File 2985-dialyzer-Optimize-infimum-on-bit-strings.patch of Package erlang

From 923ecb37fa2f24593d4f12585ffe00a7ac4a4676 Mon Sep 17 00:00:00 2001
From: Hans Bolinder <hasse@erlang.org>
Date: Wed, 28 Jul 2021 10:19:02 +0200
Subject: [PATCH 5/7] dialyzer: Optimize infimum on bit strings

t_inf/2 finds the common base of two bit string types faster in some
cases. It is a little bit slower on many cases, though.
---
 lib/dialyzer/src/erl_types.erl        | 10 ++++++----
 lib/dialyzer/test/erl_types_SUITE.erl | 15 +++++++++++++--
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/lib/hipe/cerl/erl_types.erl b/lib/hipe/cerl/erl_types.erl
index 7b88ebd59c..e381bfb64e 100644
--- a/lib/hipe/cerl/erl_types.erl
+++ b/lib/hipe/cerl/erl_types.erl
@@ -2933,7 +2933,7 @@ t_inf(?map(_, ADefK, ADefV) = A, ?map(_, BDefK, BDefV) = B, _Opaques) ->
   %% result in a none result.
   Pairs =
     map_pairwise_merge(
-      %% For optional keys in both maps, when the infinimum is none, we have
+      %% For optional keys in both maps, when the infimum is none, we have
       %% essentially concluded that K must not be a key in the map.
       fun(K, ?opt, V1, ?opt, V2) -> {K, ?opt, t_inf(V1, V2)};
 	 %% When a key is optional in one map, but mandatory in another, it
@@ -3404,9 +3404,11 @@ findfirst(N1, N2, U1, B1, U2, B2) ->
   if Val1 =:= Val2 ->
       Val1;
      Val1 > Val2 ->
-      findfirst(N1, N2+1, U1, B1, U2, B2);
+      N2_1 = N2 + max((Val1 - Val2) div U2, 1),
+      findfirst(N1, N2_1, U1, B1, U2, B2);
      Val1 < Val2 ->
-      findfirst(N1+1, N2, U1, B1, U2, B2)
+      N1_1 = N1 + max((Val2 - Val1) div U1, 1),
+      findfirst(N1_1, N2, U1, B1, U2, B2)
   end.
 
 %% Optimization. Before Erlang/OTP 25, subst_all_vars_to_any() was
@@ -4046,7 +4048,7 @@ t_subtract(?map(APairs, ADefK, ADefV) = A, ?map(_, BDefK, BDefV) = B) ->
       %%  * The arguments constrain A at least as much as B, i.e. that A so far
       %%    is a subtype of B. In that case they return false
       %%  * That for the particular arguments, A being a subtype of B does not
-      %%    hold, but the infinimum of A and B is nonempty, and by narrowing a
+      %%    hold, but the infimum of A and B is nonempty, and by narrowing a
       %%    pair in A, we can create a type that excludes some elements in the
       %%    infinumum. In that case, they will return that pair.
       %%  * That for the particular arguments, A being a subtype of B does not
-- 
2.31.1