Gregory Stark <[EMAIL PROTECTED]> writes:
> If it does constant propagation without handling overflow it could end up
> with:

>  (olddatum >> 2 << 2) & 0x3FFFFFFFC

> note that in fact truncating the high two bits as the assembler did would in
> fact be the correct thing to do here which would explain why it doesn't cause
> any actual problems.

Good point, but I also note that the places Heikki saw were inside
loops.  I think it might be some combination of the above and a loop
strength reduction optimization.

                        regards, tom lane

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