SGI compilers had diagnostic information called love notes that explains what optimizations had been applied to loops. Here is an example taken from [0].

SGI compilers had diagnostic information called love notes that explains what optimizations had been applied to loops. Here is an example taken from [0]. #<loop> Loop body line 1, nesting depth: 1, estimated iterations: 17 #<loop> Unrolled 2 times #<swps> Pipelined loop line 1 steady state #<swps> 50 estimated iterations before pipelining 2 unrollings before pipelining #<swps> 6 cycles per 2 iterations #<swps> 4 flops #<swps> ( 33% of peak) (madds count as 2) #<swps> ( 16% of peak) (madds count as 1) ( 33% of peak) #<swps> 2 flops #<swps> 2 madds #<swps> 6 mem refs #<swps> 3 integer ops ( 25% of peak) #<swps> 11 instructions ( 45% of peak) 1 short trip threshold #<swps> 5 integer registers used. #<swps> 9 float registers used. [0] https://cug.org/5-publications/proceedings_attendee_lists/2002CD/S02_Proceedings/Pages/Authors/Cellis.pdf https://cug.org/5-publications/proceedings_attendee_lists/20...