From e182ae84a17aafd1545c7549560fd8da467741d8 Mon Sep 17 00:00:00 2001
From: Luke Gorrie <luke@snabb.co>
Date: Sun, 5 Nov 2017 09:02:34 +0000
Subject: [PATCH 1/2] Add jit.tracebarrier() primitive

Create an execution barrier that a JIT trace cannot cross. During
recording, the current trace must end when it reaches a barrier and
then a new root trace starts immediately afterwards.

This is implemented as a simple "nop" C library function. The existing
"trace stitching" mechanism provides the required semantics i.e. stop
current trace, call nop function, start new trace with linkage.
---
 src/lib_jit.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/lib_jit.c b/src/lib_jit.c
index 7411328970..fdd99fd325 100644
--- a/src/lib_jit.c
+++ b/src/lib_jit.c
@@ -99,6 +99,12 @@ LJLIB_CF(jit_status)
   return (int)(L->top - L->base);
 }
 
+/* Calling this forces a trace stitch. */
+LJLIB_CF(jit_tracebarrier)
+{
+  return 0;
+}
+
 LJLIB_PUSH(top-5) LJLIB_SET(os)
 LJLIB_PUSH(top-4) LJLIB_SET(arch)
 LJLIB_PUSH(top-3) LJLIB_SET(version_num)

From 0be85c638ea341e6ab2ecae4e6f4bb3a84931918 Mon Sep 17 00:00:00 2001
From: Luke Gorrie <luke@snabb.co>
Date: Tue, 7 Nov 2017 10:01:40 +0000
Subject: [PATCH 2/2] src/reusevm: update generated files

---
 src/reusevm/lj_ffdef.h  |  1 +
 src/reusevm/lj_libdef.h | 23 ++++++++++++-----------
 src/reusevm/lj_recdef.h |  1 +
 3 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/reusevm/lj_ffdef.h b/src/reusevm/lj_ffdef.h
index 64107959dd..ffd183b9ca 100644
--- a/src/reusevm/lj_ffdef.h
+++ b/src/reusevm/lj_ffdef.h
@@ -145,6 +145,7 @@ FFDEF(jit_on)
 FFDEF(jit_off)
 FFDEF(jit_flush)
 FFDEF(jit_status)
+FFDEF(jit_tracebarrier)
 FFDEF(jit_opt_start)
 FFDEF(jit_vmprofile_open)
 FFDEF(jit_vmprofile_close)
diff --git a/src/reusevm/lj_libdef.h b/src/reusevm/lj_libdef.h
index cc5bd1f812..862dc6e0bf 100644
--- a/src/reusevm/lj_libdef.h
+++ b/src/reusevm/lj_libdef.h
@@ -271,13 +271,14 @@ static const lua_CFunction lj_lib_cf_jit[] = {
   lj_cf_jit_on,
   lj_cf_jit_off,
   lj_cf_jit_flush,
-  lj_cf_jit_status
+  lj_cf_jit_status,
+  lj_cf_jit_tracebarrier
 };
 static const uint8_t lj_lib_init_jit[] = {
-143,57,8,2,111,110,3,111,102,102,5,102,108,117,115,104,6,115,116,97,116,117,
-115,252,5,194,111,115,250,252,4,196,97,114,99,104,250,252,3,203,118,101,114,
-115,105,111,110,95,110,117,109,250,252,2,199,118,101,114,115,105,111,110,250,
-255
+143,57,9,2,111,110,3,111,102,102,5,102,108,117,115,104,6,115,116,97,116,117,
+115,12,116,114,97,99,101,98,97,114,114,105,101,114,252,5,194,111,115,250,252,
+4,196,97,114,99,104,250,252,3,203,118,101,114,115,105,111,110,95,110,117,109,
+250,252,2,199,118,101,114,115,105,111,110,250,255
 };
 #endif
 
