tarantool / luajit / 17095363889

93%

tarantool/master: 93%

Build Type

push

github

Committed by Buristan

Commit Message

x86/x64: Don't use undefined MUL/IMUL zero flag.

Reported by VrIgHtEr.

(cherry picked from commit c92d0cb19)

When emitting the arithmetic operations on registers via the
`asm_intarith()`, the next `test` instruction may be dropped since the
flag register is modified by the arithmetic instruction to be emitted.

But the `imul` instruction [1] doesn't modify ZF, so its value is
undefined. This patch prevents dropping the `test` instruction if
the emitted instruction is `imul`.

Sergey Kaplun:
* added the description and the test for the problem

[1]: https://www.felixcloutier.com/x86/imul

Part of tarantool/tarantool#11691

Coverage Stats

5713 of 6047 branches covered (94.48%)

Branch coverage included in aggregate %.

1 of 1 new or added line in 1 file covered. (100.0%)

14 existing lines in 4 files now uncovered.

21799 of 23509 relevant lines covered (92.73%)

3874317.48 hits per line