File 4341-rand-Slightly-optimize-the-mwc59-family-of... of Package erlang

Overview Repositories Revisions Requests Users Attributes Meta

File 4341-rand-Slightly-optimize-the-mwc59-family-of-functions.patch of Package erlang (Revision 9f7ba17abd41d405759f6f11f4d7ded6)

Currently displaying revision 9f7ba17abd41d405759f6f11f4d7ded6 , Show latest

From 048b36690298aa38ac2a9e29507d81606ac18e60 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Thu, 29 Sep 2022 07:00:59 +0200
Subject: [PATCH] rand: Slightly optimize the mwc59 family of functions

Recent improvements in the compiler (92611e5d2d75) and the JIT
(f8a9ccda6c4a) allows us to write more natural code using guard tests
instead of `band` operations to establish ranges for integers. This
also happens to be slightly faster.
---
 lib/stdlib/src/rand.erl | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/stdlib/src/rand.erl b/lib/stdlib/src/rand.erl
index 5f8d3a4c59..e2f0278627 100644
--- a/lib/stdlib/src/rand.erl
+++ b/lib/stdlib/src/rand.erl
@@ -1502,8 +1502,7 @@ dummy_seed({A1, A2, A3}) ->
 -type mwc59_state() :: 1..?MWC59_P-1.
 
 -spec mwc59(CX0 :: mwc59_state()) -> CX1 :: mwc59_state().
-mwc59(CX0) -> % when is_integer(CX0), 1 =< CX0, CX0 < ?MWC59_P ->
-    CX = ?MASK(59, CX0),
+mwc59(CX) when is_integer(CX), 1 =< CX, CX < ?MWC59_P ->
     C = CX bsr ?MWC59_B,
     X = ?MASK(?MWC59_B, CX),
     ?MWC59_A * X + C.
@@ -1521,18 +1520,17 @@ mwc59(CX0) -> % when is_integer(CX0), 1 =< CX0, CX0 < ?MWC59_P ->
 %%%     mwc59(CX1, N - 1).
 
 -spec mwc59_value32(CX :: mwc59_state()) -> V :: 0..?MASK(32).
-mwc59_value32(CX1) -> % when is_integer(CX1), 1 =< CX1, CX1 < ?MWC59_P ->
+mwc59_value32(CX1) when is_integer(CX1), 1 =< CX1, CX1 < ?MWC59_P ->
     CX = ?MASK(32, CX1),
     CX bxor ?BSL(32, CX, ?MWC59_XS).
 
 -spec mwc59_value(CX :: mwc59_state()) -> V :: 0..?MASK(59).
-mwc59_value(CX1) -> % when is_integer(CX1), 1 =< CX1, CX1 < ?MWC59_P ->
-    CX = ?MASK(59, CX1),
+mwc59_value(CX) when is_integer(CX), 1 =< CX, CX < ?MWC59_P ->
     CX2 = CX bxor ?BSL(59, CX, ?MWC59_XS1),
     CX2 bxor ?BSL(59, CX2, ?MWC59_XS2).
 
 -spec mwc59_float(CX :: mwc59_state()) -> V :: float().
-mwc59_float(CX1) ->
+mwc59_float(CX1) when is_integer(CX1), 1 =< CX1, CX1 < ?MWC59_P ->
     CX = ?MASK(53, CX1),
     CX2 = CX bxor ?BSL(53, CX, ?MWC59_XS1),
     CX3 = CX2 bxor ?BSL(53, CX2, ?MWC59_XS2),
-- 
2.35.3

Places

File 4341-rand-Slightly-optimize-the-mwc59-family-of-functions.patch of Package erlang (Revision 9f7ba17abd41d405759f6f11f4d7ded6)

Places