Fix a minor bug in two-address pass. It was missing a commute opportunity.
regB = move RCX
regA = op regB, regC
RAX = move regA
where both regB and regC are killed. If regB is constrainted to non-compatible
physical registers but regC is not constrainted at all, then it's better to
commute the instruction.
movl %edi, %eax
shlq $32, %rcx
leaq (%rcx,%rax), %rax
=>
movl %edi, %eax
shlq $32, %rcx
orq %rcx, %rax
rdar://
8762995
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121793
91177308-0d34-0410-b5e6-
96231b3b80d8