test: add tests from tarantool source tree

Introduced structure has the following benefits:
* Excess testing machinery currently is not required directly in
luajit repo considering whole CI process setup for tarantool and its
static linking with libluajit
* All new tests related to luajit fixes and enhancements can be added
within a single patch with the corresponding changeset

NB!: All added test chunks use tarantool tap module

Author: igormunkin

test/fold_bug_LuaJIT_505.test.lua

@@ -0,0 +1,20 @@
+#!/usr/bin/env tarantool
+
+tap = require('tap')
+
+test = tap.test("505")
+test:plan(1)
+
+-- Test file to demonstrate Lua fold machinery icorrect behavior, details:
+--     https://github.com/LuaJIT/LuaJIT/issues/505
+
+jit.opt.start("hotloop=1")
+for _ = 1, 20 do
+    local value = "abc"
+    local pos_c = string.find(value, "c", 1, true)
+    local value2 = string.sub(value, 1, pos_c - 1)
+    local pos_b = string.find(value2, "b", 2, true)
+    assert(pos_b == 2, "FAIL: position of 'b' is " .. pos_b)
+end
+
+test:ok("PASS")

test/gh.test.lua

@@ -0,0 +1,17 @@
+#!/usr/bin/env tarantool
+
+-- Miscellaneous test for LuaJIT bugs
+tap = require('tap')
+
+test = tap.test("gh")
+test:plan(2)
+--
+-- gh-3196: incorrect string length if Lua hash returns 0
+--
+h = "\x1F\x93\xE2\x1C\xCA\xDE\x28\x08\x26\x01\xED\x0A\x2F\xE4\x21\x02\x97\x77\xD9\x3E"
+test:is(h:len(), 20)
+
+h = "\x0F\x93\xE2\x1C\xCA\xDE\x28\x08\x26\x01\xED\x0A\x2F\xE4\x21\x02\x97\x77\xD9\x3E"
+test:is(h:len(), 20)
+
+test:check()

test/suite.ini

@@ -0,0 +1,5 @@
+[default]
+core = app
+description = Luajit tests
+is_parallel = True
+pretest_clean = True

