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* -march=x86_64 -mtune=generic question
@ 2022-05-25 18:58 Tom Kacvinsky
  2022-05-26  7:11 ` Andrew Haley
  0 siblings, 1 reply; 4+ messages in thread
From: Tom Kacvinsky @ 2022-05-25 18:58 UTC (permalink / raw)
  To: gcc-help

Perhaps this is a question for the gcc development list, but I thought
I'd try here first.

I am trying to figure out why GCC 12.1 generated object code is
executing a hair slower than GCC 8.3.0 generated object code.

I did run gcc with -fverbose-asm and -S, examined the assembly, and saw
that -march=x86_64 -mtune=generic was used for compilation options.

Reading the documentation. I see that -mtune=generic can change from GCC
release to release based on the most prevalent processors in use at the
time.

I did poke around at the gcc source code and (gcc/config/i386/*) to see
if I could figure out what changed from release to release and admit defeat.

Does anyone have a quick rundown on what would have changed between GCC
8.3.0 and 12.1.0 in terms of what -mtune=generic does for optimizations?

Thanks,

Tom

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2022-05-26 11:05 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-25 18:58 -march=x86_64 -mtune=generic question Tom Kacvinsky
2022-05-26  7:11 ` Andrew Haley
2022-05-26 10:13   ` Tom Kacvinsky
2022-05-26 11:05     ` Jonathan Wakely

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