bytecodealliance
x64: reduce work in non-stack using leaf functions
Cranelift has had the ability for some time to identify leaf functions; by Cranelift's definition, a leaf function is one that knows of no other call signatures. https://github.com/bytecodealliance/wasmtime/issues/1148 noted how it would be a good idea to avoid extra frame setup work in leaf functions and https://github.com/bytecodealliance/wasmtime/pull/2960 implemented this for aarch64 and s390x. This improvement was not made for x64 due to some test failures. This change avoids any frame setup for non-stack-using leaf functions in x64.
Because this updates the generated code, there are multiple sets of tests to update -- each of these is separated here into its own commit. I will follow up in the comments with benchmark results.
Here is the raw output of the benchmarking I did on my current system. It is hard to interpret the results (is it too noisy? not enough runs?) but here they are!
with the default cycles measurement:
$ taskset --cpu-list 4-5 target/release/sightglass-cli benchmark -e /tmp/main/libengine.so -e /tmp/x64-leaf-functions/libengine.so
instantiation :: cycles :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[147078 176131.13 996137] main/libengine.so
[145930 167314.60 252683] x64-leaf-functions/libengine.so
instantiation :: cycles :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[112360 132696.79 208371] main/libengine.so
[112495 136652.85 230477] x64-leaf-functions/libengine.so
instantiation :: cycles :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[368797 405530.78 502881] main/libengine.so
[371210 400482.08 545122] x64-leaf-functions/libengine.so
compilation :: cycles :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[209965278 214840438.75 230091486] main/libengine.so
[208568512 213673819.47 231217610] x64-leaf-functions/libengine.so
execution :: cycles :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[5163256 5316183.14 5716048] main/libengine.so
[5176338 5307186.55 5609513] x64-leaf-functions/libengine.so
execution :: cycles :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[520827395 523585282.78 529830174] main/libengine.so
[520812995 524419123.61 533595170] x64-leaf-functions/libengine.so
compilation :: cycles :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[394379561 403469591.05 421661750] main/libengine.so
[395049806 403016360.00 416050865] x64-leaf-functions/libengine.so
execution :: cycles :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[72041670 73242723.27 75147038] main/libengine.so
[72171609 73209119.80 74873711] x64-leaf-functions/libengine.so
compilation :: cycles :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[9360042865 9429678348.56 9517907602] main/libengine.so
[9375595405 9427505767.96 9512712326] x64-leaf-functions/libengine.so
specifying the `perf-counters` measurement:
$ taskset --cpu-list 4-5 target/release/sightglass-cli benchmark -e /tmp/main/libengine.so -e /tmp/x64-leaf-functions/libengine.so --measure perf-counters
instantiation :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[34327 37575.33 71666] main/libengine.so
[34070 36209.87 61232] x64-leaf-functions/libengine.so
execution :: cache-misses :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[737 1490.90 3397] main/libengine.so
[749 1533.36 3791] x64-leaf-functions/libengine.so
instantiation :: cpu-cycles :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[87330 108012.70 140941] main/libengine.so
[84135 110894.47 243127] x64-leaf-functions/libengine.so
instantiation :: cache-accesses :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[2719 3153.40 6610] main/libengine.so
[2754 3082.12 4528] x64-leaf-functions/libengine.so
instantiation :: cache-accesses :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[3122 4161.20 7037] main/libengine.so
[2782 4070.35 5860] x64-leaf-functions/libengine.so
compilation :: cache-misses :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[43175 63266.12 88724] main/libengine.so
[45842 64507.86 80471] x64-leaf-functions/libengine.so
instantiation :: cpu-cycles :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[78651 91367.71 218899] main/libengine.so
[79408 89770.91 211968] x64-leaf-functions/libengine.so
instantiation :: cache-misses :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[1407 1752.31 2235] main/libengine.so
[1436 1730.65 2168] x64-leaf-functions/libengine.so
execution :: cache-misses :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[3077 5807.68 10172] main/libengine.so
[3144 5877.77 13198] x64-leaf-functions/libengine.so
compilation :: cpu-cycles :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[6155268 6616904.93 7457577] main/libengine.so
