The sload_accum port of the Arria® 10 Altera_Mult_Add IP is active high.
The accum_sload port of the Arria 10 Altera_Mult_Add IP port is active low.
This is incorrectly stated in the 2016.06.10 version of the Integer Arithmetic IP Cores User Guide:
/content/dam/altera-www/global/en_US/pdfs/literature/ug/ug_lpm_alt_mfug.pdf
A future version of the Integer Arithmetic IP Cores User Guide will be updated to reflect the correct polarity as stated below:
sload_accum:
Dynamically specifies whether the accumulator value is
constant. If the sload_accum port is high, then the multiplier
output is loaded into the accumulator. Do not use accum_
sload and sload_accum simultaneously.
accum_sload:
Dynamically specifies whether the accumulator value is
constant. If the accum_sload port is low, then the multiplier
output is loaded into the accumulator. Do not use accum_
sload and sload_accum simultaneously.