@@ -287,7 +288,7 @@ static const lua_CFunction lj_lib_cf_jit_opt[] = {
   lj_cf_jit_opt_start
 };
 static const uint8_t lj_lib_init_jit_opt[] = {
-147,57,1,5,115,116,97,114,116,255
+148,57,1,5,115,116,97,114,116,255
 };
 #endif
 
@@ -301,7 +302,7 @@ static const lua_CFunction lj_lib_cf_jit_vmprofile[] = {
   lj_cf_jit_vmprofile_stop
 };
 static const uint8_t lj_lib_init_jit_vmprofile[] = {
-148,57,5,4,111,112,101,110,5,99,108,111,115,101,6,115,101,108,101,99,116,5,
+149,57,5,4,111,112,101,110,5,99,108,111,115,101,6,115,101,108,101,99,116,5,
 115,116,97,114,116,4,115,116,111,112,255
 };
 #endif
@@ -329,7 +330,7 @@ static const lua_CFunction lj_lib_cf_ffi_meta[] = {
   lj_cf_ffi_meta___ipairs
 };
 static const uint8_t lj_lib_init_ffi_meta[] = {
-153,57,19,7,95,95,105,110,100,101,120,10,95,95,110,101,119,105,110,100,101,
+154,57,19,7,95,95,105,110,100,101,120,10,95,95,110,101,119,105,110,100,101,
 120,4,95,95,101,113,5,95,95,108,101,110,4,95,95,108,116,4,95,95,108,101,8,95,
 95,99,111,110,99,97,116,6,95,95,99,97,108,108,5,95,95,97,100,100,5,95,95,115,
 117,98,5,95,95,109,117,108,5,95,95,100,105,118,5,95,95,109,111,100,5,95,95,
@@ -347,7 +348,7 @@ static const lua_CFunction lj_lib_cf_ffi_clib[] = {
   lj_cf_ffi_clib___gc
 };
 static const uint8_t lj_lib_init_ffi_clib[] = {
-171,57,3,7,95,95,105,110,100,101,120,10,95,95,110,101,119,105,110,100,101,120,
+172,57,3,7,95,95,105,110,100,101,120,10,95,95,110,101,119,105,110,100,101,120,
 4,95,95,103,99,255
 };
 #endif
@@ -359,7 +360,7 @@ static const lua_CFunction lj_lib_cf_ffi_callback[] = {
   lj_cf_ffi_callback_set
 };
 static const uint8_t lj_lib_init_ffi_callback[] = {
-174,57,3,4,102,114,101,101,3,115,101,116,252,1,199,95,95,105,110,100,101,120,
+175,57,3,4,102,114,101,101,3,115,101,116,252,1,199,95,95,105,110,100,101,120,
 250,255
 };
 #endif
@@ -386,7 +387,7 @@ static const lua_CFunction lj_lib_cf_ffi[] = {
   lj_cf_ffi_load
 };
 static const uint8_t lj_lib_init_ffi[] = {
-176,57,23,4,99,100,101,102,3,110,101,119,4,99,97,115,116,6,116,121,112,101,
+177,57,23,4,99,100,101,102,3,110,101,119,4,99,97,115,116,6,116,121,112,101,
 111,102,8,116,121,112,101,105,110,102,111,6,105,115,116,121,112,101,6,115,105,
 122,101,111,102,7,97,108,105,103,110,111,102,8,111,102,102,115,101,116,111,
 102,5,101,114,114,110,111,6,115,116,114,105,110,103,4,99,111,112,121,4,102,
diff --git a/src/reusevm/lj_recdef.h b/src/reusevm/lj_recdef.h
index 312ff199e9..436754f308 100644
--- a/src/reusevm/lj_recdef.h
+++ b/src/reusevm/lj_recdef.h
@@ -154,6 +154,7 @@ static const uint16_t recff_idmap[] = {
 0,
 0,
 0,
+0,
 0x2f00+(0),
 0x2f00+(1),
 0x3000+(MM_eq),