Hi everyone,

I've noticed something a bit weird with the Free Pascal Compiler when you use the the -a option to dump the compiled assembly files... the resultant binaries are sometimes smaller.  I recently tried it with Lazarus under x86_64-win64 (using "make distclean all install" with FPCOPT):

(-O4 -OoCONSTPROP)
241,010,289 bytes - lazarus.exe

(-a -O4 -OoCONSTPROP)
235,655,062 bytes - lazarus.exe

Anyone else noticed this? Logically, shoudn't the EXE files be completely identical?

Gareth aka. Kit

would -a disable optimizations? i guess it'd depend on the intended use of the listings it generated

-a shouldn't disable just dumps the
intermediate assembly language into .s files.

Gareth aka. Kit

Hi J. Gareth,

I once added -a to debug my Android app, and then it did not start anymore on some devices...

Bye,
Benito

J. Gareth Moreton schrieb am So., 19. Juli
2020, 05:09:

On x86 the difference is that this switches to the external assembler instead of using the internal one. That can result in differently generated files. You could compare the generated *.o files or use -Xm to compare the linker maps.

Regards,
Sven

Ah, of course!  It's still a remarkable difference though and I wonder if the internal assembler could use an update in that case.

Gareth aka. Kit

J. Gareth Moreton schrieb am So., 19. Juli
2020, 11:20:

Ah, of course! It's still a remarkable difference though and I wonder if the internal assembler could use an update in that case.

Feel free to find out where the difference comes from. ;)

Regards,
Sven

I think there is bug report about too lazy section alignment of the internal writer which could explain part of it.

I'm sure I'll have a look at it at some point!  Maybe later though.  At the moment I'm getting ready to submt a couple of new peephole optimisations, with some future extensions to them down the line - I'm just waiting for the regression tests to finish.

Gareth aka. Kit

And uploaded the new peephole optimisations. #37389 and #37390.