[LLVMdev] [RFC] [X86] Mov to push transformation in x86-32 call sequences

[Caldarale, Charles R]

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
> On Behalf Of Herbie Robinson
> Subject: Re: [LLVMdev] [RFC] [X86] Mov to push transformation in x86-32 call sequences

> > On 12/21/14 4:27 AM, Kuperstein, Michael M wrote:
> > Which performance guidelines are you referring to?

> Table C-21 in "Intel(r) 64 and IA-32 Architectures Optimization Reference Manual", September 2014.

> It hasn't changed.  It still lists push and pop instructions as 2-3 times more expensive as mov.

And verified by Agner Fog's independent measurements: 
http://www.agner.org/optimize/instruction_tables.pdf

The relevant Haswell numbers are on pages 186 - 187.

 -Chuck