[tarantool-patches] [PATCH 2/2] test/luajit-tap: Add unsink_64_kptr.test.lua

[Cyrill Gorcunov <gorcunov@gmail.com>]

Backport of openrusty/luajit2-test-suite
commit 907c536c210ebe6a147861bb4433d28c0ebfc8cd

To test unsink 64 bit pointers

Part-of #4171
---
 test/luajit-tap/unsink_64_kptr.test.lua | 44 +++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100755 test/luajit-tap/unsink_64_kptr.test.lua

diff --git a/test/luajit-tap/unsink_64_kptr.test.lua b/test/luajit-tap/unsink_64_kptr.test.lua
new file mode 100755
index 000000000..89957637b
--- /dev/null
+++ b/test/luajit-tap/unsink_64_kptr.test.lua
@@ -0,0 +1,44 @@
+#!/usr/bin/env tarantool
+
+tap = require('tap')
+
+test = tap.test("232")
+test:plan(1)
+
+--- From: Thibault Charbonnier <thibaultcha@me.com>
+--- tests: ffi: added a test case unsinking a 64-bit pointer from a constant.
+---
+--- This test case reproduces the issue observed at:
+--- https://github.com/openresty/lua-resty-core/issues/232 and was
+--- contributed by @lukego and myself.
+---
+--- Co-authored-by: Luke Gorrie <lukego@gmail.com>
+---
+local ffi = require("ffi")
+
+local array = ffi.new("struct { int x; } [1]")
+
+-- This test forces the VM to unsink a pointer that was constructed
+-- from a constant. The IR will include a 'cnewi' instruction to
+-- allocate an FFI pointer object, the pointer value will be an IR
+-- constant, the allocation will be sunk, and the allocation will
+-- at some point be "unsunk" due to a reference in the snapshot for
+-- a taken exit.
+
+-- Note: JIT will recognize <array> as a "singleton" and allow its
+-- address to be inlined ("constified") instead of looking up the
+-- upvalue at runtime.
+
+local function fn(i)
+    local struct = array[0]     -- Load pointer that the JIT will constify.
+    if i == 1000 then end       -- Force trace exit when i==1000.
+    struct.x = 0                -- Ensure that 'struct' is live after exit.
+end
+
+-- Loop over the function to make it compile and take a trace exit
+-- during the final iteration.
+for i = 1, 1000 do
+    fn(i)
+end
+
+test:ok("PASS")
-- 
2.20.1