another difference in gcc (2v) ?

[Kevin B. Hendricks]

Hi,

Lost in the huge diff was one other change, this time in the actual code
itself.

Can anyone tell me if this code resequence is legal?  The diff (-) lines
show the nonworking disassembled code (generated by -O2) while the
diff's (+) lines show the working code (generated by -O2
-fno-schedule-insns -fno-schedule-insns2.

Notice that when correct, the "cmpwi r3,0" code comes right before the
branch ("beq") while in the non-working code it has been resequenced to
come before lots of other instructions that may be setting a condition
register value (subf and srawi).

Is this a correct resequence?  I seem to remember something about a "."
being added to some assmebler instructions to indicate that it impacts a
condition register yet I see no indication of it in this sequence.

-     1c4:      80 61 00 38     lwz     r3,56(r1)
-     1c8:      80 01 00 44     lwz     r0,68(r1)
-     1cc:      2c 03 00 00     cmpwi   r3,0
-     1d0:      7c 03 00 50     subf    r0,r3,r0
-     1d4:      7c 00 16 70     srawi   r0,r0,2
+     1c4:      80 01 00 44     lwz     r0,68(r1)
+     1c8:      80 61 00 38     lwz     r3,56(r1)
+     1cc:      7c 03 00 50     subf    r0,r3,r0
+     1d0:      7c 00 16 70     srawi   r0,r0,2
+     1d4:      2c 03 00 00     cmpwi   r3,0
       1d8:      41 82 00 14     beq     1ec
<configmgr::configapi::implGetHiera\
rchicalName(configmgr::configapi::NodeAccess &)+0x1e8>


Thanks,

Kevin

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