lean4-htt

Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.

Find a file

Leonardo de Moura 04dfd55f94 perf(kernel/expr): fix hash consing performance problem The kernel support opportunistic hash consing. At commit `e63c79c81e` we have enabled this feature during tactic execution, and fixed performance problems in the Certigrad project (by @dselsam). However, this change produced unexpected performance problems in other Lean files (example: @JasonGross example at issue #1646 was 10x slower after the commit above). After analyzing the performance logs, I conjecture the hash_consing may produce a substantial performance overhead if the following property doesn't hold. - Let `cache` be the hash_consing cache, then for each `e` in `cache`, all children of `e` are also in the `cache`. If the property above is not true, we may have problem whenever we add an expression `t` containing multiple copies of a big term `T`. For example, support we insert `f T_1 T_2`, where `T_1` and `T_2` are structurally equal but are not pointer equal. Then, if we try to insert `f T_2 T_1`, we will have to compare the huge terms twice, and the comparison will be proportional to the size of `T_i`. This commit tries to address this performance problem by enforcing the property above. This is not a perfect solution since we may keep trying to create terms using big terms created before hash_consing has been enabled. After this commit, the example at issue #1646 is only 1.4x slower. It didn't impact the standard library compilation (memory nor time). I'm using this commit is a temporary workaround. We should probably remove the hash_consing support from the kernel, and implement it in key places. For example, for Certigrad, we can control memory consumption by using hash_consing only during `simp`, `instantiate_mvars` and `elaborator` finalization procedure. @gebner @kha Any ideas/suggestions for this hash_consing issue?		2017-06-23 12:41:35 -07:00
.github	chore(.github/PULL_REQUEST_TEMPLATE): typo	2017-06-12 09:56:15 -07:00
bin	chore(bin/lean-gdb): pretty-print lean::optional	2017-05-09 16:02:41 -07:00
doc	doc(changes): update	2017-06-22 08:07:25 -07:00
extras	feat(extras/depgraph): add dependency-free version of leandeps	2017-06-12 15:40:46 +02:00
images	chore(CMakeLists.txt): move Lean logo to make sure we can test leanemacs without installing Lean	2015-01-31 17:38:49 -08:00
leanpkg	refactor(library): add has_to_string back (but it produces unquoted values)	2017-06-18 18:30:10 -07:00
library	feat(library/type_context): unfold lemmas in major premise of acc.rec	2017-06-22 08:33:11 -07:00
script	chore(script/test_registry): don't stop on failure	2017-06-09 20:30:48 +02:00
src	perf(kernel/expr): fix hash consing performance problem	2017-06-23 12:41:35 -07:00
tests	fix(library/string): correctly escape non-printable characters	2017-06-23 20:39:41 +02:00
tmp	feat(frontends/lean,library/equations_compiler): store tactics for generating well founded relation and decreasing proofs	2017-05-23 15:00:29 -07:00
.appveyor.yml	chore(*): update change log, and bump work in progress version to 3.2.1	2017-06-18 11:15:09 -07:00
.appveyor.yml.in	chore(.appveyor.yml): separate upgrading and installing new packages	2017-06-03 17:42:48 +02:00
.clang-format	feat(library/vm/process): add basic process support	2017-03-28 18:08:06 -07:00
.codecov.yml	feat(.travis.yml): add codecov	2016-12-02 17:01:58 -08:00
.gitignore	chore(gitignore): ignore nix files	2017-06-19 13:16:04 +02:00
.travis.yml	fix(.travis.yml): move -t0 test to a release configuration	2017-06-19 20:35:11 +02:00
.travis.yml.in	fix(.travis.yml): move -t0 test to a release configuration	2017-06-19 20:35:11 +02:00
LICENSE	Add LICENSE file	2013-07-15 18:55:48 -07:00
README.md	feat(doc/changes.md): create change log	2017-06-14 22:42:08 -07:00