Hi all Recently I discovered that fpc refuses to use registers in my loops even with optimization turned on (-O1,-O3 used). I tested using both Linux x86 and Windows x64 version.
The results are basically the same. The compiler just uses stack variables. I've also included naive asm version of the same loop just to see the comparison. All tests were done using EpikTimer. ====================================== Intel(R) Core(TM) i5-2500K CPU @ 3.30GHz Sandy Bridge-DT XE Microsoft Windows XP Professional x64 Edition Build 3790 Free Pascal Compiler version 2.7.1 [2012/08/25] for x86_64 Result: asm 0.0256358138703286 sec for downto 0.193564002384441 sec for to 0.177300077002942 sec repeat 0.158137833298043 sec while 0.156996773175159 sec Intel(R) Core(TM)2 CPU 6600 @ 2.40GHz Linux x86 Free Pascal Compiler version 2.7.1 [2012/11/17] for i386 Result: asm 0.049642 sec for downto 0.322694 sec for to 0.312163 sec repeat 0.298781 sec while 0.298575 sec ====================================== You can easily see that asm version is about 10 times faster. Is this something that can be fixed? P.S. A full test source + assembler listings are attached. -- Regards, Denis Golovan
loop-test.tar.gz
Description: GNU Zip compressed data
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