1 Commits

Author	SHA1	Message	Date
Evan Cheng	d498c8f2c8	Teach 2addr pass to be do more commuting. If both uses of a two-address instruction are killed, but the first operand has a use before and after the def, commute if the second operand does not suffer from the same issue. ... %reg1028<def> = EXTRACT_SUBREG %reg1027<kill>, 1 %reg1029<def> = MOV8rr %reg1028 %reg1029<def> = SHR8ri %reg1029, 7, %EFLAGS<imp-def,dead> insert => %reg1030<def> = MOV8rr %reg1028 %reg1030<def> = ADD8rr %reg1028<kill>, %reg1029<kill>, %EFLAGS<imp-def,dead> In this case, it might not be possible to coalesce the second MOV8rr instruction if the first one is coalesced. So it would be profitable to commute it: %reg1028<def> = EXTRACT_SUBREG %reg1027<kill>, 1 %reg1029<def> = MOV8rr %reg1028 %reg1029<def> = SHR8ri %reg1029, 7, %EFLAGS<imp-def,dead> insert => %reg1030<def> = MOV8rr %reg1029 %reg1030<def> = ADD8rr %reg1029<kill>, %reg1028<kill>, %EFLAGS<imp-def,dead> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62954 91177308-0d34-0410-b5e6-96231b3b80d8	2009-01-25 03:53:59 +00:00