Fix a problem that Nate noticed that boils down to an over conservative check
in the code that does "select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y)))".
We now compile this loop:
LBB1_1: ; no_exit
add r6, r2, r3
subf r3, r2, r3
cmpwi cr0, r2, 0
addi r7, r5, 4
lwz r2, 0(r5)
addi r4, r4, 1
blt cr0, LBB1_4 ; no_exit
LBB1_3: ; no_exit
mr r3, r6
LBB1_4: ; no_exit
cmpwi cr0, r4, 16
mr r5, r7
bne cr0, LBB1_1 ; no_exit
into this instead:
LBB1_1: ; no_exit
srawi r6, r2, 31
add r2, r2, r6
xor r6, r2, r6
addi r7, r5, 4
lwz r2, 0(r5)
addi r4, r4, 1
add r3, r3, r6
cmpwi cr0, r4, 16
mr r5, r7
bne cr0, LBB1_1 ; no_exit
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26356
91177308-0d34-0410-b5e6-
96231b3b80d8