[6126225 6690847.15 7678328] x64-leaf-functions/libengine.so
execution :: cache-accesses :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[81061 102216.36 143392] main/libengine.so
[77609 103227.71 147886] x64-leaf-functions/libengine.so
compilation :: cache-misses :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[1651915 1872738.93 2029320] main/libengine.so
[1664784 1889497.05 2135265] x64-leaf-functions/libengine.so
execution :: cache-accesses :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[7158 9385.02 13399] main/libengine.so
[7644 9313.02 12838] x64-leaf-functions/libengine.so
compilation :: cpu-cycles :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[2128438 2336464.61 3559953] main/libengine.so
[2140962 2353988.06 3179803] x64-leaf-functions/libengine.so
compilation :: cache-accesses :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[212241 232225.91 244981] main/libengine.so
[212462 230856.73 244761] x64-leaf-functions/libengine.so
execution :: cache-misses :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[60862 77279.98 122802] main/libengine.so
[58255 77696.47 123312] x64-leaf-functions/libengine.so
instantiation :: cpu-cycles :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[104568 116986.62 131490] main/libengine.so
[99399 117542.93 247601] x64-leaf-functions/libengine.so
instantiation :: cache-accesses :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[3808 4391.63 4937] main/libengine.so
[3876 4372.42 4783] x64-leaf-functions/libengine.so
compilation :: cache-misses :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[21638 26831.51 35754] main/libengine.so
[21900 26730.18 36534] x64-leaf-functions/libengine.so
instantiation :: cache-misses :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[1936 2156.04 2496] main/libengine.so
[1836 2149.08 2508] x64-leaf-functions/libengine.so
compilation :: cpu-cycles :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[165986856 171495577.67 179161139] main/libengine.so
[166456173 172035488.63 181114155] x64-leaf-functions/libengine.so
compilation :: cache-accesses :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[4855667 5045583.38 5187008] main/libengine.so
[4835172 5061308.56 5188155] x64-leaf-functions/libengine.so
instantiation :: cache-misses :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[1376 1507.87 1900] main/libengine.so
[1394 1510.24 1704] x64-leaf-functions/libengine.so
instantiation :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[43563 54983.42 71508] main/libengine.so
[36901 55061.22 65926] x64-leaf-functions/libengine.so
compilation :: cache-accesses :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[72326 76693.08 84404] main/libengine.so
[72462 76612.53 82601] x64-leaf-functions/libengine.so
execution :: cache-accesses :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[531146 553039.20 577617] main/libengine.so
[528802 552658.15 590599] x64-leaf-functions/libengine.so
execution :: cpu-cycles :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[824144011 827131703.61 841908153] main/libengine.so
[824077161 826662188.48 838574889] x64-leaf-functions/libengine.so
execution :: cpu-cycles :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[112027942 112932466.82 115093344] main/libengine.so
[112063326 112871592.82 114011536] x64-leaf-functions/libengine.so
execution :: cpu-cycles :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[7555372 7635027.45 7825127] main/libengine.so
[7547343 7631211.45 7825383] x64-leaf-functions/libengine.so
compilation :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[207935281 208620688.17 209390775] main/libengine.so
[208127260 208673878.55 209613081] x64-leaf-functions/libengine.so
compilation :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[2479620 2550178.19 3062957] main/libengine.so
[2475971 2550707.19 3058800] x64-leaf-functions/libengine.so
compilation :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[8860156 8959184.54 9418626] main/libengine.so
[8857013 8960071.13 9438139] x64-leaf-functions/libengine.so
instantiation :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[43827 44870.44 45809] main/libengine.so
[44017 44867.48 46051] x64-leaf-functions/libengine.so
execution :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[3203656920 3203780565.63 3204071799] main/libengine.so
[3203655116 3203783546.14 3204082241] x64-leaf-functions/libengine.so
execution :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[26394462 26394717.19 26395376] main/libengine.so
[26394464 26394724.88 26395349] x64-leaf-functions/libengine.so
execution :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[319667712 319667714.29 319667716] main/libengine.so
[319667712 319667714.26 319667716] x64-leaf-functions/libengine.so