0001-Enable-SharedArrayBuffer-for-Testing.patch

From 4aebb770e48493f9ca46ca708a6271c8b0ef3045 Mon Sep 17 00:00:00 2001
From: Rick Waldron <waldron.rick@gmail.com>
Date: Mon, 26 Feb 2018 12:33:54 -0500
Subject: [PATCH] Enable SharedArrayBuffer for Testing

---
 Source/WTF/wtf/Platform.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Source/WTF/wtf/Platform.h b/Source/WTF/wtf/Platform.h
index 8ad8441a8..7aad37d3a 100644
--- a/Source/WTF/wtf/Platform.h
+++ b/Source/WTF/wtf/Platform.h
@@ -1217,7 +1217,7 @@
 #endif
 
 /* Disable SharedArrayBuffers until Spectre security concerns are mitigated. */
-#define ENABLE_SHARED_ARRAY_BUFFER 0
+#define ENABLE_SHARED_ARRAY_BUFFER 1
 
 #if (OS(DARWIN) && USE(CG)) || (USE(FREETYPE) && !PLATFORM(GTK)) || (PLATFORM(WIN) && (USE(CG) || USE(CAIRO)))
 #undef ENABLE_OPENTYPE_MATH
-- 
2.14.3 (Apple Git-98)

apply-patch.sh

git checkout -- Source/WTF/wtf/Platform.h;
git checkout master;
git pull origin master;

if [ -n `git rev-parse --verify sab-enabled` ]; then
  git checkout sab-enabled
else
  git checkout -b sab-enabled
fi;

rm 0001-Enable-SharedArrayBuffer-for-Testing.patch
wget https://gist.githubusercontent.com/rwaldron/89ed9a4bb7a459db8d54c8fe77ead4b1/raw/0001-Enable-SharedArrayBuffer-for-Testing.patch
git apply 0001-Enable-SharedArrayBuffer-for-Testing.patch
Tools/Scripts/build-jsc --ftl-jit --debug

# optional, change to correct path
ln -s /Users/rwaldron/clonez/WebKit/WebKitBuild/Debug/jsc /usr/local/bin/jsc-debug

# useful runtime flags
# --useAsyncIterator=true --useBigInt=true --useObjectRestSpread=true

Notes:

Flags cannot be used as boolean:

$ jsc-debug --useAsyncIterator --useBigInt --useObjectRestSpread
ERROR: invalid option: --useAsyncIterator
ERROR: invalid option: --useBigInt
ERROR: invalid option: --useObjectRestSpread