From fc6b25df6736157ef53e9ba743990e9edf3bd181 Mon Sep 17 00:00:00 2001
From: Jaime Bernardo <jaime@janeasystems.com>
Date: Thu, 28 Jun 2018 08:16:31 +0100
Subject: [PATCH] ios: enable concurrent garbage collection

Enables the concurrent garbage collection feature of ChakraCore
on iOS. Also restores the original ChakraCore garbage collection
memory heuristics for iOS.
---
 deps/chakrashim/core/lib/Common/CommonDefines.h     |  7 -------
 .../core/lib/Common/Memory/RecyclerHeuristic.cpp    |  5 -----
 .../lib/Common/Memory/RecyclerWriteBarrierManager.h | 10 ++++++++++
 deps/chakrashim/core/pal/src/misc/sysinfo.cpp       | 13 ++-----------
 4 files changed, 12 insertions(+), 23 deletions(-)

diff --git a/deps/chakrashim/core/lib/Common/CommonDefines.h b/deps/chakrashim/core/lib/Common/CommonDefines.h
index 4ebd0379dfc..777a29c875d 100644
--- a/deps/chakrashim/core/lib/Common/CommonDefines.h
+++ b/deps/chakrashim/core/lib/Common/CommonDefines.h
@@ -153,15 +153,8 @@
 #else
 #define SYSINFO_IMAGE_BASE_AVAILABLE 0
 #ifndef ENABLE_VALGRIND
-#if defined(__IOS__)
-//FIXME: Disabled concurrent garbage collection, which seems to require
-// RECYCLER_WRITE_BARRIER, and that is not feasable on a 18 exabyte
-// VM address space.
-#define ENABLE_CONCURRENT_GC 0
-#else
 #define ENABLE_CONCURRENT_GC 1
 #define ENABLE_ALLOCATIONS_DURING_CONCURRENT_SWEEP 1 // Only takes effect when ENABLE_CONCURRENT_GC is enabled.
-#endif //defined(__IOS__)
 #else
 #define ENABLE_CONCURRENT_GC 0
 #define ENABLE_ALLOCATIONS_DURING_CONCURRENT_SWEEP 0 // Only takes effect when ENABLE_CONCURRENT_GC is enabled.
diff --git a/deps/chakrashim/core/lib/Common/Memory/RecyclerHeuristic.cpp b/deps/chakrashim/core/lib/Common/Memory/RecyclerHeuristic.cpp
index 1b195a58fb5..a992b2f0b0d 100644
--- a/deps/chakrashim/core/lib/Common/Memory/RecyclerHeuristic.cpp
+++ b/deps/chakrashim/core/lib/Common/Memory/RecyclerHeuristic.cpp
@@ -46,12 +46,7 @@ RecyclerHeuristic::RecyclerHeuristic()
     else if (isSuccess && physicalMemoryBytes <= 1024 MEGABYTES)
     {
         // Tablet/slate/high-end Apollo scenario, including 512MB non-Apollo.
-#if defined(__IOS__)
-        // 64MB is too little for the require phase of many node modules on a mobile device.
-        baseFactor = 192;
-#else
         baseFactor = 64;
-#endif
         this->DefaultMaxFreePageCount = 64 MEGABYTES_OF_PAGES;
         this->DefaultMaxAllocPageCount = 64;
     }
diff --git a/deps/chakrashim/core/lib/Common/Memory/RecyclerWriteBarrierManager.h b/deps/chakrashim/core/lib/Common/Memory/RecyclerWriteBarrierManager.h
index 40f2030a541..d7b11a8670c 100644
--- a/deps/chakrashim/core/lib/Common/Memory/RecyclerWriteBarrierManager.h
+++ b/deps/chakrashim/core/lib/Common/Memory/RecyclerWriteBarrierManager.h
@@ -211,10 +211,20 @@ class RecyclerWriteBarrierManager
     static DWORD GetWriteBarrier(void * address);
 #endif
 
+#if defined(__IOS__)&&defined(_M_ARM64)
+//Apple documentation reveals that virtual page size is 16KB on
+// newer versions of iOS.
+    static size_t const s_WriteBarrierPageSize = 16384;
+    // A card is a DWORD. For a 16KB page size to be represented by a DWORD, each bit represents 512 bytes.
+    static uint const s_BitArrayCardTableShift = 9;
+    static uint const s_BytesPerCardBit = 1 << s_BitArrayCardTableShift;  // 512 = 1 << 9
+    static uint const s_BytesPerCard = s_BytesPerCardBit * 32;      // 16K  = 1 << 14 = 512 << 5
+#else
     static size_t const s_WriteBarrierPageSize = 4096;
     static uint const s_BitArrayCardTableShift = 7;
     static uint const s_BytesPerCardBit = 1 << s_BitArrayCardTableShift;  // 128 = 1 << 7
     static uint const s_BytesPerCard = s_BytesPerCardBit * 32;      // 4K  = 1 << 12 = 128 << 5
+#endif
 
 private:
 
diff --git a/deps/chakrashim/core/pal/src/misc/sysinfo.cpp b/deps/chakrashim/core/pal/src/misc/sysinfo.cpp
index 1317f2767a5..2a4230017a7 100644
--- a/deps/chakrashim/core/pal/src/misc/sysinfo.cpp
+++ b/deps/chakrashim/core/pal/src/misc/sysinfo.cpp
@@ -104,15 +104,6 @@ SET_DEFAULT_DEBUG_CHANNEL(MISC);
 #endif
 #endif // __LINUX__
 
-#ifdef __IOS__
-#ifdef BIT64
-// This is the size of the virtual address space on 64 bits IOS,
-// according to Apple, is 18 exabytes.
-#define MAX_PROCESS_VA_SPACE_IOS64 \
-    (18ull * 1024 * 1024 * 1024 * 1024 * 1024 * 1024)
-#endif
-#endif
-
 /*++
 Function:
   GetSystemInfo
@@ -183,13 +174,13 @@ GetSystemInfo(
     lpSystemInfo->lpMaximumApplicationAddress = (PVOID) VM_MAXUSER_ADDRESS;
 #elif defined(__LINUX__)
     lpSystemInfo->lpMaximumApplicationAddress = (PVOID) MAX_PROCESS_VA_SPACE_LINUX;
-#elif defined(__IOS__)&&defined(BIT64)
-    lpSystemInfo->lpMaximumApplicationAddress = (PVOID) MAX_PROCESS_VA_SPACE_IOS64;
 #elif defined(USERLIMIT)
     lpSystemInfo->lpMaximumApplicationAddress = (PVOID) USERLIMIT;
 #elif defined(_WIN64)
 #if defined(USRSTACK64)
     lpSystemInfo->lpMaximumApplicationAddress = (PVOID) USRSTACK64;
+#elif defined(MACH_VM_MAX_ADDRESS)
+    lpSystemInfo->lpMaximumApplicationAddress = (PVOID) MACH_VM_MAX_ADDRESS;
 #else // !USRSTACK64
 #error How come USRSTACK64 is not defined for 64bit?
 #endif // USRSTACK64