tarantool / luajit / 17231436214

93%

tarantool/master: 93%

push

github

ARM64: Fix LDP/STP fusion (again).

Reported and analyzed by Zhongwei Yao. Fix by Peter Cawley.

(cherry picked from commit b8c6ccd50)

Assume we have stores/loads from the pointer with offset +488 and -16.
The lower bits of the offset are the same as for the offset (488 + 8).
This leads to the incorrect fusion of these instructions:
| str   x20, [x21, 488]
| stur  x20, [x21, -16]
to the following instruction:
| stp   x20, x20, [x21, 488]

This patch prevents this fusion by more accurate offset comparison.

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

Part of tarantool/tarantool#11691

5713 of 6047 branches covered (94.48%)

Branch coverage included in aggregate %.

21791 of 23509 relevant lines covered (92.69%)

3878784.38 hits per line