From b950934916b2973fd4131ebfb684e53df305001a Mon Sep 17 00:00:00 2001
From: Qi Wang <interwq@gwu.edu>
Date: Wed, 8 Jun 2022 14:24:55 -0700
Subject: [PATCH] Enable retain by default on macOS.

High number of mappings result in unusually high fork() cost on macOS.  Retain
fixes the issue, at a small cost of extra VM space reserved.
---
 configure.ac | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/configure.ac b/configure.ac
index 66eb7c91..917d9a80 100644
--- a/configure.ac
+++ b/configure.ac
@@ -671,6 +671,9 @@ case "${host}" in
 	SOREV="${rev}.${so}"
 	sbrk_deprecated="1"
 	SYM_PREFIX="_"
+	if test "${LG_SIZEOF_PTR}" = "3"; then
+	  default_retain="1"
+	fi
 	;;
   *-*-freebsd*)
 	JE_APPEND_VS(CPPFLAGS, -D_BSD_SOURCE)