[Mips] Fix atomic min/max generate mips4 instructions when compiling for mips2 (#159717)
Modify instr movn/movz to mixture of beq, move, and sc.
Because atomic-min-max.ll test broken on the expensive builder, I revert
https://github.com/llvm/llvm-project/pull/149983 and resubmit this PR.
The broken reason:
In i16/i8 function expandAtomicBinOpSubword, we use two successor
after loop2MBB, one does not specify the second parameter, the other
use BranchProbability::getOne() that means 100% probability. This is
contradictory. And the second successor is also specified incorrectly.
The changess:
* llvm/lib/Target/Mips/MipsExpandPseudo.cpp:
Change loop2MBB`s second successor to correct one and delete the
second parameter BranchProbability::getOne().
* llvm/test/CodeGen/Mips/atomic-min-max.ll:
Add -verify-machineinstrs option in RUN command;
Modify i16 test and i8 test according to the changes.
Fix #145411.
llvm-project
114b3b8b - [Mips] Fix atomic min/max generate mips4 instructions when compiling for mips2 (#159717)
