Correction to last post. When applying BZHI to an input ("Result :=
Input and ((1 shl x) - 1)"), the initial "mov $-1,%eax" is unnecessary
unless the mask is being preserved, and is just:
bzhil %ecx,(ref-to-Input),%eax
Kit
On 25/10/2022 13:44, J. Gareth Moreton via fpc-devel wrote:
What I
What I want to do is the following...
Say I have the expression "(1 shl x) - 1"... under the default AMD
Athlon optimisations, you might get something like this:
(x in %cl, Result in %eax)
movl $1,%eax
shll %cl,%eax
subl $1,%eax
Under -CpCOREAVX2, you might get this (ignoring any
Thanks Michael. Sven already filled me in - the more I learn!
Kit
On 24/10/2022 16:44, Michael Van Canneyt via fpc-devel wrote:
On Mon, 24 Oct 2022, J. Gareth Moreton via fpc-devel wrote:
That's useful - thank you. Michael Van Canneyt mentioend he updated
the documentation for this -
On Mon, 24 Oct 2022, J. Gareth Moreton via fpc-devel wrote:
That's useful - thank you. Michael Van Canneyt mentioend he updated the
documentation for this - where is this usually located? It's not here,
for example: https://www.freepascal.org/docs-html/ref/refsu45.html
Daily
The more I learn!
On 24/10/2022 13:06, Sven Barth wrote:
J. Gareth Moreton via fpc-devel
schrieb am Mo., 24. Okt. 2022, 13:52:
That's useful - thank you. Michael Van Canneyt mentioend he
updated the
documentation for this - where is this usually located? It's not
here,
J. Gareth Moreton via fpc-devel schrieb am
Mo., 24. Okt. 2022, 13:52:
> That's useful - thank you. Michael Van Canneyt mentioend he updated the
> documentation for this - where is this usually located? It's not here,
> for example: https://www.freepascal.org/docs-html/ref/refsu45.html
That is
That's useful - thank you. Michael Van Canneyt mentioend he updated the
documentation for this - where is this usually located? It's not here,
for example: https://www.freepascal.org/docs-html/ref/refsu45.html
Kit
On 24/10/2022 11:58, Kai Burghardt via fpc-devel wrote:
Hi there:
On
Hi there:
On 2022‑10‑24 11:51:32 +0100, J. Gareth Moreton via fpc-devel wrote:
> [...] I've come across one situation that I need clarity on... how
> are SHL and SHR instructions handled if the shift value exceeds the word
> size?
About a half year ago I raised a documentation issue regarding
Hi everyone,
I'm looking at more optimisations under x86_64 that use the BMI
instructions. I've come across one situation that I need clarity on...
how are SHL and SHR instructions handled if the shift value exceeds the
word size?
For example, say I have the code "power2 := 1 shl
