On 31/03/14 13:18, Denys Vlasenko wrote:

On 03/31/2014 09:38 AM, Arend van Spriel wrote:

quoted

On 30/03/14 23:31, Denys Vlasenko wrote:

quoted

Automated script discovered that without forced inlining,
gcc-4.7 generates smaller code for this function.

There is no need to declare static functions inline anyway:
nowadays gcc detects single-callsite static functions
which benefit from inlining.

These patches look awfully familiar. I tend to object, but I don't know the details of this automated script.

The script removes "static" keyword, recompiles the .c file,
compares the sizes, and if code size went down,
creates a patch

quoted

How about execution time or is this only compile tested?

The change adds one pair of call/return instructions -
probably around 5-10 CPU cycles.

The function in question is a part of firmware download logic,
which is nowhere near being hot path/.

True. My remarks are on all four patches and I just replied to the first 
patch. The other patches are in interrupt handling code, ie. interrupt 
or bottom-halve context.

quoted

The other thing is that you seem to rely on a specific gcc version.
What about pre-4.7? How about different architectures.
Was this determined on x86, arm, sparc, mips.
All these questions make me say 'nay'.

Not making functions inline unless there is a good reason
is a general good coding practice. It is not a compiler-
or architecture-specific optimization.

Agree, but you seem to assume that in this case there is no good reason.

Regards,
Arend