Hi David,
On Sat, 1 Feb 2020 at 21:38, David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Fri, Jan 31, 2020 at 11:14:25AM -0700, Simon Glass wrote:
> > Hi David,
> >
> > On Tue, 28 Jan 2020 at 01:37, David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote:
> > >
> > > On Mon, Dec 02, 2019 at 06:07:16PM -0700, Simon Glass wrote:
> > > > Hi David,
> > > >
> > > > On Tue, 19 Nov 2019 at 21:01, David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote:
> > > > >
> > > > > On Tue, Nov 12, 2019 at 06:54:17PM -0700, Simon Glass wrote:
> > > > > > There does not seem to be a strong reason to inline this function.
> > > > >
> > > > > Well.. I think my rationale was just that this function should be a
> > > > > single load, followed by the call to fdt_header_size_(). I suspect
> > > > > it's not called enough for removing that to balance out the code
> > > > > overhead of an extra function. Or have you made measurements which
> > > > > show I'm wrong about that?
> > > >
> > > > Well it isn't called in U-Boot at all, other than via
> > > > fdt_check_header(). The inlined version saves 16 bytes of code space
> > > > on Thumb2.
> > > >
> > > > But even better would be to drop fdt_check_header_(). something like:
> > > >
> > > > size_t fdt_header_size(uint32_t version)
> > > > {
> > > > if (fdt_chk_version()) {
> > > > if (version <= 1)
> > > > return FDT_V1_SIZE;
> > > > else if (version <= 2)
> > > > return FDT_V2_SIZE;
> > > > else if (version <= 3)
> > > > return FDT_V3_SIZE;
> > > > else if (version <= 16)
> > > > return FDT_V16_SIZE;
> > > > }
> > > >
> > > > return FDT_V17_SIZE;
> > > > }
> > > >
> > > > That saves an additional 8 bytes.
> > >
> > > Uh.. I'm a little lost here. Is what you're suggesting moving all of
> > > fdt_check_header_() to the .h file, so it can be inlined (and
> > > therefore constant folded)?
> > >
> > > That could be a reasonable plan, though we'll need to make sure to
> > > include an out-of-line version as well, for ABI compatibility.
> >
> > OK that sounds like a pain with little gain. Let's leave it as it is
> > then.
>
> Actually, I suspect it's not that bad, I think "extern inline" does
> what we'd need.
I get lots of 'multiple definition' errors when I add 'extern inline'
to the header file for fdt_header_size().
>From here:
https://stackoverflow.com/questions/216510/what-does-extern-inline-do
extern inline: like GNU89 "inline": externally visible code is
emitted, so at most one translation unit can use this.
Can you explain a bit more about what you are thinking here? I am a
bit lost. Remember that in my next patch I have to check the
assumptions in libfdt_internl.h
Regards,
Simon