test/table_chain_bug_LuaJIT_494.test.lua

@@ -0,0 +1,178 @@
+#!/usr/bin/env tarantool
+
+tap = require('tap')
+
+test = tap.test("494")
+test:plan(1)
+
+-- Test file to demonstrate Lua table hash chain bugs discussed in
+--     https://github.com/LuaJIT/LuaJIT/issues/494
+-- Credit: prepared by Peter Cawley here with minor edits:
+--     https://gist.github.com/corsix/1fc9b13a2dd5f3659417b62dd54d4500
+
+--- Plumbing
+ffi = require"ffi"
+ffi.cdef"char* strstr(const char*, const char*)"
+strstr = ffi.C.strstr
+cast = ffi.cast
+str_hash_offset = cast("uint32_t*", strstr("*", ""))[-2] == 1 and 3 or 2
+function str_hash(s)
+    return cast("uint32_t*", strstr(s, "")) - str_hash_offset
+end
+table_new = require"table.new"
+
+--- Prepare some objects
+victims = {}
+orig_hash = {}
+for c in ("abcdef"):gmatch"." do
+    v = c .. "{09add58a-13a4-44e0-a52c-d44d0f9b2b95}"
+    victims[c] = v
+    orig_hash[c] = str_hash(v)[0]
+end
+collectgarbage()
+
+do --- Basic version of the problem
+    for k, v in pairs(victims) do
+        str_hash(v)[0] = 0
+    end
+    t = table_new(0, 8)
+    -- Make chain a -> b -> c -> d, all with a as primary
+    t[victims.a] = true
+    t[victims.d] = true
+    t[victims.c] = true
+    t[victims.b] = true
+    -- Change c's primary to b, and d's primary to c
+    t[victims.d] = nil
+    t[victims.c] = nil
+    str_hash(victims.c)[0] = 5
+    str_hash(victims.d)[0] = 6
+    t[victims.c] = true
+    t[victims.d] = true
+    -- Insert something with b as primary
+    str_hash(victims.e)[0] = 5
+    t[victims.e] = true
+    -- Check for consistency
+    for c in ("abcde"):gmatch"." do
+        assert(t[victims[c]], c)
+    end
+end
+collectgarbage()
+
+do --- Just `mn != freenode` can lead to infinite loops
+    for k, v in pairs(victims) do
+        str_hash(v)[0] = 0
+    end
+    t = table_new(0, 8)
+    -- Make chain a -> b -> c -> d, all with a as primary
+    t[victims.a] = true
+    t[victims.d] = true
+    t[victims.c] = true
+    t[victims.b] = true
+    -- Change c's primary to b, and d's primary to d
+    t[victims.d] = nil
+    t[victims.c] = nil
+    str_hash(victims.c)[0] = 5
+    str_hash(victims.d)[0] = 7
+    t[victims.c] = true
+    t[victims.d] = true
+    -- Insert something with b as primary
+    str_hash(victims.e)[0] = 5
+    t[victims.e] = true
+    -- Insert something with d as primary (infinite lookup loop)
+    str_hash(victims.f)[0] = 7
+    t[victims.f] = true
+end
+collectgarbage()
+
+do --- Just `mn != nn` can lead to infinite loops
+    for k, v in pairs(victims) do
+        str_hash(v)[0] = 0
+    end
+    t = table_new(0, 8)
+    -- Make chain a -> b -> c -> d -> e, all with a as primary
+    t[victims.a] = true
+    t[victims.e] = true
+    t[victims.d] = true
+    t[victims.c] = true
+    t[victims.b] = true
+    -- Change c's primary to b, d's primary to d, and e's primary to d
+    t[victims.e] = nil
+    t[victims.d] = nil
+    t[victims.c] = nil
+    str_hash(victims.c)[0] = 4
+    str_hash(victims.d)[0] = 6
+    str_hash(victims.e)[0] = 6
+    t[victims.c] = true
+    t[victims.d] = true
+    t[victims.e] = true
+    -- Insert something with b as primary (infinite rechaining loop)
+    str_hash(victims.f)[0] = 4
+    t[victims.f] = true
+end
+
+for i = 0, 10 do --- Non-strings can need rechaining too
+    collectgarbage()
+
+    k = tonumber((("0x%xp-1074"):format(i)))
+    str_hash(victims.a)[0] = 0
+    str_hash(victims.b)[0] = 0
+    t = table_new(0, 4)
+    -- a -> b, both with a as primary
+    t[victims.a] = true
+    t[victims.b] = true
+    -- Change b's primary to b
+    t[victims.b] = nil
+    str_hash(victims.b)[0] = 3
+    t[victims.b] = true
+    -- Might get a -> b -> k, with k's primary as b
+    t[k] = true
+    -- Change b's primary to a
+    t[victims.b] = nil
+    str_hash(victims.b)[0] = 0
+    t[victims.b] = true
+    -- Insert something with b as primary
+    str_hash(victims.c)[0] = 3
+    t[victims.c] = true
+    -- Check for consistency
+    assert(t[k], i)
+end
+
+for i = 0, 10 do --- Non-strings can be moved to freenode
+    collectgarbage()
+
+    k = false
+    str_hash(victims.a)[0] = 0
+    str_hash(victims.b)[0] = 0
+    t = table_new(0, 4)
+    -- a -> k -> b, all with a as primary
+    t[victims.a] = true
+    t[victims.b] = true
+    t[k] = true
+    -- Change b's primary to k
+    t[victims.b] = nil
+    str_hash(victims.b)[0] = 2
+    t[victims.b] = true
+    -- Insert a non-string with primary of k
+    t[tonumber((("0x%xp-1074"):format(i)))] = true
+    -- Check for consistency
+    assert(t[victims.b], i)
+end
+collectgarbage()
+
+do --- Do not forget to advance freenode in the not-string case
+    t = table_new(0, 4)
+    -- Chain of colliding numbers
+    t[0x0p-1074] = true
+    t[0x4p-1074] = true
+    t[0x8p-1074] = true
+    -- Steal middle node of the chain to be a main node (infinite walking loop)
+    t[0x2p-1074] = true
+end
+collectgarbage()
+
+--- Restore interpreter invariants, just in case
+for c, v in pairs(victims) do
+    str_hash(v)[0] = orig_hash[c]
+end
+
+test:ok("PASS")

test/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")