-base64.wasm No difference in performance. [1763190279 1763190305.83 1763190468] const-globals.so [1763190279 1763190293.73 1763190475] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-ed25519.wasm No difference in performance. [39316304089 39316304466.07 39316305704] const-globals.so [39316304147 39316304708.87 39316305724] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-ackermann.wasm No difference in performance. [11094470 11094470.07 11094471] const-globals.so [11094469 11094470.00 11094471] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-random.wasm No difference in performance. [270000313 270000319.97 270000341] const-globals.so [270000314 270000321.30 270000337] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-pwhash_argon2i.wasm No difference in performance. [3954742471 3954742529.90 3954742900] const-globals.so [3954742477 3954742512.30 3954742738] main.so execution :: instructions-retired :: benchmarks/richards/benchmark.wasm No difference in performance. [12520753206 12520753328.03 12520753758] const-globals.so [12520753204 12520753276.90 12520753560] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-pwhash_argon2id.wasm No difference in performance. [4498555857 4498555884.93 4498555942] const-globals.so [4498555861 4498555902.53 4498556116] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-auth7.wasm No difference in performance. [121908087 121908089.27 121908103] const-globals.so [121908087 121908088.90 121908097] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-seqhash.wasm No difference in performance. [40795541579 40795541753.33 40795542512] const-globals.so [40795541577 40795541869.60 40795543495] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-scalarmult_ristretto255.wasm No difference in performance. [82348883 82348884.17 82348886] const-globals.so [82348883 82348883.97 82348885] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-ctype.wasm No difference in performance. [3950019268 3950019283.77 3950019338] const-globals.so [3950019267 3950019292.10 3950019373] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-core3.wasm No difference in performance. [999325951 999325957.20 999325978] const-globals.so [999325949 999325955.17 999325973] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-auth5.wasm No difference in performance. [232226482 232226483.80 232226488] const-globals.so [232226482 232226484.27 232226488] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-matrix.wasm No difference in performance. [2686800367 2686800377.97 2686800424] const-globals.so [2686800367 2686800382.53 2686800392] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-minicsv.wasm No difference in performance. [5718001502 5718001531.13 5718001584] const-globals.so [5718001496 5718001522.30 5718001588] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-stream.wasm No difference in performance. [664961855 664961865.20 664962083] const-globals.so [664961854 664961866.00 664961903] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-randombytes.wasm No difference in performance. [28199076 28199172.73 28199536] const-globals.so [28199076 28199172.77 28199422] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-fib2.wasm No difference in performance. [14037403282 14037403342.67 14037403651] const-globals.so [14037403289 14037403328.27 14037403646] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-box7.wasm No difference in performance. [7135571315 7135571383.27 7135571928] const-globals.so [7135571315 7135571389.20 7135571546] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-heapsort.wasm No difference in performance. [3217113500 3217113532.67 3217114011] const-globals.so [3217113502 3217113534.53 3217113600] main.so execution :: instructions-retired :: benchmarks/meshoptimizer/benchmark.wasm No difference in performance. [13220474840 13220474933.17 13220475932] const-globals.so [13220474846 13220474927.97 13220475830] main.so execution :: instructions-retired :: benchmarks/rust-compression/benchmark.wasm No difference in performance. [20784023030 20784023199.77 20784023894] const-globals.so [20784023002 20784023202.93 20784024056] main.so execution :: instructions-retired :: benchmarks/hex-simd/benchmark.wasm No difference in performance. [2162941 2162941.17 2162942] const-globals.so [2162941 2162941.17 2162942] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-aead_aes256gcm2.wasm No difference in performance. [166 166.00 166] const-globals.so [166 166.00 166] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-aead_chacha20poly13052.wasm No difference in performance. [4094498 4094498.40 4094499] const-globals.so [4094498 4094498.40 4094499] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-auth.wasm No difference in performance. [458099 458099.00 458099] const-globals.so [458099 458099.00 458099] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-auth2.wasm No difference in performance. [24185 24185.00 24185] const-globals.so [24185 24185.00 24185] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-auth3.wasm No difference in performance. [48930 48930.00 48930] const-globals.so [48930 48930.00 48930] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-auth6.wasm No difference in performance. [36143 36143.00 36143] const-globals.so [36143 36143.00 36143] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-core1.wasm No difference in performance. [1145 1145.00 1145] const-globals.so [1145 1145.00 1145] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-core2.wasm No difference in performance. [1100 1100.00 1100] const-globals.so [1100 1100.00 1100] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-core5.wasm No difference in performance. [1100 1100.00 1100] const-globals.so [1100 1100.00 1100] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-core6.wasm No difference in performance. [1712 1712.00 1712] const-globals.so [1712 1712.00 1712] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-hash.wasm No difference in performance. [52679 52679.00 52679] const-globals.so [52679 52679.00 52679] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-hash3.wasm No difference in performance. [9449 9449.00 9449] const-globals.so [9449 9449.00 9449] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-misuse.wasm No difference in performance. [151 151.00 151] const-globals.so [151 151.00 151] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-onetimeauth.wasm No difference in performance. [17405 17405.00 17405] const-globals.so [17405 17405.00 17405] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-onetimeauth2.wasm No difference in performance. [151 151.00 151] const-globals.so [151 151.00 151] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-secretbox.wasm No difference in performance. [30690 30690.00 30690] const-globals.so [30690 30690.00 30690] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-secretbox2.wasm No difference in performance. [19740 19740.00 19740] const-globals.so [19740 19740.00 19740] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-shorthash.wasm No difference in performance. [20967 20967.00 20967] const-globals.so [20967 20967.00 20967] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-siphashx24.wasm No difference in performance. [24332 24332.00 24332] const-globals.so [24332 24332.00 24332] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-sodium_core.wasm No difference in performance. [474 474.00 474] const-globals.so [474 474.00 474] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-sodium_version.wasm No difference in performance. [162 162.00 162] const-globals.so [162 162.00 162] main.so execution :: instructions-retired :: benchmarks/libsodium/libsodium-stream3.wasm No difference in performance. [4334 4334.00 4334] const-globals.so [4334 4334.00 4334] main.so execution :: instructions-retired :: benchmarks/noop/benchmark.wasm No difference in performance. [151 151.00 151] const-globals.so [151 151.00 151] main.so execution :: instructions-retired :: benchmarks/shootout/shootout-nestedloop.wasm No difference in performance. [164 164.00 164] const-globals.so [164 164.00 164] main.so ``` </details>
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This is great; thanks for the optimization!
As an aside, I think these global.gets arise because of -fPIC support in the Wasm; I wonder whether the overhead was ever measured when that was introduced? I also recall having to build support into weval for this same thing (to resolve some loads that needed to be constants).
For the benchmark results: would you mind running with cycles as well? instructions-retired is nice as a less noisy measurement but (as I'm sure you know) translates into actual runtime via the IPC ratio which can vary considerably (and sometimes a bigger shift in insts-retired can translate to a smaller shift in cycles because a big modern core had extra parallelism available and soaked up the extra insts). Not that we shouldn't take this if that shifts the speedup ratio, but I'm curious how to map it back into the wallclock speedup realm.
alexcrichton
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Here are the statistically significant results for the union of the default and spidermonkey suites: |
This was referenced Jan 5, 2026
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When a global is both defined locally within the module and immutable, we can emit a constant value, rather than a vmctx load, when translating a
global.getof that global from Wasm to CLIF.This provides a surprising amount of speed ups on sightglass benchmarks, including a 1.12x speed up for the new spidermonkey-json benchmark:
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