[fpc-devel] An interesting thought... AI

J. Gareth Moreton gareth at moreton-family.com
Fri Nov 11 19:21:34 CET 2022

I'm liking these discussions!

I have done some refactoring, such as attempting to 'factor out' common 
conditions (sometimes a matching instruction, but also commonly the 
operand types).  Sometimes I choose not to factor - for example, 
sometimes I try to compute relatively cheap conditions first and delay 
things like GetNextInstruction for as long as possible due to its 
relative slowness (stepping through a linked list).

Pattern matching ideas do sound good honestly - it would especially be 
good for simple, 2-instruction optimisations, say. That's definitely 
somehing I want to try somewhere.


On 11/11/2022 10:54, Marco van de Voort via fpc-devel wrote:
> On 11-11-2022 09:57, Jonas Maebe via fpc-devel wrote:
>> On 11/11/2022 00:44, J. Gareth Moreton via fpc-devel wrote:
>>> My slight concern is that the x86 peephole optimizer is becoming 
>>> pretty bloated now
>> An alternative could be to specify the peephole optimizations in a 
>> pattern matching format, and then either write a tool that converts 
>> them to a bunch of if-then-else statements, or interpret this format 
>> directly in the compiler.
> Or maybe predicting branch taken  taking more into consideration than 
> which node of if..then..else it is.
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