RE: [PATCH v5] x86: use builtins to read eflags

[H. Peter Anvin]

On March 18, 2022 3:36:48 PM PDT, David Laight <David.Laight@xxxxxxxxxx> wrote:
>From: Segher Boessenkool
>> Sent: 18 March 2022 22:09
>...
>> It generally is a very good idea to
>> have a redzone though, without it you pay much more than necessary for
>> frame setup and teardown in leaf functions (similar to some of what the
>> misnamed "shrink-wrapping" optimisation does, but the two are mostly
>> independent, the benefits add up).
>
>Are there really leaf functions that need to spill data to stack
>where the cost of setting up a stack frame is significant?
>
>I'd have thought that was relatively rare.
>
>	David
>
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Yes.