Paul Gilmartin wrote:
On Thu, 10 Sep 2020 15:35:37 +0000, Seymour J Metz wrote:
Yes, you can always do multiple precision that way, but there is a performance
hit, especially from those conditional branches. Maybe we need skip
instructions such as the 7090 had.
Some computer architectures have an Add-With-Carry instruction
eliminating the need for some of those conditional branches.
Yes - even the newer z/Arch architecture does... the second example I
showed
in the previous posting demonstrates how the compiler handles the problem
with only a few instructions.
All those conditional branches were because the operations are being
accomplished
on the older (370) instruction set, with only 32-bit registers.
- Dave R. -
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