Undocumented optimization compiler directives

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Marladu:
Digging through the compiler code I happened to find compiler directives related to optimization that are accepted by the compiler but that I don't know what they do. Here's the list (found in globtype.pas):

{$OPTIMIZATION STRENGTH}: unknown?
{$OPTIMIZATION SCHEDULE}: unknown?
{$OPTIMIZATION AUTOINLINE}:guessing it's like delphi {$inline auto}? what rules does it follow?
{$OPTIMIZATION USERBP}: guessing it's a 64bit version of {$OPTIMIZATION USEEBP}?
{$OPTIMIZATION FASTMATH}, {$OPTIMIZATION DEADVALUES}, {$OPTIMIZATION DEADSTORE}: nicely documented at http://wiki.freepascal.org/FPC_New_Features_Trunk#Code_generator

So, anyone got details on what the first 4 do?

engkin:
I don't expect you to see answers here. Try a suitable mailing list or move your post under Free Pascal where FPK is a moderator.

--- Quote from: Marladu on January 21, 2015, 04:41:34 pm ---{$OPTIMIZATION USERBP}: guessing it's a 64bit version of {$OPTIMIZATION USEEBP}?

--- End quote ---
Yes.

marcov:
Strength is probably "Strength Reduction" (look up in wikipedia), hoisting code out of loops.

Schedule is probably instruction level scheduling.

Marladu:
Darn, I though I had posted in freepascal-general, my bad, apologies. Still, the answers are plenty good and appreciated, thanks!

I had forgotten to write about {$OPTIMIZATION FORCENOSTACKFRAME} but it doesn't seem to do anything at this time, I'm guessing when implemented it will force a nostackframe on every function where it works. For {$OPTIMIZATION AUTOINLINE} I tested it and it works, inlining small functions it can even without the inline function modifier, just don't know what rules it follows. Only did limited testing with {$OPTIMIZATION FASTMATH} but so far it looks very very excellent at improving speed of unoptimized floating point operations, and I didn't observe any precision loss as warned in those small tests.

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