From: Segher Boessenkool

Sent: 03 February 2021 21:18

...

Power9 does:

  Load with Update Instructions (RA = 0)
    EA is placed into R0.

Does that change the value of 0?
Rather reminds me of some 1960s era systems that had the small integers
at fixed (global) addresses.
FORTRAN always passes by reference, pass 0 and the address of the global
zero location was passed, the called function could change 0 to 1 for
the entire computer!

  Load with Update Instructions (RA = RT)
    The storage operand addressed by EA is accessed. The displacement
    field is added to the data returned by the load and placed into RT.

Shame that isn't standard - could be used to optimise some code.

	David

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