diff --git a/src/lj_opt_fold.c b/src/lj_opt_fold.c index e2171e1b48..2702f79f12 100644 --- a/src/lj_opt_fold.c +++ b/src/lj_opt_fold.c @@ -382,10 +382,10 @@ static uint64_t kfold_int64arith(jit_State *J, uint64_t k1, uint64_t k2, case IR_BOR: k1 |= k2; break; case IR_BXOR: k1 ^= k2; break; case IR_BSHL: k1 <<= (k2 & 63); break; - case IR_BSHR: k1 = (int32_t)((uint32_t)k1 >> (k2 & 63)); break; - case IR_BSAR: k1 >>= (k2 & 63); break; - case IR_BROL: k1 = (int32_t)lj_rol((uint32_t)k1, (k2 & 63)); break; - case IR_BROR: k1 = (int32_t)lj_ror((uint32_t)k1, (k2 & 63)); break; + case IR_BSHR: k1 >>= (k2 & 63); break; + case IR_BSAR: k1 = (uint64_t)((int64_t)k1 >> (k2 & 63)); break; + case IR_BROL: k1 = lj_rol(k1, (k2 & 63)); break; + case IR_BROR: k1 = lj_ror(k1, (k2 & 63)); break; default: lj_assertJ(0, "bad IR op %d", op); break; } #else diff --git a/test/tarantool-tests/lj-1079-fix-64-bitshift-folds.test.lua b/test/tarantool-tests/lj-1079-fix-64-bitshift-folds.test.lua new file mode 100644 index 0000000000..6cc0b319b9 --- /dev/null +++ b/test/tarantool-tests/lj-1079-fix-64-bitshift-folds.test.lua @@ -0,0 +1,74 @@ +local tap = require('tap') + +-- Test file to demonstrate LuaJIT misbehaviour on folding +-- for bitshift operations. +-- See also, https://github.com/LuaJIT/LuaJIT/issues/1079. + +local test = tap.test('lj-1079-fix-64-bitshift-folds'):skipcond({ + ['Test requires JIT enabled'] = not jit.status(), +}) + +local bit = require('bit') + +test:plan(4) + +-- Generic function for `bit.ror()`, `bit.rol()`. +local function bitop_rotation(bitop) + local r = {} + for i = 1, 4 do + -- (i & k1) o k2 ==> (i o k2) & (k1 o k2) + local int64 = bit.band(i, 7LL) + r[i] = tonumber(bitop(int64, 32)) + end + return r +end + +-- Similar function for `bit.rshift()`. +local function bitop_rshift_signed() + local r = {} + for i = 1, 4 do + -- (i & k1) o k2 ==> (i o k2) & (k1 o k2) + -- XXX: Use `-i` instead of `i` to prevent other folding due + -- to IR difference so the IRs don't match fold rule mask. + -- (-i & 7LL) < 1 << 32 => result == 0. + local int64 = bit.band(-i, 7LL) + r[i] = tonumber(bit.rshift(int64, 32)) + end + return r +end + +-- A little bit different example, which leads to the assertion +-- failure due to the incorrect recording. +local function bitop_rshift_huge() + local r = {} + for i = 1, 4 do + -- (i & k1) o k2 ==> (i o k2) & (k1 o k2) + -- XXX: Need to use cast to the int64_t via `+ 0LL`, see the + -- documentation [1] for the details. + -- [1]: https://bitop.luajit.org/semantics.html + local int64 = bit.band(2 ^ 33 + i, 2 ^ 33 + 0LL) + r[i] = tonumber(bit.rshift(int64, 32)) + end + return r +end + +local function test_64bitness(subtest, payload_func, bitop) + subtest:plan(1) + + jit.off() + jit.flush() + local results_joff = payload_func(bitop) + jit.on() + -- Reset hotcounters. + jit.opt.start('hotloop=1') + local results_jon = payload_func(bitop) + subtest:is_deeply(results_jon, results_joff, + 'same results for VM and JIT for ' .. subtest.name) +end + +test:test('rol', test_64bitness, bitop_rotation, bit.rol) +test:test('ror', test_64bitness, bitop_rotation, bit.ror) +test:test('rshift signed', test_64bitness, bitop_rshift_signed) +test:test('rshift huge', test_64bitness, bitop_rshift_huge) + +test:done(true)